elf32: more portable implementation.
The old implementation only worked on little-endian machines, and relied on a particular struct layout.
This commit is contained in:
Daniel Beer
parent
6fd161faa7
commit
f44d9d5281
141
formats/elf32.c
141
formats/elf32.c
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@ -44,11 +44,93 @@ struct elf32_info {
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int string_len;
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};
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static int parse_ehdr(Elf32_Ehdr *e, FILE *in)
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{
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uint8_t data[52];
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if (fread(data, sizeof(data), 1, in) != 1)
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return -1;
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memcpy(e->e_ident, data, EI_NIDENT);
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e->e_type = LE_WORD(data, 16);
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e->e_machine = LE_WORD(data, 18);
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e->e_version = LE_LONG(data, 20);
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e->e_entry = LE_LONG(data, 24);
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e->e_phoff = LE_LONG(data, 28);
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e->e_shoff = LE_LONG(data, 32);
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e->e_flags = LE_LONG(data, 36);
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e->e_ehsize = LE_WORD(data, 40);
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e->e_phentsize = LE_WORD(data, 42);
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e->e_phnum = LE_WORD(data, 44);
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e->e_shentsize = LE_WORD(data, 46);
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e->e_shnum = LE_WORD(data, 48);
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e->e_shstrndx = LE_WORD(data, 50);
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return 0;
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}
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static int parse_phdr(Elf32_Phdr *p, FILE *in)
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{
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uint8_t data[32];
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if (fread(data, sizeof(data), 1, in) != 1)
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return -1;
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p->p_type = LE_LONG(data, 0);
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p->p_offset = LE_LONG(data, 4);
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p->p_vaddr = LE_LONG(data, 8);
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p->p_paddr = LE_LONG(data, 12);
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p->p_filesz = LE_LONG(data, 16);
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p->p_memsz = LE_LONG(data, 20);
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p->p_flags = LE_LONG(data, 24);
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p->p_align = LE_LONG(data, 28);
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return 0;
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}
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static int parse_shdr(Elf32_Shdr *s, FILE *in)
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{
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uint8_t data[40];
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if (fread(data, sizeof(data), 1, in) != 1)
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return -1;
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s->sh_name = LE_LONG(data, 0);
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s->sh_type = LE_LONG(data, 4);
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s->sh_flags = LE_LONG(data, 8);
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s->sh_addr = LE_LONG(data, 12);
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s->sh_offset = LE_LONG(data, 16);
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s->sh_size = LE_LONG(data, 20);
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s->sh_link = LE_LONG(data, 24);
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s->sh_info = LE_LONG(data, 28);
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s->sh_addralign = LE_LONG(data, 32);
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s->sh_entsize = LE_LONG(data, 36);
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return 0;
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}
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static int parse_sym(Elf32_Sym *s, FILE *in)
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{
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uint8_t data[16];
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if (fread(data, sizeof(data), 1, in) != 1)
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return -1;
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s->st_name = LE_LONG(data, 0);
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s->st_value = LE_LONG(data, 4);
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s->st_size = LE_LONG(data, 8);
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s->st_info = data[12];
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s->st_other = data[13];
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s->st_shndx = LE_WORD(data, 14);
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return 0;
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}
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static int read_ehdr(struct elf32_info *info, FILE *in)
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{
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/* Read and check the ELF header */
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rewind(in);
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if (fread(&info->file_ehdr, sizeof(info->file_ehdr), 1, in) == 0) {
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if (parse_ehdr(&info->file_ehdr, in) < 0) {
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pr_error("elf32: couldn't read ELF header");
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return -1;
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}
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@ -79,8 +161,7 @@ static int read_phdr(struct elf32_info *info, FILE *in)
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return -1;
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}
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if (fread(&info->file_phdrs[i],
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sizeof(info->file_phdrs[0]), 1, in) == 0) {
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if (parse_phdr(&info->file_phdrs[i], in) < 0) {
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printc_err("elf32: can't read phdr %d: %s\n",
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i, last_error());
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return -1;
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@ -108,8 +189,7 @@ static int read_shdr(struct elf32_info *info, FILE *in)
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return -1;
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}
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if (fread(&info->file_shdrs[i],
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sizeof(info->file_shdrs[0]), 1, in) == 0) {
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if (parse_shdr(&info->file_shdrs[i], in) < 0) {
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printc_err("elf32: can't read shdr %d: %s\n",
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i, last_error());
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return -1;
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@ -217,7 +297,7 @@ static int load_strings(struct elf32_info *info, FILE *in, Elf32_Shdr *s)
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return -1;
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}
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if (!fread(info->string_tab, 1, info->string_len, in)) {
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if (!fread(info->string_tab, info->string_len, 1, in)) {
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if (ferror(in)) {
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pr_error("elf32: error reading strings");
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return -1;
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@ -296,50 +376,39 @@ static Elf32_Shdr *find_shdr(struct elf32_info *info, Elf32_Word type)
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static int syms_load_syms(struct elf32_info *info, FILE *in,
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Elf32_Shdr *s)
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{
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Elf32_Sym syms[N_SYMS];
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int len = s->sh_size / sizeof(syms[0]);
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int len = s->sh_size / 16;
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int i;
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if (fseek(in, s->sh_offset, SEEK_SET) < 0) {
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pr_error("elf32: can't seek to symbols");
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return -1;
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}
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while (len) {
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int req = N_SYMS > len ? len : N_SYMS;
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int count = fread(syms, sizeof(syms[0]), req, in);
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int i;
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for (i = 0; i < len; i++) {
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Elf32_Sym y;
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int st;
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const char *name;
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if (!count) {
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printc_err("elf32: eof reading symbols\n");
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return -1;
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}
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if (count < 0) {
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if (parse_sym(&y, in) < 0) {
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pr_error("elf32: error reading symbols");
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return -1;
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}
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for (i = 0; i < count; i++) {
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Elf32_Sym *y = &syms[i];
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int st = ELF32_ST_TYPE(y->st_info);
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const char *name = info->string_tab + y->st_name;
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st = ELF32_ST_TYPE(y.st_info);
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name = info->string_tab + y.st_name;
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if (y->st_name > info->string_len) {
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printc_err("elf32: symbol out of "
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"bounds\n");
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return -1;
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}
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if (name[0] &&
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(st == STT_OBJECT || st == STT_FUNC ||
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st == STT_SECTION || st == STT_COMMON ||
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st == STT_TLS) &&
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stab_set(info->string_tab + y->st_name,
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y->st_value) < 0)
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return -1;
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if (y.st_name > info->string_len) {
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printc_err("elf32: symbol out of bounds\n");
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return -1;
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}
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len -= count;
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if (name[0] &&
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(st == STT_OBJECT || st == STT_FUNC ||
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st == STT_SECTION || st == STT_COMMON ||
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st == STT_TLS) &&
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stab_set(info->string_tab + y.st_name,
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y.st_value) < 0)
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return -1;
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}
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return 0;
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