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/*      $NetBSD: suff.c,v 1.368 2023/02/14 21:38:31 rillig Exp $        */

/*
 * Copyright (c) 1988, 1989, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (c) 1989 by Berkeley Softworks
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Maintain suffix lists and find implicit dependents using suffix
 * transformation rules such as ".c.o".
 *
 * Interface:
 *      Suff_Init       Initialize the module.
 *
 *      Suff_End        Clean up the module.
 *
 *      Suff_ExtendPaths
 *                      Extend the search path of each suffix to include the
 *                      default search path.
 *
 *      Suff_ClearSuffixes
 *                      Clear out all the suffixes and transformations.
 *
 *      Suff_IsTransform
 *                      See if the passed string is a transformation rule.
 *
 *      Suff_AddSuffix  Add the passed string as another known suffix.
 *
 *      Suff_GetPath    Return the search path for the given suffix.
 *
 *      Suff_AddInclude
 *                      Mark the given suffix as denoting an include file.
 *
 *      Suff_AddLib     Mark the given suffix as denoting a library.
 *
 *      Suff_AddTransform
 *                      Add another transformation to the suffix graph.
 *
 *      Suff_SetNull    Define the suffix to consider the suffix of
 *                      any file that doesn't have a known one.
 *
 *      Suff_FindDeps   Find implicit sources for and the location of
 *                      a target based on its suffix. Returns the
 *                      bottom-most node added to the graph or NULL
 *                      if the target had no implicit sources.
 *
 *      Suff_FindPath   Return the appropriate path to search in order to
 *                      find the node.
 */

#include "make.h"
#include "dir.h"

/*      "@(#)suff.c     8.4 (Berkeley) 3/21/94" */
MAKE_RCSID("$NetBSD: suff.c,v 1.368 2023/02/14 21:38:31 rillig Exp $");

typedef List SuffixList;
typedef ListNode SuffixListNode;

typedef List CandidateList;
typedef ListNode CandidateListNode;

/* The defined suffixes, such as '.c', '.o', '.l'. */
static SuffixList sufflist = LST_INIT;
#ifdef CLEANUP
/* The suffixes to be cleaned up at the end. */
static SuffixList suffClean = LST_INIT;
#endif

/*
 * The transformation rules, such as '.c.o' to transform '.c' into '.o',
 * or simply '.c' to transform 'file.c' into 'file'.
 */
static GNodeList transforms = LST_INIT;

/*
 * Counter for assigning suffix numbers.
 * TODO: What are these suffix numbers used for?
 */
static int sNum = 0;

typedef List SuffixListList;

/*
 * A suffix such as ".c" or ".o" that may be used in suffix transformation
 * rules such as ".c.o:".
 */
typedef struct Suffix {
        /* The suffix itself, such as ".c" */
        char *name;
        /* Length of the name, to avoid strlen calls */
        size_t nameLen;
        /*
         * This suffix marks include files.  Their search path ends up in the
         * undocumented special variable '.INCLUDES'.
         */
        bool include:1;
        /*
         * This suffix marks library files.  Their search path ends up in the
         * undocumented special variable '.LIBS'.
         */
        bool library:1;
        /*
         * The empty suffix.
         *
         * XXX: What is the difference between the empty suffix and the null
         * suffix?
         *
         * XXX: Why is SUFF_NULL needed at all? Wouldn't nameLen == 0 mean
         * the same?
         */
        bool isNull:1;
        /* The path along which files of this suffix may be found */
        SearchPath *searchPath;

        /* The suffix number; TODO: document the purpose of this number */
        int sNum;
        /* Reference count of list membership and several other places */
        int refCount;

        /* Suffixes we have a transformation to */
        SuffixList parents;
        /* Suffixes we have a transformation from */
        SuffixList children;
        /*
         * Lists in which this suffix is referenced.
         *
         * XXX: These lists are used nowhere, they are just appended to, for
         * no apparent reason.  They do have the side effect of increasing
         * refCount though.
         */
        SuffixListList ref;
} Suffix;

/*
 * A candidate when searching for implied sources.
 *
 * For example, when "src.o" is to be made, a typical candidate is "src.c"
 * via the transformation rule ".c.o".  If that doesn't exist, maybe there is
 * another transformation rule ".pas.c" that would make "src.pas" an indirect
 * candidate as well.  The first such chain that leads to an existing file or
 * node is finally chosen to be made.
 */
typedef struct Candidate {
        /* The file or node to look for. */
        char *file;
        /*
         * The prefix from which file was formed. Its memory is shared among
         * all candidates.
         */
        char *prefix;
        /* The suffix on the file. */
        Suffix *suff;

        /*
         * The candidate that can be made from this, or NULL for the
         * top-level candidate.
         */
        struct Candidate *parent;
        /* The node describing the file. */
        GNode *node;

        /*
         * Count of existing children, only used for memory management, so we
         * don't free this candidate too early or too late.
         */
        int numChildren;
#ifdef DEBUG_SRC
        CandidateList childrenList;
#endif
} Candidate;

typedef struct CandidateSearcher {

        CandidateList list;

        /*
         * TODO: Add HashSet for seen entries, to avoid endless loops such as
         * in suff-transform-endless.mk.
         */

} CandidateSearcher;


/* TODO: Document the difference between nullSuff and emptySuff. */
/* The NULL suffix is used when a file has no known suffix */
static Suffix *nullSuff;
/* The empty suffix required for POSIX single-suffix transformation rules */
static Suffix *emptySuff;


static Suffix *
Suffix_Ref(Suffix *suff)
{
        suff->refCount++;
        return suff;
}

/* Change the value of a Suffix variable, adjusting the reference counts. */
static void
Suffix_Reassign(Suffix **var, Suffix *suff)
{
        if (*var != NULL)
                (*var)->refCount--;
        *var = suff;
        suff->refCount++;
}

/* Set a Suffix variable to NULL, adjusting the reference count. */
static void
Suffix_Unassign(Suffix **var)
{
        if (*var != NULL)
                (*var)->refCount--;
        *var = NULL;
}

/*
 * See if pref is a prefix of str.
 * Return NULL if it ain't, pointer to character in str after prefix if so.
 */
static const char *
StrTrimPrefix(const char *pref, const char *str)
{
        while (*str != '\0' && *pref == *str) {
                pref++;
                str++;
        }

        return *pref != '\0' ? NULL : str;
}

/*
 * See if suff is a suffix of str, and if so, return the pointer to the suffix
 * in str, which at the same time marks the end of the prefix.
 */
static const char *
StrTrimSuffix(const char *str, size_t strLen, const char *suff, size_t suffLen)
{
        const char *suffInStr;
        size_t i;

        if (strLen < suffLen)
                return NULL;

        suffInStr = str + strLen - suffLen;
        for (i = 0; i < suffLen; i++)
                if (suff[i] != suffInStr[i])
                        return NULL;

        return suffInStr;
}

/*
 * See if suff is a suffix of name, and if so, return the end of the prefix
 * in name.
 */
static const char *
Suffix_TrimSuffix(const Suffix *suff, size_t nameLen, const char *nameEnd)
{
        return StrTrimSuffix(nameEnd - nameLen, nameLen,
            suff->name, suff->nameLen);
}

static bool
Suffix_IsSuffix(const Suffix *suff, size_t nameLen, const char *nameEnd)
{
        return Suffix_TrimSuffix(suff, nameLen, nameEnd) != NULL;
}

static Suffix *
FindSuffixByNameLen(const char *name, size_t nameLen)
{
        SuffixListNode *ln;

        for (ln = sufflist.first; ln != NULL; ln = ln->next) {
                Suffix *suff = ln->datum;
                if (suff->nameLen == nameLen &&
                    memcmp(suff->name, name, nameLen) == 0)
                        return suff;
        }
        return NULL;
}

static Suffix *
FindSuffixByName(const char *name)
{
        return FindSuffixByNameLen(name, strlen(name));
}

static GNode *
FindTransformByName(const char *name)
{
        GNodeListNode *ln;

        for (ln = transforms.first; ln != NULL; ln = ln->next) {
                GNode *gn = ln->datum;
                if (strcmp(gn->name, name) == 0)
                        return gn;
        }
        return NULL;
}

static void
SuffixList_Unref(SuffixList *list, Suffix *suff)
{
        SuffixListNode *ln = Lst_FindDatum(list, suff);
        if (ln != NULL) {
                Lst_Remove(list, ln);
                suff->refCount--;
        }
}

/* Free up all memory associated with the given suffix structure. */
static void
Suffix_Free(Suffix *suff)
{

        if (suff == nullSuff)
                nullSuff = NULL;

        if (suff == emptySuff)
                emptySuff = NULL;

#if 0
        /* We don't delete suffixes in order, so we cannot use this */
        if (suff->refCount != 0)
                Punt("Internal error deleting suffix `%s' with refcount = %d",
                    suff->name, suff->refCount);
#endif

        Lst_Done(&suff->ref);
        Lst_Done(&suff->children);
        Lst_Done(&suff->parents);
        SearchPath_Free(suff->searchPath);

        free(suff->name);
        free(suff);
}

static void
SuffFree(void *p)
{
        Suffix_Free(p);
}

/* Remove the suffix from the list, and free if it is otherwise unused. */
static void
SuffixList_Remove(SuffixList *list, Suffix *suff)
{
        SuffixList_Unref(list, suff);
        if (suff->refCount == 0) {
                /* XXX: can lead to suff->refCount == -1 */
                SuffixList_Unref(&sufflist, suff);
                DEBUG1(SUFF, "Removing suffix \"%s\"\n", suff->name);
                SuffFree(suff);
        }
}

/*
 * Insert the suffix into the list, keeping the list ordered by suffix
 * number.
 */
static void
SuffixList_Insert(SuffixList *list, Suffix *suff)
{
        SuffixListNode *ln;
        Suffix *listSuff = NULL;

        for (ln = list->first; ln != NULL; ln = ln->next) {
                listSuff = ln->datum;
                if (listSuff->sNum >= suff->sNum)
                        break;
        }

        if (ln == NULL) {
                DEBUG2(SUFF, "inserting \"%s\" (%d) at end of list\n",
                    suff->name, suff->sNum);
                Lst_Append(list, Suffix_Ref(suff));
                Lst_Append(&suff->ref, list);
        } else if (listSuff->sNum != suff->sNum) {
                DEBUG4(SUFF, "inserting \"%s\" (%d) before \"%s\" (%d)\n",
                    suff->name, suff->sNum, listSuff->name, listSuff->sNum);
                Lst_InsertBefore(list, ln, Suffix_Ref(suff));
                Lst_Append(&suff->ref, list);
        } else {
                DEBUG2(SUFF, "\"%s\" (%d) is already there\n",
                    suff->name, suff->sNum);
        }
}

static void
Relate(Suffix *srcSuff, Suffix *targSuff)
{
        SuffixList_Insert(&targSuff->children, srcSuff);
        SuffixList_Insert(&srcSuff->parents, targSuff);
}

static Suffix *
Suffix_New(const char *name)
{
        Suffix *suff = bmake_malloc(sizeof *suff);

        suff->name = bmake_strdup(name);
        suff->nameLen = strlen(suff->name);
        suff->searchPath = SearchPath_New();
        Lst_Init(&suff->children);
        Lst_Init(&suff->parents);
        Lst_Init(&suff->ref);
        suff->sNum = sNum++;
        suff->include = false;
        suff->library = false;
        suff->isNull = false;
        suff->refCount = 1; /* XXX: why 1? It's not assigned anywhere yet. */

        return suff;
}

/*
 * Nuke the list of suffixes but keep all transformation rules around. The
 * transformation graph is destroyed in this process, but we leave the list
 * of rules so when a new graph is formed, the rules will remain. This
 * function is called when a line '.SUFFIXES:' with an empty suffixes list is
 * encountered in a makefile.
 */
void
Suff_ClearSuffixes(void)
{
#ifdef CLEANUP
        Lst_MoveAll(&suffClean, &sufflist);
#endif
        DEBUG0(SUFF, "Clearing all suffixes\n");
        Lst_Init(&sufflist);
        sNum = 0;
        if (nullSuff != NULL)
                SuffFree(nullSuff);
        emptySuff = nullSuff = Suffix_New("");

        SearchPath_AddAll(nullSuff->searchPath, &dirSearchPath);
        nullSuff->include = false;
        nullSuff->library = false;
        nullSuff->isNull = true;
}

/*
 * Parse a transformation string such as ".c.o" to find its two component
 * suffixes (the source ".c" and the target ".o").  If there are no such
 * suffixes, try a single-suffix transformation as well.
 *
 * Return true if the string is a valid transformation.
 */
static bool
ParseTransform(const char *str, Suffix **out_src, Suffix **out_targ)
{
        SuffixListNode *ln;
        Suffix *single = NULL;

        /*
         * Loop looking first for a suffix that matches the start of the
         * string and then for one that exactly matches the rest of it. If
         * we can find two that meet these criteria, we've successfully
         * parsed the string.
         */
        for (ln = sufflist.first; ln != NULL; ln = ln->next) {
                Suffix *src = ln->datum;

                if (StrTrimPrefix(src->name, str) == NULL)
                        continue;

                if (str[src->nameLen] == '\0') {
                        single = src;
                } else {
                        Suffix *targ = FindSuffixByName(str + src->nameLen);
                        if (targ != NULL) {
                                *out_src = src;
                                *out_targ = targ;
                                return true;
                        }
                }
        }

        if (single != NULL) {
                /*
                 * There was a suffix that encompassed the entire string, so we
                 * assume it was a transformation to the null suffix (thank you
                 * POSIX; search for "single suffix" or "single-suffix").
                 *
                 * We still prefer to find a double rule over a singleton,
                 * hence we leave this check until the end.
                 *
                 * XXX: Use emptySuff over nullSuff?
                 */
                *out_src = single;
                *out_targ = nullSuff;
                return true;
        }
        return false;
}

/*
 * Return true if the given string is a transformation rule, that is, a
 * concatenation of two known suffixes such as ".c.o" or a single suffix
 * such as ".o".
 */
bool
Suff_IsTransform(const char *str)
{
        Suffix *src, *targ;

        return ParseTransform(str, &src, &targ);
}

/*
 * Add the transformation rule to the list of rules and place the
 * transformation itself in the graph.
 *
 * The transformation is linked to the two suffixes mentioned in the name.
 *
 * Input:
 *      name            must have the form ".from.to" or just ".from"
 *
 * Results:
 *      The created or existing transformation node in the transforms list
 */
GNode *
Suff_AddTransform(const char *name)
{
        Suffix *srcSuff;
        Suffix *targSuff;

        GNode *gn = FindTransformByName(name);
        if (gn == NULL) {
                /*
                 * Make a new graph node for the transformation. It will be
                 * filled in by the Parse module.
                 */
                gn = GNode_New(name);
                Lst_Append(&transforms, gn);
        } else {
                /*
                 * New specification for transformation rule. Just nuke the
                 * old list of commands so they can be filled in again. We
                 * don't actually free the commands themselves, because a
                 * given command can be attached to several different
                 * transformations.
                 */
                Lst_Done(&gn->commands);
                Lst_Init(&gn->commands);
                Lst_Done(&gn->children);
                Lst_Init(&gn->children);
        }

        gn->type = OP_TRANSFORM;

        {
                /* TODO: Avoid the redundant parsing here. */
                bool ok = ParseTransform(name, &srcSuff, &targSuff);
                assert(ok);
                /* LINTED 129 *//* expression has null effect */
                (void)ok;
        }

        /* Link the two together in the proper relationship and order. */
        DEBUG2(SUFF, "defining transformation from `%s' to `%s'\n",
            srcSuff->name, targSuff->name);
        Relate(srcSuff, targSuff);

        return gn;
}

/*
 * Handle the finish of a transformation definition, removing the
 * transformation from the graph if it has neither commands nor sources.
 *
 * If the node has no commands or children, the children and parents lists
 * of the affected suffixes are altered.
 *
 * Input:
 *      gn              Node for transformation
 */
void
Suff_EndTransform(GNode *gn)
{
        Suffix *srcSuff, *targSuff;
        SuffixList *srcSuffParents;

        if ((gn->type & OP_DOUBLEDEP) && !Lst_IsEmpty(&gn->cohorts))
                gn = gn->cohorts.last->datum;

        if (!(gn->type & OP_TRANSFORM))
                return;

        if (!Lst_IsEmpty(&gn->commands) || !Lst_IsEmpty(&gn->children)) {
                DEBUG1(SUFF, "transformation %s complete\n", gn->name);
                return;
        }

        /*
         * SuffParseTransform() may fail for special rules which are not
         * actual transformation rules. (e.g. .DEFAULT)
         */
        if (!ParseTransform(gn->name, &srcSuff, &targSuff))
                return;

        DEBUG2(SUFF, "deleting incomplete transformation from `%s' to `%s'\n",
            srcSuff->name, targSuff->name);

        /*
         * Remember the parents since srcSuff could be deleted in
         * SuffixList_Remove.
         */
        srcSuffParents = &srcSuff->parents;
        SuffixList_Remove(&targSuff->children, srcSuff);
        SuffixList_Remove(srcSuffParents, targSuff);
}

/*
 * Called from Suff_AddSuffix to search through the list of
 * existing transformation rules and rebuild the transformation graph when
 * it has been destroyed by Suff_ClearSuffixes. If the given rule is a
 * transformation involving this suffix and another, existing suffix, the
 * proper relationship is established between the two.
 *
 * The appropriate links will be made between this suffix and others if
 * transformation rules exist for it.
 *
 * Input:
 *      transform       Transformation to test
 *      suff            Suffix to rebuild
 */
static void
RebuildGraph(GNode *transform, Suffix *suff)
{
        const char *name = transform->name;
        size_t nameLen = strlen(name);
        const char *toName;

        /*
         * See if it is a transformation from this suffix to another suffix.
         */
        toName = StrTrimPrefix(suff->name, name);
        if (toName != NULL) {
                Suffix *to = FindSuffixByName(toName);
                if (to != NULL) {
                        Relate(suff, to);
                        return;
                }
        }

        /*
         * See if it is a transformation from another suffix to this suffix.
         */
        toName = Suffix_TrimSuffix(suff, nameLen, name + nameLen);
        if (toName != NULL) {
                Suffix *from = FindSuffixByNameLen(name,
                    (size_t)(toName - name));
                if (from != NULL)
                        Relate(from, suff);
        }
}

/*
 * During Suff_AddSuffix, search through the list of existing targets and find
 * if any of the existing targets can be turned into a transformation rule.
 *
 * If such a target is found and the target is the current main target, the
 * main target is set to NULL and the next target examined (if that exists)
 * becomes the main target.
 *
 * Results:
 *      true iff a new main target has been selected.
 */
static bool
UpdateTarget(GNode *target, Suffix *suff, bool *inout_removedMain)
{
        Suffix *srcSuff, *targSuff;
        char *ptr;

        if (mainNode == NULL && *inout_removedMain &&
            GNode_IsMainCandidate(target)) {
                DEBUG1(MAKE, "Setting main node to \"%s\"\n", target->name);
                mainNode = target;
                /*
                 * XXX: Why could it be a good idea to return true here?
                 * The main task of this function is to turn ordinary nodes
                 * into transformations, no matter whether or not a new .MAIN
                 * node has been found.
                 */
                /*
                 * XXX: Even when changing this to false, none of the existing
                 * unit tests fails.
                 */
                return true;
        }

        if (target->type == OP_TRANSFORM)
                return false;

        /*
         * XXX: What about a transformation ".cpp.c"?  If ".c" is added as
         * a new suffix, it seems wrong that this transformation would be
         * skipped just because ".c" happens to be a prefix of ".cpp".
         */
        ptr = strstr(target->name, suff->name);
        if (ptr == NULL)
                return false;

        /*
         * XXX: In suff-rebuild.mk, in the line '.SUFFIXES: .c .b .a', this
         * condition prevents the rule '.b.c' from being added again during
         * Suff_AddSuffix(".b").
         *
         * XXX: Removing this paragraph makes suff-add-later.mk use massive
         * amounts of memory.
         */
        if (ptr == target->name)
                return false;

        if (ParseTransform(target->name, &srcSuff, &targSuff)) {
                if (mainNode == target) {
                        DEBUG1(MAKE,
                            "Setting main node from \"%s\" back to null\n",
                            target->name);
                        *inout_removedMain = true;
                        mainNode = NULL;
                }
                Lst_Done(&target->children);
                Lst_Init(&target->children);
                target->type = OP_TRANSFORM;

                /*
                 * Link the two together in the proper relationship and order.
                 */
                DEBUG2(SUFF, "defining transformation from `%s' to `%s'\n",
                    srcSuff->name, targSuff->name);
                Relate(srcSuff, targSuff);
        }
        return false;
}

/*
 * Look at all existing targets to see if adding this suffix will make one
 * of the current targets mutate into a suffix rule.
 *
 * This is ugly, but other makes treat all targets that start with a '.' as
 * suffix rules.
 */
static void
UpdateTargets(Suffix *suff)
{
        bool removedMain = false;
        GNodeListNode *ln;

        for (ln = Targ_List()->first; ln != NULL; ln = ln->next) {
                GNode *gn = ln->datum;
                if (UpdateTarget(gn, suff, &removedMain))
                        break;
        }
}

/*
 * Add the suffix to the end of the list of known suffixes.
 * Should we restructure the suffix graph? Make doesn't.
 *
 * A GNode is created for the suffix (XXX: this sounds completely wrong) and
 * a Suffix structure is created and added to the suffixes list unless the
 * suffix was already known.
 * The mainNode passed can be modified if a target mutated into a
 * transform and that target happened to be the main target.
 *
 * Input:
 *      name            the name of the suffix to add
 */
void
Suff_AddSuffix(const char *name)
{
        GNodeListNode *ln;

        Suffix *suff = FindSuffixByName(name);
        if (suff != NULL)
                return;

        suff = Suffix_New(name);
        Lst_Append(&sufflist, suff);
        DEBUG1(SUFF, "Adding suffix \"%s\"\n", suff->name);

        UpdateTargets(suff);

        /*
         * Look for any existing transformations from or to this suffix.
         * XXX: Only do this after a Suff_ClearSuffixes?
         */
        for (ln = transforms.first; ln != NULL; ln = ln->next)
                RebuildGraph(ln->datum, suff);
}

/* Return the search path for the given suffix, or NULL. */
SearchPath *
Suff_GetPath(const char *name)
{
        Suffix *suff = FindSuffixByName(name);
        return suff != NULL ? suff->searchPath : NULL;
}

/*
 * Extend the search paths for all suffixes to include the default search
 * path (dirSearchPath).
 *
 * The default search path can be defined using the special target '.PATH'.
 * The search path of each suffix can be defined using the special target
 * '.PATH<suffix>'.
 *
 * If paths were specified for the ".h" suffix, the directories are stuffed
 * into a global variable called ".INCLUDES" with each directory preceded by
 * '-I'. The same is done for the ".a" suffix, except the variable is called
 * ".LIBS" and the flag is '-L'.
 */
void
Suff_ExtendPaths(void)
{
        SuffixListNode *ln;
        char *flags;
        SearchPath *includesPath = SearchPath_New();
        SearchPath *libsPath = SearchPath_New();

        for (ln = sufflist.first; ln != NULL; ln = ln->next) {
                Suffix *suff = ln->datum;
                if (!Lst_IsEmpty(&suff->searchPath->dirs)) {
#ifdef INCLUDES
                        if (suff->include)
                                SearchPath_AddAll(includesPath,
                                    suff->searchPath);
#endif
#ifdef LIBRARIES
                        if (suff->library)
                                SearchPath_AddAll(libsPath, suff->searchPath);
#endif
                        SearchPath_AddAll(suff->searchPath, &dirSearchPath);
                } else {
                        SearchPath_Free(suff->searchPath);
                        suff->searchPath = Dir_CopyDirSearchPath();
                }
        }

        flags = SearchPath_ToFlags(includesPath, "-I");
        Global_Set(".INCLUDES", flags);
        free(flags);

        flags = SearchPath_ToFlags(libsPath, "-L");
        Global_Set(".LIBS", flags);
        free(flags);

        SearchPath_Free(includesPath);
        SearchPath_Free(libsPath);
}

/*
 * Add the given suffix as a type of file which gets included.
 * Called when a '.INCLUDES: .h' line is parsed.
 * To have an effect, the suffix must already exist.
 * This affects the magic variable '.INCLUDES'.
 */
void
Suff_AddInclude(const char *suffName)
{
        Suffix *suff = FindSuffixByName(suffName);
        if (suff != NULL)
                suff->include = true;
}

/*
 * Add the given suffix as a type of file which is a library.
 * Called when a '.LIBS: .a' line is parsed.
 * To have an effect, the suffix must already exist.
 * This affects the magic variable '.LIBS'.
 */
void
Suff_AddLib(const char *suffName)
{
        Suffix *suff = FindSuffixByName(suffName);
        if (suff != NULL)
                suff->library = true;
}

/********** Implicit Source Search Functions *********/

static void
CandidateSearcher_Init(CandidateSearcher *cs)
{
        Lst_Init(&cs->list);
}

static void
CandidateSearcher_Done(CandidateSearcher *cs)
{
        Lst_Done(&cs->list);
}

static void
CandidateSearcher_Add(CandidateSearcher *cs, Candidate *cand)
{
        /* TODO: filter duplicates */
        Lst_Append(&cs->list, cand);
}

static void
CandidateSearcher_AddIfNew(CandidateSearcher *cs, Candidate *cand)
{
        /* TODO: filter duplicates */
        if (Lst_FindDatum(&cs->list, cand) == NULL)
                Lst_Append(&cs->list, cand);
}

static void
CandidateSearcher_MoveAll(CandidateSearcher *cs, CandidateList *list)
{
        /* TODO: filter duplicates */
        Lst_MoveAll(&cs->list, list);
}


#ifdef DEBUG_SRC
static void
CandidateList_PrintAddrs(CandidateList *list)
{
        CandidateListNode *ln;

        for (ln = list->first; ln != NULL; ln = ln->next) {
                Candidate *cand = ln->datum;
                debug_printf(" %p:%s", cand, cand->file);
        }
        debug_printf("\n");
}
#endif

static Candidate *
Candidate_New(char *name, char *prefix, Suffix *suff, Candidate *parent,
              GNode *gn)
{
        Candidate *cand = bmake_malloc(sizeof *cand);

        cand->file = name;
        cand->prefix = prefix;
        cand->suff = Suffix_Ref(suff);
        cand->parent = parent;
        cand->node = gn;
        cand->numChildren = 0;
#ifdef DEBUG_SRC
        Lst_Init(&cand->childrenList);
#endif

        return cand;
}

/* Add a new candidate to the list. */
/*ARGSUSED*/
static void
CandidateList_Add(CandidateList *list, char *srcName, Candidate *targ,
                  Suffix *suff, const char *debug_tag MAKE_ATTR_UNUSED)
{
        Candidate *cand = Candidate_New(srcName, targ->prefix, suff, targ,
            NULL);
        targ->numChildren++;
        Lst_Append(list, cand);

#ifdef DEBUG_SRC
        Lst_Append(&targ->childrenList, cand);
        debug_printf("%s add suff %p:%s candidate %p:%s to list %p:",
            debug_tag, targ, targ->file, cand, cand->file, list);
        CandidateList_PrintAddrs(list);
#endif
}

/*
 * Add all candidates to the list that can be formed by applying a suffix to
 * the candidate.
 */
static void
CandidateList_AddCandidatesFor(CandidateList *list, Candidate *cand)
{
        SuffixListNode *ln;
        for (ln = cand->suff->children.first; ln != NULL; ln = ln->next) {
                Suffix *suff = ln->datum;

                if (suff->isNull && suff->name[0] != '\0') {
                        /*
                         * If the suffix has been marked as the NULL suffix,
                         * also create a candidate for a file with no suffix
                         * attached.
                         */
                        CandidateList_Add(list, bmake_strdup(cand->prefix),
                            cand, suff, "1");
                }

                CandidateList_Add(list, str_concat2(cand->prefix, suff->name),
                    cand, suff, "2");
        }
}

/*
 * Free the first candidate in the list that is not referenced anymore.
 * Return whether a candidate was removed.
 */
static bool
RemoveCandidate(CandidateList *srcs)
{
        CandidateListNode *ln;

#ifdef DEBUG_SRC
        debug_printf("cleaning list %p:", srcs);
        CandidateList_PrintAddrs(srcs);
#endif

        for (ln = srcs->first; ln != NULL; ln = ln->next) {
                Candidate *src = ln->datum;

                if (src->numChildren == 0) {
                        if (src->parent == NULL)
                                free(src->prefix);
                        else {
#ifdef DEBUG_SRC
                                /* XXX: Lst_RemoveDatum */
                                CandidateListNode *ln2;
                                ln2 = Lst_FindDatum(&src->parent->childrenList,
                                    src);
                                if (ln2 != NULL)
                                        Lst_Remove(&src->parent->childrenList,
                                            ln2);
#endif
                                src->parent->numChildren--;
                        }
#ifdef DEBUG_SRC
                        debug_printf("free: list %p src %p:%s children %d\n",
                            srcs, src, src->file, src->numChildren);
                        Lst_Done(&src->childrenList);
#endif
                        Lst_Remove(srcs, ln);
                        free(src->file);
                        free(src);
                        return true;
                }
#ifdef DEBUG_SRC
                else {
                        debug_printf("keep: list %p src %p:%s children %d:",
                            srcs, src, src->file, src->numChildren);
                        CandidateList_PrintAddrs(&src->childrenList);
                }
#endif
        }

        return false;
}

/* Find the first existing file/target in srcs. */
static Candidate *
FindThem(CandidateList *srcs, CandidateSearcher *cs)
{
        HashSet seen;

        HashSet_Init(&seen);

        while (!Lst_IsEmpty(srcs)) {
                Candidate *src = Lst_Dequeue(srcs);

#ifdef DEBUG_SRC
                debug_printf("remove from list %p src %p:%s\n",
                    srcs, src, src->file);
#endif
                DEBUG1(SUFF, "\ttrying %s...", src->file);

                /*
                 * A file is considered to exist if either a node exists in the
                 * graph for it or the file actually exists.
                 */
                if (Targ_FindNode(src->file) != NULL) {
                found:
                        HashSet_Done(&seen);
                        DEBUG0(SUFF, "got it\n");
                        return src;
                }

                {
                        char *file = Dir_FindFile(src->file,
                            src->suff->searchPath);
                        if (file != NULL) {
                                free(file);
                                goto found;
                        }
                }

                DEBUG0(SUFF, "not there\n");

                if (HashSet_Add(&seen, src->file))
                        CandidateList_AddCandidatesFor(srcs, src);
                else {
                        DEBUG1(SUFF, "FindThem: skipping duplicate \"%s\"\n",
                            src->file);
                }

                CandidateSearcher_Add(cs, src);
        }

        HashSet_Done(&seen);
        return NULL;
}

/*
 * See if any of the children of the candidate's GNode is one from which the
 * target can be transformed. If there is one, a candidate is put together
 * for it and returned.
 */
static Candidate *
FindCmds(Candidate *targ, CandidateSearcher *cs)
{
        GNodeListNode *gln;
        GNode *tgn;             /* Target GNode */
        GNode *sgn;             /* Source GNode */
        size_t prefLen;         /* The length of the defined prefix */
        Suffix *suff;           /* Suffix of the matching candidate */
        Candidate *ret;         /* Return value */

        tgn = targ->node;
        prefLen = strlen(targ->prefix);

        for (gln = tgn->children.first; gln != NULL; gln = gln->next) {
                const char *base;

                sgn = gln->datum;

                if (sgn->type & OP_OPTIONAL && Lst_IsEmpty(&tgn->commands)) {
                        /*
                         * We haven't looked to see if .OPTIONAL files exist
                         * yet, so don't use one as the implicit source.
                         * This allows us to use .OPTIONAL in .depend files so
                         * make won't complain "don't know how to make xxx.h"
                         * when a dependent file has been moved/deleted.
                         */
                        continue;
                }

                base = str_basename(sgn->name);
                if (strncmp(base, targ->prefix, prefLen) != 0)
                        continue;
                /*
                 * The node matches the prefix, see if it has a known suffix.
                 */
                suff = FindSuffixByName(base + prefLen);
                if (suff == NULL)
                        continue;

                /*
                 * It even has a known suffix, see if there's a transformation
                 * defined between the node's suffix and the target's suffix.
                 *
                 * XXX: Handle multi-stage transformations here, too.
                 */

                if (Lst_FindDatum(&suff->parents, targ->suff) != NULL)
                        break;
        }

        if (gln == NULL)
                return NULL;

        ret = Candidate_New(bmake_strdup(sgn->name), targ->prefix, suff, targ,
            sgn);
        targ->numChildren++;
#ifdef DEBUG_SRC
        debug_printf("3 add targ %p:%s ret %p:%s\n",
            targ, targ->file, ret, ret->file);
        Lst_Append(&targ->childrenList, ret);
#endif
        CandidateSearcher_Add(cs, ret);
        DEBUG1(SUFF, "\tusing existing source %s\n", sgn->name);
        return ret;
}

static void
ExpandWildcards(GNodeListNode *cln, GNode *pgn)
{
        GNode *cgn = cln->datum;
        StringList expansions;

        if (!Dir_HasWildcards(cgn->name))
                return;

        /*
         * Expand the word along the chosen path
         */
        Lst_Init(&expansions);
        SearchPath_Expand(Suff_FindPath(cgn), cgn->name, &expansions);

        while (!Lst_IsEmpty(&expansions)) {
                GNode *gn;
                /*
                 * Fetch next expansion off the list and find its GNode
                 */
                char *cp = Lst_Dequeue(&expansions);

                DEBUG1(SUFF, "%s...", cp);
                gn = Targ_GetNode(cp);

                /* Insert gn before the original child. */
                Lst_InsertBefore(&pgn->children, cln, gn);
                Lst_Append(&gn->parents, pgn);
                pgn->unmade++;
        }

        Lst_Done(&expansions);

        DEBUG0(SUFF, "\n");

        /*
         * Now the source is expanded, remove it from the list of children to
         * keep it from being processed.
         */
        pgn->unmade--;
        Lst_Remove(&pgn->children, cln);
        Lst_Remove(&cgn->parents, Lst_FindDatum(&cgn->parents, pgn));
}

/*
 * Break the result into a vector of strings whose nodes we can find, then
 * add those nodes to the members list.
 *
 * Unfortunately, we can't use Str_Words because it doesn't understand about
 * variable expressions with spaces in them.
 */
static void
ExpandChildrenRegular(char *cp, GNode *pgn, GNodeList *members)
{
        char *start;

        pp_skip_hspace(&cp);
        start = cp;
        while (*cp != '\0') {
                if (*cp == ' ' || *cp == '\t') {
                        GNode *gn;
                        /*
                         * White-space -- terminate element, find the node,
                         * add it, skip any further spaces.
                         */
                        *cp++ = '\0';
                        gn = Targ_GetNode(start);
                        Lst_Append(members, gn);
                        pp_skip_hspace(&cp);
                        /* Continue at the next non-space. */
                        start = cp;
                } else if (*cp == '$') {
                        /* Skip over the variable expression. */
                        const char *nested_p = cp;
                        FStr junk = Var_Parse(&nested_p, pgn, VARE_PARSE_ONLY);
                        /* TODO: handle errors */
                        if (junk.str == var_Error) {
                                Parse_Error(PARSE_FATAL,
                                    "Malformed variable expression at \"%s\"",
                                    cp);
                                cp++;
                        } else {
                                cp += nested_p - cp;
                        }

                        FStr_Done(&junk);
                } else if (cp[0] == '\\' && cp[1] != '\0') {
                        /* Escaped something -- skip over it. */
                        /*
                         * XXX: In other places, escaping at this syntactical
                         * position is done by a '$', not a '\'.  The '\' is
                         * only used in variable modifiers.
                         */
                        cp += 2;
                } else {
                        cp++;
                }
        }

        if (cp != start) {
                /*
                 * Stuff left over -- add it to the list too
                 */
                GNode *gn = Targ_GetNode(start);
                Lst_Append(members, gn);
        }
}

/*
 * Expand the names of any children of a given node that contain variable
 * expressions or file wildcards into actual targets.
 *
 * The expanded node is removed from the parent's list of children, and the
 * parent's unmade counter is decremented, but other nodes may be added.
 *
 * Input:
 *      cln             Child to examine
 *      pgn             Parent node being processed
 */
static void
ExpandChildren(GNodeListNode *cln, GNode *pgn)
{
        GNode *cgn = cln->datum;
        char *cp;               /* Expanded value */

        if (!Lst_IsEmpty(&cgn->order_pred) || !Lst_IsEmpty(&cgn->order_succ))
                /* It is all too hard to process the result of .ORDER */
                return;

        if (cgn->type & OP_WAIT)
                /* Ignore these (& OP_PHONY ?) */
                return;

        /*
         * First do variable expansion -- this takes precedence over wildcard
         * expansion. If the result contains wildcards, they'll be gotten to
         * later since the resulting words are tacked on to the end of the
         * children list.
         */
        if (strchr(cgn->name, '$') == NULL) {
                ExpandWildcards(cln, pgn);
                return;
        }

        DEBUG1(SUFF, "Expanding \"%s\"...", cgn->name);
        cp = Var_Subst(cgn->name, pgn, VARE_UNDEFERR);
        /* TODO: handle errors */

        {
                GNodeList members = LST_INIT;

                if (cgn->type & OP_ARCHV) {
                        /*
                         * Node was an 'archive(member)' target, so
                         * call on the Arch module to find the nodes for us,
                         * expanding variables in the parent's scope.
                         */
                        char *p = cp;
                        (void)Arch_ParseArchive(&p, &members, pgn);
                } else {
                        ExpandChildrenRegular(cp, pgn, &members);
                }

                /*
                 * Add all elements of the members list to the parent node.
                 */
                while (!Lst_IsEmpty(&members)) {
                        GNode *gn = Lst_Dequeue(&members);

                        DEBUG1(SUFF, "%s...", gn->name);
                        /*
                         * Add gn to the parents child list before the
                         * original child.
                         */
                        Lst_InsertBefore(&pgn->children, cln, gn);
                        Lst_Append(&gn->parents, pgn);
                        pgn->unmade++;
                        /* Expand wildcards on new node */
                        ExpandWildcards(cln->prev, pgn);
                }
                Lst_Done(&members);

                free(cp);
        }

        DEBUG0(SUFF, "\n");

        /*
         * Now the source is expanded, remove it from the list of children to
         * keep it from being processed.
         */
        pgn->unmade--;
        Lst_Remove(&pgn->children, cln);
        Lst_Remove(&cgn->parents, Lst_FindDatum(&cgn->parents, pgn));
}

static void
ExpandAllChildren(GNode *gn)
{
        GNodeListNode *ln, *nln;

        for (ln = gn->children.first; ln != NULL; ln = nln) {
                nln = ln->next;
                ExpandChildren(ln, gn);
        }
}

/*
 * Find a path along which to expand the node.
 *
 * If the node has a known suffix, use that path.
 * If it has no known suffix, use the default system search path.
 *
 * Input:
 *      gn              Node being examined
 *
 * Results:
 *      The appropriate path to search for the GNode.
 */
SearchPath *
Suff_FindPath(GNode *gn)
{
        Suffix *suff = gn->suffix;

        if (suff == NULL) {
                char *name = gn->name;
                size_t nameLen = strlen(gn->name);
                SuffixListNode *ln;
                for (ln = sufflist.first; ln != NULL; ln = ln->next)
                        if (Suffix_IsSuffix(ln->datum, nameLen, name + nameLen))
                                break;

                DEBUG1(SUFF, "Wildcard expanding \"%s\"...", gn->name);
                if (ln != NULL)
                        suff = ln->datum;
                /*
                 * XXX: Here we can save the suffix so we don't have to do
                 * this again.
                 */
        }

        if (suff != NULL) {
                DEBUG1(SUFF, "suffix is \"%s\"...\n", suff->name);
                return suff->searchPath;
        } else {
                DEBUG0(SUFF, "\n");
                return &dirSearchPath;  /* Use default search path */
        }
}

/*
 * Apply a transformation rule, given the source and target nodes and
 * suffixes.
 *
 * The source and target are linked and the commands from the transformation
 * are added to the target node's commands list. The target also inherits all
 * the sources for the transformation rule.
 *
 * Results:
 *      true if successful, false if not.
 */
static bool
ApplyTransform(GNode *tgn, GNode *sgn, Suffix *tsuff, Suffix *ssuff)
{
        GNodeListNode *ln;
        char *tname;            /* Name of transformation rule */
        GNode *gn;              /* Node for the transformation rule */

        /* Form the proper links between the target and source. */
        Lst_Append(&tgn->children, sgn);
        Lst_Append(&sgn->parents, tgn);
        tgn->unmade++;

        /* Locate the transformation rule itself. */
        tname = str_concat2(ssuff->name, tsuff->name);
        gn = FindTransformByName(tname);
        free(tname);

        /* This can happen when linking an OP_MEMBER and OP_ARCHV node. */
        if (gn == NULL)
                return false;

        DEBUG3(SUFF, "\tapplying %s -> %s to \"%s\"\n",
            ssuff->name, tsuff->name, tgn->name);

        /* Record last child; Make_HandleUse may add child nodes. */
        ln = tgn->children.last;

        /* Apply the rule. */
        Make_HandleUse(gn, tgn);

        /* Deal with wildcards and variables in any acquired sources. */
        ln = ln != NULL ? ln->next : NULL;
        while (ln != NULL) {
                GNodeListNode *nln = ln->next;
                ExpandChildren(ln, tgn);
                ln = nln;
        }

        /*
         * Keep track of another parent to which this node is transformed so
         * the .IMPSRC variable can be set correctly for the parent.
         */
        Lst_Append(&sgn->implicitParents, tgn);

        return true;
}

/*
 * Member has a known suffix, so look for a transformation rule from
 * it to a possible suffix of the archive.
 *
 * Rather than searching through the entire list, we just look at
 * suffixes to which the member's suffix may be transformed.
 */
static void
ExpandMember(GNode *gn, const char *eoarch, GNode *mem, Suffix *memSuff)
{
        GNodeListNode *ln;
        size_t nameLen = (size_t)(eoarch - gn->name);

        /* Use first matching suffix... */
        for (ln = memSuff->parents.first; ln != NULL; ln = ln->next)
                if (Suffix_IsSuffix(ln->datum, nameLen, eoarch))
                        break;

        if (ln != NULL) {
                /* Got one -- apply it */
                Suffix *suff = ln->datum;
                if (!ApplyTransform(gn, mem, suff, memSuff)) {
                        DEBUG2(SUFF, "\tNo transformation from %s -> %s\n",
                            memSuff->name, suff->name);
                }
        }
}

static void FindDeps(GNode *, CandidateSearcher *);

/*
 * Locate dependencies for an OP_ARCHV node.
 *
 * Input:
 *      gn              Node for which to locate dependencies
 *
 * Side Effects:
 *      Same as Suff_FindDeps
 */
static void
FindDepsArchive(GNode *gn, CandidateSearcher *cs)
{
        char *eoarch;           /* End of archive portion */
        char *eoname;           /* End of member portion */
        GNode *mem;             /* Node for member */
        Suffix *memSuff;
        const char *name;       /* Start of member's name */

        /*
         * The node is an archive(member) pair. so we must find a
         * suffix for both of them.
         */
        eoarch = strchr(gn->name, '(');
        eoname = strchr(eoarch, ')');

        /*
         * Caller guarantees the format `libname(member)', via
         * Arch_ParseArchive.
         */
        assert(eoarch != NULL);
        assert(eoname != NULL);

        *eoname = '\0';         /* Nuke parentheses during suffix search */
        *eoarch = '\0';         /* So a suffix can be found */

        name = eoarch + 1;

        /*
         * To simplify things, call Suff_FindDeps recursively on the member
         * now, so we can simply compare the member's .PREFIX and .TARGET
         * variables to locate its suffix. This allows us to figure out the
         * suffix to use for the archive without having to do a quadratic
         * search over the suffix list, backtracking for each one.
         */
        mem = Targ_GetNode(name);
        FindDeps(mem, cs);

        /* Create the link between the two nodes right off. */
        Lst_Append(&gn->children, mem);
        Lst_Append(&mem->parents, gn);
        gn->unmade++;

        /* Copy in the variables from the member node to this one. */
        Var_Set(gn, PREFIX, GNode_VarPrefix(mem));
        Var_Set(gn, TARGET, GNode_VarTarget(mem));

        memSuff = mem->suffix;
        if (memSuff == NULL) {  /* Didn't know what it was. */
                DEBUG0(SUFF, "using null suffix\n");
                memSuff = nullSuff;
        }


        /* Set the other two local variables required for this target. */
        Var_Set(gn, MEMBER, name);
        Var_Set(gn, ARCHIVE, gn->name);
        /* Set $@ for compatibility with other makes. */
        Var_Set(gn, TARGET, gn->name);

        /*
         * Now we've got the important local variables set, expand any sources
         * that still contain variables or wildcards in their names.
         */
        ExpandAllChildren(gn);

        if (memSuff != NULL)
                ExpandMember(gn, eoarch, mem, memSuff);

        /*
         * Replace the opening and closing parens now we've no need of the
         * separate pieces.
         */
        *eoarch = '(';
        *eoname = ')';

        /*
         * Pretend gn appeared to the left of a dependency operator so the
         * user needn't provide a transformation from the member to the
         * archive.
         */
        if (!GNode_IsTarget(gn))
                gn->type |= OP_DEPENDS;

        /*
         * Flag the member as such so we remember to look in the archive for
         * its modification time. The OP_JOIN | OP_MADE is needed because
         * this target should never get made.
         */
        mem->type |= OP_MEMBER | OP_JOIN | OP_MADE;
}

/*
 * If the node is a library, it is the arch module's job to find it
 * and set the TARGET variable accordingly. We merely provide the
 * search path, assuming all libraries end in ".a" (if the suffix
 * hasn't been defined, there's nothing we can do for it, so we just
 * set the TARGET variable to the node's name in order to give it a
 * value).
 */
static void
FindDepsLib(GNode *gn)
{
        Suffix *suff = FindSuffixByName(LIBSUFF);
        if (suff != NULL) {
                Suffix_Reassign(&gn->suffix, suff);
                Arch_FindLib(gn, suff->searchPath);
        } else {
                Suffix_Unassign(&gn->suffix);
                Var_Set(gn, TARGET, gn->name);
        }

        /*
         * Because a library (-lfoo) target doesn't follow the standard
         * filesystem conventions, we don't set the regular variables for
         * the thing. .PREFIX is simply made empty.
         */
        Var_Set(gn, PREFIX, "");
}

static void
FindDepsRegularKnown(const char *name, size_t nameLen, GNode *gn,
                     CandidateList *srcs, CandidateList *targs)
{
        SuffixListNode *ln;
        Candidate *targ;
        char *pref;

        for (ln = sufflist.first; ln != NULL; ln = ln->next) {
                Suffix *suff = ln->datum;
                if (!Suffix_IsSuffix(suff, nameLen, name + nameLen))
                        continue;

                pref = bmake_strldup(name, (size_t)(nameLen - suff->nameLen));
                targ = Candidate_New(bmake_strdup(gn->name), pref, suff, NULL,
                    gn);

                CandidateList_AddCandidatesFor(srcs, targ);

                /* Record the target so we can nuke it. */
                Lst_Append(targs, targ);
        }
}

static void
FindDepsRegularUnknown(GNode *gn, const char *sopref,
                       CandidateList *srcs, CandidateList *targs)
{
        Candidate *targ;

        if (!Lst_IsEmpty(targs) || nullSuff == NULL)
                return;

        DEBUG1(SUFF, "\tNo known suffix on %s. Using .NULL suffix\n", gn->name);

        targ = Candidate_New(bmake_strdup(gn->name), bmake_strdup(sopref),
            nullSuff, NULL, gn);

        /*
         * Only use the default suffix rules if we don't have commands
         * defined for this gnode; traditional make programs used to not
         * define suffix rules if the gnode had children but we don't do
         * this anymore.
         */
        if (Lst_IsEmpty(&gn->commands))
                CandidateList_AddCandidatesFor(srcs, targ);
        else {
                DEBUG0(SUFF, "not ");
        }

        DEBUG0(SUFF, "adding suffix rules\n");

        Lst_Append(targs, targ);
}

/*
 * Deal with finding the thing on the default search path. We always do
 * that, not only if the node is only a source (not on the lhs of a
 * dependency operator or [XXX] it has neither children or commands) as
 * the old pmake did.
 */
static void
FindDepsRegularPath(GNode *gn, Candidate *targ)
{
        if (gn->type & (OP_PHONY | OP_NOPATH))
                return;

        free(gn->path);
        gn->path = Dir_FindFile(gn->name,
            targ == NULL ? &dirSearchPath : targ->suff->searchPath);
        if (gn->path == NULL)
                return;

        Var_Set(gn, TARGET, gn->path);

        if (targ != NULL) {
                /*
                 * Suffix known for the thing -- trim the suffix off
                 * the path to form the proper .PREFIX variable.
                 */
                size_t savep = strlen(gn->path) - targ->suff->nameLen;
                char savec;

                Suffix_Reassign(&gn->suffix, targ->suff);

                savec = gn->path[savep];
                gn->path[savep] = '\0';

                Var_Set(gn, PREFIX, str_basename(gn->path));

                gn->path[savep] = savec;
        } else {
                /*
                 * The .PREFIX gets the full path if the target has no
                 * known suffix.
                 */
                Suffix_Unassign(&gn->suffix);
                Var_Set(gn, PREFIX, str_basename(gn->path));
        }
}

/*
 * Locate implicit dependencies for regular targets.
 *
 * Input:
 *      gn              Node for which to find sources
 *
 * Side Effects:
 *      Same as Suff_FindDeps
 */
static void
FindDepsRegular(GNode *gn, CandidateSearcher *cs)
{
        /* List of sources at which to look */
        CandidateList srcs = LST_INIT;
        /*
         * List of targets to which things can be transformed.
         * They all have the same file, but different suff and prefix fields.
         */
        CandidateList targs = LST_INIT;
        Candidate *bottom;      /* Start of found transformation path */
        Candidate *src;
        Candidate *targ;

        const char *name = gn->name;
        size_t nameLen = strlen(name);

#ifdef DEBUG_SRC
        DEBUG1(SUFF, "FindDepsRegular \"%s\"\n", gn->name);
#endif

        /*
         * We're caught in a catch-22 here. On the one hand, we want to use
         * any transformation implied by the target's sources, but we can't
         * examine the sources until we've expanded any variables/wildcards
         * they may hold, and we can't do that until we've set up the
         * target's local variables and we can't do that until we know what
         * the proper suffix for the target is (in case there are two
         * suffixes one of which is a suffix of the other) and we can't know
         * that until we've found its implied source, which we may not want
         * to use if there's an existing source that implies a different
         * transformation.
         *
         * In an attempt to get around this, which may not work all the time,
         * but should work most of the time, we look for implied sources
         * first, checking transformations to all possible suffixes of the
         * target, use what we find to set the target's local variables,
         * expand the children, then look for any overriding transformations
         * they imply. Should we find one, we discard the one we found before.
         */
        bottom = NULL;
        targ = NULL;

        if (!(gn->type & OP_PHONY)) {

                FindDepsRegularKnown(name, nameLen, gn, &srcs, &targs);

                /* Handle target of unknown suffix... */
                FindDepsRegularUnknown(gn, name, &srcs, &targs);

                /*
                 * Using the list of possible sources built up from the target
                 * suffix(es), try and find an existing file/target that
                 * matches.
                 */
                bottom = FindThem(&srcs, cs);

                if (bottom == NULL) {
                        /*
                         * No known transformations -- use the first suffix
                         * found for setting the local variables.
                         */
                        if (targs.first != NULL)
                                targ = targs.first->datum;
                        else
                                targ = NULL;
                } else {
                        /*
                         * Work up the transformation path to find the suffix
                         * of the target to which the transformation was made.
                         */
                        for (targ = bottom;
                             targ->parent != NULL; targ = targ->parent)
                                continue;
                }
        }

        Var_Set(gn, TARGET, GNode_Path(gn));
        Var_Set(gn, PREFIX, targ != NULL ? targ->prefix : gn->name);

        /*
         * Now we've got the important local variables set, expand any sources
         * that still contain variables or wildcards in their names.
         */
        {
                GNodeListNode *ln, *nln;
                for (ln = gn->children.first; ln != NULL; ln = nln) {
                        nln = ln->next;
                        ExpandChildren(ln, gn);
                }
        }

        if (targ == NULL) {
                DEBUG1(SUFF, "\tNo valid suffix on %s\n", gn->name);

        sfnd_abort:
                FindDepsRegularPath(gn, targ);
                goto sfnd_return;
        }

        /*
         * If the suffix indicates that the target is a library, mark that in
         * the node's type field.
         */
        if (targ->suff->library)
                gn->type |= OP_LIB;

        /*
         * Check for overriding transformation rule implied by sources
         */
        if (!Lst_IsEmpty(&gn->children)) {
                src = FindCmds(targ, cs);

                if (src != NULL) {
                        /*
                         * Free up all the candidates in the transformation
                         * path, up to but not including the parent node.
                         */
                        while (bottom != NULL && bottom->parent != NULL) {
                                CandidateSearcher_AddIfNew(cs, bottom);
                                bottom = bottom->parent;
                        }
                        bottom = src;
                }
        }

        if (bottom == NULL) {
                /* No idea from where it can come -- return now. */
                goto sfnd_abort;
        }

        /*
         * We now have a list of candidates headed by 'bottom' and linked via
         * their 'parent' pointers. What we do next is create links between
         * source and target nodes (which may or may not have been created)
         * and set the necessary local variables in each target.
         *
         * The commands for each target are set from the commands of the
         * transformation rule used to get from the src suffix to the targ
         * suffix. Note that this causes the commands list of the original
         * node, gn, to be replaced with the commands of the final
         * transformation rule.
         */
        if (bottom->node == NULL)
                bottom->node = Targ_GetNode(bottom->file);

        for (src = bottom; src->parent != NULL; src = src->parent) {
                targ = src->parent;

                Suffix_Reassign(&src->node->suffix, src->suff);

                if (targ->node == NULL)
                        targ->node = Targ_GetNode(targ->file);

                ApplyTransform(targ->node, src->node,
                    targ->suff, src->suff);

                if (targ->node != gn) {
                        /*
                         * Finish off the dependency-search process for any
                         * nodes between bottom and gn (no point in questing
                         * around the filesystem for their implicit source
                         * when it's already known). Note that the node
                         * can't have any sources that need expanding, since
                         * SuffFindThem will stop on an existing node, so all
                         * we need to do is set the standard variables.
                         */
                        targ->node->type |= OP_DEPS_FOUND;
                        Var_Set(targ->node, PREFIX, targ->prefix);
                        Var_Set(targ->node, TARGET, targ->node->name);
                }
        }

        Suffix_Reassign(&gn->suffix, src->suff);

        /*
         * Nuke the transformation path and the candidates left over in the
         * two lists.
         */
sfnd_return:
        if (bottom != NULL)
                CandidateSearcher_AddIfNew(cs, bottom);

        while (RemoveCandidate(&srcs) || RemoveCandidate(&targs))
                continue;

        CandidateSearcher_MoveAll(cs, &srcs);
        CandidateSearcher_MoveAll(cs, &targs);
}

static void
CandidateSearcher_CleanUp(CandidateSearcher *cs)
{
        while (RemoveCandidate(&cs->list))
                continue;
        assert(Lst_IsEmpty(&cs->list));
}


/*
 * Find implicit sources for the target.
 *
 * Nodes are added to the graph as children of the passed-in node. The nodes
 * are marked to have their IMPSRC variable filled in. The PREFIX variable
 * is set for the given node and all its implied children.
 *
 * The path found by this target is the shortest path in the transformation
 * graph, which may pass through nonexistent targets, to an existing target.
 * The search continues on all paths from the root suffix until a file is
 * found. I.e. if there's a path .o -> .c -> .l -> .l,v from the root and the
 * .l,v file exists but the .c and .l files don't, the search will branch out
 * in all directions from .o and again from all the nodes on the next level
 * until the .l,v node is encountered.
 */
void
Suff_FindDeps(GNode *gn)
{
        CandidateSearcher cs;

        CandidateSearcher_Init(&cs);

        FindDeps(gn, &cs);

        CandidateSearcher_CleanUp(&cs);
        CandidateSearcher_Done(&cs);
}

static void
FindDeps(GNode *gn, CandidateSearcher *cs)
{
        if (gn->type & OP_DEPS_FOUND)
                return;
        gn->type |= OP_DEPS_FOUND;

        /* Make sure we have these set, may get revised below. */
        Var_Set(gn, TARGET, GNode_Path(gn));
        Var_Set(gn, PREFIX, gn->name);

        DEBUG1(SUFF, "SuffFindDeps \"%s\"\n", gn->name);

        if (gn->type & OP_ARCHV)
                FindDepsArchive(gn, cs);
        else if (gn->type & OP_LIB)
                FindDepsLib(gn);
        else
                FindDepsRegular(gn, cs);
}

/*
 * Define which suffix is the null suffix.
 *
 * Need to handle the changing of the null suffix gracefully so the old
 * transformation rules don't just go away.
 *
 * Input:
 *      name            Name of null suffix
 */
void
Suff_SetNull(const char *name)
{
        Suffix *suff = FindSuffixByName(name);
        if (suff == NULL) {
                Parse_Error(PARSE_WARNING,
                    "Desired null suffix %s not defined",
                    name);
                return;
        }

        if (nullSuff != NULL)
                nullSuff->isNull = false;
        suff->isNull = true;
        /* XXX: Here's where the transformation mangling would take place. */
        nullSuff = suff;
}

/* Initialize the suffixes module. */
void
Suff_Init(void)
{
        /*
         * Create null suffix for single-suffix rules (POSIX). The thing
         * doesn't actually go on the suffix list or everyone will think
         * that's its suffix.
         */
        Suff_ClearSuffixes();
}


/* Clean up the suffixes module. */
void
Suff_End(void)
{
#ifdef CLEANUP
        Lst_DoneCall(&sufflist, SuffFree);
        Lst_DoneCall(&suffClean, SuffFree);
        if (nullSuff != NULL)
                SuffFree(nullSuff);
        Lst_Done(&transforms);
#endif
}


static void
PrintSuffNames(const char *prefix, const SuffixList *suffs)
{
        SuffixListNode *ln;

        debug_printf("#\t%s: ", prefix);
        for (ln = suffs->first; ln != NULL; ln = ln->next) {
                const Suffix *suff = ln->datum;
                debug_printf("%s ", suff->name);
        }
        debug_printf("\n");
}

static void
Suffix_Print(const Suffix *suff)
{
        Buffer buf;

        Buf_InitSize(&buf, 16);
        Buf_AddFlag(&buf, suff->include, "SUFF_INCLUDE");
        Buf_AddFlag(&buf, suff->library, "SUFF_LIBRARY");
        Buf_AddFlag(&buf, suff->isNull, "SUFF_NULL");

        debug_printf("# \"%s\" (num %d, ref %d)",
            suff->name, suff->sNum, suff->refCount);
        if (buf.len > 0)
                debug_printf(" (%s)", buf.data);
        debug_printf("\n");

        Buf_Done(&buf);

        PrintSuffNames("To", &suff->parents);
        PrintSuffNames("From", &suff->children);

        debug_printf("#\tSearch Path: ");
        SearchPath_Print(suff->searchPath);
        debug_printf("\n");
}

static void
PrintTransformation(GNode *t)
{
        debug_printf("%-16s:", t->name);
        Targ_PrintType(t->type);
        debug_printf("\n");
        Targ_PrintCmds(t);
        debug_printf("\n");
}

void
Suff_PrintAll(void)
{
        debug_printf("#*** Suffixes:\n");
        {
                SuffixListNode *ln;
                for (ln = sufflist.first; ln != NULL; ln = ln->next)
                        Suffix_Print(ln->datum);
        }

        debug_printf("#*** Transformations:\n");
        {
                GNodeListNode *ln;
                for (ln = transforms.first; ln != NULL; ln = ln->next)
                        PrintTransformation(ln->datum);
        }
}

char *
Suff_NamesStr(void)
{
        Buffer buf;
        SuffixListNode *ln;
        Suffix *suff;

        Buf_InitSize(&buf, 16);
        for (ln = sufflist.first; ln != NULL; ln = ln->next) {
                suff = ln->datum;
                if (ln != sufflist.first)
                        Buf_AddByte(&buf, ' ');
                Buf_AddStr(&buf, suff->name);
        }
        return Buf_DoneData(&buf);
}