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