5 #include <libelfu/libelfu.h>
8 static void parseSymtab(ElfuElf *me, ElfuScn *ms, ElfuScn**origScnArr)
17 /* Parse symbols from their elfclass-specific format */
18 if (me->elfclass == ELFCLASS32) {
19 for (i = 1; (i + 1) * sizeof(Elf32_Sym) <= ms->shdr.sh_size; i++) {
20 Elf32_Sym *cursym = ((Elf32_Sym*)ms->databuf) + i;
21 ElfuSym *newsym = malloc(sizeof(*sym));
24 newsym->name = cursym->st_name;
25 newsym->value = cursym->st_value;
26 newsym->size = cursym->st_size;
27 newsym->bind = ELF32_ST_BIND(cursym->st_info);
28 newsym->type = ELF32_ST_TYPE(cursym->st_info);
29 newsym->other = cursym->st_other;
30 newsym->shndx = cursym->st_shndx;
32 CIRCLEQ_INSERT_TAIL(&ms->symtab.syms, newsym, elem);
34 } else if (me->elfclass == ELFCLASS64) {
35 for (i = 1; (i + 1) * sizeof(Elf64_Sym) <= ms->shdr.sh_size; i++) {
36 Elf64_Sym *cursym = ((Elf64_Sym*)ms->databuf) + i;
37 ElfuSym *newsym = malloc(sizeof(*sym));
40 newsym->name = cursym->st_name;
41 newsym->value = cursym->st_value;
42 newsym->size = cursym->st_size;
43 newsym->bind = ELF64_ST_BIND(cursym->st_info);
44 newsym->type = ELF64_ST_TYPE(cursym->st_info);
45 newsym->other = cursym->st_other;
46 newsym->shndx = cursym->st_shndx;
48 CIRCLEQ_INSERT_TAIL(&ms->symtab.syms, newsym, elem);
51 /* Unknown elfclass */
55 /* For each section, find the section it points to if any. */
56 CIRCLEQ_FOREACH(sym, &ms->symtab.syms, elem) {
64 sym->scnptr = origScnArr[sym->shndx - 1];
71 static void parseReltab32(ElfuScn *ms)
79 for (i = 0; (i + 1) * sizeof(Elf32_Rel) <= ms->shdr.sh_size; i++) {
80 Elf32_Rel *currel = &(((Elf32_Rel*)ms->databuf)[i]);
83 rel = malloc(sizeof(*rel));
86 rel->offset = currel->r_offset;
87 rel->sym = ELF32_R_SYM(currel->r_info);
88 rel->type = ELF32_R_TYPE(currel->r_info);
92 CIRCLEQ_INSERT_TAIL(&ms->reltab.rels, rel, elem);
97 static void parseRelatab64(ElfuScn *ms)
105 for (i = 0; (i + 1) * sizeof(Elf64_Rela) <= ms->shdr.sh_size; i++) {
106 Elf64_Rela *currel = &(((Elf64_Rela*)ms->databuf)[i]);
109 rel = malloc(sizeof(*rel));
112 rel->offset = currel->r_offset;
113 rel->sym = ELF64_R_SYM(currel->r_info);
114 rel->type = ELF64_R_TYPE(currel->r_info);
116 rel->addend = currel->r_addend;
118 CIRCLEQ_INSERT_TAIL(&ms->reltab.rels, rel, elem);
123 static int cmpScnOffs(const void *ms1, const void *ms2)
125 ElfuScn *s1 = *(ElfuScn**)ms1;
126 ElfuScn *s2 = *(ElfuScn**)ms2;
131 s1 = *(ElfuScn**)ms1;
132 s2 = *(ElfuScn**)ms2;
138 if (s1->shdr.sh_offset < s2->shdr.sh_offset) {
140 } else if (s1->shdr.sh_offset == s2->shdr.sh_offset) {
142 } else /* if (s1->shdr.sh_offset > s2->shdr.sh_offset) */ {
149 static ElfuPhdr* parentPhdr(ElfuElf *me, ElfuScn *ms)
156 CIRCLEQ_FOREACH(mp, &me->phdrList, elem) {
157 if (mp->phdr.p_type != PT_LOAD) {
161 if (PHDR_CONTAINS_SCN_IN_MEMORY(&mp->phdr, &ms->shdr)) {
165 /* Give sections a second chance if they do not have any sh_addr
167 /* Actually we don't, because it's ambiguous.
168 * Re-enable for experiments with strangely-formatted files.
169 if (ms->shdr.sh_addr == 0
170 && PHDR_CONTAINS_SCN_IN_FILE(&mp->phdr, &ms->shdr)
171 && OFFS_END(ms->shdr.sh_offset, ms->shdr.sh_size)
172 <= OFFS_END(mp->phdr.p_offset, mp->phdr.p_memsz)) {
182 static ElfuPhdr* modelFromPhdr(GElf_Phdr *phdr)
188 mp = malloc(sizeof(ElfuPhdr));
190 ELFU_WARN("modelFromPhdr: malloc() failed for ElfuPhdr.\n");
196 CIRCLEQ_INIT(&mp->childScnList);
197 CIRCLEQ_INIT(&mp->childPhdrList);
203 static ElfuScn* modelFromSection(Elf_Scn *scn)
209 ms = elfu_mScnAlloc();
215 assert(gelf_getshdr(scn, &ms->shdr) == &ms->shdr);
217 /* Copy each data part in source segment */
218 if (SCNFILESIZE(&ms->shdr) > 0) {
221 ms->databuf = malloc(ms->shdr.sh_size);
223 ELFU_WARN("modelFromSection: malloc() failed for data buffer (%x bytes).\n", (unsigned)ms->shdr.sh_size);
227 /* A non-empty section should contain at least one data block. */
228 data = elf_rawdata(scn, NULL);
231 /* elf_rawdata() always returns ELF_T_BYTE */
232 assert(data->d_type == ELF_T_BYTE);
235 if (data->d_off + data->d_size > ms->shdr.sh_size) {
236 ELFU_WARN("modelFromSection: libelf delivered a bogus data blob. Skipping\n");
238 memcpy((char*)ms->databuf + data->d_off, data->d_buf, data->d_size);
241 data = elf_rawdata(scn, data);
257 ElfuElf* elfu_mFromElf(Elf *e)
261 size_t i, numPhdr, numShdr;
262 ElfuScn **secArray = NULL;
265 if (elfu_eCheck(e)) {
269 me = malloc(sizeof(ElfuElf));
271 ELFU_WARN("elfu_mFromElf: malloc() failed for ElfuElf.\n");
277 CIRCLEQ_INIT(&me->phdrList);
278 CIRCLEQ_INIT(&me->orphanScnList);
282 me->elfclass = gelf_getclass(e);
283 assert(me->elfclass != ELFCLASSNONE);
284 assert(gelf_getehdr(e, &me->ehdr) == &me->ehdr);
287 /* Get the section string table index */
288 if (elf_getshdrstrndx(e, &shstrndx) != 0) {
294 assert(!elf_getphdrnum(e, &numPhdr));
295 for (i = 0; i < numPhdr; i++) {
299 assert(gelf_getphdr(e, i, &phdr) == &phdr);
301 mp = modelFromPhdr(&phdr);
306 CIRCLEQ_INSERT_TAIL(&me->phdrList, mp, elem);
312 /* Find PHDR -> PHDR dependencies (needs sorted sections) */
313 CIRCLEQ_FOREACH(mp, &me->phdrList, elem) {
316 if (mp->phdr.p_type != PT_LOAD) {
320 CIRCLEQ_FOREACH(mp2, &me->phdrList, elem) {
325 if (mp->phdr.p_vaddr <= mp2->phdr.p_vaddr
326 && OFFS_END(mp2->phdr.p_vaddr, mp2->phdr.p_memsz) <= OFFS_END(mp->phdr.p_vaddr, mp->phdr.p_memsz)) {
327 CIRCLEQ_INSERT_TAIL(&mp->childPhdrList, mp2, elemChildPhdr);
335 assert(!elf_getshdrnum(e, &numShdr));
337 secArray = malloc((numShdr - 1) * sizeof(*secArray));
339 ELFU_WARN("elfu_mFromElf: malloc() failed for secArray.\n");
343 for (i = 1; i < numShdr; i++) {
347 scn = elf_getscn(e, i);
350 ms = modelFromSection(scn);
363 /* Find sh_link and sh_info dependencies (needs sections in original order) */
364 for (i = 0; i < numShdr - 1; i++) {
365 ElfuScn *ms = secArray[i];
367 switch (ms->shdr.sh_type) {
370 if (ms->shdr.sh_info > 0) {
371 ms->infoptr = secArray[ms->shdr.sh_info - 1];
379 case SHT_GNU_verneed:
380 if (ms->shdr.sh_link > 0) {
381 ms->linkptr = secArray[ms->shdr.sh_link - 1];
387 /* Parse symtabs (needs sections in original order) */
388 for (i = 0; i < numShdr - 1; i++) {
389 ElfuScn *ms = secArray[i];
391 switch (ms->shdr.sh_type) {
395 parseSymtab(me, ms, secArray);
401 /* Parse relocations */
402 for (i = 0; i < numShdr - 1; i++) {
403 ElfuScn *ms = secArray[i];
405 switch (ms->shdr.sh_type) {
407 if (me->elfclass == ELFCLASS32) {
409 } else if (me->elfclass == ELFCLASS64) {
410 /* Not used on x86-64 */
415 if (me->elfclass == ELFCLASS32) {
416 /* Not used on x86-32 */
418 } else if (me->elfclass == ELFCLASS64) {
426 /* Sort sections by file offset */
427 qsort(secArray, numShdr - 1, sizeof(*secArray), cmpScnOffs);
430 /* Find PHDR -> Section dependencies (needs sorted sections) */
431 for (i = 0; i < numShdr - 1; i++) {
432 ElfuScn *ms = secArray[i];
434 ElfuPhdr *parent = parentPhdr(me, ms);
437 GElf_Off shaddr = parent->phdr.p_vaddr +
438 (ms->shdr.sh_offset - parent->phdr.p_offset);
440 if (ms->shdr.sh_addr == 0) {
441 ms->shdr.sh_addr = shaddr;
443 assert(ms->shdr.sh_addr == shaddr);
446 CIRCLEQ_INSERT_TAIL(&parent->childScnList, ms, elemChildScn);
448 CIRCLEQ_INSERT_TAIL(&me->orphanScnList, ms, elemChildScn);
462 // TODO: Free data structures
465 ELFU_WARN("elfu_mFromElf: Failed to load file.\n");