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 static int run_pipe(const char *unpacker, const char *pager, char *man_filename)
  27 {
  28         char *cmd;
  29
  30         if (access(man_filename, R_OK) != 0)
  31                 return 0;
  32
  33         if (option_mask32 & OPT_w) {
  34                 puts(man_filename);
  35                 return 1;
  36         }
  37
  38         /* "2>&1" added so that nroff errors are shown in pager too.
  39          * Otherwise it may show just empty screen */
  40         cmd = xasprintf("%s '%s' | gtbl | nroff -Tlatin1 -mandoc 2>&1 | %s",
  41                         unpacker, man_filename, pager);
  42         system(cmd);
  43         free(cmd);
  44         return 1;
  45 }
  46
  47 /* man_filename is of the form "/dir/dir/dir/name.s.bz2" */
  48 static int show_manpage(const char *pager, char *man_filename)
  49 {
  50         int len;
  51
  52         if (run_pipe("bunzip2 -c", pager, man_filename))
  53                 return 1;
  54
  55         len = strlen(man_filename) - 1;
  56
  57         man_filename[len] = '\0'; /* ".bz2" -> ".gz" */
  58         man_filename[len - 2] = 'g';
  59         if (run_pipe("gunzip -c", pager, man_filename))
  60                 return 1;
  61
  62         man_filename[len - 3] = '\0'; /* ".gz" -> "" */
  63         if (run_pipe("cat", pager, man_filename))
  64                 return 1;
  65
  66         return 0;
  67 }
  68
  69 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  70 int man_main(int argc ATTRIBUTE_UNUSED, char **argv)
  71 {
  72         FILE *cf;
  73         const char *pager;
  74         char **man_path_list;
  75         char *sec_list;
  76         char *cur_path, *cur_sect;
  77         char *line, *value;
  78         int count_mp, cur_mp;
  79         int opt, not_found;
  80
  81         opt_complementary = "-1"; /* at least one argument */
  82         opt = getopt32(argv, "+aw");
  83         argv += optind;
  84
  85         sec_list = xstrdup("1:2:3:4:5:6:7:8:9");
  86         /* Last valid man_path_list[] is [0x10] */
  87         man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
  88         count_mp = 0;
  89         man_path_list[0] = xstrdup(getenv("MANPATH"));
  90         if (man_path_list[0])
  91                 count_mp++;
  92         pager = getenv("MANPAGER");
  93         if (!pager) {
  94                 pager = getenv("PAGER");
  95                 if (!pager)
  96                         pager = "more";
  97         }
  98
  99         /* Parse man.conf */
 100         cf = fopen_or_warn("/etc/man.conf", "r");
 101         if (cf) {
 102                 /* go through man configuration file and search relevant paths, sections */
 103                 while ((line = xmalloc_fgetline(cf)) != NULL) {
 104                         trim(line); /* remove whitespace at the beginning/end */
 105                         if (isspace(line[7])) {
 106                                 line[7] = '\0';
 107                                 value = skip_whitespace(&line[8]);
 108                                 *skip_non_whitespace(value) = '\0';
 109                                 if (strcmp("MANPATH", line) == 0) {
 110                                         man_path_list[count_mp] = xstrdup(value);
 111                                         count_mp++;
 112                                         /* man_path_list is NULL terminated */
 113                                         man_path_list[count_mp] = NULL;
 114                                         if (!(count_mp & 0xf)) { /* 0x10, 0x20 etc */
 115                                                 /* so that last valid man_path_list[] is [count_mp + 0x10] */
 116                                                 man_path_list = xrealloc(man_path_list,
 117                                                         (count_mp + 0x11) * sizeof(man_path_list[0]));
 118                                         }
 119                                 }
 120                                 if (strcmp("MANSECT", line) == 0) {
 121                                         free(sec_list);
 122                                         sec_list = xstrdup(value);
 123                                 }
 124                         }
 125                         free(line);
 126                 }
 127                 fclose(cf);
 128         }
 129
 130 // TODO: my man3/getpwuid.3.gz contains just one line:
 131 // .so man3/getpwnam.3
 132 // (and I _dont_ have man3/getpwnam.3, I have man3/getpwnam.3.gz)
 133 // need to support this...
 134
 135         not_found = 0;
 136         do { /* for each argv[] */
 137                 int found = 0;
 138                 cur_mp = 0;
 139                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 140                         /* for each MANPATH */
 141                         do { /* for each MANPATH item */
 142                                 char *next_path = strchrnul(cur_path, ':');
 143                                 int path_len = next_path - cur_path;
 144                                 cur_sect = sec_list;
 145                                 do { /* for each section */
 146                                         char *next_sect = strchrnul(cur_sect, ':');
 147                                         int sect_len = next_sect - cur_sect;
 148
 149                                         char *man_filename = xasprintf("%.*s/man%.*s/%s.%.*s" ".bz2",
 150                                                                 path_len, cur_path,
 151                                                                 sect_len, cur_sect,
 152                                                                 *argv,
 153                                                                 sect_len, cur_sect);
 154                                         found |= show_manpage(pager, man_filename);
 155                                         free(man_filename);
 156                                         if (found && !(opt & OPT_a))
 157                                                 goto next_arg;
 158                                         cur_sect = next_sect;
 159                                         while (*cur_sect == ':')
 160                                                 cur_sect++;
 161                                 } while (*cur_sect);
 162                                 cur_path = next_path;
 163                                 while (*cur_path == ':')
 164                                         cur_path++;
 165                         } while (*cur_path);
 166                 }
 167                 if (!found) {
 168                         bb_error_msg("no manual entry for '%s'", *argv);
 169                         not_found = 1;
 170                 }
 171  next_arg:
 172                 argv++;
 173         } while (*argv);
 174
 175         return not_found;
 176 }