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 ATTRIBUTE_UNUSED, char **argv)
  77 {
  78         FILE *cf;
  79         const char *pager;
  80         char **man_path_list;
  81         char *sec_list;
  82         char *cur_path, *cur_sect;
  83         char *line, *value;
  84         int count_mp, cur_mp;
  85         int opt, not_found;
  86
  87         opt_complementary = "-1"; /* at least one argument */
  88         opt = getopt32(argv, "+aw");
  89         argv += optind;
  90
  91         sec_list = xstrdup("1:2:3:4:5:6:7:8:9");
  92         /* Last valid man_path_list[] is [0x10] */
  93         man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
  94         count_mp = 0;
  95         man_path_list[0] = xstrdup(getenv("MANPATH"));
  96         if (man_path_list[0])
  97                 count_mp++;
  98         pager = getenv("MANPAGER");
  99         if (!pager) {
 100                 pager = getenv("PAGER");
 101                 if (!pager)
 102                         pager = "more";
 103         }
 104
 105         /* Parse man.conf */
 106         cf = fopen_or_warn("/etc/man.conf", "r");
 107         if (cf) {
 108                 /* go through man configuration file and search relevant paths, sections */
 109                 while ((line = xmalloc_fgetline(cf)) != NULL) {
 110                         trim(line); /* remove whitespace at the beginning/end */
 111                         if (isspace(line[7])) {
 112                                 line[7] = '\0';
 113                                 value = skip_whitespace(&line[8]);
 114                                 *skip_non_whitespace(value) = '\0';
 115                                 if (strcmp("MANPATH", line) == 0) {
 116                                         man_path_list[count_mp] = xstrdup(value);
 117                                         count_mp++;
 118                                         /* man_path_list is NULL terminated */
 119                                         man_path_list[count_mp] = NULL;
 120                                         if (!(count_mp & 0xf)) { /* 0x10, 0x20 etc */
 121                                                 /* so that last valid man_path_list[] is [count_mp + 0x10] */
 122                                                 man_path_list = xrealloc(man_path_list,
 123                                                         (count_mp + 0x11) * sizeof(man_path_list[0]));
 124                                         }
 125                                 }
 126                                 if (strcmp("MANSECT", line) == 0) {
 127                                         free(sec_list);
 128                                         sec_list = xstrdup(value);
 129                                 }
 130                         }
 131                         free(line);
 132                 }
 133                 fclose(cf);
 134         }
 135
 136 // TODO: my man3/getpwuid.3.gz contains just one line:
 137 // .so man3/getpwnam.3
 138 // (and I _dont_ have man3/getpwnam.3, I have man3/getpwnam.3.gz)
 139 // need to support this...
 140
 141         not_found = 0;
 142         do { /* for each argv[] */
 143                 int found = 0;
 144                 cur_mp = 0;
 145                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 146                         /* for each MANPATH */
 147                         do { /* for each MANPATH item */
 148                                 char *next_path = strchrnul(cur_path, ':');
 149                                 int path_len = next_path - cur_path;
 150                                 cur_sect = sec_list;
 151                                 do { /* for each section */
 152                                         char *next_sect = strchrnul(cur_sect, ':');
 153                                         int sect_len = next_sect - cur_sect;
 154                                         char *man_filename;
 155                                         int cat0man1 = 0;
 156
 157                                         /* Search for cat, then man page */
 158                                         while (cat0man1 < 2) {
 159                                                 int found_here;
 160                                                 man_filename = xasprintf("%.*s/%s%.*s/%s.%.*s" ".bz2",
 161                                                                 path_len, cur_path,
 162                                                                 STR_catNULmanNUL + cat0man1 * 4,
 163                                                                 sect_len, cur_sect,
 164                                                                 *argv,
 165                                                                 sect_len, cur_sect);
 166                                                 found_here = show_manpage(pager, man_filename, cat0man1);
 167                                                 found |= found_here;
 168                                                 cat0man1 += found_here + 1;
 169                                                 free(man_filename);
 170                                         }
 171
 172                                         if (found && !(opt & OPT_a))
 173                                                 goto next_arg;
 174                                         cur_sect = next_sect;
 175                                         while (*cur_sect == ':')
 176                                                 cur_sect++;
 177                                 } while (*cur_sect);
 178                                 cur_path = next_path;
 179                                 while (*cur_path == ':')
 180                                         cur_path++;
 181                         } while (*cur_path);
 182                 }
 183                 if (!found) {
 184                         bb_error_msg("no manual entry for '%s'", *argv);
 185                         not_found = 1;
 186                 }
 187  next_arg:
 188                 argv++;
 189         } while (*argv);
 190
 191         return not_found;
 192 }