+++ /dev/null
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <dyld.h>
-
-static int fixup_rela(struct dyld_info *info, const Elf32_Rela *rela,
- Elf32_Addr (*resolve_import)(const char *),
- const char **error_out)
-{
- const Elf32_Sym *sym = NULL;
- if(ELF32_R_SYM(rela->r_info) != 0)
- sym = &info->symtab[ELF32_R_SYM(rela->r_info)];
- Elf32_Addr value;
-
- switch(ELF32_R_TYPE(rela->r_info)) {
- case R_OR1K_NONE:
- return 1; // Does nothing.
-
- case R_OR1K_RELATIVE:
- value = info->base + rela->r_addend;
- break;
-
- case R_OR1K_32:
- case R_OR1K_GLOB_DAT:
- case R_OR1K_JMP_SLOT:
- value = (Elf32_Addr)dyld_lookup(&info->strtab[sym->st_name], info);
- if(value != 0)
- break;
-
- value = resolve_import(&info->strtab[sym->st_name]);
- if(value == 0) {
- static char error[256];
- snprintf(error, sizeof(error),
- "ELF object has an unresolved symbol: %s",
- &info->strtab[sym->st_name]);
- *error_out = error;
- return 0;
- }
- break;
-
- default:
- *error_out = "ELF object uses an unsupported relocation type";
- return 0;
- }
-
- memcpy((Elf32_Addr*)(info->base + rela->r_offset), &value,
- sizeof(Elf32_Addr));
-
- return 1;
-}
-
-int dyld_load(const void *shlib, Elf32_Addr base,
- Elf32_Addr (*resolve_import)(const char *),
- struct dyld_info *info, const char **error_out)
-{
- const Elf32_Ehdr *ehdr = (const Elf32_Ehdr *)shlib;
-
- const unsigned char expected_ident[EI_NIDENT] = {
- ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3,
- ELFCLASS32, ELFDATA2MSB, EV_CURRENT,
- ELFOSABI_NONE, /* ABI version */ 0
- };
- if(memcmp(ehdr->e_ident, expected_ident, EI_NIDENT) ||
- ehdr->e_type != ET_DYN) {
- *error_out = "ELF object is not a shared library";
- return 0;
- }
-
-#ifdef __or1k__
- if(ehdr->e_machine != EM_OPENRISC) {
- *error_out = "ELF object does not contain OpenRISC machine code";
- return 0;
- }
-#else
-#error Unsupported architecture
-#endif
-
- const Elf32_Phdr *phdr = (const Elf32_Phdr *)((intptr_t)shlib + ehdr->e_phoff);
- const Elf32_Dyn *dyn = NULL;
- for(int i = 0; i < ehdr->e_phnum; i++) {
- if(phdr[i].p_type == PT_DYNAMIC)
- dyn = (const Elf32_Dyn *)((intptr_t)shlib + phdr[i].p_offset);
-
- memcpy((void*)(base + phdr[i].p_vaddr),
- (const void*)((intptr_t)shlib + phdr[i].p_offset),
- phdr[i].p_filesz);
- }
-
- if(dyn == NULL) {
- *error_out = "ELF object does not have a PT_DYNAMIC header";
- return 0;
- }
-
- const char *strtab = NULL;
- const Elf32_Sym *symtab = NULL;
- const Elf32_Rela *rela = NULL, *pltrel = NULL;
- const Elf32_Word *hash = NULL;
- Elf32_Word init = 0;
- size_t syment = sizeof(Elf32_Sym), relaent = sizeof(Elf32_Rela),
- relanum = 0, pltrelnum = 0;
- while(dyn->d_tag != DT_NULL) {
- switch(dyn->d_tag) {
- case DT_STRTAB: strtab = (const char *)(base + dyn->d_un.d_ptr); break;
- case DT_SYMTAB: symtab = (const Elf32_Sym *)(base + dyn->d_un.d_ptr); break;
- case DT_SYMENT: syment = dyn->d_un.d_val; break;
- case DT_RELA: rela = (const Elf32_Rela *)(base + dyn->d_un.d_ptr); break;
- case DT_RELAENT: relaent = dyn->d_un.d_val; break;
- case DT_RELASZ: relanum = dyn->d_un.d_val / sizeof(Elf32_Rela); break;
- case DT_JMPREL: pltrel = (const Elf32_Rela *)(base + dyn->d_un.d_ptr); break;
- case DT_PLTRELSZ: pltrelnum = dyn->d_un.d_val / sizeof(Elf32_Rela); break;
- case DT_HASH: hash = (const Elf32_Word *)(base + dyn->d_un.d_ptr); break;
- case DT_INIT: init = dyn->d_un.d_val; break;
-
- case DT_REL:
- *error_out = "ELF object uses Rel relocations, which are not supported";
- return 0;
- }
-
- ++dyn;
- }
-
- if(symtab == NULL || syment == 0 || strtab == NULL) {
- *error_out = "ELF object must contain a symbol table";
- return 0;
- }
-
- if(syment != sizeof(Elf32_Sym) || relaent != sizeof(Elf32_Rela)) {
- *error_out = "ELF object uses an unknown format for symbols and relocations";
- return 0;
- }
-
- info->base = base;
- info->init = (void*)(base + init);
- info->strtab = strtab;
- info->symtab = symtab;
- info->hash.nbucket = hash[0];
- info->hash.nchain = hash[1];
- info->hash.bucket = &hash[2];
- info->hash.chain = &hash[2 + info->hash.nbucket];
-
- for(int i = 0; i < relanum; i++) {
- if(!fixup_rela(info, &rela[i], resolve_import, error_out))
- return 0;
- }
-
- for(int i = 0; i < pltrelnum; i++) {
- if(!fixup_rela(info, &pltrel[i], resolve_import, error_out))
- return 0;
- }
-
- return 1;
-}
-
-static unsigned long elf_hash(const unsigned char *name)
-{
- unsigned long h = 0, g;
- while(*name) {
- h = (h << 4) + *name++;
- if((g = h & 0xf0000000)) {
- h ^= g >> 24;
- h &= ~g;
- }
- }
- return h;
-}
-
-void *dyld_lookup(const char *symbol, struct dyld_info *info)
-{
- unsigned hash = elf_hash((const unsigned char*) symbol);
- unsigned index = info->hash.bucket[hash % info->hash.nbucket];
- while(strcmp(&info->strtab[info->symtab[index].st_name], symbol)) {
- if(index == STN_UNDEF)
- return NULL;
- index = info->hash.chain[index];
- }
-
- Elf32_Addr value = info->symtab[index].st_value;
- if(value != 0)
- return (void*)(info->base + value);
- else
- return NULL;
-}
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