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:     "\nOptions:"
  11 //usage:     "\n        -a      Display all pages"
  12 //usage:     "\n        -w      Show page locations"
  13
  14 #include "libbb.h"
  15
  16 enum {
  17         OPT_a = 1, /* all */
  18         OPT_w = 2, /* print path */
  19 };
  20
  21 /* This is what I see on my desktop system being executed:
  22
  23 (
  24 echo ".ll 12.4i"
  25 echo ".nr LL 12.4i"
  26 echo ".pl 1100i"
  27 gunzip -c '/usr/man/man1/bzip2.1.gz'
  28 echo ".\\\""
  29 echo ".pl \n(nlu+10"
  30 ) | gtbl | nroff -Tlatin1 -mandoc | less
  31
  32 */
  33
  34 #if ENABLE_FEATURE_SEAMLESS_LZMA
  35 #define Z_SUFFIX ".lzma"
  36 #elif ENABLE_FEATURE_SEAMLESS_BZ2
  37 #define Z_SUFFIX ".bz2"
  38 #elif ENABLE_FEATURE_SEAMLESS_GZ
  39 #define Z_SUFFIX ".gz"
  40 #else
  41 #define Z_SUFFIX ""
  42 #endif
  43
  44 static int show_manpage(const char *pager, char *man_filename, int man, int level);
  45
  46 static int run_pipe(const char *pager, char *man_filename, int man, int level)
  47 {
  48         char *cmd;
  49
  50         /* Prevent man page link loops */
  51         if (level > 10)
  52                 return 0;
  53
  54         if (access(man_filename, R_OK) != 0)
  55                 return 0;
  56
  57         if (option_mask32 & OPT_w) {
  58                 puts(man_filename);
  59                 return 1;
  60         }
  61
  62         if (man) { /* man page, not cat page */
  63                 /* Is this a link to another manpage? */
  64                 /* The link has the following on the first line: */
  65                 /* ".so another_man_page" */
  66
  67                 struct stat sb;
  68                 char *line;
  69                 char *linkname, *p;
  70
  71                 /* On my system:
  72                  * man1/genhostid.1.gz: 203 bytes - smallest real manpage
  73                  * man2/path_resolution.2.gz: 114 bytes - largest link
  74                  */
  75                 xstat(man_filename, &sb);
  76                 if (sb.st_size > 300) /* err on the safe side */
  77                         goto ordinary_manpage;
  78
  79                 line = xmalloc_open_zipped_read_close(man_filename, NULL);
  80                 if (!line || strncmp(line, ".so ", 4) != 0) {
  81                         free(line);
  82                         goto ordinary_manpage;
  83                 }
  84                 /* Example: man2/path_resolution.2.gz contains
  85                  * ".so man7/path_resolution.7\n<junk>"
  86                  */
  87                 *strchrnul(line, '\n') = '\0';
  88                 linkname = skip_whitespace(&line[4]);
  89
  90                 /* If link has no slashes, we just replace man page name.
  91                  * If link has slashes (however many), we go back *once*.
  92                  * ".so zzz/ggg/page.3" does NOT go back two levels. */
  93                 p = strrchr(man_filename, '/');
  94                 if (!p)
  95                         goto ordinary_manpage;
  96                 *p = '\0';
  97                 if (strchr(linkname, '/')) {
  98                         p = strrchr(man_filename, '/');
  99                         if (!p)
 100                                 goto ordinary_manpage;
 101                         *p = '\0';
 102                 }
 103
 104                 /* Links do not have .gz extensions, even if manpage
 105                  * is compressed */
 106                 man_filename = xasprintf("%s/%s" Z_SUFFIX, man_filename, linkname);
 107                 free(line);
 108                 /* Note: we leak "new" man_filename string as well... */
 109                 if (show_manpage(pager, man_filename, man, level + 1))
 110                         return 1;
 111                 /* else: show the link, it's better than nothing */
 112         }
 113
 114  ordinary_manpage:
 115         close(STDIN_FILENO);
 116         open_zipped(man_filename); /* guaranteed to use fd 0 (STDIN_FILENO) */
 117         /* "2>&1" is added so that nroff errors are shown in pager too.
 118          * Otherwise it may show just empty screen */
 119         cmd = xasprintf(
 120                 man ? "gtbl | nroff -Tlatin1 -mandoc 2>&1 | %s"
 121                     : "%s",
 122                 pager);
 123         system(cmd);
 124         free(cmd);
 125         return 1;
 126 }
 127
 128 /* man_filename is of the form "/dir/dir/dir/name.s" Z_SUFFIX */
 129 static int show_manpage(const char *pager, char *man_filename, int man, int level)
 130 {
 131 #if ENABLE_FEATURE_SEAMLESS_LZMA
 132         if (run_pipe(pager, man_filename, man, level))
 133                 return 1;
 134 #endif
 135
 136 #if ENABLE_FEATURE_SEAMLESS_BZ2
 137 #if ENABLE_FEATURE_SEAMLESS_LZMA
 138         strcpy(strrchr(man_filename, '.') + 1, "bz2");
 139 #endif
 140         if (run_pipe(pager, man_filename, man, level))
 141                 return 1;
 142 #endif
 143
 144 #if ENABLE_FEATURE_SEAMLESS_GZ
 145 #if ENABLE_FEATURE_SEAMLESS_LZMA || ENABLE_FEATURE_SEAMLESS_BZ2
 146         strcpy(strrchr(man_filename, '.') + 1, "gz");
 147 #endif
 148         if (run_pipe(pager, man_filename, man, level))
 149                 return 1;
 150 #endif
 151
 152 #if ENABLE_FEATURE_SEAMLESS_LZMA || ENABLE_FEATURE_SEAMLESS_BZ2 || ENABLE_FEATURE_SEAMLESS_GZ
 153         *strrchr(man_filename, '.') = '\0';
 154 #endif
 155         if (run_pipe(pager, man_filename, man, level))
 156                 return 1;
 157
 158         return 0;
 159 }
 160
 161 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 162 int man_main(int argc UNUSED_PARAM, char **argv)
 163 {
 164         parser_t *parser;
 165         const char *pager;
 166         char **man_path_list;
 167         char *sec_list;
 168         char *cur_path, *cur_sect;
 169         int count_mp, cur_mp;
 170         int opt, not_found;
 171         char *token[2];
 172
 173         opt_complementary = "-1"; /* at least one argument */
 174         opt = getopt32(argv, "+aw");
 175         argv += optind;
 176
 177         sec_list = xstrdup("1:2:3:4:5:6:7:8:9");
 178         /* Last valid man_path_list[] is [0x10] */
 179         count_mp = 0;
 180         man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
 181         man_path_list[0] = getenv("MANPATH");
 182         if (!man_path_list[0]) /* default, may be overridden by /etc/man.conf */
 183                 man_path_list[0] = (char*)"/usr/man";
 184         else
 185                 count_mp++;
 186         pager = getenv("MANPAGER");
 187         if (!pager) {
 188                 pager = getenv("PAGER");
 189                 if (!pager)
 190                         pager = "more";
 191         }
 192
 193         /* Parse man.conf[ig] or man_db.conf */
 194         /* man version 1.6f uses man.config */
 195         /* man-db implementation of man uses man_db.conf */
 196         parser = config_open2("/etc/man.config", fopen_for_read);
 197         if (!parser)
 198                 parser = config_open2("/etc/man.conf", fopen_for_read);
 199         if (!parser)
 200                 parser = config_open2("/etc/man_db.conf", fopen_for_read);
 201
 202         while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 203                 if (!token[1])
 204                         continue;
 205                 if (strcmp("MANDATORY_MANPATH"+10, token[0]) == 0 /* "MANPATH"? */
 206                  || strcmp("MANDATORY_MANPATH", token[0]) == 0
 207                 ) {
 208                         char *path = token[1];
 209                         while (*path) {
 210                                 char *next_path;
 211                                 char **path_element;
 212
 213                                 next_path = strchr(path, ':');
 214                                 if (next_path) {
 215                                         *next_path = '\0';
 216                                         if (next_path++ == path) /* "::"? */
 217                                                 goto next;
 218                                 }
 219                                 /* Do we already have path? */
 220                                 path_element = man_path_list;
 221                                 while (*path_element) {
 222                                         if (strcmp(*path_element, path) == 0)
 223                                                 goto skip;
 224                                         path_element++;
 225                                 }
 226                                 man_path_list = xrealloc_vector(man_path_list, 4, count_mp);
 227                                 man_path_list[count_mp] = xstrdup(path);
 228                                 count_mp++;
 229                                 /* man_path_list is NULL terminated */
 230                                 /*man_path_list[count_mp] = NULL; - xrealloc_vector did it */
 231  skip:
 232                                 if (!next_path)
 233                                         break;
 234  next:
 235                                 path = next_path;
 236                         }
 237                 }
 238                 if (strcmp("MANSECT", token[0]) == 0) {
 239                         free(sec_list);
 240                         sec_list = xstrdup(token[1]);
 241                 }
 242         }
 243         config_close(parser);
 244
 245         not_found = 0;
 246         do { /* for each argv[] */
 247                 int found = 0;
 248                 cur_mp = 0;
 249
 250                 if (strchr(*argv, '/')) {
 251                         found = show_manpage(pager, *argv, /*man:*/ 1, 0);
 252                         goto check_found;
 253                 }
 254                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 255                         /* for each MANPATH */
 256                         cur_sect = sec_list;
 257                         do { /* for each section */
 258                                 char *next_sect = strchrnul(cur_sect, ':');
 259                                 int sect_len = next_sect - cur_sect;
 260                                 char *man_filename;
 261                                 int cat0man1 = 0;
 262
 263                                 /* Search for cat, then man page */
 264                                 while (cat0man1 < 2) {
 265                                         int found_here;
 266                                         man_filename = xasprintf("%s/%s%.*s/%s.%.*s" Z_SUFFIX,
 267                                                         cur_path,
 268                                                         "cat\0man" + (cat0man1 * 4),
 269                                                         sect_len, cur_sect,
 270                                                         *argv,
 271                                                         sect_len, cur_sect);
 272                                         found_here = show_manpage(pager, man_filename, cat0man1, 0);
 273                                         found |= found_here;
 274                                         cat0man1 += found_here + 1;
 275                                         free(man_filename);
 276                                 }
 277
 278                                 if (found && !(opt & OPT_a))
 279                                         goto next_arg;
 280                                 cur_sect = next_sect;
 281                                 while (*cur_sect == ':')
 282                                         cur_sect++;
 283                         } while (*cur_sect);
 284                 }
 285  check_found:
 286                 if (!found) {
 287                         bb_error_msg("no manual entry for '%s'", *argv);
 288                         not_found = 1;
 289                 }
 290  next_arg:
 291                 argv++;
 292         } while (*argv);
 293
 294         return not_found;
 295 }