elf.c revision 76224 
1#ifndef lint
2static const char rcsid[] =
3  "$FreeBSD: head/usr.bin/gprof/elf.c 76224 2001-05-02 23:56:21Z obrien $";
4#endif /* not lint */
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
18static bool wantsym(const Elf_Sym *, const char *);
19
20/* Things which get -E excluded by default. */
21static char	*excludes[] = { ".mcount", "_mcleanup", NULL };
22
23int
24elf_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
95static bool
96wantsym(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}
111