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#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <gelf.h>
#include <libelfu/libelfu.h>
void elfu_mExpandNobits(ElfuElf *me, GElf_Off off)
{
ElfuScn *ms;
ElfuPhdr *mp;
GElf_Xword expansionSize;
assert(me);
expansionSize = 0;
/* Find the maximum amount we need to expand by. Check PHDRs first */
CIRCLEQ_FOREACH(mp, &me->phdrList, elem) {
GElf_Off off2 = mp->phdr.p_offset;
GElf_Off end2 = mp->phdr.p_offset + mp->phdr.p_filesz;
if (end2 == off) {
GElf_Xword size2 = mp->phdr.p_memsz - mp->phdr.p_filesz;
if (size2 > expansionSize) {
expansionSize = size2;
}
} else if (end2 > off) {
if (off2 < off) {
/*
* Found a PHDR whose file contents overlaps with the section
* to be filled. This means that it relies on the NOBITS area
* being actually 0 bytes, and the expansion would ruin it.
*/
fprintf(stderr, "mExpandNobits: Found PHDR spanning expansion offset. Aborting.\n");
return;
}
} else {
// end2 < off, and the PHDR is unaffected.
continue;
}
}
/* Now check SHDRs */
CIRCLEQ_FOREACH(ms, &me->scnList, elem) {
if (ms->shdr.sh_offset == off) {
if (ms->shdr.sh_type == SHT_NOBITS) {
if (ms->shdr.sh_size > expansionSize) {
expansionSize = ms->shdr.sh_size;
}
}
}
}
/* Expand! */
/* Move all following PHDR offsets further down the file. */
CIRCLEQ_FOREACH(mp, &me->phdrList, elem) {
GElf_Off off2 = mp->phdr.p_offset;
GElf_Off end2 = mp->phdr.p_offset + mp->phdr.p_filesz;
if (off2 >= off) {
mp->phdr.p_offset += expansionSize;
} else {
if (end2 == off) {
/* This PHDR now has corresponding bytes in the file for every
* byte in memory. */
mp->phdr.p_filesz = mp->phdr.p_memsz;
}
}
}
/* Move the following sections */
CIRCLEQ_FOREACH(ms, &me->scnList, elem) {
if (ms->shdr.sh_offset >= off) {
if (ms->shdr.sh_offset > off
|| ms->shdr.sh_type != SHT_NOBITS) {
ms->shdr.sh_offset += expansionSize;
}
}
}
/* Move SHDR/PHDR tables */
if (me->ehdr.e_shoff >= off) {
me->ehdr.e_shoff += expansionSize;
}
if (me->ehdr.e_phoff >= off) {
me->ehdr.e_phoff += expansionSize;
}
/* Convert any NOBITS at off to PROGBITS */
CIRCLEQ_FOREACH(ms, &me->scnList, elem) {
if (ms->shdr.sh_offset == off) {
if (ms->shdr.sh_type == SHT_NOBITS) {
ms->data.d_buf = malloc(ms->shdr.sh_size);
memset(ms->data.d_buf, '\0', ms->shdr.sh_size);
if (!ms->data.d_buf) {
fprintf(stderr, "mExpandNobits: Could not allocate %jd bytes for NOBITS expansion.\n", ms->shdr.sh_size);
}
ms->data.d_align = 1;
ms->data.d_off = 0;
ms->data.d_type = ELF_T_BYTE;
ms->data.d_size = ms->shdr.sh_size;
ms->data.d_version = elf_version(EV_NONE);
ms->shdr.sh_type = SHT_PROGBITS;
}
}
}
}
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