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                 /* Test whether the man page is not a link to another one. */
  53                 /* The link has the following on the first line: */
  54                 /* ".so another_man_page" */
  55                 struct stat sb;
  56                 char *line;
  57                 char *linkname, *p;
  58
  59                 /* On my system:
  60                  * man1/genhostid.1.gz: 203 bytes - smallest real manpage
  61                  * man2/path_resolution.2.gz: 114 bytes - largest link
  62                  */
  63                 xstat(man_filename, &sb);
  64                 if (sb.st_size > 300) /* err on the safe side */
  65                         goto ordinary_manpage;
  66
  67                 line = xmalloc_open_zipped_read_close(man_filename, NULL);
  68                 if (!line || strncmp(line, ".so ", 4) != 0) {
  69                         free(line);
  70                         goto ordinary_manpage;
  71                 }
  72                 /* Example: man2/path_resolution.2.gz contains
  73                  * ".so man7/path_resolution.7\n<junk>"
  74                  */
  75                 *strchrnul(line, '\n') = '\0';
  76                 linkname = p = skip_whitespace(&line[4]);
  77                 while (1) {
  78                         char *newname_slash, *oldname_slash;
  79
  80                         oldname_slash = strrchr(man_filename, '/');
  81                         if (!oldname_slash)
  82                                 goto ordinary_manpage;
  83                         *oldname_slash = '\0';
  84                         newname_slash = strchr(p, '/');
  85                         if (!newname_slash)
  86                                 break;
  87                         p = newname_slash + 1;
  88                 }
  89                 man_filename = xasprintf("%s/%s" ".bz2", man_filename, linkname);
  90                 free(line);
  91                 /* Note: we leak "new" man_filename string as well... */
  92                 if (show_manpage(pager, man_filename, man, level + 1))
  93                         return 1;
  94                 /* else: show the link, it's better than nothing */
  95         }
  96
  97  ordinary_manpage:
  98         /* "2>&1" is added so that nroff errors are shown in pager too.
  99          * Otherwise it may show just empty screen */
 100         cmd = xasprintf(
 101                 man ? "%s '%s' | gtbl | nroff -Tlatin1 -mandoc 2>&1 | %s"
 102                     : "%s '%s' | %s",
 103                 unpacker, man_filename, pager);
 104         system(cmd);
 105         free(cmd);
 106         return 1;
 107 }
 108
 109 /* man_filename is of the form "/dir/dir/dir/name.s.bz2" */
 110 static int show_manpage(const char *pager, char *man_filename, int man, int level)
 111 {
 112         int len;
 113
 114         if (run_pipe("bunzip2 -c", pager, man_filename, man, level))
 115                 return 1;
 116
 117         len = strlen(man_filename) - 1;
 118
 119         man_filename[len] = '\0'; /* ".bz2" -> ".gz" */
 120         man_filename[len - 2] = 'g';
 121         if (run_pipe("gunzip -c", pager, man_filename, man, level))
 122                 return 1;
 123
 124         man_filename[len - 3] = '\0'; /* ".gz" -> "" */
 125         if (run_pipe(STR_cat, pager, man_filename, man, level))
 126                 return 1;
 127
 128         return 0;
 129 }
 130
 131 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 132 int man_main(int argc UNUSED_PARAM, char **argv)
 133 {
 134         parser_t *parser;
 135         const char *pager;
 136         char **man_path_list;
 137         char *sec_list;
 138         char *cur_path, *cur_sect;
 139         int count_mp, cur_mp;
 140         int opt, not_found;
 141         char *token[2];
 142
 143         opt_complementary = "-1"; /* at least one argument */
 144         opt = getopt32(argv, "+aw");
 145         argv += optind;
 146
 147         sec_list = xstrdup("1:2:3:4:5:6:7:8:9");
 148         /* Last valid man_path_list[] is [0x10] */
 149         man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
 150         count_mp = 0;
 151         man_path_list[0] = xstrdup(getenv("MANPATH"));
 152         if (man_path_list[0])
 153                 count_mp++;
 154         pager = getenv("MANPAGER");
 155         if (!pager) {
 156                 pager = getenv("PAGER");
 157                 if (!pager)
 158                         pager = "more";
 159         }
 160
 161         /* Parse man.conf */
 162         parser = config_open("/etc/man.conf");
 163         while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 164                 if (!token[1])
 165                         continue;
 166                 if (strcmp("MANPATH", token[0]) == 0) {
 167                         man_path_list = xrealloc_vector(man_path_list, 4, count_mp);
 168                         man_path_list[count_mp] = xstrdup(token[1]);
 169                         count_mp++;
 170                         /* man_path_list is NULL terminated */
 171                         /*man_path_list[count_mp] = NULL; - xrealloc_vector did it */
 172                 }
 173                 if (strcmp("MANSECT", token[0]) == 0) {
 174                         free(sec_list);
 175                         sec_list = xstrdup(token[1]);
 176                 }
 177         }
 178         config_close(parser);
 179
 180         not_found = 0;
 181         do { /* for each argv[] */
 182                 int found = 0;
 183                 cur_mp = 0;
 184                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 185                         /* for each MANPATH */
 186                         do { /* for each MANPATH item */
 187                                 char *next_path = strchrnul(cur_path, ':');
 188                                 int path_len = next_path - cur_path;
 189                                 cur_sect = sec_list;
 190                                 do { /* for each section */
 191                                         char *next_sect = strchrnul(cur_sect, ':');
 192                                         int sect_len = next_sect - cur_sect;
 193                                         char *man_filename;
 194                                         int cat0man1 = 0;
 195
 196                                         /* Search for cat, then man page */
 197                                         while (cat0man1 < 2) {
 198                                                 int found_here;
 199                                                 man_filename = xasprintf("%.*s/%s%.*s/%s.%.*s" ".bz2",
 200                                                                 path_len, cur_path,
 201                                                                 STR_catNULmanNUL + cat0man1 * 4,
 202                                                                 sect_len, cur_sect,
 203                                                                 *argv,
 204                                                                 sect_len, cur_sect);
 205                                                 found_here = show_manpage(pager, man_filename, cat0man1, 0);
 206                                                 found |= found_here;
 207                                                 cat0man1 += found_here + 1;
 208                                                 free(man_filename);
 209                                         }
 210
 211                                         if (found && !(opt & OPT_a))
 212                                                 goto next_arg;
 213                                         cur_sect = next_sect;
 214                                         while (*cur_sect == ':')
 215                                                 cur_sect++;
 216                                 } while (*cur_sect);
 217                                 cur_path = next_path;
 218                                 while (*cur_path == ':')
 219                                         cur_path++;
 220                         } while (*cur_path);
 221                 }
 222                 if (!found) {
 223                         bb_error_msg("no manual entry for '%s'", *argv);
 224                         not_found = 1;
 225                 }
 226  next_arg:
 227                 argv++;
 228         } while (*argv);
 229
 230         return not_found;
 231 }