usr.bin/gprof/elf.c

   1 /*
   2  * $FreeBSD: src/usr.bin/gprof/elf.c,v 1.2.2.1 2001/07/11 23:59:11 obrien Exp $
   3  * $DragonFly: src/usr.bin/gprof/elf.c,v 1.2 2003/06/17 04:29:27 dillon Exp $
   4  */
   5
   6 #include <sys/types.h>
   7 #include <sys/mman.h>
   8 #include <sys/stat.h>
   9 #include <machine/elf.h>
  10
  11 #include <err.h>
  12 #include <fcntl.h>
  13 #include <string.h>
  14 #include <unistd.h>
  15
  16 #include "gprof.h"
  17
  18 static bool wantsym(const Elf_Sym *, const char *);
  19
  20 /* Things which get -E excluded by default. */
  21 static char     *excludes[] = { ".mcount", "_mcleanup", NULL };
  22
  23 int
  24 elf_getnfile(const char *filename, char ***defaultEs)
  25 {
  26     int fd;
  27     Elf_Ehdr h;
  28     struct stat s;
  29     void *mapbase;
  30     const char *base;
  31     const Elf_Shdr *shdrs;
  32     const Elf_Shdr *sh_symtab;
  33     const Elf_Shdr *sh_strtab;
  34     const char *strtab;
  35     const Elf_Sym *symtab;
  36     int symtabct;
  37     int i;
  38
  39     if ((fd = open(filename, O_RDONLY)) == -1)
  40         err(1, "%s", filename);
  41     if (read(fd, &h, sizeof h) != sizeof h || !IS_ELF(h)) {
  42         close(fd);
  43         return -1;
  44     }
  45     if (fstat(fd, &s) == -1)
  46         err(1, "Cannot fstat %s", filename);
  47     if ((mapbase = mmap(0, s.st_size, PROT_READ, MAP_SHARED, fd, 0)) ==
  48       MAP_FAILED)
  49         err(1, "Cannot mmap %s", filename);
  50     close(fd);
  51
  52     base = (const char *)mapbase;
  53     shdrs = (const Elf_Shdr *)(base + h.e_shoff);
  54
  55     /* Find the symbol table and associated string table section. */
  56     for (i = 1;  i < h.e_shnum;  i++)
  57         if (shdrs[i].sh_type == SHT_SYMTAB)
  58             break;
  59     if (i == h.e_shnum)
  60         errx(1, "%s has no symbol table", filename);
  61     sh_symtab = &shdrs[i];
  62     sh_strtab = &shdrs[sh_symtab->sh_link];
  63
  64     symtab = (const Elf_Sym *)(base + sh_symtab->sh_offset);
  65     symtabct = sh_symtab->sh_size / sh_symtab->sh_entsize;
  66     strtab = (const char *)(base + sh_strtab->sh_offset);
  67
  68     /* Count the symbols that we're interested in. */
  69     nname = 0;
  70     for (i = 1;  i < symtabct;  i++)
  71         if (wantsym(&symtab[i], strtab))
  72             nname++;
  73
  74     /* Allocate memory for them, plus a terminating entry. */
  75     if ((nl = (nltype *)calloc(nname + 1, sizeof(nltype))) == NULL)
  76         errx(1, "Insufficient memory for symbol table");
  77
  78     /* Read them in. */
  79     npe = nl;
  80     for (i = 1;  i < symtabct;  i++) {
  81         const Elf_Sym *sym = &symtab[i];
  82
  83         if (wantsym(sym, strtab)) {
  84             npe->value = sym->st_value;
  85             npe->name = strtab + sym->st_name;
  86             npe++;
  87         }
  88     }
  89     npe->value = -1;
  90
  91     *defaultEs = excludes;
  92     return 0;
  93 }
  94
  95 static bool
  96 wantsym(const Elf_Sym *sym, const char *strtab)
  97 {
  98     int type;
  99     int bind;
 100
 101     type = ELF_ST_TYPE(sym->st_info);
 102     bind = ELF_ST_BIND(sym->st_info);
 103
 104     if (type != STT_FUNC ||
 105       (aflag && bind == STB_LOCAL) ||
 106       (uflag && strchr(strtab + sym->st_name, '.') != NULL))
 107         return 0;
 108
 109     return 1;
 110 }