2 * Copyright (c) 2006-2011 Joseph Koshy
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 #include <sys/param.h>
44 ELFTC_VCSID("$Id: elf_update.c 3190 2015-05-04 15:23:08Z jkoshy $");
49 * - Case 1: ELF_F_LAYOUT is asserted
50 * In this case the application has full control over where the
51 * section header table, program header table, and section data
52 * will reside. The library only perform error checks.
54 * - Case 2: ELF_F_LAYOUT is not asserted
56 * The library will do the object layout using the following
58 * - The executable header is placed first, are required by the
60 * - The program header table is placed immediately following the
62 * - Section data, if any, is placed after the program header
63 * table, aligned appropriately.
64 * - The section header table, if needed, is placed last.
66 * There are two sub-cases to be taken care of:
68 * - Case 2a: e->e_cmd == ELF_C_READ or ELF_C_RDWR
70 * In this sub-case, the underlying ELF object may already have
71 * content in it, which the application may have modified. The
72 * library will retrieve content from the existing object as
75 * - Case 2b: e->e_cmd == ELF_C_WRITE
77 * The ELF object is being created afresh in this sub-case;
78 * there is no pre-existing content in the underlying ELF
83 * The types of extents in an ELF object.
93 * A extent descriptor, used when laying out an ELF object.
96 SLIST_ENTRY(_Elf_Extent) ex_next;
97 uint64_t ex_start; /* Start of the region. */
98 uint64_t ex_size; /* The size of the region. */
99 enum elf_extent ex_type; /* Type of region. */
100 void *ex_desc; /* Associated descriptor. */
103 SLIST_HEAD(_Elf_Extent_List, _Elf_Extent);
106 * Compute the extents of a section, by looking at the data
107 * descriptors associated with it. The function returns 1
108 * if successful, or zero if an error was detected.
111 _libelf_compute_section_extents(Elf *e, Elf_Scn *s, off_t rc)
120 struct _Libelf_Data *ld;
121 uint64_t scn_size, scn_alignment;
122 uint64_t sh_align, sh_entsize, sh_offset, sh_size;
126 shdr32 = &s->s_shdr.s_shdr32;
127 shdr64 = &s->s_shdr.s_shdr64;
128 if (ec == ELFCLASS32) {
129 sh_type = shdr32->sh_type;
130 sh_align = (uint64_t) shdr32->sh_addralign;
131 sh_entsize = (uint64_t) shdr32->sh_entsize;
132 sh_offset = (uint64_t) shdr32->sh_offset;
133 sh_size = (uint64_t) shdr32->sh_size;
135 sh_type = shdr64->sh_type;
136 sh_align = shdr64->sh_addralign;
137 sh_entsize = shdr64->sh_entsize;
138 sh_offset = shdr64->sh_offset;
139 sh_size = shdr64->sh_size;
142 assert(sh_type != SHT_NULL && sh_type != SHT_NOBITS);
144 elftype = _libelf_xlate_shtype(sh_type);
145 if (elftype > ELF_T_LAST) {
146 LIBELF_SET_ERROR(SECTION, 0);
151 sh_align = _libelf_falign(elftype, ec);
154 * Compute the section's size and alignment using the data
155 * descriptors associated with the section.
157 if (STAILQ_EMPTY(&s->s_data)) {
159 * The section's content (if any) has not been read in
160 * yet. If section is not dirty marked dirty, we can
161 * reuse the values in the 'sh_size' and 'sh_offset'
162 * fields of the section header.
164 if ((s->s_flags & ELF_F_DIRTY) == 0) {
166 * If the library is doing the layout, then we
167 * compute the new start offset for the
168 * section based on the current offset and the
169 * section's alignment needs.
171 * If the application is doing the layout, we
172 * can use the value in the 'sh_offset' field
173 * in the section header directly.
175 if (e->e_flags & ELF_F_LAYOUT)
176 goto updatedescriptor;
182 * Otherwise, we need to bring in the section's data
183 * from the underlying ELF object.
185 if (e->e_cmd != ELF_C_WRITE && elf_getdata(s, NULL) == NULL)
190 * Loop through the section's data descriptors.
194 STAILQ_FOREACH(ld, &s->s_data, d_next) {
199 * The data buffer's type is known.
201 if (d->d_type >= ELF_T_NUM) {
202 LIBELF_SET_ERROR(DATA, 0);
207 * The data buffer's version is supported.
209 if (d->d_version != e->e_version) {
210 LIBELF_SET_ERROR(VERSION, 0);
215 * The buffer's alignment is non-zero and a power of
218 if ((d_align = d->d_align) == 0 ||
219 (d_align & (d_align - 1))) {
220 LIBELF_SET_ERROR(DATA, 0);
225 * The buffer's size should be a multiple of the
226 * memory size of the underlying type.
228 msz = _libelf_msize(d->d_type, ec, e->e_version);
229 if (d->d_size % msz) {
230 LIBELF_SET_ERROR(DATA, 0);
235 * If the application is controlling layout, then the
236 * d_offset field should be compatible with the
237 * buffer's specified alignment.
239 if ((e->e_flags & ELF_F_LAYOUT) &&
240 (d->d_off & (d_align - 1))) {
241 LIBELF_SET_ERROR(LAYOUT, 0);
246 * Compute the section's size.
248 if (e->e_flags & ELF_F_LAYOUT) {
249 if ((uint64_t) d->d_off + d->d_size > scn_size)
250 scn_size = d->d_off + d->d_size;
252 scn_size = roundup2(scn_size, d->d_align);
254 fsz = _libelf_fsize(d->d_type, ec, d->d_version,
255 (size_t) d->d_size / msz);
260 * The section's alignment is the maximum alignment
261 * needed for its data buffers.
263 if (d_align > scn_alignment)
264 scn_alignment = d_align;
269 * If the application is requesting full control over the
270 * layout of the section, check the section's specified size,
271 * offsets and alignment for sanity.
273 if (e->e_flags & ELF_F_LAYOUT) {
274 if (scn_alignment > sh_align ||
275 sh_offset % sh_align ||
276 sh_size < scn_size ||
277 sh_offset % _libelf_falign(elftype, ec)) {
278 LIBELF_SET_ERROR(LAYOUT, 0);
281 goto updatedescriptor;
285 * Otherwise, compute the values in the section header.
287 * The section alignment is the maximum alignment for any of
288 * its contained data descriptors.
290 if (scn_alignment > sh_align)
291 sh_align = scn_alignment;
294 * If the section entry size is zero, try and fill in an
295 * appropriate entry size. Per the elf(5) manual page
296 * sections without fixed-size entries should have their
297 * 'sh_entsize' field set to zero.
299 if (sh_entsize == 0 &&
300 (sh_entsize = _libelf_fsize(elftype, ec, e->e_version,
308 * Compute the new offset for the section based on
309 * the section's alignment needs.
311 sh_offset = roundup((uint64_t) rc, sh_align);
314 * Update the section header.
316 if (ec == ELFCLASS32) {
317 shdr32->sh_addralign = (uint32_t) sh_align;
318 shdr32->sh_entsize = (uint32_t) sh_entsize;
319 shdr32->sh_offset = (uint32_t) sh_offset;
320 shdr32->sh_size = (uint32_t) sh_size;
322 shdr64->sh_addralign = sh_align;
323 shdr64->sh_entsize = sh_entsize;
324 shdr64->sh_offset = sh_offset;
325 shdr64->sh_size = sh_size;
330 * Update the section descriptor.
333 s->s_offset = sh_offset;
339 * Free a list of extent descriptors.
343 _libelf_release_extents(struct _Elf_Extent_List *extents)
345 struct _Elf_Extent *ex;
347 while ((ex = SLIST_FIRST(extents)) != NULL) {
348 SLIST_REMOVE_HEAD(extents, ex_next);
354 * Check if an extent 's' defined by [start..start+size) is free.
355 * This routine assumes that the given extent list is sorted in order
356 * of ascending extent offsets.
360 _libelf_extent_is_unused(struct _Elf_Extent_List *extents,
361 const uint64_t start, const uint64_t size, struct _Elf_Extent **prevt)
364 struct _Elf_Extent *t, *pt;
365 const uint64_t smax = start + size;
367 /* First, look for overlaps with existing extents. */
369 SLIST_FOREACH(t, extents, ex_next) {
371 tmax = tmin + t->ex_size;
375 * 't' lies entirely before 's': ...| t |...| s |...
379 } else if (smax <= tmin) {
381 * 's' lies entirely before 't', and after 'pt':
382 * ...| pt |...| s |...| t |...
385 pt->ex_start + pt->ex_size <= start);
388 /* 's' and 't' overlap. */
398 * Insert an extent into the list of extents.
402 _libelf_insert_extent(struct _Elf_Extent_List *extents, int type,
403 uint64_t start, uint64_t size, void *desc)
405 struct _Elf_Extent *ex, *prevt;
407 assert(type >= ELF_EXTENT_EHDR && type <= ELF_EXTENT_SHDR);
412 * If the requested range overlaps with an existing extent,
415 if (!_libelf_extent_is_unused(extents, start, size, &prevt)) {
416 LIBELF_SET_ERROR(LAYOUT, 0);
420 /* Allocate and fill in a new extent descriptor. */
421 if ((ex = malloc(sizeof(struct _Elf_Extent))) == NULL) {
422 LIBELF_SET_ERROR(RESOURCE, errno);
425 ex->ex_start = start;
430 /* Insert the region descriptor into the list. */
432 SLIST_INSERT_AFTER(prevt, ex, ex_next);
434 SLIST_INSERT_HEAD(extents, ex, ex_next);
439 * Recompute section layout.
443 _libelf_resync_sections(Elf *e, off_t rc, struct _Elf_Extent_List *extents)
452 * Make a pass through sections, computing the extent of each
455 STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next) {
456 if (ec == ELFCLASS32)
457 sh_type = s->s_shdr.s_shdr32.sh_type;
459 sh_type = s->s_shdr.s_shdr64.sh_type;
461 if (sh_type == SHT_NOBITS || sh_type == SHT_NULL)
464 if (_libelf_compute_section_extents(e, s, rc) == 0)
470 if (!_libelf_insert_extent(extents, ELF_EXTENT_SECTION,
471 s->s_offset, s->s_size, s))
474 if ((size_t) rc < s->s_offset + s->s_size)
475 rc = (off_t) (s->s_offset + s->s_size);
482 * Recompute the layout of the ELF object and update the internal data
483 * structures associated with the ELF descriptor.
485 * Returns the size in bytes the ELF object would occupy in its file
488 * After a successful call to this function, the following structures
491 * - The ELF header is updated.
492 * - All extents in the ELF object are sorted in order of ascending
493 * addresses. Sections have their section header table entries
494 * updated. An error is signalled if an overlap was detected among
496 * - Data descriptors associated with sections are checked for valid
497 * types, offsets and alignment.
499 * After a resync_elf() successfully returns, the ELF descriptor is
500 * ready for being handed over to _libelf_write_elf().
504 _libelf_resync_elf(Elf *e, struct _Elf_Extent_List *extents)
507 unsigned int eh_byteorder, eh_version;
510 off_t rc, phoff, shoff;
519 assert(ec == ELFCLASS32 || ec == ELFCLASS64);
524 if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
530 if (ec == ELFCLASS32) {
531 eh_byteorder = eh32->e_ident[EI_DATA];
532 eh_class = eh32->e_ident[EI_CLASS];
533 phoff = (off_t) eh32->e_phoff;
534 shoff = (off_t) eh32->e_shoff;
535 eh_version = eh32->e_version;
537 eh_byteorder = eh64->e_ident[EI_DATA];
538 eh_class = eh64->e_ident[EI_CLASS];
539 phoff = (off_t) eh64->e_phoff;
540 shoff = (off_t) eh64->e_shoff;
541 eh_version = eh64->e_version;
544 if (phoff < 0 || shoff < 0) {
545 LIBELF_SET_ERROR(HEADER, 0);
549 if (eh_version == EV_NONE)
550 eh_version = EV_CURRENT;
552 if (eh_version != e->e_version) { /* always EV_CURRENT */
553 LIBELF_SET_ERROR(VERSION, 0);
557 if (eh_class != e->e_class) {
558 LIBELF_SET_ERROR(CLASS, 0);
562 if (e->e_cmd != ELF_C_WRITE && eh_byteorder != e->e_byteorder) {
563 LIBELF_SET_ERROR(HEADER, 0);
567 shnum = e->e_u.e_elf.e_nscn;
568 phnum = e->e_u.e_elf.e_nphdr;
570 e->e_byteorder = eh_byteorder;
572 #define INITIALIZE_EHDR(E,EC,V) do { \
573 unsigned int _version = (unsigned int) (V); \
574 (E)->e_ident[EI_MAG0] = ELFMAG0; \
575 (E)->e_ident[EI_MAG1] = ELFMAG1; \
576 (E)->e_ident[EI_MAG2] = ELFMAG2; \
577 (E)->e_ident[EI_MAG3] = ELFMAG3; \
578 (E)->e_ident[EI_CLASS] = (unsigned char) (EC); \
579 (E)->e_ident[EI_VERSION] = (_version & 0xFFU); \
580 (E)->e_ehsize = (uint16_t) _libelf_fsize(ELF_T_EHDR, \
581 (EC), _version, (size_t) 1); \
582 (E)->e_phentsize = (uint16_t) ((phnum == 0) ? 0 : \
583 _libelf_fsize(ELF_T_PHDR, (EC), _version, \
585 (E)->e_shentsize = (uint16_t) _libelf_fsize(ELF_T_SHDR, \
586 (EC), _version, (size_t) 1); \
589 if (ec == ELFCLASS32)
590 INITIALIZE_EHDR(eh32, ec, eh_version);
592 INITIALIZE_EHDR(eh64, ec, eh_version);
594 (void) elf_flagehdr(e, ELF_C_SET, ELF_F_DIRTY);
596 rc += (off_t) _libelf_fsize(ELF_T_EHDR, ec, eh_version, (size_t) 1);
598 if (!_libelf_insert_extent(extents, ELF_EXTENT_EHDR, 0, (uint64_t) rc,
603 * Compute the layout the program header table, if one is
604 * present. The program header table needs to be aligned to a
605 * `natural' boundary.
608 fsz = _libelf_fsize(ELF_T_PHDR, ec, eh_version, phnum);
609 align = _libelf_falign(ELF_T_PHDR, ec);
611 if (e->e_flags & ELF_F_LAYOUT) {
613 * Check offsets for sanity.
616 LIBELF_SET_ERROR(LAYOUT, 0);
620 if (phoff % (off_t) align) {
621 LIBELF_SET_ERROR(LAYOUT, 0);
626 phoff = roundup(rc, (off_t) align);
628 rc = phoff + (off_t) fsz;
630 phdr = _libelf_getphdr(e, ec);
632 if (!_libelf_insert_extent(extents, ELF_EXTENT_PHDR,
633 (uint64_t) phoff, fsz, phdr))
639 * Compute the layout of the sections associated with the
643 if (e->e_cmd != ELF_C_WRITE &&
644 (e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 &&
645 _libelf_load_section_headers(e, ehdr) == 0)
648 if ((rc = _libelf_resync_sections(e, rc, extents)) < 0)
652 * Compute the space taken up by the section header table, if
655 * If ELF_F_LAYOUT has been asserted, the application may have
656 * placed the section header table in between existing
657 * sections, so the net size of the file need not increase due
658 * to the presence of the section header table.
660 * If the library is responsible for laying out the object,
661 * the section header table is placed after section data.
664 fsz = _libelf_fsize(ELF_T_SHDR, ec, eh_version, shnum);
665 align = _libelf_falign(ELF_T_SHDR, ec);
667 if (e->e_flags & ELF_F_LAYOUT) {
668 if (shoff % (off_t) align) {
669 LIBELF_SET_ERROR(LAYOUT, 0);
673 shoff = roundup(rc, (off_t) align);
675 if (shoff + (off_t) fsz > rc)
676 rc = shoff + (off_t) fsz;
678 if (!_libelf_insert_extent(extents, ELF_EXTENT_SHDR,
679 (uint64_t) shoff, fsz, NULL))
685 * Set the fields of the Executable Header that could potentially use
686 * extended numbering.
688 _libelf_setphnum(e, ehdr, ec, phnum);
689 _libelf_setshnum(e, ehdr, ec, shnum);
692 * Update the `e_phoff' and `e_shoff' fields if the library is
695 if ((e->e_flags & ELF_F_LAYOUT) == 0) {
696 if (ec == ELFCLASS32) {
697 eh32->e_phoff = (uint32_t) phoff;
698 eh32->e_shoff = (uint32_t) shoff;
700 eh64->e_phoff = (uint64_t) phoff;
701 eh64->e_shoff = (uint64_t) shoff;
709 * Write out the contents of an ELF section.
713 _libelf_write_scn(Elf *e, unsigned char *nf, struct _Elf_Extent *ex)
721 struct _Libelf_Data *ld;
722 uint64_t sh_off, sh_size;
723 size_t fsz, msz, nobjects;
725 assert(ex->ex_type == ELF_EXTENT_SECTION);
728 rc = (off_t) ex->ex_start;
730 if ((ec = e->e_class) == ELFCLASS32) {
731 sh_type = s->s_shdr.s_shdr32.sh_type;
732 sh_size = (uint64_t) s->s_shdr.s_shdr32.sh_size;
734 sh_type = s->s_shdr.s_shdr64.sh_type;
735 sh_size = s->s_shdr.s_shdr64.sh_size;
739 * Ignore sections that do not allocate space in the file.
741 if (sh_type == SHT_NOBITS || sh_type == SHT_NULL || sh_size == 0)
744 elftype = _libelf_xlate_shtype(sh_type);
745 assert(elftype >= ELF_T_FIRST && elftype <= ELF_T_LAST);
747 sh_off = s->s_offset;
748 assert(sh_off % _libelf_falign(elftype, ec) == 0);
751 * If the section has a `rawdata' descriptor, and the section
752 * contents have not been modified, use its contents directly.
753 * The `s_rawoff' member contains the offset into the original
754 * file, while `s_offset' contains its new location in the
758 if (STAILQ_EMPTY(&s->s_data)) {
760 if ((d = elf_rawdata(s, NULL)) == NULL)
763 STAILQ_FOREACH(ld, &s->s_rawdata, d_next) {
767 if ((uint64_t) rc < sh_off + d->d_off)
768 (void) memset(nf + rc,
769 LIBELF_PRIVATE(fillchar),
770 (size_t) (sh_off + d->d_off -
772 rc = (off_t) (sh_off + d->d_off);
774 assert(d->d_buf != NULL);
775 assert(d->d_type == ELF_T_BYTE);
776 assert(d->d_version == e->e_version);
778 (void) memcpy(nf + rc,
779 e->e_rawfile + s->s_rawoff + d->d_off,
782 rc += (off_t) d->d_size;
789 * Iterate over the set of data descriptors for this section.
790 * The prior call to _libelf_resync_elf() would have setup the
791 * descriptors for this step.
794 dst.d_version = e->e_version;
796 STAILQ_FOREACH(ld, &s->s_data, d_next) {
800 msz = _libelf_msize(d->d_type, ec, e->e_version);
802 if ((uint64_t) rc < sh_off + d->d_off)
803 (void) memset(nf + rc,
804 LIBELF_PRIVATE(fillchar),
805 (size_t) (sh_off + d->d_off - (uint64_t) rc));
807 rc = (off_t) (sh_off + d->d_off);
809 assert(d->d_buf != NULL);
810 assert(d->d_version == e->e_version);
812 assert(d->d_size % msz == 0);
814 nobjects = (size_t) (d->d_size / msz);
816 fsz = _libelf_fsize(d->d_type, ec, e->e_version, nobjects);
821 if (_libelf_xlate(&dst, d, e->e_byteorder, ec, ELF_TOFILE) ==
832 * Write out an ELF Executable Header.
836 _libelf_write_ehdr(Elf *e, unsigned char *nf, struct _Elf_Extent *ex)
843 assert(ex->ex_type == ELF_EXTENT_EHDR);
844 assert(ex->ex_start == 0); /* Ehdr always comes first. */
848 ehdr = _libelf_ehdr(e, ec, 0);
849 assert(ehdr != NULL);
851 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1);
852 msz = _libelf_msize(ELF_T_EHDR, ec, e->e_version);
854 (void) memset(&dst, 0, sizeof(dst));
855 (void) memset(&src, 0, sizeof(src));
859 src.d_type = ELF_T_EHDR;
860 src.d_version = dst.d_version = e->e_version;
865 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) ==
869 return ((off_t) fsz);
873 * Write out an ELF program header table.
877 _libelf_write_phdr(Elf *e, unsigned char *nf, struct _Elf_Extent *ex)
887 assert(ex->ex_type == ELF_EXTENT_PHDR);
890 ehdr = _libelf_ehdr(e, ec, 0);
891 phnum = e->e_u.e_elf.e_nphdr;
895 if (ec == ELFCLASS32) {
896 eh32 = (Elf32_Ehdr *) ehdr;
897 phoff = (uint64_t) eh32->e_phoff;
899 eh64 = (Elf64_Ehdr *) ehdr;
900 phoff = eh64->e_phoff;
904 assert(ex->ex_start == phoff);
905 assert(phoff % _libelf_falign(ELF_T_PHDR, ec) == 0);
907 (void) memset(&dst, 0, sizeof(dst));
908 (void) memset(&src, 0, sizeof(src));
910 fsz = _libelf_fsize(ELF_T_PHDR, ec, e->e_version, phnum);
913 src.d_buf = _libelf_getphdr(e, ec);
914 src.d_version = dst.d_version = e->e_version;
915 src.d_type = ELF_T_PHDR;
916 src.d_size = phnum * _libelf_msize(ELF_T_PHDR, ec,
920 dst.d_buf = nf + ex->ex_start;
922 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) ==
926 return ((off_t) (phoff + fsz));
930 * Write out an ELF section header table.
934 _libelf_write_shdr(Elf *e, unsigned char *nf, struct _Elf_Extent *ex)
945 assert(ex->ex_type == ELF_EXTENT_SHDR);
948 ehdr = _libelf_ehdr(e, ec, 0);
949 nscn = e->e_u.e_elf.e_nscn;
951 if (ec == ELFCLASS32) {
952 eh32 = (Elf32_Ehdr *) ehdr;
953 shoff = (uint64_t) eh32->e_shoff;
955 eh64 = (Elf64_Ehdr *) ehdr;
956 shoff = eh64->e_shoff;
960 assert(shoff % _libelf_falign(ELF_T_SHDR, ec) == 0);
961 assert(ex->ex_start == shoff);
963 (void) memset(&dst, 0, sizeof(dst));
964 (void) memset(&src, 0, sizeof(src));
966 src.d_type = ELF_T_SHDR;
967 src.d_size = _libelf_msize(ELF_T_SHDR, ec, e->e_version);
968 src.d_version = dst.d_version = e->e_version;
970 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1);
972 STAILQ_FOREACH(scn, &e->e_u.e_elf.e_scn, s_next) {
973 if (ec == ELFCLASS32)
974 src.d_buf = &scn->s_shdr.s_shdr32;
976 src.d_buf = &scn->s_shdr.s_shdr64;
979 dst.d_buf = nf + ex->ex_start + scn->s_ndx * fsz;
981 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec,
986 return ((off_t) (ex->ex_start + nscn * fsz));
990 * Write out the file image.
992 * The original file could have been mapped in with an ELF_C_RDWR
993 * command and the application could have added new content or
994 * re-arranged its sections before calling elf_update(). Consequently
995 * its not safe to work `in place' on the original file. So we
996 * malloc() the required space for the updated ELF object and build
997 * the object there and write it out to the underlying file at the
998 * end. Note that the application may have opened the underlying file
999 * in ELF_C_RDWR and only retrieved/modified a few sections. We take
1000 * care to avoid translating file sections unnecessarily.
1002 * Gaps in the coverage of the file by the file's sections will be
1003 * filled with the fill character set by elf_fill(3).
1007 _libelf_write_elf(Elf *e, off_t newsize, struct _Elf_Extent_List *extents)
1010 Elf_Scn *scn, *tscn;
1011 struct _Elf_Extent *ex;
1012 unsigned char *newfile;
1014 assert(e->e_kind == ELF_K_ELF);
1015 assert(e->e_cmd == ELF_C_RDWR || e->e_cmd == ELF_C_WRITE);
1016 assert(e->e_fd >= 0);
1018 if ((newfile = malloc((size_t) newsize)) == NULL) {
1019 LIBELF_SET_ERROR(RESOURCE, errno);
1020 return ((off_t) -1);
1024 SLIST_FOREACH(ex, extents, ex_next) {
1026 /* Fill inter-extent gaps. */
1027 if (ex->ex_start > (size_t) rc)
1028 (void) memset(newfile + rc, LIBELF_PRIVATE(fillchar),
1029 (size_t) (ex->ex_start - (uint64_t) rc));
1031 switch (ex->ex_type) {
1032 case ELF_EXTENT_EHDR:
1033 if ((nrc = _libelf_write_ehdr(e, newfile, ex)) < 0)
1037 case ELF_EXTENT_PHDR:
1038 if ((nrc = _libelf_write_phdr(e, newfile, ex)) < 0)
1042 case ELF_EXTENT_SECTION:
1043 if ((nrc = _libelf_write_scn(e, newfile, ex)) < 0)
1047 case ELF_EXTENT_SHDR:
1048 if ((nrc = _libelf_write_shdr(e, newfile, ex)) < 0)
1057 assert(ex->ex_start + ex->ex_size == (size_t) nrc);
1063 assert(rc == newsize);
1066 * For regular files, throw away existing file content and
1067 * unmap any existing mappings.
1069 if ((e->e_flags & LIBELF_F_SPECIAL_FILE) == 0) {
1070 if (ftruncate(e->e_fd, (off_t) 0) < 0 ||
1071 lseek(e->e_fd, (off_t) 0, SEEK_SET)) {
1072 LIBELF_SET_ERROR(IO, errno);
1076 if (e->e_flags & LIBELF_F_RAWFILE_MMAP) {
1077 assert(e->e_rawfile != NULL);
1078 assert(e->e_cmd == ELF_C_RDWR);
1079 if (munmap(e->e_rawfile, e->e_rawsize) < 0) {
1080 LIBELF_SET_ERROR(IO, errno);
1088 * Write out the new contents.
1090 if (write(e->e_fd, newfile, (size_t) newsize) != newsize) {
1091 LIBELF_SET_ERROR(IO, errno);
1096 * For files opened in ELF_C_RDWR mode, set up the new 'raw'
1099 if (e->e_cmd == ELF_C_RDWR) {
1100 assert(e->e_rawfile != NULL);
1101 assert((e->e_flags & LIBELF_F_RAWFILE_MALLOC) ||
1102 (e->e_flags & LIBELF_F_RAWFILE_MMAP));
1103 if (e->e_flags & LIBELF_F_RAWFILE_MALLOC) {
1105 e->e_rawfile = newfile;
1109 else if (e->e_flags & LIBELF_F_RAWFILE_MMAP) {
1110 if ((e->e_rawfile = mmap(NULL, (size_t) newsize,
1111 PROT_READ, MAP_PRIVATE, e->e_fd, (off_t) 0)) ==
1113 LIBELF_SET_ERROR(IO, errno);
1117 #endif /* ELFTC_HAVE_MMAP */
1119 /* Record the new size of the file. */
1120 e->e_rawsize = (size_t) newsize;
1122 /* File opened in ELF_C_WRITE mode. */
1123 assert(e->e_rawfile == NULL);
1127 * Reset flags, remove existing section descriptors and
1128 * {E,P}HDR pointers so that a subsequent elf_get{e,p}hdr()
1129 * and elf_getscn() will function correctly.
1132 e->e_flags &= ~ELF_F_DIRTY;
1134 STAILQ_FOREACH_SAFE(scn, &e->e_u.e_elf.e_scn, s_next, tscn)
1135 _libelf_release_scn(scn);
1137 if (e->e_class == ELFCLASS32) {
1138 free(e->e_u.e_elf.e_ehdr.e_ehdr32);
1139 if (e->e_u.e_elf.e_phdr.e_phdr32)
1140 free(e->e_u.e_elf.e_phdr.e_phdr32);
1142 e->e_u.e_elf.e_ehdr.e_ehdr32 = NULL;
1143 e->e_u.e_elf.e_phdr.e_phdr32 = NULL;
1145 free(e->e_u.e_elf.e_ehdr.e_ehdr64);
1146 if (e->e_u.e_elf.e_phdr.e_phdr64)
1147 free(e->e_u.e_elf.e_phdr.e_phdr64);
1149 e->e_u.e_elf.e_ehdr.e_ehdr64 = NULL;
1150 e->e_u.e_elf.e_phdr.e_phdr64 = NULL;
1153 /* Free the temporary buffer. */
1162 return ((off_t) -1);
1166 * Update an ELF object.
1170 elf_update(Elf *e, Elf_Cmd c)
1174 struct _Elf_Extent_List extents;
1178 if (e == NULL || e->e_kind != ELF_K_ELF ||
1179 (c != ELF_C_NULL && c != ELF_C_WRITE)) {
1180 LIBELF_SET_ERROR(ARGUMENT, 0);
1184 if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) {
1185 LIBELF_SET_ERROR(CLASS, 0);
1189 if (e->e_version == EV_NONE)
1190 e->e_version = EV_CURRENT;
1192 if (c == ELF_C_WRITE && e->e_cmd == ELF_C_READ) {
1193 LIBELF_SET_ERROR(MODE, 0);
1197 SLIST_INIT(&extents);
1199 if ((rc = _libelf_resync_elf(e, &extents)) < 0)
1202 if (c == ELF_C_NULL)
1207 LIBELF_SET_ERROR(SEQUENCE, 0);
1211 rc = _libelf_write_elf(e, rc, &extents);
1214 _libelf_release_extents(&extents);