DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Mercurial (27a812186ff4)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231
// vim:ts=8:sw=2:et:
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "leaky.h"

#ifdef USE_BFD
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <libgen.h>
#include <bfd.h>
#include <cxxabi.h>

static bfd *try_debug_file(const char *filename, unsigned long crc32)
{
  int fd = open(filename, O_RDONLY);
  if (fd < 0)
    return nullptr;

  unsigned char buf[4*1024];
  unsigned long crc = 0;

  while (1) {
    ssize_t count = read(fd, buf, sizeof(buf));
    if (count <= 0)
      break;

    crc = bfd_calc_gnu_debuglink_crc32(crc, buf, count);
  }

  close(fd);

  if (crc != crc32)
    return nullptr;

  bfd *object = bfd_openr(filename, nullptr);
  if (!bfd_check_format(object, bfd_object)) {
    bfd_close(object);
    return nullptr;
  }

  return object;
}

static bfd *find_debug_file(bfd *lib, const char *aFileName)
{
  // check for a separate debug file with symbols
  asection *sect = bfd_get_section_by_name(lib, ".gnu_debuglink");

  if (!sect)
    return nullptr;

  bfd_size_type debuglinkSize = bfd_section_size (objfile->obfd, sect);

  char *debuglink = new char[debuglinkSize];
  bfd_get_section_contents(lib, sect, debuglink, 0, debuglinkSize);

  // crc checksum is aligned to 4 bytes, and after the NUL.
  int crc_offset = (int(strlen(debuglink)) & ~3) + 4;
  unsigned long crc32 = bfd_get_32(lib, debuglink + crc_offset);

  // directory component
  char *dirbuf = strdup(aFileName);
  const char *dir = dirname(dirbuf);

  static const char debug_subdir[] = ".debug";
  // This is gdb's default global debugging info directory, but gdb can
  // be instructed to use a different directory.
  static const char global_debug_dir[] = "/usr/lib/debug";

  char *filename =
    new char[strlen(global_debug_dir) + strlen(dir) + crc_offset + 3];

  // /path/debuglink
  sprintf(filename, "%s/%s", dir, debuglink);
  bfd *debugFile = try_debug_file(filename, crc32);
  if (!debugFile) {

    // /path/.debug/debuglink
    sprintf(filename, "%s/%s/%s", dir, debug_subdir, debuglink);
    debugFile = try_debug_file(filename, crc32);
    if (!debugFile) {

      // /usr/lib/debug/path/debuglink
      sprintf(filename, "%s/%s/%s", global_debug_dir, dir, debuglink);
      debugFile = try_debug_file(filename, crc32);
    }
  }

  delete[] filename;
  free(dirbuf);
  delete[] debuglink;

  return debugFile;
}


// Use an indirect array to avoid copying tons of objects
Symbol ** leaky::ExtendSymbols(int num)
{
  long n = numExternalSymbols + num;

  externalSymbols = (Symbol**)
                    realloc(externalSymbols,
                            (size_t) (sizeof(externalSymbols[0]) * n));
  Symbol *new_array = new Symbol[n];
  for (int i = 0; i < num; i++) {
    externalSymbols[i + numExternalSymbols] = &new_array[i];
  }
  lastSymbol = externalSymbols + n;
  Symbol **sp = externalSymbols + numExternalSymbols;
  numExternalSymbols = n;
  return sp;
}

#define NEXT_SYMBOL do { sp++; \
                         if (sp >= lastSymbol) { \
                           sp = ExtendSymbols(16384); \
                         } \
                       } while (0)

void leaky::ReadSymbols(const char *aFileName, u_long aBaseAddress)
{
  int initialSymbols = usefulSymbols;
  if (nullptr == externalSymbols) {
    externalSymbols = (Symbol**) calloc(sizeof(Symbol*),10000);
    Symbol *new_array = new Symbol[10000];
    for (int i = 0; i < 10000; i++) {
      externalSymbols[i] = &new_array[i];
    }
    numExternalSymbols = 10000;
  }
  Symbol** sp = externalSymbols + usefulSymbols;
  lastSymbol = externalSymbols + numExternalSymbols;

  // Create a dummy symbol for the library so, if it doesn't have any
  // symbols, we show it by library.
  (*sp)->Init(aFileName, aBaseAddress);
  NEXT_SYMBOL;

  bfd_boolean kDynamic = (bfd_boolean) false;

  static int firstTime = 1;
  if (firstTime) {
    firstTime = 0;
    bfd_init ();
  }

  bfd* lib = bfd_openr(aFileName, nullptr);
  if (nullptr == lib) {
    return;
  }
  if (!bfd_check_format(lib, bfd_object)) {
    bfd_close(lib);
    return;
  }

  bfd *symbolFile = find_debug_file(lib, aFileName);

  // read mini symbols
  PTR minisyms;
  unsigned int size;
  long symcount = 0;

  if (symbolFile) {
    symcount = bfd_read_minisymbols(symbolFile, kDynamic, &minisyms, &size);
    if (symcount == 0) {
      bfd_close(symbolFile);
    } else {
      bfd_close(lib);
    }
  }
  if (symcount == 0) {
    symcount = bfd_read_minisymbols(lib, kDynamic, &minisyms, &size);
    if (symcount == 0) {
      // symtab is empty; try dynamic symbols
      kDynamic = (bfd_boolean) true;
      symcount = bfd_read_minisymbols(lib, kDynamic, &minisyms, &size);
    }
    symbolFile = lib;
  }

  asymbol* store;
  store = bfd_make_empty_symbol(symbolFile);

  // Scan symbols
  size_t demangle_buffer_size = 128;
  char *demangle_buffer = (char*) malloc(demangle_buffer_size);
  bfd_byte* from = (bfd_byte *) minisyms;
  bfd_byte* fromend = from + symcount * size;
  for (; from < fromend; from += size) {
    asymbol *sym;
    sym = bfd_minisymbol_to_symbol(symbolFile, kDynamic, (const PTR) from, store);

    symbol_info syminfo;
    bfd_get_symbol_info (symbolFile, sym, &syminfo);

//    if ((syminfo.type == 'T') || (syminfo.type == 't')) {
      const char* nm = bfd_asymbol_name(sym);
      if (nm && nm[0]) {
        char* dnm = nullptr;
        if (strncmp("__thunk", nm, 7)) {
          dnm =
            abi::__cxa_demangle(nm, demangle_buffer, &demangle_buffer_size, 0);
          if (dnm) {
            demangle_buffer = dnm;
          }
        }
        (*sp)->Init(dnm ? dnm : nm, syminfo.value + aBaseAddress);
        NEXT_SYMBOL;
      }
//    }
  }

  free(demangle_buffer);
  demangle_buffer = nullptr;

  bfd_close(symbolFile);

  int interesting = sp - externalSymbols;
  if (!quiet) {
    printf("%s provided %d symbols\n", aFileName,
           interesting - initialSymbols);
  }
  usefulSymbols = interesting;
}

#endif /* USE_BFD */