2 * Copyright (c) 1989, 1993
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33 * $FreeBSD: src/lib/libc/gen/nlist.c,v 1.12.2.1 2001/07/11 23:59:09 obrien Exp $
35 * @(#)nlist.c 8.1 (Berkeley) 6/4/93
38 #include "namespace.h"
39 #include <sys/param.h>
49 #include "un-namespace.h"
51 #define _NLIST_DO_AOUT
55 #include <machine/elf.h>
56 #include <elf-hints.h>
59 int __fdnlist(int, struct nlist *);
60 int __aout_fdnlist(int, struct nlist *);
61 int __elf_fdnlist(int, struct nlist *);
64 nlist(const char *name, struct nlist *list)
68 fd = _open(name, O_RDONLY, 0);
71 n = __fdnlist(fd, list);
76 static struct nlist_handlers {
77 int (*fn)(int fd, struct nlist *list);
88 __fdnlist(int fd, struct nlist *list)
93 for (i = 0; i < NELEM(nlist_fn); i++) {
94 n = (nlist_fn[i].fn)(fd, list);
101 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)
103 #ifdef _NLIST_DO_AOUT
105 __aout_fdnlist(int fd, struct nlist *list)
107 struct nlist *p, *symtab;
108 caddr_t strtab, a_out_mmap;
109 off_t stroff, symoff;
115 /* check that file is at least as large as struct exec! */
116 if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec)))
119 /* Check for files too large to mmap. */
120 if (st.st_size > SIZE_T_MAX) {
126 * Map the whole a.out file into our address space.
127 * We then find the string table withing this area.
128 * We do not just mmap the string table, as it probably
129 * does not start at a page boundary - we save ourselves a
130 * lot of nastiness by mmapping the whole file.
132 * This gives us an easy way to randomly access all the strings,
133 * without making the memory allocation permanent as with
134 * malloc/free (i.e., munmap will return it to the system).
136 a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0);
137 if (a_out_mmap == MAP_FAILED)
140 exec = (struct exec *)a_out_mmap;
141 if (N_BADMAG(*exec)) {
142 munmap(a_out_mmap, (size_t)st.st_size);
146 symoff = N_SYMOFF(*exec);
147 symsize = exec->a_syms;
148 stroff = symoff + symsize;
150 /* find the string table in our mmapped area */
151 strtab = a_out_mmap + stroff;
152 symtab = (struct nlist *)(a_out_mmap + symoff);
155 * clean out any left-over information for all valid entries.
156 * Type and value defined to be 0 if not found; historical
157 * versions cleared other and desc as well. Also figure out
158 * the largest string length so don't read any more of the
159 * string table than we have to.
161 * XXX clearing anything other than n_type and n_value violates
162 * the semantics given in the man page.
165 for (p = list; !ISLAST(p); ++p) {
173 while (symsize > 0) {
176 symsize-= sizeof(struct nlist);
177 soff = symtab->n_un.n_strx;
180 if (soff != 0 && (symtab->n_type & N_STAB) == 0)
181 for (p = list; !ISLAST(p); p++)
182 if (!strcmp(&strtab[soff], p->n_un.n_name)) {
183 p->n_value = symtab->n_value;
184 p->n_type = symtab->n_type;
185 p->n_desc = symtab->n_desc;
186 p->n_other = symtab->n_other;
192 munmap(a_out_mmap, (size_t)st.st_size);
198 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int);
201 * __elf_is_okay__ - Determine if ehdr really
202 * is ELF and valid for the target platform.
204 * WARNING: This is NOT a ELF ABI function and
205 * as such it's use should be restricted.
208 __elf_is_okay__(Elf_Ehdr *ehdr)
212 * We need to check magic, class size, endianess,
213 * and version before we look at the rest of the
214 * Elf_Ehdr structure. These few elements are
215 * represented in a machine independant fashion.
218 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS &&
219 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA &&
220 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) {
222 /* Now check the machine dependant header */
223 if (ehdr->e_machine == ELF_TARG_MACH &&
224 ehdr->e_version == ELF_TARG_VER)
231 __elf_fdnlist(int fd, struct nlist *list)
234 Elf_Off symoff = 0, symstroff = 0;
235 Elf_Word symsize = 0, symstrsize = 0;
243 Elf_Shdr *shdr = NULL;
248 /* Make sure obj is OK */
249 if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
250 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) ||
251 !__elf_is_okay__(&ehdr) ||
255 /* calculate section header table size */
256 shdr_size = ehdr.e_shentsize * ehdr.e_shnum;
259 /* Make sure it's not too big to mmap */
260 if (shdr_size > SIZE_T_MAX) {
266 /* mmap section header table */
267 base = mmap(NULL, (size_t)shdr_size, PROT_READ, 0, fd,
268 (off_t)ehdr.e_shoff);
269 if (base == MAP_FAILED)
271 shdr = (Elf_Shdr *)base;
274 * Find the symbol table entry and it's corresponding
275 * string table entry. Version 1.1 of the ABI states
276 * that there is only one symbol table but that this
277 * could change in the future.
279 for (i = 0; i < ehdr.e_shnum; i++) {
280 if (shdr[i].sh_type == SHT_SYMTAB) {
281 symoff = shdr[i].sh_offset;
282 symsize = shdr[i].sh_size;
283 symstroff = shdr[shdr[i].sh_link].sh_offset;
284 symstrsize = shdr[shdr[i].sh_link].sh_size;
290 /* Check for files too large to mmap. */
291 if (symstrsize > SIZE_T_MAX) {
298 * Map string table into our address space. This gives us
299 * an easy way to randomly access all the strings, without
300 * making the memory allocation permanent as with malloc/free
301 * (i.e., munmap will return it to the system).
303 base = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd,
305 if (base == MAP_FAILED)
307 strtab = (char *)base;
310 * clean out any left-over information for all valid entries.
311 * Type and value defined to be 0 if not found; historical
312 * versions cleared other and desc as well. Also figure out
313 * the largest string length so don't read any more of the
314 * string table than we have to.
316 * XXX clearing anything other than n_type and n_value violates
317 * the semantics given in the man page.
320 for (p = list; !ISLAST(p); ++p) {
328 /* Don't process any further if object is stripped. */
332 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) {
337 while (symsize > 0 && nent > 0) {
338 cc = MIN(symsize, sizeof(sbuf));
339 if (_read(fd, sbuf, cc) != cc)
342 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) {
344 struct nlist *p_local;
346 name = strtab + s->st_name;
349 for (p_local = list; !ISLAST(p_local); p_local++) {
350 if ((p_local->n_un.n_name[0] == '_' &&
351 strcmp(name, p_local->n_un.n_name+1) == 0)
352 || strcmp(name, p_local->n_un.n_name) == 0) {
353 elf_sym_to_nlist(p_local, s, shdr,
364 munmap(strtab, symstrsize);
366 munmap(shdr, shdr_size);
372 * Convert an Elf_Sym into an nlist structure. This fills in only the
373 * n_value and n_type members.
376 elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum)
378 nl->n_value = s->st_value;
380 switch (s->st_shndx) {
386 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ?
390 if (s->st_shndx >= shnum)
393 Elf_Shdr *sh = shdr + s->st_shndx;
395 nl->n_type = sh->sh_type == SHT_PROGBITS ?
396 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) :
397 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF);
402 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
403 ELF_ST_BIND(s->st_info) == STB_WEAK)
406 #endif /* _NLIST_DO_ELF */