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 $
34 * $DragonFly: src/lib/libc/gen/nlist.c,v 1.4 2004/06/06 15:05:55 hmp Exp $
36 * @(#)nlist.c 8.1 (Berkeley) 6/4/93
39 #include <sys/param.h>
50 #define _NLIST_DO_AOUT
54 #include <machine/elf.h>
55 #include <elf-hints.h>
58 int __fdnlist (int, struct nlist *);
59 int __aout_fdnlist (int, struct nlist *);
60 int __elf_fdnlist (int, struct nlist *);
69 fd = _open(name, O_RDONLY, 0);
72 n = __fdnlist(fd, list);
77 static struct nlist_handlers {
78 int (*fn) (int fd, struct nlist *list);
95 for (i = 0; i < sizeof(nlist_fn) / sizeof(nlist_fn[0]); i++) {
96 n = (nlist_fn[i].fn)(fd, list);
103 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)
105 #ifdef _NLIST_DO_AOUT
107 __aout_fdnlist(fd, list)
111 struct nlist *p, *symtab;
112 caddr_t strtab, a_out_mmap;
113 off_t stroff, symoff;
119 /* check that file is at least as large as struct exec! */
120 if ((fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec)))
123 /* Check for files too large to mmap. */
124 if (st.st_size > SIZE_T_MAX) {
130 * Map the whole a.out file into our address space.
131 * We then find the string table withing this area.
132 * We do not just mmap the string table, as it probably
133 * does not start at a page boundary - we save ourselves a
134 * lot of nastiness by mmapping the whole file.
136 * This gives us an easy way to randomly access all the strings,
137 * without making the memory allocation permanent as with
138 * malloc/free (i.e., munmap will return it to the system).
140 a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0);
141 if (a_out_mmap == MAP_FAILED)
144 exec = (struct exec *)a_out_mmap;
145 if (N_BADMAG(*exec)) {
146 munmap(a_out_mmap, (size_t)st.st_size);
150 symoff = N_SYMOFF(*exec);
151 symsize = exec->a_syms;
152 stroff = symoff + symsize;
154 /* find the string table in our mmapped area */
155 strtab = a_out_mmap + stroff;
156 symtab = (struct nlist *)(a_out_mmap + symoff);
159 * clean out any left-over information for all valid entries.
160 * Type and value defined to be 0 if not found; historical
161 * versions cleared other and desc as well. Also figure out
162 * the largest string length so don't read any more of the
163 * string table than we have to.
165 * XXX clearing anything other than n_type and n_value violates
166 * the semantics given in the man page.
169 for (p = list; !ISLAST(p); ++p) {
177 while (symsize > 0) {
180 symsize-= sizeof(struct nlist);
181 soff = symtab->n_un.n_strx;
184 if (soff != 0 && (symtab->n_type & N_STAB) == 0)
185 for (p = list; !ISLAST(p); p++)
186 if (!strcmp(&strtab[soff], p->n_un.n_name)) {
187 p->n_value = symtab->n_value;
188 p->n_type = symtab->n_type;
189 p->n_desc = symtab->n_desc;
190 p->n_other = symtab->n_other;
196 munmap(a_out_mmap, (size_t)st.st_size);
202 static void elf_sym_to_nlist (struct nlist *, Elf_Sym *, Elf_Shdr *, int);
205 * __elf_is_okay__ - Determine if ehdr really
206 * is ELF and valid for the target platform.
208 * WARNING: This is NOT a ELF ABI function and
209 * as such it's use should be restricted.
212 __elf_is_okay__(ehdr)
217 * We need to check magic, class size, endianess,
218 * and version before we look at the rest of the
219 * Elf_Ehdr structure. These few elements are
220 * represented in a machine independant fashion.
223 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS &&
224 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA &&
225 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) {
227 /* Now check the machine dependant header */
228 if (ehdr->e_machine == ELF_TARG_MACH &&
229 ehdr->e_version == ELF_TARG_VER)
236 __elf_fdnlist(fd, list)
241 Elf_Off symoff = 0, symstroff = 0;
242 Elf_Word symsize = 0, symstrsize = 0;
250 Elf_Shdr *shdr = NULL;
256 /* Make sure obj is OK */
257 if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
258 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) ||
259 !__elf_is_okay__(&ehdr) ||
263 /* calculate section header table size */
264 shdr_size = ehdr.e_shentsize * ehdr.e_shnum;
266 /* Make sure it's not too big to mmap */
267 if (shdr_size > SIZE_T_MAX) {
272 /* mmap section header table */
273 base = mmap(NULL, (size_t)shdr_size, PROT_READ, 0, fd,
274 (off_t)ehdr.e_shoff);
275 if (base == MAP_FAILED)
277 shdr = (Elf_Shdr *)base;
280 * Find the symbol table entry and it's corresponding
281 * string table entry. Version 1.1 of the ABI states
282 * that there is only one symbol table but that this
283 * could change in the future.
285 for (i = 0; i < ehdr.e_shnum; i++) {
286 if (shdr[i].sh_type == SHT_SYMTAB) {
287 symoff = shdr[i].sh_offset;
288 symsize = shdr[i].sh_size;
289 symstroff = shdr[shdr[i].sh_link].sh_offset;
290 symstrsize = shdr[shdr[i].sh_link].sh_size;
295 /* Check for files too large to mmap. */
296 if (symstrsize > SIZE_T_MAX) {
301 * Map string table into our address space. This gives us
302 * an easy way to randomly access all the strings, without
303 * making the memory allocation permanent as with malloc/free
304 * (i.e., munmap will return it to the system).
306 base = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd,
308 if (base == MAP_FAILED)
310 strtab = (char *)base;
313 * clean out any left-over information for all valid entries.
314 * Type and value defined to be 0 if not found; historical
315 * versions cleared other and desc as well. Also figure out
316 * the largest string length so don't read any more of the
317 * string table than we have to.
319 * XXX clearing anything other than n_type and n_value violates
320 * the semantics given in the man page.
323 for (p = list; !ISLAST(p); ++p) {
331 /* Don't process any further if object is stripped. */
335 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) {
340 while (symsize > 0 && nent > 0) {
341 cc = MIN(symsize, sizeof(sbuf));
342 if (_read(fd, sbuf, cc) != cc)
345 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) {
349 name = strtab + s->st_name;
352 for (p = list; !ISLAST(p); p++) {
353 if ((p->n_un.n_name[0] == '_' &&
354 strcmp(name, p->n_un.n_name+1) == 0)
355 || strcmp(name, p->n_un.n_name) == 0) {
356 elf_sym_to_nlist(p, s, shdr,
367 munmap(strtab, symstrsize);
369 munmap(shdr, shdr_size);
375 * Convert an Elf_Sym into an nlist structure. This fills in only the
376 * n_value and n_type members.
379 elf_sym_to_nlist(nl, s, shdr, shnum)
385 nl->n_value = s->st_value;
387 switch (s->st_shndx) {
393 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ?
397 if (s->st_shndx >= shnum)
400 Elf_Shdr *sh = shdr + s->st_shndx;
402 nl->n_type = sh->sh_type == SHT_PROGBITS ?
403 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) :
404 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF);
409 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
410 ELF_ST_BIND(s->st_info) == STB_WEAK)
413 #endif /* _NLIST_DO_ELF */