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comparison agent/src/os/bsd/symtab.c @ 3960:f08d439fab8c

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7089790: integrate bsd-port changes Reviewed-by: kvn, twisti, jrose Contributed-by: Kurt Miller <kurt@intricatesoftware.com>, Greg Lewis <glewis@eyesbeyond.com>, Jung-uk Kim <jkim@freebsd.org>, Christos Zoulas <christos@zoulas.com>, Landon Fuller <landonf@plausible.coop>, The FreeBSD Foundation <board@freebsdfoundation.org>, Michael Franz <mvfranz@gmail.com>, Roger Hoover <rhoover@apple.com>, Alexander Strange <astrange@apple.com>
author never
date Sun, 25 Sep 2011 16:03:29 -0700
parents
children 436b4a3231bf
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3959:eda6988c0d81 3960:f08d439fab8c
1 /*
2 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include <unistd.h>
26 #include <search.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <db.h>
30 #include <fcntl.h>
31 #include "symtab.h"
32 #include "salibelf.h"
33
34
35 // ----------------------------------------------------
36 // functions for symbol lookups
37 // ----------------------------------------------------
38
39 struct elf_section {
40 ELF_SHDR *c_shdr;
41 void *c_data;
42 };
43
44 struct elf_symbol {
45 char *name;
46 uintptr_t offset;
47 uintptr_t size;
48 };
49
50 typedef struct symtab {
51 char *strs;
52 size_t num_symbols;
53 struct elf_symbol *symbols;
54 DB* hash_table;
55 } symtab_t;
56
57 // read symbol table from given fd.
58 struct symtab* build_symtab(int fd) {
59 ELF_EHDR ehdr;
60 struct symtab* symtab = NULL;
61
62 // Reading of elf header
63 struct elf_section *scn_cache = NULL;
64 int cnt = 0;
65 ELF_SHDR* shbuf = NULL;
66 ELF_SHDR* cursct = NULL;
67 ELF_PHDR* phbuf = NULL;
68 int symtab_found = 0;
69 int dynsym_found = 0;
70 uint32_t symsection = SHT_SYMTAB;
71
72 uintptr_t baseaddr = (uintptr_t)-1;
73
74 lseek(fd, (off_t)0L, SEEK_SET);
75 if (! read_elf_header(fd, &ehdr)) {
76 // not an elf
77 return NULL;
78 }
79
80 // read ELF header
81 if ((shbuf = read_section_header_table(fd, &ehdr)) == NULL) {
82 goto quit;
83 }
84
85 baseaddr = find_base_address(fd, &ehdr);
86
87 scn_cache = calloc(ehdr.e_shnum, sizeof(*scn_cache));
88 if (scn_cache == NULL) {
89 goto quit;
90 }
91
92 for (cursct = shbuf, cnt = 0; cnt < ehdr.e_shnum; cnt++) {
93 scn_cache[cnt].c_shdr = cursct;
94 if (cursct->sh_type == SHT_SYMTAB ||
95 cursct->sh_type == SHT_STRTAB ||
96 cursct->sh_type == SHT_DYNSYM) {
97 if ( (scn_cache[cnt].c_data = read_section_data(fd, &ehdr, cursct)) == NULL) {
98 goto quit;
99 }
100 }
101
102 if (cursct->sh_type == SHT_SYMTAB)
103 symtab_found++;
104
105 if (cursct->sh_type == SHT_DYNSYM)
106 dynsym_found++;
107
108 cursct++;
109 }
110
111 if (!symtab_found && dynsym_found)
112 symsection = SHT_DYNSYM;
113
114 for (cnt = 1; cnt < ehdr.e_shnum; cnt++) {
115 ELF_SHDR *shdr = scn_cache[cnt].c_shdr;
116
117 if (shdr->sh_type == symsection) {
118 ELF_SYM *syms;
119 int j, n, rslt;
120 size_t size;
121
122 // FIXME: there could be multiple data buffers associated with the
123 // same ELF section. Here we can handle only one buffer. See man page
124 // for elf_getdata on Solaris.
125
126 // guarantee(symtab == NULL, "multiple symtab");
127 symtab = calloc(1, sizeof(*symtab));
128 if (symtab == NULL) {
129 goto quit;
130 }
131 // the symbol table
132 syms = (ELF_SYM *)scn_cache[cnt].c_data;
133
134 // number of symbols
135 n = shdr->sh_size / shdr->sh_entsize;
136
137 // create hash table, we use berkeley db to
138 // manipulate the hash table.
139 symtab->hash_table = dbopen(NULL, O_CREAT | O_RDWR, 0600, DB_HASH, NULL);
140 // guarantee(symtab->hash_table, "unexpected failure: dbopen");
141
142 // shdr->sh_link points to the section that contains the actual strings
143 // for symbol names. the st_name field in ELF_SYM is just the
144 // string table index. we make a copy of the string table so the
145 // strings will not be destroyed by elf_end.
146 size = scn_cache[shdr->sh_link].c_shdr->sh_size;
147 symtab->strs = malloc(size);
148 memcpy(symtab->strs, scn_cache[shdr->sh_link].c_data, size);
149
150 // allocate memory for storing symbol offset and size;
151 symtab->num_symbols = n;
152 symtab->symbols = calloc(n , sizeof(*symtab->symbols));
153
154 // copy symbols info our symtab and enter them info the hash table
155 for (j = 0; j < n; j++, syms++) {
156 DBT key, value;
157 char *sym_name = symtab->strs + syms->st_name;
158
159 // skip non-object and non-function symbols
160 int st_type = ELF_ST_TYPE(syms->st_info);
161 if ( st_type != STT_FUNC && st_type != STT_OBJECT)
162 continue;
163 // skip empty strings and undefined symbols
164 if (*sym_name == '\0' || syms->st_shndx == SHN_UNDEF) continue;
165
166 symtab->symbols[j].name = sym_name;
167 symtab->symbols[j].offset = syms->st_value - baseaddr;
168 symtab->symbols[j].size = syms->st_size;
169
170 key.data = sym_name;
171 key.size = strlen(sym_name) + 1;
172 value.data = &(symtab->symbols[j]);
173 value.size = sizeof(void *);
174 (*symtab->hash_table->put)(symtab->hash_table, &key, &value, 0);
175 }
176 }
177 }
178
179 quit:
180 if (shbuf) free(shbuf);
181 if (phbuf) free(phbuf);
182 if (scn_cache) {
183 for (cnt = 0; cnt < ehdr.e_shnum; cnt++) {
184 if (scn_cache[cnt].c_data != NULL) {
185 free(scn_cache[cnt].c_data);
186 }
187 }
188 free(scn_cache);
189 }
190 return symtab;
191 }
192
193 void destroy_symtab(struct symtab* symtab) {
194 if (!symtab) return;
195 if (symtab->strs) free(symtab->strs);
196 if (symtab->symbols) free(symtab->symbols);
197 if (symtab->hash_table) {
198 symtab->hash_table->close(symtab->hash_table);
199 }
200 free(symtab);
201 }
202
203 uintptr_t search_symbol(struct symtab* symtab, uintptr_t base,
204 const char *sym_name, int *sym_size) {
205 DBT key, value;
206 int ret;
207
208 // library does not have symbol table
209 if (!symtab || !symtab->hash_table)
210 return 0;
211
212 key.data = (char*)(uintptr_t)sym_name;
213 key.size = strlen(sym_name) + 1;
214 ret = (*symtab->hash_table->get)(symtab->hash_table, &key, &value, 0);
215 if (ret == 0) {
216 struct elf_symbol *sym = value.data;
217 uintptr_t rslt = (uintptr_t) ((char*)base + sym->offset);
218 if (sym_size) *sym_size = sym->size;
219 return rslt;
220 }
221
222 quit:
223 return 0;
224 }
225
226 const char* nearest_symbol(struct symtab* symtab, uintptr_t offset,
227 uintptr_t* poffset) {
228 int n = 0;
229 if (!symtab) return NULL;
230 for (; n < symtab->num_symbols; n++) {
231 struct elf_symbol* sym = &(symtab->symbols[n]);
232 if (sym->name != NULL &&
233 offset >= sym->offset && offset < sym->offset + sym->size) {
234 if (poffset) *poffset = (offset - sym->offset);
235 return sym->name;
236 }
237 }
238 return NULL;
239 }