2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1989, 1993
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32 #include <sys/cdefs.h>
33 __SCCSID("@(#)nlist.c 8.1 (Berkeley) 6/4/93");
34 #include "namespace.h"
35 #include <sys/param.h>
39 #include <arpa/inet.h>
46 #include "un-namespace.h"
48 #include <machine/elf.h>
49 #include <elf-hints.h>
51 int __fdnlist(int, struct nlist *);
52 int __elf_fdnlist(int, struct nlist *);
53 int __elf_is_okay__(Elf_Ehdr *);
56 nlist(const char *name, struct nlist *list)
60 fd = _open(name, O_RDONLY | O_CLOEXEC, 0);
63 n = __fdnlist(fd, list);
68 static struct nlist_handlers {
69 int (*fn)(int fd, struct nlist *list);
75 __fdnlist(int fd, struct nlist *list)
80 for (i = 0; i < nitems(nlist_fn); i++) {
81 n = (nlist_fn[i].fn)(fd, list);
88 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)
90 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int);
93 * __elf_is_okay__ - Determine if ehdr really
94 * is ELF and valid for the target platform.
96 * WARNING: This is NOT an ELF ABI function and
97 * as such its use should be restricted.
100 __elf_is_okay__(Elf_Ehdr *ehdr)
104 * We need to check magic, class size, endianess,
105 * and version before we look at the rest of the
106 * Elf_Ehdr structure. These few elements are
107 * represented in a machine independent fashion.
110 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS &&
111 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA &&
112 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) {
114 /* Now check the machine dependant header */
115 if (ehdr->e_machine == ELF_TARG_MACH &&
116 ehdr->e_version == ELF_TARG_VER)
123 __elf_fdnlist(int fd, struct nlist *list)
126 Elf_Off symoff = 0, symstroff = 0;
127 Elf_Size symsize = 0, symstrsize = 0;
135 Elf_Shdr *shdr = NULL;
140 /* Make sure obj is OK */
141 if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
142 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) ||
143 !__elf_is_okay__(&ehdr) ||
147 /* calculate section header table size */
148 shdr_size = ehdr.e_shentsize * ehdr.e_shnum;
150 /* Make sure it's not too big to mmap */
151 if (shdr_size > SIZE_T_MAX) {
156 /* mmap section header table */
157 base = mmap(NULL, (size_t)shdr_size, PROT_READ, MAP_PRIVATE, fd,
158 (off_t)ehdr.e_shoff);
159 if (base == MAP_FAILED)
161 shdr = (Elf_Shdr *)base;
164 * Find the symbol table entry and it's corresponding
165 * string table entry. Version 1.1 of the ABI states
166 * that there is only one symbol table but that this
167 * could change in the future.
169 for (i = 0; i < ehdr.e_shnum; i++) {
170 if (shdr[i].sh_type == SHT_SYMTAB) {
171 symoff = shdr[i].sh_offset;
172 symsize = shdr[i].sh_size;
173 symstroff = shdr[shdr[i].sh_link].sh_offset;
174 symstrsize = shdr[shdr[i].sh_link].sh_size;
179 /* Check for files too large to mmap. */
180 if (symstrsize > SIZE_T_MAX) {
185 * Map string table into our address space. This gives us
186 * an easy way to randomly access all the strings, without
187 * making the memory allocation permanent as with malloc/free
188 * (i.e., munmap will return it to the system).
190 base = mmap(NULL, (size_t)symstrsize, PROT_READ, MAP_PRIVATE, fd,
192 if (base == MAP_FAILED)
194 strtab = (char *)base;
197 * clean out any left-over information for all valid entries.
198 * Type and value defined to be 0 if not found; historical
199 * versions cleared other and desc as well. Also figure out
200 * the largest string length so don't read any more of the
201 * string table than we have to.
203 * XXX clearing anything other than n_type and n_value violates
204 * the semantics given in the man page.
207 for (p = list; !ISLAST(p); ++p) {
215 /* Don't process any further if object is stripped. */
219 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) {
224 while (symsize > 0 && nent > 0) {
225 cc = MIN(symsize, sizeof(sbuf));
226 if (_read(fd, sbuf, cc) != cc)
229 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) {
233 name = strtab + s->st_name;
236 for (p = list; !ISLAST(p); p++) {
237 if ((p->n_un.n_name[0] == '_' &&
238 strcmp(name, p->n_un.n_name+1) == 0)
239 || strcmp(name, p->n_un.n_name) == 0) {
240 elf_sym_to_nlist(p, s, shdr,
251 munmap(strtab, symstrsize);
253 munmap(shdr, shdr_size);
259 * Convert an Elf_Sym into an nlist structure. This fills in only the
260 * n_value and n_type members.
263 elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum)
265 nl->n_value = s->st_value;
267 switch (s->st_shndx) {
273 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ?
277 if (s->st_shndx >= shnum)
280 Elf_Shdr *sh = shdr + s->st_shndx;
282 nl->n_type = sh->sh_type == SHT_PROGBITS ?
283 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) :
284 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF);
289 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
290 ELF_ST_BIND(s->st_info) == STB_WEAK)