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 //TODO: make gz/bz2 support conditional on FEATURE_SEAMLESS_GZ/BZ2,
  31 // add SEAMLESS_LZMA support
  32
  33 static int show_manpage(const char *pager, char *man_filename, int man, int level);
  34
  35 static int run_pipe(const char *unpacker, 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" ".bz2", 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         /* "2>&1" is added so that nroff errors are shown in pager too.
 105          * Otherwise it may show just empty screen */
 106         cmd = xasprintf(
 107                 man ? "%s '%s' 2>&1 | gtbl | nroff -Tlatin1 -mandoc 2>&1 | %s"
 108                     : "%s '%s' 2>&1 | %s",
 109                 unpacker, man_filename, pager);
 110         system(cmd);
 111         free(cmd);
 112         return 1;
 113 }
 114
 115 /* man_filename is of the form "/dir/dir/dir/name.s.bz2" */
 116 static int show_manpage(const char *pager, char *man_filename, int man, int level)
 117 {
 118         int len;
 119
 120         if (run_pipe("bunzip2 -c", pager, man_filename, man, level))
 121                 return 1;
 122
 123         len = strlen(man_filename) - 1;
 124
 125         man_filename[len] = '\0'; /* ".bz2" -> ".gz" */
 126         man_filename[len - 2] = 'g';
 127         if (run_pipe("gunzip -c", pager, man_filename, man, level))
 128                 return 1;
 129
 130         man_filename[len - 3] = '\0'; /* ".gz" -> "" */
 131         if (run_pipe(STR_cat, pager, man_filename, man, level))
 132                 return 1;
 133
 134         return 0;
 135 }
 136
 137 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 138 int man_main(int argc UNUSED_PARAM, char **argv)
 139 {
 140         parser_t *parser;
 141         const char *pager;
 142         char **man_path_list;
 143         char *sec_list;
 144         char *cur_path, *cur_sect;
 145         int count_mp, cur_mp;
 146         int opt, not_found;
 147         char *token[2];
 148
 149         opt_complementary = "-1"; /* at least one argument */
 150         opt = getopt32(argv, "+aw");
 151         argv += optind;
 152
 153         sec_list = xstrdup("1:2:3:4:5:6:7:8:9");
 154         /* Last valid man_path_list[] is [0x10] */
 155         man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
 156         count_mp = 0;
 157         man_path_list[0] = xstrdup(getenv("MANPATH"));
 158         if (man_path_list[0])
 159                 count_mp++;
 160         pager = getenv("MANPAGER");
 161         if (!pager) {
 162                 pager = getenv("PAGER");
 163                 if (!pager)
 164                         pager = "more";
 165         }
 166
 167         /* Parse man.conf */
 168         parser = config_open("/etc/man.conf");
 169         while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 170                 if (!token[1])
 171                         continue;
 172                 if (strcmp("MANPATH", token[0]) == 0) {
 173                         man_path_list = xrealloc_vector(man_path_list, 4, count_mp);
 174                         man_path_list[count_mp] = xstrdup(token[1]);
 175                         count_mp++;
 176                         /* man_path_list is NULL terminated */
 177                         /*man_path_list[count_mp] = NULL; - xrealloc_vector did it */
 178                 }
 179                 if (strcmp("MANSECT", token[0]) == 0) {
 180                         free(sec_list);
 181                         sec_list = xstrdup(token[1]);
 182                 }
 183         }
 184         config_close(parser);
 185
 186         not_found = 0;
 187         do { /* for each argv[] */
 188                 int found = 0;
 189                 cur_mp = 0;
 190                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 191                         /* for each MANPATH */
 192                         do { /* for each MANPATH item */
 193                                 char *next_path = strchrnul(cur_path, ':');
 194                                 int path_len = next_path - cur_path;
 195                                 cur_sect = sec_list;
 196                                 do { /* for each section */
 197                                         char *next_sect = strchrnul(cur_sect, ':');
 198                                         int sect_len = next_sect - cur_sect;
 199                                         char *man_filename;
 200                                         int cat0man1 = 0;
 201
 202                                         /* Search for cat, then man page */
 203                                         while (cat0man1 < 2) {
 204                                                 int found_here;
 205                                                 man_filename = xasprintf("%.*s/%s%.*s/%s.%.*s" ".bz2",
 206                                                                 path_len, cur_path,
 207                                                                 STR_catNULmanNUL + cat0man1 * 4,
 208                                                                 sect_len, cur_sect,
 209                                                                 *argv,
 210                                                                 sect_len, cur_sect);
 211                                                 found_here = show_manpage(pager, man_filename, cat0man1, 0);
 212                                                 found |= found_here;
 213                                                 cat0man1 += found_here + 1;
 214                                                 free(man_filename);
 215                                         }
 216
 217                                         if (found && !(opt & OPT_a))
 218                                                 goto next_arg;
 219                                         cur_sect = next_sect;
 220                                         while (*cur_sect == ':')
 221                                                 cur_sect++;
 222                                 } while (*cur_sect);
 223                                 cur_path = next_path;
 224                                 while (*cur_path == ':')
 225                                         cur_path++;
 226                         } while (*cur_path);
 227                 }
 228                 if (!found) {
 229                         bb_error_msg("no manual entry for '%s'", *argv);
 230                         not_found = 1;
 231                 }
 232  next_arg:
 233                 argv++;
 234         } while (*argv);
 235
 236         return not_found;
 237 }