/* * @(#)dlfcn.c 1.11 revision of 96/04/10 20:12:51 * This is an unpublished work copyright (c) 1992 HELIOS Software GmbH * 30159 Hannover, Germany */ /* * Changes marked with `--jwe' were made on April 7 1996 by John W. Eaton * to support g++ and/or use with Octave. */ /* * This makes my life easier with Octave. --jwe */ #ifdef HAVE_CONFIG_H #include #endif #include #include #include #include #include #include #include #include #include "dlfcn.h" /* * We simulate dlopen() et al. through a call to load. Because AIX has * no call to find an exported symbol we read the loader section of the * loaded module and build a list of exported symbols and their virtual * address. */ typedef struct { char *name; /* the symbols's name */ void *addr; /* its relocated virtual address */ } Export, *ExportPtr; /* * xlC uses the following structure to list its constructors and * destructors. This is gleaned from the output of munch. */ typedef struct { void (*init)(void); /* call static constructors */ void (*term)(void); /* call static destructors */ } Cdtor, *CdtorPtr; typedef void (*GccCDtorPtr)(void); /* * The void * handle returned from dlopen is actually a ModulePtr. */ typedef struct Module { struct Module *next; char *name; /* module name for refcounting */ int refCnt; /* the number of references */ void *entry; /* entry point from load */ struct dl_info *info; /* optional init/terminate functions */ CdtorPtr cdtors; /* optional C++ constructors */ GccCDtorPtr gcc_ctor; /* g++ constructors --jwe */ GccCDtorPtr gcc_dtor; /* g++ destructors --jwe */ int nExports; /* the number of exports found */ ExportPtr exports; /* the array of exports */ } Module, *ModulePtr; /* * We keep a list of all loaded modules to be able to call the fini * handlers and destructors at atexit() time. */ static ModulePtr modList; /* * The last error from one of the dl* routines is kept in static * variables here. Each error is returned only once to the caller. */ static char errbuf[BUFSIZ]; static int errvalid; /* * The `fixed' gcc header files on AIX 3.2.5 provide a prototype for * strdup(). --jwe */ #ifndef HAVE_STRDUP extern char *strdup(const char *); #endif static void caterr(char *); static int readExports(ModulePtr); static void terminate(void); static void *findMain(void); void *dlopen(const char *path, int mode) { ModulePtr mp; static void *mainModule; /* * Upon the first call register a terminate handler that will * close all libraries. Also get a reference to the main module * for use with loadbind. */ if (!mainModule) { if ((mainModule = findMain()) == NULL) return NULL; atexit(terminate); } /* * Scan the list of modules if we have the module already loaded. */ for (mp = modList; mp; mp = mp->next) if (strcmp(mp->name, path) == 0) { mp->refCnt++; return mp; } if ((mp = (ModulePtr)calloc(1, sizeof(*mp))) == NULL) { errvalid++; snprintf (errbuf, sizeof(errbuf), "calloc: %s", strerror(errno)); return NULL; } if ((mp->name = strdup(path)) == NULL) { errvalid++; snprintf (errbuf, sizeof(errbuf), "strdup: %s", strerror(errno)); free(mp); return NULL; } /* * load should be declared load(const char *...). Thus we * cast the path to a normal char *. Ugly. */ if ((mp->entry = (void *)load((char *)path, L_NOAUTODEFER, NULL)) == NULL) { free(mp->name); free(mp); errvalid++; snprintf (errbuf, sizeof(errbuf), "dlopen: %s: ", path); /* * If AIX says the file is not executable, the error * can be further described by querying the loader about * the last error. */ if (errno == ENOEXEC) { char *tmp[BUFSIZ/sizeof(char *)]; if (loadquery(L_GETMESSAGES, tmp, sizeof(tmp)) == -1) strlcpy(errbuf, strerror(errno), sizeof(errbuf)); else { char **p; for (p = tmp; *p; p++) caterr(*p); } } else strlcat(errbuf, strerror(errno), sizeof(errbuf)); return NULL; } mp->refCnt = 1; mp->next = modList; modList = mp; if (loadbind(0, mainModule, mp->entry) == -1) { dlclose(mp); errvalid++; snprintf (errbuf, sizeof(errbuf), "loadbind: %s", strerror(errno)); return NULL; } /* * If the user wants global binding, loadbind against all other * loaded modules. */ if (mode & RTLD_GLOBAL) { ModulePtr mp1; for (mp1 = mp->next; mp1; mp1 = mp1->next) if (loadbind(0, mp1->entry, mp->entry) == -1) { dlclose(mp); errvalid++; snprintf (errbuf, sizeof(errbuf), "loadbind: %s", strerror(errno)); return NULL; } } if (readExports(mp) == -1) { dlclose(mp); return NULL; } /* * If there is a dl_info structure, call the init function. */ if (mp->info = (struct dl_info *)dlsym(mp, "dl_info")) { if (mp->info->init) (*mp->info->init)(); } else errvalid = 0; /* * If the shared object was compiled using xlC we will need * to call static constructors (and later on dlclose destructors). */ if (mp->cdtors = (CdtorPtr)dlsym(mp, "__cdtors")) { CdtorPtr cp = mp->cdtors; while (cp->init || cp->term) { if (cp->init && cp->init != (void (*)(void))0xffffffff) (*cp->init)(); cp++; } /* * If the shared object was compiled using g++, we will need * to call global constructors using the _GLOBAL__DI function, * and later, global destructors using the _GLOBAL_DD * funciton. --jwe */ } else if (mp->gcc_ctor = (GccCDtorPtr)dlsym(mp, "_GLOBAL__DI")) { (*mp->gcc_ctor)(); mp->gcc_dtor = (GccCDtorPtr)dlsym(mp, "_GLOBAL__DD"); } else errvalid = 0; return mp; } /* * Attempt to decipher an AIX loader error message and append it * to our static error message buffer. */ static void caterr(char *s) { char *p = s; while (*p >= '0' && *p <= '9') p++; switch(atoi(s)) { case L_ERROR_TOOMANY: strlcat(errbuf, "to many errors", sizeof(errbuf)); break; case L_ERROR_NOLIB: strlcat(errbuf, "can't load library", sizeof(errbuf)); strlcat(errbuf, p, sizeof(errbuf)); break; case L_ERROR_UNDEF: strlcat(errbuf, "can't find symbol", sizeof(errbuf)); strlcat(errbuf, p, sizeof(errbuf)); break; case L_ERROR_RLDBAD: strlcat(errbuf, "bad RLD", sizeof(errbuf)); strlcat(errbuf, p, sizeof(errbuf)); break; case L_ERROR_FORMAT: strlcat(errbuf, "bad exec format in", sizeof(errbuf)); strlcat(errbuf, p, sizeof(errbuf)); break; case L_ERROR_ERRNO: strlcat(errbuf, strerror(atoi(++p)), sizeof(errbuf)); break; default: strlcat(errbuf, s, sizeof(errbuf)); break; } } void *dlsym(void *handle, const char *symbol) { ModulePtr mp = (ModulePtr)handle; ExportPtr ep; int i; /* * Could speed up the search, but I assume that one assigns * the result to function pointers anyways. */ for (ep = mp->exports, i = mp->nExports; i; i--, ep++) if (strcmp(ep->name, symbol) == 0) return ep->addr; errvalid++; snprintf (errbuf, sizeof(errbuf), "dlsym: undefined symbol %s", symbol); return NULL; } char *dlerror(void) { if (errvalid) { errvalid = 0; return errbuf; } return NULL; } int dlclose(void *handle) { ModulePtr mp = (ModulePtr)handle; int result; ModulePtr mp1; if (--mp->refCnt > 0) return 0; if (mp->info && mp->info->fini) (*mp->info->fini)(); if (mp->cdtors) { CdtorPtr cp = mp->cdtors; while (cp->init || cp->term) { if (cp->term && cp->init != (void (*)(void))0xffffffff) (*cp->term)(); cp++; } /* * If the function to handle global destructors for g++ * exists, call it. --jwe */ } else if (mp->gcc_dtor) { (*mp->gcc_dtor)(); } result = unload(mp->entry); if (result == -1) { errvalid++; snprintf (errbuf, sizeof(errbuf), "%s", strerror(errno)); } if (mp->exports) { ExportPtr ep; int i; for (ep = mp->exports, i = mp->nExports; i; i--, ep++) if (ep->name) free(ep->name); free(mp->exports); } if (mp == modList) modList = mp->next; else { for (mp1 = modList; mp1; mp1 = mp1->next) if (mp1->next == mp) { mp1->next = mp->next; break; } } free(mp->name); free(mp); return result; } static void terminate(void) { while (modList) dlclose(modList); } /* * Build the export table from the XCOFF .loader section. */ static int readExports(ModulePtr mp) { LDFILE *ldp = NULL; SCNHDR sh, shdata; LDHDR *lhp; char *ldbuf; LDSYM *ls; int i; ExportPtr ep; if ((ldp = ldopen(mp->name, ldp)) == NULL) { struct ld_info *lp; char *buf; int size = 4*1024; if (errno != ENOENT) { errvalid++; snprintf(errbuf, sizeof(errbuf), "readExports: %s", strerror(errno)); return -1; } /* * The module might be loaded due to the LIBPATH * environment variable. Search for the loaded * module using L_GETINFO. */ if ((buf = malloc(size)) == NULL) { errvalid++; snprintf(errbuf, sizeof(errbuf), "readExports: %s", strerror(errno)); return -1; } while ((i = loadquery(L_GETINFO, buf, size)) == -1 && errno == ENOMEM) { free(buf); size += 4*1024; if ((buf = malloc(size)) == NULL) { errvalid++; snprintf(errbuf, sizeof(errbuf), "readExports: %s", strerror(errno)); return -1; } } if (i == -1) { errvalid++; snprintf(errbuf, sizeof(errbuf), "readExports: %s", strerror(errno)); free(buf); return -1; } /* * Traverse the list of loaded modules. The entry point * returned by load() does actually point to the data * segment origin. */ lp = (struct ld_info *)buf; while (lp) { if (lp->ldinfo_dataorg == mp->entry) { ldp = ldopen(lp->ldinfo_filename, ldp); break; } if (lp->ldinfo_next == 0) lp = NULL; else lp = (struct ld_info *)((char *)lp + lp->ldinfo_next); } free(buf); if (!ldp) { errvalid++; snprintf (errbuf, sizeof(errbuf), "readExports: %s", strerror(errno)); return -1; } } if (TYPE(ldp) != U802TOCMAGIC) { errvalid++; snprintf(errbuf, sizeof(errbuf), "readExports: bad magic"); while(ldclose(ldp) == FAILURE) ; return -1; } /* * Get the padding for the data section. This is needed for * AIX 4.1 compilers. This is used when building the final * function pointer to the exported symbol. */ if (ldnshread(ldp, _DATA, &shdata) != SUCCESS) { errvalid++; snprintf(errbuf, sizeof(errbuf), "readExports: cannot read data section header"); while(ldclose(ldp) == FAILURE) ; return -1; } if (ldnshread(ldp, _LOADER, &sh) != SUCCESS) { errvalid++; snprintf(errbuf, sizeof(errbuf), "readExports: cannot read loader section header"); while(ldclose(ldp) == FAILURE) ; return -1; } /* * We read the complete loader section in one chunk, this makes * finding long symbol names residing in the string table easier. */ if ((ldbuf = (char *)malloc(sh.s_size)) == NULL) { errvalid++; snprintf (errbuf, sizeof(errbuf), "readExports: %s", strerror(errno)); while(ldclose(ldp) == FAILURE) ; return -1; } if (FSEEK(ldp, sh.s_scnptr, BEGINNING) != OKFSEEK) { errvalid++; snprintf(errbuf, sizeof(errbuf), "readExports: cannot seek to loader section"); free(ldbuf); while(ldclose(ldp) == FAILURE) ; return -1; } if (FREAD(ldbuf, sh.s_size, 1, ldp) != 1) { errvalid++; snprintf(errbuf, sizeof(errbuf), "readExports: cannot read loader section"); free(ldbuf); while(ldclose(ldp) == FAILURE) ; return -1; } lhp = (LDHDR *)ldbuf; ls = (LDSYM *)(ldbuf+LDHDRSZ); /* * Count the number of exports to include in our export table. */ for (i = lhp->l_nsyms; i; i--, ls++) { if (!LDR_EXPORT(*ls)) continue; mp->nExports++; } if ((mp->exports = (ExportPtr)calloc(mp->nExports, sizeof(*mp->exports))) == NULL) { errvalid++; snprintf (errbuf, sizeof(errbuf), "readExports: %s", strerror(errno)); free(ldbuf); while(ldclose(ldp) == FAILURE) ; return -1; } /* * Fill in the export table. All entries are relative to * the entry point we got from load. */ ep = mp->exports; ls = (LDSYM *)(ldbuf+LDHDRSZ); for (i = lhp->l_nsyms; i; i--, ls++) { char *symname; char tmpsym[SYMNMLEN+1]; if (!LDR_EXPORT(*ls)) continue; if (ls->l_zeroes == 0) symname = ls->l_offset+lhp->l_stoff+ldbuf; else { /* * The l_name member is not zero terminated, we * must copy the first SYMNMLEN chars and make * sure we have a zero byte at the end. */ strlcpy (tmpsym, ls->l_name, SYMNMLEN + 1); symname = tmpsym; } ep->name = strdup(symname); ep->addr = (void *)((unsigned long)mp->entry + ls->l_value - shdata.s_vaddr); ep++; } free(ldbuf); while(ldclose(ldp) == FAILURE) ; return 0; } /* * Find the main modules entry point. This is used as export pointer * for loadbind() to be able to resolve references to the main part. */ static void * findMain(void) { struct ld_info *lp; char *buf; int size = 4*1024; int i; void *ret; if ((buf = malloc(size)) == NULL) { errvalid++; snprintf (errbuf, sizeof(errbuf), "findMail: %s", strerror(errno)); return NULL; } while ((i = loadquery(L_GETINFO, buf, size)) == -1 && errno == ENOMEM) { free(buf); size += 4*1024; if ((buf = malloc(size)) == NULL) { errvalid++; snprintf (errbuf, sizeof(errbuf), "findMail: %s", strerror(errno)); return NULL; } } if (i == -1) { errvalid++; snprintf (errbuf, sizeof(errbuf), "findMail: %s", strerror(errno)); free(buf); return NULL; } /* * The first entry is the main module. The entry point * returned by load() does actually point to the data * segment origin. */ lp = (struct ld_info *)buf; ret = lp->ldinfo_dataorg; free(buf); return ret; }