1 /* $OpenBSD: ksyms.c,v 1.8 2015/02/07 03:26:20 tedu Exp $ */
2
3 /*
4 * Copyright (c) 2008 Miodrag Vallat.
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 #include <unistd.h>
20 #include <ctype.h>
21 #include <errno.h>
22 #include <fcntl.h>
23 #include <string.h>
24
25 #include <sys/exec.h>
26 #include <sys/elf64.h>
27
28 #include "hangman.h"
29
30 typedef Elf64_Ehdr Elf_Ehdr;
31 typedef Elf64_Shdr Elf_Shdr;
32
33 static int ksyms_elf_parse(void);
34
35 void
sym_getword(void)36 sym_getword(void)
37 {
38 uint tries;
39 off_t pos;
40 int buflen;
41 char symbuf[1 + BUFSIZ], *sym, *end;
42 size_t symlen;
43
44 for (tries = 0; tries < MAXBADWORDS; tries++) {
45 pos = arc4random_uniform(symsize);
46 if (lseek(symfd, pos + symoffs, SEEK_SET) == -1)
47 continue;
48 buflen = read(symfd, symbuf, BUFSIZ);
49 if (buflen < 0)
50 continue;
51
52 /*
53 * The buffer is hopefully large enough to hold at least
54 * a complete symbol, i.e. two occurences of NUL, or
55 * one occurence of NUL and the buffer containing the end
56 * of the string table. We make sure the buffer will be
57 * NUL terminated in all cases.
58 */
59 if (buflen + pos >= symsize)
60 buflen = symsize - pos;
61 *(end = symbuf + buflen) = '\0';
62
63 for (sym = symbuf; *sym != '\0'; sym++)
64 ;
65 if (sym == end)
66 continue;
67
68 symlen = strlen(++sym);
69 if (symlen < MINLEN || symlen > MAXLEN)
70 continue;
71
72 /* ignore symbols containing dots or dollar signs */
73 if (strchr(sym, '.') != NULL || strchr(sym, '$') != NULL)
74 continue;
75
76 break;
77 }
78
79 if (tries >= MAXBADWORDS) {
80 mvcur(0, COLS - 1, LINES -1, 0);
81 endwin();
82 errx(1, "can't seem a suitable symbol in %s",
83 Dict_name);
84 }
85
86 strlcpy(Word, sym, sizeof(Word));
87 strlcpy(Known, sym, sizeof(Known));
88 for (sym = Known; *sym != '\0'; sym++) {
89 if (*sym == '-')
90 *sym = '_'; /* try not to confuse player */
91 if (isalnum((unsigned char)*sym))
92 *sym = '-';
93 }
94 }
95
96 int
sym_setup(void)97 sym_setup(void)
98 {
99 if ((symfd = open(Dict_name, O_RDONLY)) < 0)
100 return -1;
101
102 if (ksyms_elf_parse() == 0)
103 return 0;
104
105 close(symfd);
106 errno = ENOEXEC;
107 return -1;
108 }
109
110 int
ksyms_elf_parse(void)111 ksyms_elf_parse(void)
112 {
113 Elf_Ehdr eh;
114 Elf_Shdr sh;
115 uint s;
116
117 if (lseek(symfd, 0, SEEK_SET) == -1)
118 return -1;
119
120 if (read(symfd, &eh, sizeof(eh)) != sizeof(eh))
121 return -1;
122
123 if (!IS_ELF(eh))
124 return -1;
125
126 if (lseek(symfd, eh.e_shoff, SEEK_SET) == -1)
127 return -1;
128
129 symoffs = 0;
130 symsize = 0;
131
132 for (s = 0; s < eh.e_shnum; s++) {
133 if (read(symfd, &sh, sizeof(sh)) != sizeof(sh))
134 return -1;
135
136 /*
137 * There should be two string table sections, one with the
138 * name of the sections themselves, and one with the symbol
139 * names. Just pick the largest one.
140 */
141 if (sh.sh_type == SHT_STRTAB) {
142 if (symsize > (off_t)sh.sh_size)
143 continue;
144
145 symoffs = (off_t)sh.sh_offset;
146 symsize = (off_t)sh.sh_size;
147 }
148 }
149
150 if (symsize == 0)
151 return -1;
152
153 return 0;
154 }
155