ash: some beautification work, no code changes
[oweals/busybox.git] / miscutils / man.c
1 /* mini man implementation for busybox
2  * Copyright (C) 2008 Denys Vlasenko <vda.linux@googlemail.com>
3  * Licensed under GPLv2, see file LICENSE in this tarball for details.
4  */
5
6 #include "libbb.h"
7
8 enum {
9         OPT_a = 1, /* all */
10         OPT_w = 2, /* print path */
11 };
12
13 /* This is what I see on my desktop system being executed:
14
15 (
16 echo ".ll 12.4i"
17 echo ".nr LL 12.4i"
18 echo ".pl 1100i"
19 gunzip -c '/usr/man/man1/bzip2.1.gz'
20 echo ".\\\""
21 echo ".pl \n(nlu+10"
22 ) | gtbl | nroff -Tlatin1 -mandoc | less
23
24 */
25
26 #if ENABLE_FEATURE_SEAMLESS_LZMA
27 #define Z_SUFFIX ".lzma"
28 #elif ENABLE_FEATURE_SEAMLESS_BZ2
29 #define Z_SUFFIX ".bz2"
30 #elif ENABLE_FEATURE_SEAMLESS_GZ
31 #define Z_SUFFIX ".gz"
32 #else
33 #define Z_SUFFIX ""
34 #endif
35
36 static int show_manpage(const char *pager, char *man_filename, int man, int level);
37
38 static int run_pipe(const char *pager, char *man_filename, int man, int level)
39 {
40         char *cmd;
41
42         /* Prevent man page link loops */
43         if (level > 10)
44                 return 0;
45
46         if (access(man_filename, R_OK) != 0)
47                 return 0;
48
49         if (option_mask32 & OPT_w) {
50                 puts(man_filename);
51                 return 1;
52         }
53
54         if (man) { /* man page, not cat page */
55                 /* Is this a link to another manpage? */
56                 /* The link has the following on the first line: */
57                 /* ".so another_man_page" */
58
59                 struct stat sb;
60                 char *line;
61                 char *linkname, *p;
62
63                 /* On my system:
64                  * man1/genhostid.1.gz: 203 bytes - smallest real manpage
65                  * man2/path_resolution.2.gz: 114 bytes - largest link
66                  */
67                 xstat(man_filename, &sb);
68                 if (sb.st_size > 300) /* err on the safe side */
69                         goto ordinary_manpage;
70
71                 line = xmalloc_open_zipped_read_close(man_filename, NULL);
72                 if (!line || strncmp(line, ".so ", 4) != 0) {
73                         free(line);
74                         goto ordinary_manpage;
75                 }
76                 /* Example: man2/path_resolution.2.gz contains
77                  * ".so man7/path_resolution.7\n<junk>"
78                  */
79                 *strchrnul(line, '\n') = '\0';
80                 linkname = skip_whitespace(&line[4]);
81
82                 /* If link has no slashes, we just replace man page name.
83                  * If link has slashes (however many), we go back *once*.
84                  * ".so zzz/ggg/page.3" does NOT go back two levels. */
85                 p = strrchr(man_filename, '/');
86                 if (!p)
87                         goto ordinary_manpage;
88                 *p = '\0';
89                 if (strchr(linkname, '/')) {
90                         p = strrchr(man_filename, '/');
91                         if (!p)
92                                 goto ordinary_manpage;
93                         *p = '\0';
94                 }
95
96                 /* Links do not have .gz extensions, even if manpage
97                  * is compressed */
98                 man_filename = xasprintf("%s/%s" Z_SUFFIX, man_filename, linkname);
99                 free(line);
100                 /* Note: we leak "new" man_filename string as well... */
101                 if (show_manpage(pager, man_filename, man, level + 1))
102                         return 1;
103                 /* else: show the link, it's better than nothing */
104         }
105
106  ordinary_manpage:
107         close(STDIN_FILENO);
108         open_zipped(man_filename); /* guaranteed to use fd 0 (STDIN_FILENO) */
109         /* "2>&1" is added so that nroff errors are shown in pager too.
110          * Otherwise it may show just empty screen */
111         cmd = xasprintf(
112                 man ? "gtbl | nroff -Tlatin1 -mandoc 2>&1 | %s"
113                     : "%s",
114                 pager);
115         system(cmd);
116         free(cmd);
117         return 1;
118 }
119
120 /* man_filename is of the form "/dir/dir/dir/name.s" Z_SUFFIX */
121 static int show_manpage(const char *pager, char *man_filename, int man, int level)
122 {
123 #if ENABLE_FEATURE_SEAMLESS_LZMA
124         if (run_pipe(pager, man_filename, man, level))
125                 return 1;
126 #endif
127
128 #if ENABLE_FEATURE_SEAMLESS_BZ2
129 #if ENABLE_FEATURE_SEAMLESS_LZMA
130         strcpy(strrchr(man_filename, '.') + 1, "bz2");
131 #endif
132         if (run_pipe(pager, man_filename, man, level))
133                 return 1;
134 #endif
135
136 #if ENABLE_FEATURE_SEAMLESS_GZ
137 #if ENABLE_FEATURE_SEAMLESS_LZMA || ENABLE_FEATURE_SEAMLESS_BZ2
138         strcpy(strrchr(man_filename, '.') + 1, "gz");
139 #endif
140         if (run_pipe(pager, man_filename, man, level))
141                 return 1;
142 #endif
143
144 #if ENABLE_FEATURE_SEAMLESS_LZMA || ENABLE_FEATURE_SEAMLESS_BZ2 || ENABLE_FEATURE_SEAMLESS_GZ
145         *strrchr(man_filename, '.') = '\0';
146 #endif
147         if (run_pipe(pager, man_filename, man, level))
148                 return 1;
149
150         return 0;
151 }
152
153 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
154 int man_main(int argc UNUSED_PARAM, char **argv)
155 {
156         parser_t *parser;
157         const char *pager;
158         char **man_path_list;
159         char *sec_list;
160         char *cur_path, *cur_sect;
161         int count_mp, cur_mp;
162         int opt, not_found;
163         char *token[2];
164
165         opt_complementary = "-1"; /* at least one argument */
166         opt = getopt32(argv, "+aw");
167         argv += optind;
168
169         sec_list = xstrdup("1:2:3:4:5:6:7:8:9");
170         /* Last valid man_path_list[] is [0x10] */
171         count_mp = 0;
172         man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
173         man_path_list[0] = getenv("MANPATH");
174         if (!man_path_list[0]) /* default, may be overridden by /etc/man.conf */
175                 man_path_list[0] = (char*)"/usr/man";
176         else
177                 count_mp++;
178         pager = getenv("MANPAGER");
179         if (!pager) {
180                 pager = getenv("PAGER");
181                 if (!pager)
182                         pager = "more";
183         }
184
185         /* Parse man.conf */
186         parser = config_open2("/etc/man.conf", fopen_for_read);
187         while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
188                 if (!token[1])
189                         continue;
190                 if (strcmp("MANPATH", token[0]) == 0) {
191                         /* Do we already have it? */
192                         char **path_element = man_path_list;
193                         while (*path_element) {
194                                 if (strcmp(*path_element, token[1]) == 0)
195                                         goto skip;
196                                 path_element++;
197                         }
198                         man_path_list = xrealloc_vector(man_path_list, 4, count_mp);
199                         man_path_list[count_mp] = xstrdup(token[1]);
200                         count_mp++;
201                         /* man_path_list is NULL terminated */
202                         /*man_path_list[count_mp] = NULL; - xrealloc_vector did it */
203                 }
204                 if (strcmp("MANSECT", token[0]) == 0) {
205                         free(sec_list);
206                         sec_list = xstrdup(token[1]);
207                 }
208  skip: ;
209         }
210         config_close(parser);
211
212         not_found = 0;
213         do { /* for each argv[] */
214                 int found = 0;
215                 cur_mp = 0;
216
217                 if (strchr(*argv, '/')) {
218                         found = show_manpage(pager, *argv, /*man:*/ 1, 0);
219                         goto check_found;
220                 }
221                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
222                         /* for each MANPATH */
223                         do { /* for each MANPATH item */
224                                 char *next_path = strchrnul(cur_path, ':');
225                                 int path_len = next_path - cur_path;
226                                 cur_sect = sec_list;
227                                 do { /* for each section */
228                                         char *next_sect = strchrnul(cur_sect, ':');
229                                         int sect_len = next_sect - cur_sect;
230                                         char *man_filename;
231                                         int cat0man1 = 0;
232
233                                         /* Search for cat, then man page */
234                                         while (cat0man1 < 2) {
235                                                 int found_here;
236                                                 man_filename = xasprintf("%.*s/%s%.*s/%s.%.*s" Z_SUFFIX,
237                                                                 path_len, cur_path,
238                                                                 "cat\0man" + (cat0man1 * 4),
239                                                                 sect_len, cur_sect,
240                                                                 *argv,
241                                                                 sect_len, cur_sect);
242                                                 found_here = show_manpage(pager, man_filename, cat0man1, 0);
243                                                 found |= found_here;
244                                                 cat0man1 += found_here + 1;
245                                                 free(man_filename);
246                                         }
247
248                                         if (found && !(opt & OPT_a))
249                                                 goto next_arg;
250                                         cur_sect = next_sect;
251                                         while (*cur_sect == ':')
252                                                 cur_sect++;
253                                 } while (*cur_sect);
254                                 cur_path = next_path;
255                                 while (*cur_path == ':')
256                                         cur_path++;
257                         } while (*cur_path);
258                 }
259  check_found:
260                 if (!found) {
261                         bb_error_msg("no manual entry for '%s'", *argv);
262                         not_found = 1;
263                 }
264  next_arg:
265                 argv++;
266         } while (*argv);
267
268         return not_found;
269 }