1#include <elf.h>
2#include <link.h>
3#include <limits.h>
4#include <stdint.h>
5#include <string.h>
6#include "libc.h"
7#include "syscall.h"
8
9#ifdef VDSO_USEFUL
10
11#if ULONG_MAX == 0xffffffff
12typedef Elf32_Ehdr Ehdr;
13typedef Elf32_Phdr Phdr;
14typedef Elf32_Sym Sym;
15typedef Elf32_Verdef Verdef;
16typedef Elf32_Verdaux Verdaux;
17#else
18typedef Elf64_Ehdr Ehdr;
19typedef Elf64_Phdr Phdr;
20typedef Elf64_Sym Sym;
21typedef Elf64_Verdef Verdef;
22typedef Elf64_Verdaux Verdaux;
23#endif
24
25static int checkver(Verdef *def, int vsym, const char *vername, char *strings)
26{
27 vsym &= 0x7fff;
28 for (;;) {
29 if (!(def->vd_flags & VER_FLG_BASE)
30 && (def->vd_ndx & 0x7fff) == vsym)
31 break;
32 if (def->vd_next == 0)
33 return 0;
34 def = (Verdef *)((char *)def + def->vd_next);
35 }
36 Verdaux *aux = (Verdaux *)((char *)def + def->vd_aux);
37 return !strcmp(vername, strings + aux->vda_name);
38}
39
40#define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON)
41#define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
42
43void *__vdsosym(const char *vername, const char *name)
44{
45 size_t i;
46 for (i=0; libc.auxv[i] != AT_SYSINFO_EHDR; i+=2)
47 if (!libc.auxv[i]) return 0;
48 if (!libc.auxv[i+1]) return 0;
49 Ehdr *eh = (void *)libc.auxv[i+1];
50 Phdr *ph = (void *)((char *)eh + eh->e_phoff);
51 size_t *dynv=0, base=-1;
52 for (i=0; i<eh->e_phnum; i++, ph=(void *)((char *)ph+eh->e_phentsize)) {
53 if (ph->p_type == PT_LOAD)
54 base = (size_t)eh + ph->p_offset - ph->p_vaddr;
55 else if (ph->p_type == PT_DYNAMIC)
56 dynv = (void *)((char *)eh + ph->p_offset);
57 }
58 if (!dynv || base==(size_t)-1) return 0;
59
60 char *strings = 0;
61 Sym *syms = 0;
62 Elf_Symndx *hashtab = 0;
63 uint16_t *versym = 0;
64 Verdef *verdef = 0;
65
66 for (i=0; dynv[i]; i+=2) {
67 void *p = (void *)(base + dynv[i+1]);
68 switch(dynv[i]) {
69 case DT_STRTAB: strings = p; break;
70 case DT_SYMTAB: syms = p; break;
71 case DT_HASH: hashtab = p; break;
72 case DT_VERSYM: versym = p; break;
73 case DT_VERDEF: verdef = p; break;
74 }
75 }
76
77 if (!strings || !syms || !hashtab) return 0;
78 if (!verdef) versym = 0;
79
80 for (i=0; i<hashtab[1]; i++) {
81 if (!(1<<(syms[i].st_info&0xf) & OK_TYPES)) continue;
82 if (!(1<<(syms[i].st_info>>4) & OK_BINDS)) continue;
83 if (!syms[i].st_shndx) continue;
84 if (strcmp(name, strings+syms[i].st_name)) continue;
85 if (versym && !checkver(verdef, versym[i], vername, strings))
86 continue;
87 return (void *)(base + syms[i].st_value);
88 }
89
90 return 0;
91}
92
93#endif