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 cat)
  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(cat ? "%s '%s' | %s"
  45                         : "%s '%s' | gtbl | nroff -Tlatin1 -mandoc 2>&1 | %s",
  46                         unpacker, man_filename, pager);
  47         system(cmd);
  48         free(cmd);
  49         return 1;
  50 }
  51
  52 /* man_filename is of the form "/dir/dir/dir/name.s.bz2" */
  53 static int show_manpage(const char *pager, char *man_filename, int cat)
  54 {
  55         int len;
  56
  57         if (run_pipe("bunzip2 -c", pager, man_filename, cat))
  58                 return 1;
  59
  60         len = strlen(man_filename) - 1;
  61
  62         man_filename[len] = '\0'; /* ".bz2" -> ".gz" */
  63         man_filename[len - 2] = 'g';
  64         if (run_pipe("gunzip -c", pager, man_filename, cat))
  65                 return 1;
  66
  67         man_filename[len - 3] = '\0'; /* ".gz" -> "" */
  68         if (run_pipe(STR_cat, pager, man_filename, cat))
  69                 return 1;
  70
  71         return 0;
  72 }
  73
  74 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  75 int man_main(int argc ATTRIBUTE_UNUSED, char **argv)
  76 {
  77         FILE *cf;
  78         const char *pager;
  79         char **man_path_list;
  80         char *sec_list;
  81         char *cur_path, *cur_sect;
  82         char *line, *value;
  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         cf = fopen_or_warn("/etc/man.conf", "r");
 106         if (cf) {
 107                 /* go through man configuration file and search relevant paths, sections */
 108                 while ((line = xmalloc_fgetline(cf)) != NULL) {
 109                         trim(line); /* remove whitespace at the beginning/end */
 110                         if (isspace(line[7])) {
 111                                 line[7] = '\0';
 112                                 value = skip_whitespace(&line[8]);
 113                                 *skip_non_whitespace(value) = '\0';
 114                                 if (strcmp("MANPATH", line) == 0) {
 115                                         man_path_list[count_mp] = xstrdup(value);
 116                                         count_mp++;
 117                                         /* man_path_list is NULL terminated */
 118                                         man_path_list[count_mp] = NULL;
 119                                         if (!(count_mp & 0xf)) { /* 0x10, 0x20 etc */
 120                                                 /* so that last valid man_path_list[] is [count_mp + 0x10] */
 121                                                 man_path_list = xrealloc(man_path_list,
 122                                                         (count_mp + 0x11) * sizeof(man_path_list[0]));
 123                                         }
 124                                 }
 125                                 if (strcmp("MANSECT", line) == 0) {
 126                                         free(sec_list);
 127                                         sec_list = xstrdup(value);
 128                                 }
 129                         }
 130                         free(line);
 131                 }
 132                 fclose(cf);
 133         }
 134
 135 // TODO: my man3/getpwuid.3.gz contains just one line:
 136 // .so man3/getpwnam.3
 137 // (and I _dont_ have man3/getpwnam.3, I have man3/getpwnam.3.gz)
 138 // need to support this...
 139
 140         not_found = 0;
 141         do { /* for each argv[] */
 142                 int found = 0;
 143                 cur_mp = 0;
 144                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 145                         /* for each MANPATH */
 146                         do { /* for each MANPATH item */
 147                                 char *next_path = strchrnul(cur_path, ':');
 148                                 int path_len = next_path - cur_path;
 149                                 cur_sect = sec_list;
 150                                 do { /* for each section */
 151                                         char *next_sect = strchrnul(cur_sect, ':');
 152                                         int sect_len = next_sect - cur_sect;
 153                                         char *man_filename;
 154                                         int cat0man1 = 0;
 155
 156                                         /* Search for cat, then man page */
 157                                         while (cat0man1 < 2) {
 158                                                 int found_here;
 159                                                 man_filename = xasprintf("%.*s/%s%.*s/%s.%.*s" ".bz2",
 160                                                                 path_len, cur_path,
 161                                                                 STR_catNULmanNUL + cat0man1 * 4,
 162                                                                 sect_len, cur_sect,
 163                                                                 *argv,
 164                                                                 sect_len, cur_sect);
 165                                                 found_here = show_manpage(pager, man_filename, cat0man1);
 166                                                 found |= found_here;
 167                                                 cat0man1 += found_here + 1;
 168                                                 free(man_filename);
 169                                         }
 170
 171                                         if (found && !(opt & OPT_a))
 172                                                 goto next_arg;
 173                                         cur_sect = next_sect;
 174                                         while (*cur_sect == ':')
 175                                                 cur_sect++;
 176                                 } while (*cur_sect);
 177                                 cur_path = next_path;
 178                                 while (*cur_path == ':')
 179                                         cur_path++;
 180                         } while (*cur_path);
 181                 }
 182                 if (!found) {
 183                         bb_error_msg("no manual entry for '%s'", *argv);
 184                         not_found = 1;
 185                 }
 186  next_arg:
 187                 argv++;
 188         } while (*argv);
 189
 190         return not_found;
 191 }