tools/jprof/elf.cpp

   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/. */
   4
   5 #include "leaky.h"
   6
   7 #ifdef USE_ELF
   8
   9 #include "leaky.h"
  10 #include <stdio.h>
  11 #include <malloc.h>
  12 #include <libelf/libelf.h>
  13 #include <unistd.h>
  14 #include <fcntl.h>
  15 #include <string.h>
  16
  17 void leaky::readSymbols(const char *fileName)
  18 {
  19     int fd = ::open(fileName, O_RDONLY);
  20     if (fd < 0) {
  21         fprintf(stderr, "%s: unable to open \"%s\"\n", applicationName,
  22                 fileName);
  23         exit(-1);
  24     }
  25
  26     elf_version(EV_CURRENT);
  27     Elf *elf = elf_begin(fd, ELF_C_READ, 0);
  28     if (!elf) {
  29         fprintf(stderr, "%s: \"%s\": has no symbol table\n", applicationName,
  30                 fileName);
  31         exit(-1);
  32     }
  33
  34     long alloced = 10000;
  35     Symbol* syms = (Symbol*) malloc(sizeof(Symbol) * 10000);
  36     Symbol* sp = syms;
  37     Symbol* last = syms + alloced;
  38
  39     // Get each of the relevant sections and add them to the list of
  40     // symbols.
  41     Elf32_Ehdr *ehdr = elf32_getehdr(elf);
  42     if (!ehdr) {
  43         fprintf(stderr, "%s: elf library lossage\n", applicationName);
  44         exit(-1);
  45     }
  46 #if 0
  47     Elf32_Half ndx = ehdr->e_shstrndx;
  48 #endif
  49
  50     Elf_Scn *scn = 0;
  51     int strtabndx = -1;
  52     for (int i = 1; (scn = elf_nextscn(elf, scn)) != 0; i++) {
  53         Elf32_Shdr *shdr = elf32_getshdr(scn);
  54 #if 0
  55         char *name = elf_strptr(elf, ndx, (size_t) shdr->sh_name);
  56         printf("Section %s (%d 0x%x)\n", name ? name : "(null)",
  57                shdr->sh_type, shdr->sh_type);
  58 #endif
  59         if (shdr->sh_type == SHT_STRTAB) {
  60             /* We assume here that string tables preceed symbol tables... */
  61             strtabndx = i;
  62             continue;
  63         }
  64 #if 0
  65         if (shdr->sh_type == SHT_DYNAMIC) {
  66             /* Dynamic */
  67             Elf_Data *data = elf_getdata(scn, 0);
  68             if (!data || !data->d_size) {
  69                 printf("No data...");
  70                 continue;
  71             }
  72
  73             Elf32_Dyn *dyn = (Elf32_Dyn*) data->d_buf;
  74             Elf32_Dyn *lastdyn =
  75                 (Elf32_Dyn*) ((char*) data->d_buf + data->d_size);
  76             for (; dyn < lastdyn; dyn++) {
  77                 printf("tag=%d value=0x%x\n", dyn->d_tag, dyn->d_un.d_val);
  78             }
  79         } else
  80 #endif
  81         if ((shdr->sh_type == SHT_SYMTAB) ||
  82             (shdr->sh_type == SHT_DYNSYM)) {
  83             /* Symbol table */
  84             Elf_Data *data = elf_getdata(scn, 0);
  85             if (!data || !data->d_size) {
  86                 printf("No data...");
  87                 continue;
  88             }
  89
  90             /* In theory we now have the symbols... */
  91             Elf32_Sym *esym = (Elf32_Sym*) data->d_buf;
  92             Elf32_Sym *lastsym =
  93                 (Elf32_Sym*) ((char*) data->d_buf + data->d_size);
  94             for (; esym < lastsym; esym++) {
  95 #if 0
  96                 char *nm = elf_strptr(elf, strtabndx, (size_t)esym->st_name);
  97                 printf("%20s 0x%08x %02x %02x\n",
  98                        nm, esym->st_value, ELF32_ST_BIND(esym->st_info),
  99                        ELF32_ST_TYPE(esym->st_info));
 100 #endif
 101                 if ((esym->st_value == 0) ||
 102                     (ELF32_ST_BIND(esym->st_info) == STB_WEAK) ||
 103                     (ELF32_ST_BIND(esym->st_info) == STB_NUM) ||
 104                     (ELF32_ST_TYPE(esym->st_info) != STT_FUNC)) {
 105                     continue;
 106                 }
 107 #if 1
 108                 char *nm = elf_strptr(elf, strtabndx, (size_t)esym->st_name);
 109 #endif
 110                 sp->name = nm ? strdup(nm) : "(no name)";
 111                 sp->address = esym->st_value;
 112                 sp++;
 113                 if (sp >= last) {
 114                     long n = alloced + 10000;
 115                     syms = (Symbol*)
 116                         realloc(syms, (size_t) (sizeof(Symbol) * n));
 117                     last = syms + n;
 118                     sp = syms + alloced;
 119                     alloced = n;
 120                 }
 121             }
 122         }
 123     }
 124
 125     int interesting = sp - syms;
 126     if (!quiet) {
 127         printf("Total of %d symbols\n", interesting);
 128     }
 129     usefulSymbols = interesting;
 130     externalSymbols = syms;
 131 }
 132
 133 #endif /* USE_ELF */