elf.c revision 331722 
1/*-
2 * Copyright (c) 1983, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#if 0
31/* From: */
32#ifndef lint
33static char sccsid[] = "@(#)gprof.c	8.1 (Berkeley) 6/6/93";
34#endif /* not lint */
35#endif
36
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD: stable/11/usr.bin/gprof/elf.c 331722 2018-03-29 02:50:57Z eadler $");
39
40#include <sys/types.h>
41#include <sys/mman.h>
42#include <sys/stat.h>
43#include <machine/elf.h>
44
45#include <err.h>
46#include <fcntl.h>
47#include <string.h>
48#include <unistd.h>
49
50#include "gprof.h"
51
52static bool wantsym(const Elf_Sym *, const char *);
53
54/* Things which get -E excluded by default. */
55static char	*excludes[] = { ".mcount", "_mcleanup", NULL };
56
57int
58elf_getnfile(const char *filename, char ***defaultEs)
59{
60    int fd;
61    Elf_Ehdr h;
62    struct stat s;
63    void *mapbase;
64    const char *base;
65    const Elf_Shdr *shdrs;
66    const Elf_Shdr *sh_symtab;
67    const Elf_Shdr *sh_strtab;
68    const char *strtab;
69    const Elf_Sym *symtab;
70    int symtabct;
71    int i;
72
73    if ((fd = open(filename, O_RDONLY)) == -1)
74	err(1, "%s", filename);
75    if (read(fd, &h, sizeof h) != sizeof h || !IS_ELF(h)) {
76	close(fd);
77	return -1;
78    }
79    if (fstat(fd, &s) == -1)
80	err(1, "cannot fstat %s", filename);
81    if ((mapbase = mmap(0, s.st_size, PROT_READ, MAP_SHARED, fd, 0)) ==
82      MAP_FAILED)
83	err(1, "cannot mmap %s", filename);
84    close(fd);
85
86    base = (const char *)mapbase;
87    shdrs = (const Elf_Shdr *)(base + h.e_shoff);
88
89    /* Find the symbol table and associated string table section. */
90    for (i = 1;  i < h.e_shnum;  i++)
91	if (shdrs[i].sh_type == SHT_SYMTAB)
92	    break;
93    if (i == h.e_shnum)
94	errx(1, "%s has no symbol table", filename);
95    sh_symtab = &shdrs[i];
96    sh_strtab = &shdrs[sh_symtab->sh_link];
97
98    symtab = (const Elf_Sym *)(base + sh_symtab->sh_offset);
99    symtabct = sh_symtab->sh_size / sh_symtab->sh_entsize;
100    strtab = (const char *)(base + sh_strtab->sh_offset);
101
102    /* Count the symbols that we're interested in. */
103    nname = 0;
104    for (i = 1;  i < symtabct;  i++)
105	if (wantsym(&symtab[i], strtab))
106	    nname++;
107
108    /* Allocate memory for them, plus a terminating entry. */
109    if ((nl = (nltype *)calloc(nname + 1, sizeof(nltype))) == NULL)
110	errx(1, "insufficient memory for symbol table");
111
112    /* Read them in. */
113    npe = nl;
114    for (i = 1;  i < symtabct;  i++) {
115	const Elf_Sym *sym = &symtab[i];
116
117	if (wantsym(sym, strtab)) {
118	    npe->value = sym->st_value;
119	    npe->name = strtab + sym->st_name;
120	    npe++;
121	}
122    }
123    npe->value = -1;
124
125    *defaultEs = excludes;
126    return 0;
127}
128
129static bool
130wantsym(const Elf_Sym *sym, const char *strtab)
131{
132    int type;
133    int bind;
134
135    type = ELF_ST_TYPE(sym->st_info);
136    bind = ELF_ST_BIND(sym->st_info);
137
138    if (type != STT_FUNC ||
139      (aflag && bind == STB_LOCAL) ||
140      (uflag && strchr(strtab + sym->st_name, '.') != NULL))
141	return 0;
142
143    return 1;
144}
145