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 source tree.
   4  */
   5
   6 //usage:#define man_trivial_usage
   7 //usage:       "[-aw] [MANPAGE]..."
   8 //usage:#define man_full_usage "\n\n"
   9 //usage:       "Format and display manual page\n"
  10 //usage:     "\n        -a      Display all pages"
  11 //usage:     "\n        -w      Show page locations"
  12
  13 #include "libbb.h"
  14
  15 enum {
  16         OPT_a = 1, /* all */
  17         OPT_w = 2, /* print path */
  18 };
  19
  20 /* This is what I see on my desktop system being executed:
  21
  22 (
  23 echo ".ll 12.4i"
  24 echo ".nr LL 12.4i"
  25 echo ".pl 1100i"
  26 gunzip -c '/usr/man/man1/bzip2.1.gz'
  27 echo ".\\\""
  28 echo ".pl \n(nlu+10"
  29 ) | gtbl | nroff -Tlatin1 -mandoc | less
  30
  31 */
  32
  33 static int show_manpage(const char *pager, char *man_filename, int man, int level);
  34
  35 static int run_pipe(const char *pager, char *man_filename, int man, int level)
  36 {
  37         char *cmd;
  38
  39         /* Prevent man page link loops */
  40         if (level > 10)
  41                 return 0;
  42
  43         if (access(man_filename, R_OK) != 0)
  44                 return 0;
  45
  46         if (option_mask32 & OPT_w) {
  47                 puts(man_filename);
  48                 return 1;
  49         }
  50
  51         if (man) { /* man page, not cat page */
  52                 /* Is this a link to another manpage? */
  53                 /* The link has the following on the first line: */
  54                 /* ".so another_man_page" */
  55
  56                 struct stat sb;
  57                 char *line;
  58                 char *linkname, *p;
  59
  60                 /* On my system:
  61                  * man1/genhostid.1.gz: 203 bytes - smallest real manpage
  62                  * man2/path_resolution.2.gz: 114 bytes - largest link
  63                  */
  64                 xstat(man_filename, &sb);
  65                 if (sb.st_size > 300) /* err on the safe side */
  66                         goto ordinary_manpage;
  67
  68                 line = xmalloc_open_zipped_read_close(man_filename, NULL);
  69                 if (!line || strncmp(line, ".so ", 4) != 0) {
  70                         free(line);
  71                         goto ordinary_manpage;
  72                 }
  73                 /* Example: man2/path_resolution.2.gz contains
  74                  * ".so man7/path_resolution.7\n<junk>"
  75                  */
  76                 *strchrnul(line, '\n') = '\0';
  77                 linkname = skip_whitespace(&line[4]);
  78
  79                 /* If link has no slashes, we just replace man page name.
  80                  * If link has slashes (however many), we go back *once*.
  81                  * ".so zzz/ggg/page.3" does NOT go back two levels. */
  82                 p = strrchr(man_filename, '/');
  83                 if (!p)
  84                         goto ordinary_manpage;
  85                 *p = '\0';
  86                 if (strchr(linkname, '/')) {
  87                         p = strrchr(man_filename, '/');
  88                         if (!p)
  89                                 goto ordinary_manpage;
  90                         *p = '\0';
  91                 }
  92
  93                 /* Links do not have .gz extensions, even if manpage
  94                  * is compressed */
  95                 man_filename = xasprintf("%s/%s", man_filename, linkname);
  96                 free(line);
  97                 /* Note: we leak "new" man_filename string as well... */
  98                 if (show_manpage(pager, man_filename, man, level + 1))
  99                         return 1;
 100                 /* else: show the link, it's better than nothing */
 101         }
 102
 103  ordinary_manpage:
 104         close(STDIN_FILENO);
 105         open_zipped(man_filename); /* guaranteed to use fd 0 (STDIN_FILENO) */
 106         /* "2>&1" is added so that nroff errors are shown in pager too.
 107          * Otherwise it may show just empty screen */
 108         cmd = xasprintf(
 109                 man ? "gtbl | nroff -Tlatin1 -mandoc 2>&1 | %s"
 110                     : "%s",
 111                 pager);
 112         system(cmd);
 113         free(cmd);
 114         return 1;
 115 }
 116
 117 /* man_filename is of the form "/dir/dir/dir/name.s" */
 118 static int show_manpage(const char *pager, char *man_filename, int man, int level)
 119 {
 120 #if SEAMLESS_COMPRESSION
 121         /* We leak this allocation... */
 122         char *filename_with_zext = xasprintf("%s.lzma", man_filename);
 123         char *ext = strrchr(filename_with_zext, '.') + 1;
 124 #endif
 125
 126 #if ENABLE_FEATURE_SEAMLESS_LZMA
 127         if (run_pipe(pager, filename_with_zext, man, level))
 128                 return 1;
 129 #endif
 130 #if ENABLE_FEATURE_SEAMLESS_XZ
 131         strcpy(ext, "xz");
 132         if (run_pipe(pager, filename_with_zext, man, level))
 133                 return 1;
 134 #endif
 135 #if ENABLE_FEATURE_SEAMLESS_BZ2
 136         strcpy(ext, "bz2");
 137         if (run_pipe(pager, filename_with_zext, man, level))
 138                 return 1;
 139 #endif
 140 #if ENABLE_FEATURE_SEAMLESS_GZ
 141         strcpy(ext, "gz");
 142         if (run_pipe(pager, filename_with_zext, man, level))
 143                 return 1;
 144 #endif
 145
 146         return run_pipe(pager, man_filename, man, level);
 147 }
 148
 149 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 150 int man_main(int argc UNUSED_PARAM, char **argv)
 151 {
 152         parser_t *parser;
 153         const char *pager;
 154         char **man_path_list;
 155         char *sec_list;
 156         char *cur_path, *cur_sect;
 157         int count_mp, cur_mp;
 158         int opt, not_found;
 159         char *token[2];
 160
 161         opt_complementary = "-1"; /* at least one argument */
 162         opt = getopt32(argv, "+aw");
 163         argv += optind;
 164
 165         sec_list = xstrdup("0p:1:1p:2:3:3p:4:5:6:7:8:9");
 166         /* Last valid man_path_list[] is [0x10] */
 167         count_mp = 0;
 168         man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
 169         man_path_list[0] = getenv("MANPATH");
 170         if (!man_path_list[0]) /* default, may be overridden by /etc/man.conf */
 171                 man_path_list[0] = (char*)"/usr/man";
 172         else
 173                 count_mp++;
 174         pager = getenv("MANPAGER");
 175         if (!pager) {
 176                 pager = getenv("PAGER");
 177                 if (!pager)
 178                         pager = "more";
 179         }
 180
 181         /* Parse man.conf[ig] or man_db.conf */
 182         /* man version 1.6f uses man.config */
 183         /* man-db implementation of man uses man_db.conf */
 184         parser = config_open2("/etc/man.config", fopen_for_read);
 185         if (!parser)
 186                 parser = config_open2("/etc/man.conf", fopen_for_read);
 187         if (!parser)
 188                 parser = config_open2("/etc/man_db.conf", fopen_for_read);
 189
 190         while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 191                 if (!token[1])
 192                         continue;
 193                 if (strcmp("MANDATORY_MANPATH"+10, token[0]) == 0 /* "MANPATH"? */
 194                  || strcmp("MANDATORY_MANPATH", token[0]) == 0
 195                 ) {
 196                         char *path = token[1];
 197                         while (*path) {
 198                                 char *next_path;
 199                                 char **path_element;
 200
 201                                 next_path = strchr(path, ':');
 202                                 if (next_path) {
 203                                         *next_path = '\0';
 204                                         if (next_path++ == path) /* "::"? */
 205                                                 goto next;
 206                                 }
 207                                 /* Do we already have path? */
 208                                 path_element = man_path_list;
 209                                 while (*path_element) {
 210                                         if (strcmp(*path_element, path) == 0)
 211                                                 goto skip;
 212                                         path_element++;
 213                                 }
 214                                 man_path_list = xrealloc_vector(man_path_list, 4, count_mp);
 215                                 man_path_list[count_mp] = xstrdup(path);
 216                                 count_mp++;
 217                                 /* man_path_list is NULL terminated */
 218                                 /*man_path_list[count_mp] = NULL; - xrealloc_vector did it */
 219  skip:
 220                                 if (!next_path)
 221                                         break;
 222  next:
 223                                 path = next_path;
 224                         }
 225                 }
 226                 if (strcmp("MANSECT", token[0]) == 0) {
 227                         free(sec_list);
 228                         sec_list = xstrdup(token[1]);
 229                 }
 230         }
 231         config_close(parser);
 232
 233         not_found = 0;
 234         do { /* for each argv[] */
 235                 int found = 0;
 236                 cur_mp = 0;
 237
 238                 if (strchr(*argv, '/')) {
 239                         found = show_manpage(pager, *argv, /*man:*/ 1, 0);
 240                         goto check_found;
 241                 }
 242                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 243                         /* for each MANPATH */
 244                         cur_sect = sec_list;
 245                         do { /* for each section */
 246                                 char *next_sect = strchrnul(cur_sect, ':');
 247                                 int sect_len = next_sect - cur_sect;
 248                                 char *man_filename;
 249                                 int cat0man1 = 0;
 250
 251                                 /* Search for cat, then man page */
 252                                 while (cat0man1 < 2) {
 253                                         int found_here;
 254                                         man_filename = xasprintf("%s/%s%.*s/%s.%.*s",
 255                                                         cur_path,
 256                                                         "cat\0man" + (cat0man1 * 4),
 257                                                         sect_len, cur_sect,
 258                                                         *argv,
 259                                                         sect_len, cur_sect);
 260                                         found_here = show_manpage(pager, man_filename, cat0man1, 0);
 261                                         found |= found_here;
 262                                         cat0man1 += found_here + 1;
 263                                         free(man_filename);
 264                                 }
 265
 266                                 if (found && !(opt & OPT_a))
 267                                         goto next_arg;
 268                                 cur_sect = next_sect;
 269                                 while (*cur_sect == ':')
 270                                         cur_sect++;
 271                         } while (*cur_sect);
 272                 }
 273  check_found:
 274                 if (!found) {
 275                         bb_error_msg("no manual entry for '%s'", *argv);
 276                         not_found = 1;
 277                 }
 278  next_arg:
 279                 argv++;
 280         } while (*argv);
 281
 282         return not_found;
 283 }