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         man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
 172         count_mp = 0;
 173         man_path_list[0] = xstrdup(getenv("MANPATH"));
 174         if (man_path_list[0])
 175                 count_mp++;
 176         pager = getenv("MANPAGER");
 177         if (!pager) {
 178                 pager = getenv("PAGER");
 179                 if (!pager)
 180                         pager = "more";
 181         }
 182
 183         /* Parse man.conf */
 184         parser = config_open("/etc/man.conf");
 185         while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 186                 if (!token[1])
 187                         continue;
 188                 if (strcmp("MANPATH", token[0]) == 0) {
 189                         man_path_list = xrealloc_vector(man_path_list, 4, count_mp);
 190                         man_path_list[count_mp] = xstrdup(token[1]);
 191                         count_mp++;
 192                         /* man_path_list is NULL terminated */
 193                         /*man_path_list[count_mp] = NULL; - xrealloc_vector did it */
 194                 }
 195                 if (strcmp("MANSECT", token[0]) == 0) {
 196                         free(sec_list);
 197                         sec_list = xstrdup(token[1]);
 198                 }
 199         }
 200         config_close(parser);
 201
 202         not_found = 0;
 203         do { /* for each argv[] */
 204                 int found = 0;
 205                 cur_mp = 0;
 206
 207                 if (strchr(*argv, '/')) {
 208                         found = show_manpage(pager, *argv, /*man:*/ 1, 0);
 209                         goto check_found;
 210                 }
 211                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 212                         /* for each MANPATH */
 213                         do { /* for each MANPATH item */
 214                                 char *next_path = strchrnul(cur_path, ':');
 215                                 int path_len = next_path - cur_path;
 216                                 cur_sect = sec_list;
 217                                 do { /* for each section */
 218                                         char *next_sect = strchrnul(cur_sect, ':');
 219                                         int sect_len = next_sect - cur_sect;
 220                                         char *man_filename;
 221                                         int cat0man1 = 0;
 222
 223                                         /* Search for cat, then man page */
 224                                         while (cat0man1 < 2) {
 225                                                 int found_here;
 226                                                 man_filename = xasprintf("%.*s/%s%.*s/%s.%.*s" Z_SUFFIX,
 227                                                                 path_len, cur_path,
 228                                                                 "cat\0man" + (cat0man1 * 4),
 229                                                                 sect_len, cur_sect,
 230                                                                 *argv,
 231                                                                 sect_len, cur_sect);
 232                                                 found_here = show_manpage(pager, man_filename, cat0man1, 0);
 233                                                 found |= found_here;
 234                                                 cat0man1 += found_here + 1;
 235                                                 free(man_filename);
 236                                         }
 237
 238                                         if (found && !(opt & OPT_a))
 239                                                 goto next_arg;
 240                                         cur_sect = next_sect;
 241                                         while (*cur_sect == ':')
 242                                                 cur_sect++;
 243                                 } while (*cur_sect);
 244                                 cur_path = next_path;
 245                                 while (*cur_path == ':')
 246                                         cur_path++;
 247                         } while (*cur_path);
 248                 }
 249  check_found:
 250                 if (!found) {
 251                         bb_error_msg("no manual entry for '%s'", *argv);
 252                         not_found = 1;
 253                 }
 254  next_arg:
 255                 argv++;
 256         } while (*argv);
 257
 258         return not_found;
 259 }