The Tor Browser: tools/reorder/elf_symbol

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 #include <string>

     6 #include <fstream>

     7 #include <errno.h>

     8 #include <fcntl.h>

     9 #include <stdlib.h>

    10 #include <stdio.h>

    11 #include <unistd.h>

    12 #include <sys/stat.h>

    14 #include "elf_symbol_table.h"

    15 #include "elf_utils.h"

    17 int

    18 elf_symbol_table::init(const char *name)

    19 {

    20     // Open the file readonly.

    21     m_fd = open(name, O_RDONLY);

    22     if (m_fd < 0) {

    23         perror(name);

    24         return m_fd;

    25     }

    27     // Get its size.

    28     struct stat statbuf;

    29     if (fstat(m_fd, &statbuf) < 0) {

    30         perror(name);

    31         return -1;

    32     }

    34     m_size = statbuf.st_size;

    36     // Memory map it.

    37     m_mapping = mmap(0, m_size, PROT_READ, MAP_SHARED, m_fd, 0);

    38     if (m_mapping == MAP_FAILED) {

    39         perror(name);

    40         return -1;

    41     }

    43     // Make sure it's an ELF header.

    44     const Elf32_Ehdr *ehdr = reinterpret_cast<const Elf32_Ehdr *>(m_mapping);

    45     if (elf_verify_header(ehdr) < 0)

    46         return -1;

    48     const char *mapping = reinterpret_cast<const char *>(m_mapping);

    50     // Find the section headers

    51     const Elf32_Shdr *shdrs

    52         = reinterpret_cast<const Elf32_Shdr *>(mapping + ehdr->e_shoff);

    54     // find the section header string table, .shstrtab

    55     const Elf32_Shdr *shstrtabsh = shdrs + ehdr->e_shstrndx;

    56     const char *shstrtab = mapping + shstrtabsh->sh_offset;

    58     // parse the sections we care about

    59     int shndx = 0;

    60     const Elf32_Shdr *shlimit = shdrs + ehdr->e_shnum;

    61     for (const Elf32_Shdr *shdr = shdrs; shdr < shlimit; ++shdr, ++shndx) {

    62         basic_string<char> name(shstrtab + shdr->sh_name);

    63         if (name == ".symtab") {

    64             m_symbols = reinterpret_cast<const Elf32_Sym *>(mapping + shdr->sh_offset);

    65             m_nsymbols = shdr->sh_size / sizeof(Elf32_Sym);

    66         }

    67         else if (name == ".strtab") {

    68             m_strtab = mapping + shdr->sh_offset;

    69         }

    70         else if (name == ".text") {

    71             m_text_shndx = shndx;

    72         }

    73     }

    75     // Parse the symbol table

    76     const Elf32_Sym *limit = m_symbols + m_nsymbols;

    77     for (const Elf32_Sym *sym = m_symbols; sym < limit; ++sym) {

    78         if (is_function(sym)) {

    79 #ifdef DEBUG

    80             hex(cout);

    81             cout << sym->st_value << endl;

    82 #endif

    83             m_rsymtab.put(sym->st_value, sym->st_value + sym->st_size, sym);

    84         }

    85     }

    87     return 0;

    88 }

    90 int

    91 elf_symbol_table::finish()

    92 {

    93     if (m_mapping != MAP_FAILED) {

    94         munmap(m_mapping, m_size);

    95         m_mapping = MAP_FAILED;

    96     }

    98     if (m_fd >= 0) {

    99         close(m_fd);

   100         m_fd = -1;

   101     }

   103     return 0;

   104 }

   106 const Elf32_Sym *

   107 elf_symbol_table::lookup(unsigned int addr) const

   108 {

   109     rsymtab_t::const_iterator result = m_rsymtab.get(addr);

   110     return result != m_rsymtab.end() ? reinterpret_cast<const Elf32_Sym *>(*result) : 0;

   111 }

   113 const char *

   114 elf_symbol_table::get_symbol_name(const Elf32_Sym *sym) const

   115 {

   116     return m_strtab + sym->st_name;

   117 }

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