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29 * $FreeBSD: src/lib/libc/gen/nlist.c,v 1.12.2.1 2001/07/11 23:59:09 obrien Exp $
31 * @(#)nlist.c 8.1 (Berkeley) 6/4/93
34 #include "namespace.h"
35 #include <sys/param.h>
45 #include "un-namespace.h"
47 #define _NLIST_DO_AOUT
51 #include <machine/elf.h>
52 #include <elf-hints.h>
55 int __fdnlist(int, struct nlist *);
56 int __aout_fdnlist(int, struct nlist *);
57 int __elf_fdnlist(int, struct nlist *);
60 nlist(const char *name, struct nlist *list)
64 fd = _open(name, O_RDONLY | O_CLOEXEC, 0);
67 n = __fdnlist(fd, list);
72 static struct nlist_handlers {
73 int (*fn)(int fd, struct nlist *list);
84 __fdnlist(int fd, struct nlist *list)
89 for (i = 0; i < NELEM(nlist_fn); i++) {
90 n = (nlist_fn[i].fn)(fd, list);
97 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)
101 __aout_fdnlist(int fd, struct nlist *list)
103 struct nlist *p, *symtab;
104 caddr_t strtab, a_out_mmap;
105 off_t stroff, symoff;
111 /* check that file is at least as large as struct exec! */
112 if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec)))
115 /* Check for files too large to mmap. */
116 if (st.st_size > SIZE_T_MAX) {
122 * Map the whole a.out file into our address space.
123 * We then find the string table withing this area.
124 * We do not just mmap the string table, as it probably
125 * does not start at a page boundary - we save ourselves a
126 * lot of nastiness by mmapping the whole file.
128 * This gives us an easy way to randomly access all the strings,
129 * without making the memory allocation permanent as with
130 * malloc/free (i.e., munmap will return it to the system).
132 a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0);
133 if (a_out_mmap == MAP_FAILED)
136 exec = (struct exec *)a_out_mmap;
137 if (N_BADMAG(*exec)) {
138 munmap(a_out_mmap, (size_t)st.st_size);
142 symoff = N_SYMOFF(*exec);
143 symsize = exec->a_syms;
144 stroff = symoff + symsize;
146 /* find the string table in our mmapped area */
147 strtab = a_out_mmap + stroff;
148 symtab = (struct nlist *)(a_out_mmap + symoff);
151 * clean out any left-over information for all valid entries.
152 * Type and value defined to be 0 if not found; historical
153 * versions cleared other and desc as well. Also figure out
154 * the largest string length so don't read any more of the
155 * string table than we have to.
157 * XXX clearing anything other than n_type and n_value violates
158 * the semantics given in the man page.
161 for (p = list; !ISLAST(p); ++p) {
169 while (symsize > 0) {
172 symsize-= sizeof(struct nlist);
173 soff = symtab->n_un.n_strx;
176 if (soff != 0 && (symtab->n_type & N_STAB) == 0)
177 for (p = list; !ISLAST(p); p++)
178 if (!strcmp(&strtab[soff], p->n_un.n_name)) {
179 p->n_value = symtab->n_value;
180 p->n_type = symtab->n_type;
181 p->n_desc = symtab->n_desc;
182 p->n_other = symtab->n_other;
188 munmap(a_out_mmap, (size_t)st.st_size);
194 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int);
197 * __elf_is_okay__ - Determine if ehdr really
198 * is ELF and valid for the target platform.
200 * WARNING: This is NOT a ELF ABI function and
201 * as such it's use should be restricted.
204 __elf_is_okay__(Elf_Ehdr *ehdr)
208 * We need to check magic, class size, endianess,
209 * and version before we look at the rest of the
210 * Elf_Ehdr structure. These few elements are
211 * represented in a machine independant fashion.
214 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS &&
215 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA &&
216 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) {
218 /* Now check the machine dependant header */
219 if (ehdr->e_machine == ELF_TARG_MACH &&
220 ehdr->e_version == ELF_TARG_VER)
227 __elf_fdnlist(int fd, struct nlist *list)
230 Elf_Off symoff = 0, symstroff = 0;
231 Elf_Word symsize = 0, symstrsize = 0;
239 Elf_Shdr *shdr = NULL;
244 /* Make sure obj is OK */
245 if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
246 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) ||
247 !__elf_is_okay__(&ehdr) ||
251 /* calculate section header table size */
252 shdr_size = ehdr.e_shentsize * ehdr.e_shnum;
255 /* Make sure it's not too big to mmap */
256 if (shdr_size > SIZE_T_MAX) {
262 /* mmap section header table */
263 base = mmap(NULL, (size_t)shdr_size, PROT_READ, 0, fd,
264 (off_t)ehdr.e_shoff);
265 if (base == MAP_FAILED)
267 shdr = (Elf_Shdr *)base;
270 * Find the symbol table entry and it's corresponding
271 * string table entry. Version 1.1 of the ABI states
272 * that there is only one symbol table but that this
273 * could change in the future.
275 for (i = 0; i < ehdr.e_shnum; i++) {
276 if (shdr[i].sh_type == SHT_SYMTAB) {
277 symoff = shdr[i].sh_offset;
278 symsize = shdr[i].sh_size;
279 symstroff = shdr[shdr[i].sh_link].sh_offset;
280 symstrsize = shdr[shdr[i].sh_link].sh_size;
286 /* Check for files too large to mmap. */
287 if (symstrsize > SIZE_T_MAX) {
294 * Map string table into our address space. This gives us
295 * an easy way to randomly access all the strings, without
296 * making the memory allocation permanent as with malloc/free
297 * (i.e., munmap will return it to the system).
299 base = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd,
301 if (base == MAP_FAILED)
303 strtab = (char *)base;
306 * clean out any left-over information for all valid entries.
307 * Type and value defined to be 0 if not found; historical
308 * versions cleared other and desc as well. Also figure out
309 * the largest string length so don't read any more of the
310 * string table than we have to.
312 * XXX clearing anything other than n_type and n_value violates
313 * the semantics given in the man page.
316 for (p = list; !ISLAST(p); ++p) {
324 /* Don't process any further if object is stripped. */
328 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) {
333 while (symsize > 0 && nent > 0) {
334 cc = MIN(symsize, sizeof(sbuf));
335 if (_read(fd, sbuf, cc) != cc)
338 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) {
340 struct nlist *p_local;
342 name = strtab + s->st_name;
345 for (p_local = list; !ISLAST(p_local); p_local++) {
346 if ((p_local->n_un.n_name[0] == '_' &&
347 strcmp(name, p_local->n_un.n_name+1) == 0)
348 || strcmp(name, p_local->n_un.n_name) == 0) {
349 elf_sym_to_nlist(p_local, s, shdr,
360 munmap(strtab, symstrsize);
362 munmap(shdr, shdr_size);
368 * Convert an Elf_Sym into an nlist structure. This fills in only the
369 * n_value and n_type members.
372 elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum)
374 nl->n_value = s->st_value;
376 switch (s->st_shndx) {
382 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ?
386 if (s->st_shndx >= shnum)
389 Elf_Shdr *sh = shdr + s->st_shndx;
391 nl->n_type = sh->sh_type == SHT_PROGBITS ?
392 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) :
393 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF);
398 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
399 ELF_ST_BIND(s->st_info) == STB_WEAK)
402 #endif /* _NLIST_DO_ELF */