diff options
Diffstat (limited to 'scripts/elf-parse.c')
| -rw-r--r-- | scripts/elf-parse.c | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/scripts/elf-parse.c b/scripts/elf-parse.c new file mode 100644 index 000000000000..99869ff91a8c --- /dev/null +++ b/scripts/elf-parse.c @@ -0,0 +1,198 @@ +#include <sys/types.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <stdbool.h> +#include <string.h> +#include <unistd.h> +#include <errno.h> + +#include "elf-parse.h" + +struct elf_funcs elf_parser; + +/* + * Get the whole file as a programming convenience in order to avoid + * malloc+lseek+read+free of many pieces. If successful, then mmap + * avoids copying unused pieces; else just read the whole file. + * Open for both read and write. + */ +static void *map_file(char const *fname, size_t *size) +{ + int fd; + struct stat sb; + void *addr = NULL; + + fd = open(fname, O_RDWR); + if (fd < 0) { + perror(fname); + return NULL; + } + if (fstat(fd, &sb) < 0) { + perror(fname); + goto out; + } + if (!S_ISREG(sb.st_mode)) { + fprintf(stderr, "not a regular file: %s\n", fname); + goto out; + } + + addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); + if (addr == MAP_FAILED) { + fprintf(stderr, "Could not mmap file: %s\n", fname); + goto out; + } + + *size = sb.st_size; + +out: + close(fd); + return addr; +} + +static int elf_parse(const char *fname, void *addr, uint32_t types) +{ + Elf_Ehdr *ehdr = addr; + uint16_t type; + + switch (ehdr->e32.e_ident[EI_DATA]) { + case ELFDATA2LSB: + elf_parser.r = rle; + elf_parser.r2 = r2le; + elf_parser.r8 = r8le; + elf_parser.w = wle; + elf_parser.w8 = w8le; + break; + case ELFDATA2MSB: + elf_parser.r = rbe; + elf_parser.r2 = r2be; + elf_parser.r8 = r8be; + elf_parser.w = wbe; + elf_parser.w8 = w8be; + break; + default: + fprintf(stderr, "unrecognized ELF data encoding %d: %s\n", + ehdr->e32.e_ident[EI_DATA], fname); + return -1; + } + + if (memcmp(ELFMAG, ehdr->e32.e_ident, SELFMAG) != 0 || + ehdr->e32.e_ident[EI_VERSION] != EV_CURRENT) { + fprintf(stderr, "unrecognized ELF file %s\n", fname); + return -1; + } + + type = elf_parser.r2(&ehdr->e32.e_type); + if (!((1 << type) & types)) { + fprintf(stderr, "Invalid ELF type file %s\n", fname); + return -1; + } + + switch (ehdr->e32.e_ident[EI_CLASS]) { + case ELFCLASS32: { + elf_parser.ehdr_shoff = ehdr32_shoff; + elf_parser.ehdr_shentsize = ehdr32_shentsize; + elf_parser.ehdr_shstrndx = ehdr32_shstrndx; + elf_parser.ehdr_shnum = ehdr32_shnum; + elf_parser.shdr_addr = shdr32_addr; + elf_parser.shdr_offset = shdr32_offset; + elf_parser.shdr_link = shdr32_link; + elf_parser.shdr_size = shdr32_size; + elf_parser.shdr_name = shdr32_name; + elf_parser.shdr_type = shdr32_type; + elf_parser.shdr_entsize = shdr32_entsize; + elf_parser.sym_type = sym32_type; + elf_parser.sym_name = sym32_name; + elf_parser.sym_value = sym32_value; + elf_parser.sym_shndx = sym32_shndx; + elf_parser.rela_offset = rela32_offset; + elf_parser.rela_info = rela32_info; + elf_parser.rela_addend = rela32_addend; + elf_parser.rela_write_addend = rela32_write_addend; + + if (elf_parser.r2(&ehdr->e32.e_ehsize) != sizeof(Elf32_Ehdr) || + elf_parser.r2(&ehdr->e32.e_shentsize) != sizeof(Elf32_Shdr)) { + fprintf(stderr, + "unrecognized ET_EXEC/ET_DYN file: %s\n", fname); + return -1; + } + + } + break; + case ELFCLASS64: { + elf_parser.ehdr_shoff = ehdr64_shoff; + elf_parser.ehdr_shentsize = ehdr64_shentsize; + elf_parser.ehdr_shstrndx = ehdr64_shstrndx; + elf_parser.ehdr_shnum = ehdr64_shnum; + elf_parser.shdr_addr = shdr64_addr; + elf_parser.shdr_offset = shdr64_offset; + elf_parser.shdr_link = shdr64_link; + elf_parser.shdr_size = shdr64_size; + elf_parser.shdr_name = shdr64_name; + elf_parser.shdr_type = shdr64_type; + elf_parser.shdr_entsize = shdr64_entsize; + elf_parser.sym_type = sym64_type; + elf_parser.sym_name = sym64_name; + elf_parser.sym_value = sym64_value; + elf_parser.sym_shndx = sym64_shndx; + elf_parser.rela_offset = rela64_offset; + elf_parser.rela_info = rela64_info; + elf_parser.rela_addend = rela64_addend; + elf_parser.rela_write_addend = rela64_write_addend; + + if (elf_parser.r2(&ehdr->e64.e_ehsize) != sizeof(Elf64_Ehdr) || + elf_parser.r2(&ehdr->e64.e_shentsize) != sizeof(Elf64_Shdr)) { + fprintf(stderr, + "unrecognized ET_EXEC/ET_DYN file: %s\n", + fname); + return -1; + } + + } + break; + default: + fprintf(stderr, "unrecognized ELF class %d %s\n", + ehdr->e32.e_ident[EI_CLASS], fname); + return -1; + } + return 0; +} + +int elf_map_machine(void *addr) +{ + Elf_Ehdr *ehdr = addr; + + return elf_parser.r2(&ehdr->e32.e_machine); +} + +int elf_map_long_size(void *addr) +{ + Elf_Ehdr *ehdr = addr; + + return ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8; +} + +void *elf_map(char const *fname, size_t *size, uint32_t types) +{ + void *addr; + int ret; + + addr = map_file(fname, size); + if (!addr) + return NULL; + + ret = elf_parse(fname, addr, types); + if (ret < 0) { + elf_unmap(addr, *size); + return NULL; + } + + return addr; +} + +void elf_unmap(void *addr, size_t size) +{ + munmap(addr, size); +} |