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 /* Trick gcc to reuse "cat" string. */
  27 #define STR_catNULmanNUL "cat\0man"
  28 #define STR_cat          "cat\0man"
  29
  30 static int run_pipe(const char *unpacker, const char *pager, char *man_filename, int man)
  31 {
  32         char *cmd;
  33
  34         if (access(man_filename, R_OK) != 0)
  35                 return 0;
  36
  37         if (option_mask32 & OPT_w) {
  38                 puts(man_filename);
  39                 return 1;
  40         }
  41
  42         /* "2>&1" is added so that nroff errors are shown in pager too.
  43          * Otherwise it may show just empty screen */
  44         cmd = xasprintf(
  45                 man ? "%s '%s' | gtbl | nroff -Tlatin1 -mandoc 2>&1 | %s"
  46                     : "%s '%s' | %s",
  47                 unpacker, man_filename, pager);
  48         system(cmd);
  49         free(cmd);
  50         return 1;
  51 }
  52
  53 /* man_filename is of the form "/dir/dir/dir/name.s.bz2" */
  54 static int show_manpage(const char *pager, char *man_filename, int man)
  55 {
  56         int len;
  57
  58         if (run_pipe("bunzip2 -c", pager, man_filename, man))
  59                 return 1;
  60
  61         len = strlen(man_filename) - 1;
  62
  63         man_filename[len] = '\0'; /* ".bz2" -> ".gz" */
  64         man_filename[len - 2] = 'g';
  65         if (run_pipe("gunzip -c", pager, man_filename, man))
  66                 return 1;
  67
  68         man_filename[len - 3] = '\0'; /* ".gz" -> "" */
  69         if (run_pipe(STR_cat, pager, man_filename, man))
  70                 return 1;
  71
  72         return 0;
  73 }
  74
  75 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  76 int man_main(int argc UNUSED_PARAM, char **argv)
  77 {
  78         parser_t *parser;
  79         const char *pager;
  80         char **man_path_list;
  81         char *sec_list;
  82         char *cur_path, *cur_sect;
  83         int count_mp, cur_mp;
  84         int opt, not_found;
  85
  86         opt_complementary = "-1"; /* at least one argument */
  87         opt = getopt32(argv, "+aw");
  88         argv += optind;
  89
  90         sec_list = xstrdup("1:2:3:4:5:6:7:8:9");
  91         /* Last valid man_path_list[] is [0x10] */
  92         man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
  93         count_mp = 0;
  94         man_path_list[0] = xstrdup(getenv("MANPATH"));
  95         if (man_path_list[0])
  96                 count_mp++;
  97         pager = getenv("MANPAGER");
  98         if (!pager) {
  99                 pager = getenv("PAGER");
 100                 if (!pager)
 101                         pager = "more";
 102         }
 103
 104         /* Parse man.conf */
 105         parser = config_open("/etc/man.conf");
 106         if (parser) {
 107                 /* go through man configuration file and search relevant paths, sections */
 108                 char *token[2];
 109                 while (config_read(parser, token, 2, 0, "# \t", PARSE_LAST_IS_GREEDY)) {
 110                         if (!token[1])
 111                                 continue;
 112                         if (strcmp("MANPATH", token[0]) == 0) {
 113                                 man_path_list[count_mp] = xstrdup(token[1]);
 114                                 count_mp++;
 115                                 /* man_path_list is NULL terminated */
 116                                 man_path_list[count_mp] = NULL;
 117                                 man_path_list = xrealloc_vector(man_path_list, 4, count_mp);
 118                         }
 119                         if (strcmp("MANSECT", token[0]) == 0) {
 120                                 free(sec_list);
 121                                 sec_list = xstrdup(token[1]);
 122                         }
 123                 }
 124                 config_close(parser);
 125         }
 126
 127 // TODO: my man3/getpwuid.3.gz contains just one line:
 128 // .so man3/getpwnam.3
 129 // (and I _dont_ have man3/getpwnam.3, I have man3/getpwnam.3.gz)
 130 // need to support this...
 131
 132         not_found = 0;
 133         do { /* for each argv[] */
 134                 int found = 0;
 135                 cur_mp = 0;
 136                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 137                         /* for each MANPATH */
 138                         do { /* for each MANPATH item */
 139                                 char *next_path = strchrnul(cur_path, ':');
 140                                 int path_len = next_path - cur_path;
 141                                 cur_sect = sec_list;
 142                                 do { /* for each section */
 143                                         char *next_sect = strchrnul(cur_sect, ':');
 144                                         int sect_len = next_sect - cur_sect;
 145                                         char *man_filename;
 146                                         int cat0man1 = 0;
 147
 148                                         /* Search for cat, then man page */
 149                                         while (cat0man1 < 2) {
 150                                                 int found_here;
 151                                                 man_filename = xasprintf("%.*s/%s%.*s/%s.%.*s" ".bz2",
 152                                                                 path_len, cur_path,
 153                                                                 STR_catNULmanNUL + cat0man1 * 4,
 154                                                                 sect_len, cur_sect,
 155                                                                 *argv,
 156                                                                 sect_len, cur_sect);
 157                                                 found_here = show_manpage(pager, man_filename, cat0man1);
 158                                                 found |= found_here;
 159                                                 cat0man1 += found_here + 1;
 160                                                 free(man_filename);
 161                                         }
 162
 163                                         if (found && !(opt & OPT_a))
 164                                                 goto next_arg;
 165                                         cur_sect = next_sect;
 166                                         while (*cur_sect == ':')
 167                                                 cur_sect++;
 168                                 } while (*cur_sect);
 169                                 cur_path = next_path;
 170                                 while (*cur_path == ':')
 171                                         cur_path++;
 172                         } while (*cur_path);
 173                 }
 174                 if (!found) {
 175                         bb_error_msg("no manual entry for '%s'", *argv);
 176                         not_found = 1;
 177                 }
 178  next_arg:
 179                 argv++;
 180         } while (*argv);
 181
 182         return not_found;
 183 }