5 #include <libelfu/libelfu.h>
8 static void parseSymtab(ElfuElf *me, ElfuScn *ms, ElfuScn**origScnArr)
14 assert(ms->data.d_buf);
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->data.d_buf) + 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;
34 CIRCLEQ_INSERT_TAIL(&ms->symtab.syms, newsym, elem);
36 } else if (me->elfclass == ELFCLASS64) {
37 for (i = 1; (i + 1) * sizeof(Elf64_Sym) <= ms->shdr.sh_size; i++) {
38 Elf64_Sym *cursym = ((Elf64_Sym*)ms->data.d_buf) + i;
39 ElfuSym *newsym = malloc(sizeof(*sym));
42 newsym->name = cursym->st_name;
43 newsym->value = cursym->st_value;
44 newsym->size = cursym->st_size;
45 newsym->bind = ELF64_ST_BIND(cursym->st_info);
46 newsym->type = ELF64_ST_TYPE(cursym->st_info);
47 newsym->other = cursym->st_other;
48 newsym->shndx = cursym->st_shndx;
52 CIRCLEQ_INSERT_TAIL(&ms->symtab.syms, newsym, elem);
59 /* For each section, find the section it points to if any. */
60 CIRCLEQ_FOREACH(sym, &ms->symtab.syms, elem) {
68 sym->scnptr = origScnArr[sym->shndx - 1];
75 static void parseReltab32(ElfuScn *ms)
80 assert(ms->data.d_buf);
83 for (i = 0; (i + 1) * sizeof(Elf32_Rel) <= ms->shdr.sh_size; i++) {
84 Elf32_Rel *currel = &(((Elf32_Rel*)ms->data.d_buf)[i]);
87 rel = malloc(sizeof(*rel));
90 rel->offset = currel->r_offset;
91 rel->sym = ELF32_R_SYM(currel->r_info);
92 rel->type = ELF32_R_TYPE(currel->r_info);
96 CIRCLEQ_INSERT_TAIL(&ms->reltab.rels, rel, elem);
101 static void parseRelatab64(ElfuScn *ms)
106 assert(ms->data.d_buf);
109 for (i = 0; (i + 1) * sizeof(Elf64_Rela) <= ms->shdr.sh_size; i++) {
110 Elf64_Rela *currel = &(((Elf64_Rela*)ms->data.d_buf)[i]);
113 rel = malloc(sizeof(*rel));
116 rel->offset = currel->r_offset;
117 rel->sym = ELF64_R_SYM(currel->r_info);
118 rel->type = ELF64_R_TYPE(currel->r_info);
120 rel->addend = currel->r_addend;
122 CIRCLEQ_INSERT_TAIL(&ms->reltab.rels, rel, elem);
127 static int cmpScnOffs(const void *ms1, const void *ms2)
132 ElfuScn *s1 = *(ElfuScn**)ms1;
133 ElfuScn *s2 = *(ElfuScn**)ms2;
139 if (s1->shdr.sh_offset < s2->shdr.sh_offset) {
141 } else if (s1->shdr.sh_offset == s2->shdr.sh_offset) {
143 } else /* if (s1->shdr.sh_offset > s2->shdr.sh_offset) */ {
150 static ElfuPhdr* parentPhdr(ElfuElf *me, ElfuScn *ms)
157 CIRCLEQ_FOREACH(mp, &me->phdrList, elem) {
158 if (mp->phdr.p_type != PT_LOAD) {
162 if (PHDR_CONTAINS_SCN_IN_MEMORY(&mp->phdr, &ms->shdr)) {
166 /* Give sections a second chance if they do not have any sh_addr
168 /* Actually we don't, because it's ambiguous.
169 * Re-enable for experiments with strangely-formatted files.
170 if (ms->shdr.sh_addr == 0
171 && PHDR_CONTAINS_SCN_IN_FILE(&mp->phdr, &ms->shdr)
172 && OFFS_END(ms->shdr.sh_offset, ms->shdr.sh_size)
173 <= OFFS_END(mp->phdr.p_offset, mp->phdr.p_memsz)) {
183 static ElfuPhdr* modelFromPhdr(GElf_Phdr *phdr)
189 mp = malloc(sizeof(ElfuPhdr));
191 ELFU_WARN("modelFromPhdr: malloc() failed for ElfuPhdr.\n");
197 CIRCLEQ_INIT(&mp->childScnList);
198 CIRCLEQ_INIT(&mp->childPhdrList);
204 static ElfuScn* modelFromSection(Elf_Scn *scn)
210 ms = malloc(sizeof(ElfuScn));
212 ELFU_WARN("modelFromSection: malloc() failed for ElfuScn.\n");
217 assert(gelf_getshdr(scn, &ms->shdr) == &ms->shdr);
220 /* Copy each data part in source segment */
221 ms->data.d_align = 1;
222 ms->data.d_buf = NULL;
224 ms->data.d_type = ELF_T_BYTE;
225 ms->data.d_size = ms->shdr.sh_size;
226 ms->data.d_version = elf_version(EV_NONE);
227 if (ms->shdr.sh_type != SHT_NOBITS
228 && ms->shdr.sh_size > 0) {
231 ms->data.d_buf = malloc(ms->shdr.sh_size);
232 if (!ms->data.d_buf) {
233 ELFU_WARN("modelFromSection: malloc() failed for data buffer (%jx bytes).\n", ms->shdr.sh_size);
237 /* A non-empty section should contain at least one data block. */
238 data = elf_rawdata(scn, NULL);
241 ms->data.d_align = data->d_align;
242 ms->data.d_type = data->d_type;
243 ms->data.d_version = data->d_version;
246 if (data->d_off + data->d_size > ms->shdr.sh_size) {
247 ELFU_WARN("modelFromSection: libelf delivered a bogus data blob. Skipping\n");
249 memcpy(ms->data.d_buf + data->d_off, data->d_buf, data->d_size);
252 data = elf_rawdata(scn, data);
261 CIRCLEQ_INIT(&ms->symtab.syms);
262 CIRCLEQ_INIT(&ms->reltab.rels);
277 ElfuElf* elfu_mFromElf(Elf *e)
281 size_t i, numPhdr, numShdr;
282 ElfuScn **secArray = NULL;
285 if (elfu_eCheck(e)) {
289 me = malloc(sizeof(ElfuElf));
291 ELFU_WARN("elfu_mFromElf: malloc() failed for ElfuElf.\n");
297 CIRCLEQ_INIT(&me->phdrList);
298 CIRCLEQ_INIT(&me->orphanScnList);
302 me->elfclass = gelf_getclass(e);
303 assert(me->elfclass != ELFCLASSNONE);
304 assert(gelf_getehdr(e, &me->ehdr) == &me->ehdr);
307 /* Get the section string table index */
308 if (elf_getshdrstrndx(e, &shstrndx) != 0) {
314 assert(!elf_getphdrnum(e, &numPhdr));
315 for (i = 0; i < numPhdr; i++) {
319 assert(gelf_getphdr(e, i, &phdr) == &phdr);
321 mp = modelFromPhdr(&phdr);
326 CIRCLEQ_INSERT_TAIL(&me->phdrList, mp, elem);
332 /* Find PHDR -> PHDR dependencies (needs sorted sections) */
333 CIRCLEQ_FOREACH(mp, &me->phdrList, elem) {
336 if (mp->phdr.p_type != PT_LOAD) {
340 CIRCLEQ_FOREACH(mp2, &me->phdrList, elem) {
345 if (mp->phdr.p_vaddr <= mp2->phdr.p_vaddr
346 && OFFS_END(mp2->phdr.p_vaddr, mp2->phdr.p_memsz) <= OFFS_END(mp->phdr.p_vaddr, mp->phdr.p_memsz)) {
347 CIRCLEQ_INSERT_TAIL(&mp->childPhdrList, mp2, elemChildPhdr);
355 assert(!elf_getshdrnum(e, &numShdr));
357 secArray = malloc((numShdr - 1) * sizeof(*secArray));
359 ELFU_WARN("elfu_mFromElf: malloc() failed for secArray.\n");
363 for (i = 1; i < numShdr; i++) {
367 scn = elf_getscn(e, i);
370 ms = modelFromSection(scn);
383 /* Find sh_link and sh_info dependencies (needs sections in original order) */
384 for (i = 0; i < numShdr - 1; i++) {
385 ElfuScn *ms = secArray[i];
387 switch (ms->shdr.sh_type) {
390 if (ms->shdr.sh_info > 0) {
391 ms->infoptr = secArray[ms->shdr.sh_info - 1];
399 case SHT_GNU_verneed:
400 if (ms->shdr.sh_link > 0) {
401 ms->linkptr = secArray[ms->shdr.sh_link - 1];
407 /* Parse symtabs (needs sections in original order) */
408 for (i = 0; i < numShdr - 1; i++) {
409 ElfuScn *ms = secArray[i];
411 switch (ms->shdr.sh_type) {
415 parseSymtab(me, ms, secArray);
421 /* Parse relocations */
422 for (i = 0; i < numShdr - 1; i++) {
423 ElfuScn *ms = secArray[i];
425 switch (ms->shdr.sh_type) {
427 if (me->elfclass == ELFCLASS32) {
429 } else if (me->elfclass == ELFCLASS64) {
430 // Not used on x86-64
434 if (me->elfclass == ELFCLASS32) {
436 } else if (me->elfclass == ELFCLASS64) {
444 /* Sort sections by file offset */
445 qsort(secArray, numShdr - 1, sizeof(*secArray), cmpScnOffs);
448 /* Find PHDR -> Section dependencies (needs sorted sections) */
449 for (i = 0; i < numShdr - 1; i++) {
450 ElfuScn *ms = secArray[i];
452 ElfuPhdr *parent = parentPhdr(me, ms);
455 GElf_Off shaddr = parent->phdr.p_vaddr +
456 (ms->shdr.sh_offset - parent->phdr.p_offset);
458 if (ms->shdr.sh_addr == 0) {
459 ms->shdr.sh_addr = shaddr;
461 assert(ms->shdr.sh_addr == shaddr);
464 CIRCLEQ_INSERT_TAIL(&parent->childScnList, ms, elemChildScn);
466 CIRCLEQ_INSERT_TAIL(&me->orphanScnList, ms, elemChildScn);
480 // TODO: Free data structures
483 ELFU_WARN("elfu_mFromElf: Failed to load file.\n");