diff options
Diffstat (limited to 'elf/readelflib.c')
| -rw-r--r-- | elf/readelflib.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/elf/readelflib.c b/elf/readelflib.c new file mode 100644 index 0000000..26444ad --- /dev/null +++ b/elf/readelflib.c @@ -0,0 +1,220 @@ +/* Copyright (C) 1999, 2000, 2001, 2002 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Andreas Jaeger <aj@suse.de>, 1999 and + Jakub Jelinek <jakub@redhat.com>, 1999. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +/* This code is a heavily simplified version of the readelf program + that's part of the current binutils development version. For architectures + which need to handle both 32bit and 64bit ELF libraries, this file is + included twice for each arch size. */ + +/* check_ptr checks that a pointer is in the mmaped file and doesn't + point outside it. */ +#undef check_ptr +#define check_ptr(ptr) \ +do \ + { \ + if ((void *)(ptr) < file_contents \ + || (void *)(ptr) > (file_contents+file_length)) \ + { \ + error (0, 0, _("file %s is truncated\n"), file_name); \ + return 1; \ + } \ + } \ + while (0); + +/* Returns 0 if everything is ok, != 0 in case of error. */ +int +process_elf_file (const char *file_name, const char *lib, int *flag, + unsigned int *osversion, char **soname, void *file_contents, + size_t file_length) +{ + int i; + unsigned int j; + ElfW(Addr) loadaddr; + unsigned int dynamic_addr; + size_t dynamic_size; + char *program_interpreter; + + ElfW(Ehdr) *elf_header; + ElfW(Phdr) *elf_pheader, *segment; + ElfW(Dyn) *dynamic_segment, *dyn_entry; + char *dynamic_strings; + + elf_header = (ElfW(Ehdr) *) file_contents; + *osversion = 0; + + if (elf_header->e_ident [EI_CLASS] != ElfW (CLASS)) + { + if (opt_verbose) + { + if (elf_header->e_ident [EI_CLASS] == ELFCLASS32) + error (0, 0, _("%s is a 32 bit ELF file.\n"), file_name); + else if (elf_header->e_ident [EI_CLASS] == ELFCLASS64) + error (0, 0, _("%s is a 64 bit ELF file.\n"), file_name); + else + error (0, 0, _("Unknown ELFCLASS in file %s.\n"), file_name); + } + return 1; + } + + if (elf_header->e_type != ET_DYN) + { + error (0, 0, _("%s is not a shared object file (Type: %d).\n"), file_name, + elf_header->e_type); + return 1; + } + + /* Get information from elf program header. */ + elf_pheader = (ElfW(Phdr) *) (elf_header->e_phoff + file_contents); + check_ptr (elf_pheader); + + /* The library is an elf library, now search for soname and + libc5/libc6. */ + *flag = FLAG_ELF; + + loadaddr = -1; + dynamic_addr = 0; + dynamic_size = 0; + program_interpreter = NULL; + for (i = 0, segment = elf_pheader; + i < elf_header->e_phnum; i++, segment++) + { + check_ptr (segment); + + switch (segment->p_type) + { + case PT_LOAD: + if (loadaddr == (ElfW(Addr)) -1) + loadaddr = segment->p_vaddr - segment->p_offset; + break; + + case PT_DYNAMIC: + if (dynamic_addr) + error (0, 0, _("more than one dynamic segment\n")); + + dynamic_addr = segment->p_offset; + dynamic_size = segment->p_filesz; + break; + + case PT_INTERP: + program_interpreter = (char *) (file_contents + segment->p_offset); + check_ptr (program_interpreter); + + /* Check if this is enough to classify the binary. */ + for (j = 0; j < sizeof (interpreters) / sizeof (interpreters [0]); + ++j) + if (strcmp (program_interpreter, interpreters[j].soname) == 0) + { + *flag = interpreters[j].flag; + break; + } + break; + + case PT_NOTE: + if (!*osversion && segment->p_filesz == 32 && segment->p_align >= 4) + { + ElfW(Word) *abi_note = (ElfW(Word) *) (file_contents + + segment->p_offset); + if (abi_note [0] == 4 && abi_note [1] == 16 && abi_note [2] == 1 + && memcmp (abi_note + 3, "GNU", 4) == 0) + *osversion = (abi_note [4] << 24) | + ((abi_note [5] & 0xff) << 16) | + ((abi_note [6] & 0xff) << 8) | + (abi_note [7] & 0xff); + } + break; + + default: + break; + } + + } + if (loadaddr == (ElfW(Addr)) -1) + { + /* Very strange. */ + loadaddr = 0; + } + + /* Now we can read the dynamic sections. */ + if (dynamic_size == 0) + return 1; + + dynamic_segment = (ElfW(Dyn) *) (file_contents + dynamic_addr); + check_ptr (dynamic_segment); + + /* Find the string table. */ + dynamic_strings = NULL; + for (dyn_entry = dynamic_segment; dyn_entry->d_tag != DT_NULL; + ++dyn_entry) + { + check_ptr (dyn_entry); + if (dyn_entry->d_tag == DT_STRTAB) + { + dynamic_strings = (char *) (file_contents + dyn_entry->d_un.d_val - loadaddr); + check_ptr (dynamic_strings); + break; + } + } + + if (dynamic_strings == NULL) + return 1; + + /* Now read the DT_NEEDED and DT_SONAME entries. */ + for (dyn_entry = dynamic_segment; dyn_entry->d_tag != DT_NULL; + ++dyn_entry) + { + if (dyn_entry->d_tag == DT_NEEDED || dyn_entry->d_tag == DT_SONAME) + { + char *name = dynamic_strings + dyn_entry->d_un.d_val; + check_ptr (name); + + if (dyn_entry->d_tag == DT_NEEDED) + { + + if (*flag == FLAG_ELF) + { + /* Check if this is enough to classify the binary. */ + for (j = 0; + j < sizeof (known_libs) / sizeof (known_libs [0]); + ++j) + if (strcmp (name, known_libs [j].soname) == 0) + { + *flag = known_libs [j].flag; + break; + } + } + } + + else if (dyn_entry->d_tag == DT_SONAME) + *soname = xstrdup (name); + + /* Do we have everything we need? */ + if (*soname && *flag != FLAG_ELF) + return 0; + } + } + + /* We reach this point only if the file doesn't contain a DT_SONAME + or if we can't classify the library. If it doesn't have a + soname, return the name of the library. */ + if (*soname == NULL) + *soname = xstrdup (lib); + + return 0; +} |