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, /*fail_if_not_compressed:*/ 0); /* 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                 /* replaced -Tlatin1 with -Tascii for non-UTF8 displays */
 110                 man ? "gtbl | nroff -Tascii -mandoc 2>&1 | %s"
 111                     : "%s",
 112                 pager);
 113         system(cmd);
 114         free(cmd);
 115         return 1;
 116 }
 117
 118 /* man_filename is of the form "/dir/dir/dir/name.s" */
 119 static int show_manpage(const char *pager, char *man_filename, int man, int level)
 120 {
 121 #if SEAMLESS_COMPRESSION
 122         /* We leak this allocation... */
 123         char *filename_with_zext = xasprintf("%s.lzma", man_filename);
 124         char *ext = strrchr(filename_with_zext, '.') + 1;
 125 #endif
 126
 127 #if ENABLE_FEATURE_SEAMLESS_LZMA
 128         if (run_pipe(pager, filename_with_zext, man, level))
 129                 return 1;
 130 #endif
 131 #if ENABLE_FEATURE_SEAMLESS_XZ
 132         strcpy(ext, "xz");
 133         if (run_pipe(pager, filename_with_zext, man, level))
 134                 return 1;
 135 #endif
 136 #if ENABLE_FEATURE_SEAMLESS_BZ2
 137         strcpy(ext, "bz2");
 138         if (run_pipe(pager, filename_with_zext, man, level))
 139                 return 1;
 140 #endif
 141 #if ENABLE_FEATURE_SEAMLESS_GZ
 142         strcpy(ext, "gz");
 143         if (run_pipe(pager, filename_with_zext, man, level))
 144                 return 1;
 145 #endif
 146
 147         return run_pipe(pager, man_filename, man, level);
 148 }
 149
 150 static char **add_MANPATH(char **man_path_list, int *count_mp, char *path)
 151 {
 152         if (path) while (*path) {
 153                 char *next_path;
 154                 char **path_element;
 155
 156                 next_path = strchr(path, ':');
 157                 if (next_path) {
 158                         *next_path = '\0';
 159                         if (next_path++ == path) /* "::"? */
 160                                 goto next;
 161                 }
 162                 /* Do we already have path? */
 163                 path_element = man_path_list;
 164                 if (path_element) while (*path_element) {
 165                         if (strcmp(*path_element, path) == 0)
 166                                 goto skip;
 167                         path_element++;
 168                 }
 169                 man_path_list = xrealloc_vector(man_path_list, 4, *count_mp);
 170                 man_path_list[*count_mp] = xstrdup(path);
 171                 (*count_mp)++;
 172                 /* man_path_list is NULL terminated */
 173                 /* man_path_list[*count_mp] = NULL; - xrealloc_vector did it */
 174  skip:
 175                 if (!next_path)
 176                         break;
 177  next:
 178                 path = next_path;
 179         }
 180         return man_path_list;
 181 }
 182
 183 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 184 int man_main(int argc UNUSED_PARAM, char **argv)
 185 {
 186         parser_t *parser;
 187         const char *pager = ENABLE_LESS ? "less" : "more";
 188         char *sec_list;
 189         char *cur_path, *cur_sect;
 190         char **man_path_list;
 191         int count_mp;
 192         int cur_mp;
 193         int opt, not_found;
 194         char *token[2];
 195
 196         opt_complementary = "-1"; /* at least one argument */
 197         opt = getopt32(argv, "+aw");
 198         argv += optind;
 199
 200         sec_list = xstrdup("0p:1:1p:2:3:3p:4:5:6:7:8:9");
 201
 202         count_mp = 0;
 203         man_path_list = add_MANPATH(NULL, &count_mp,
 204                         getenv("MANDATORY_MANPATH"+10) /* "MANPATH" */
 205         );
 206         if (!man_path_list) {
 207                 /* default, may be overridden by /etc/man.conf */
 208                 man_path_list = xzalloc(2 * sizeof(man_path_list[0]));
 209                 man_path_list[0] = (char*)"/usr/man";
 210                 /* count_mp stays 0.
 211                  * Thus, man.conf will overwrite man_path_list[0]
 212                  * if a path is defined there.
 213                  */
 214         }
 215
 216         /* Parse man.conf[ig] or man_db.conf */
 217         /* man version 1.6f uses man.config */
 218         /* man-db implementation of man uses man_db.conf */
 219         parser = config_open2("/etc/man.config", fopen_for_read);
 220         if (!parser)
 221                 parser = config_open2("/etc/man.conf", fopen_for_read);
 222         if (!parser)
 223                 parser = config_open2("/etc/man_db.conf", fopen_for_read);
 224
 225         while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 226                 if (!token[1])
 227                         continue;
 228                 if (strcmp("DEFINE", token[0]) == 0) {
 229                         if (strncmp("pager", token[1], 5) == 0) {
 230                                 pager = xstrdup(skip_whitespace(token[1]) + 5);
 231                         }
 232                 } else
 233                 if (strcmp("MANDATORY_MANPATH"+10, token[0]) == 0 /* "MANPATH"? */
 234                  || strcmp("MANDATORY_MANPATH", token[0]) == 0
 235                 ) {
 236                         man_path_list = add_MANPATH(man_path_list, &count_mp, token[1]);
 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         {
 246                 /* environment overrides setting from man.config */
 247                 char *env_pager = getenv("MANPAGER");
 248                 if (!env_pager)
 249                         env_pager = getenv("PAGER");
 250                 if (env_pager)
 251                         pager = env_pager;
 252         }
 253
 254         not_found = 0;
 255         do { /* for each argv[] */
 256                 int found = 0;
 257                 cur_mp = 0;
 258
 259                 if (strchr(*argv, '/')) {
 260                         found = show_manpage(pager, *argv, /*man:*/ 1, 0);
 261                         goto check_found;
 262                 }
 263                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 264                         /* for each MANPATH */
 265                         cur_sect = sec_list;
 266                         do { /* for each section */
 267                                 char *next_sect = strchrnul(cur_sect, ':');
 268                                 int sect_len = next_sect - cur_sect;
 269                                 char *man_filename;
 270                                 int cat0man1 = 0;
 271
 272                                 /* Search for cat, then man page */
 273                                 while (cat0man1 < 2) {
 274                                         int found_here;
 275                                         man_filename = xasprintf("%s/%s%.*s/%s.%.*s",
 276                                                         cur_path,
 277                                                         "cat\0man" + (cat0man1 * 4),
 278                                                         sect_len, cur_sect,
 279                                                         *argv,
 280                                                         sect_len, cur_sect);
 281                                         found_here = show_manpage(pager, man_filename, cat0man1, 0);
 282                                         found |= found_here;
 283                                         cat0man1 += found_here + 1;
 284                                         free(man_filename);
 285                                 }
 286
 287                                 if (found && !(opt & OPT_a))
 288                                         goto next_arg;
 289                                 cur_sect = next_sect;
 290                                 while (*cur_sect == ':')
 291                                         cur_sect++;
 292                         } while (*cur_sect);
 293                 }
 294  check_found:
 295                 if (!found) {
 296                         bb_error_msg("no manual entry for '%s'", *argv);
 297                         not_found = 1;
 298                 }
 299  next_arg:
 300                 argv++;
 301         } while (*argv);
 302
 303         return not_found;
 304 }