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 source tree.
   4  */
   5
   6 //usage:#define man_trivial_usage
   7 //usage:       "[-aw] [MANPAGE]..."
   8 //usage:#define man_full_usage "\n\n"
   9 //usage:       "Format and display manual page\n"
  10 //usage:     "\n        -a      Display all pages"
  11 //usage:     "\n        -w      Show page locations"
  12 //usage:     "\n"
  13 //usage:     "\n$COLUMNS overrides output width"
  14
  15 #include "libbb.h"
  16 #include "common_bufsiz.h"
  17
  18 enum {
  19         OPT_a = 1, /* all */
  20         OPT_w = 2, /* print path */
  21 };
  22
  23 /* This is what I see on my desktop system being executed:
  24 (
  25 echo ".ll 12.4i"
  26 echo ".nr LL 12.4i"
  27 echo ".pl 1100i"
  28 gunzip -c '/usr/man/man1/bzip2.1.gz'
  29 echo ".\\\""
  30 echo ".pl \n(nlu+10"
  31 ) | gtbl | nroff -Tlatin1 -mandoc | less
  32
  33 Some systems use -Tascii.
  34
  35 On another system I see this:
  36
  37 ... | tbl | nroff -mandoc -rLL=<NNN>n -rLT=<NNN>n -Tutf8 | less
  38
  39 where <NNN> is screen width minus 5.
  40 Replacing "DEFINE nroff nroff -mandoc" in /etc/man_db.conf
  41 changes "nroff -mandoc" part; -rLL=<NNN>n, -rLT=<NNN>n and -Tutf8 parts are
  42 appended to the user-specified command.
  43
  44 Redirecting to a pipe or file sets GROFF_NO_SGR=1 to prevent color escapes,
  45 and uses "col -b -p -x" instead of pager, this filters out backspace
  46 and underscore tricks.
  47 */
  48
  49 struct globals {
  50         const char *col;
  51         const char *tbl;
  52         const char *nroff;
  53         const char *pager;
  54 } FIX_ALIASING;
  55 #define G (*(struct globals*)bb_common_bufsiz1)
  56 #define INIT_G() do { \
  57         setup_common_bufsiz(); \
  58         G.col = "col"; \
  59         G.tbl = "tbl"; \
  60         /* Removed -Tlatin1. Assuming system nroff has suitable default */ \
  61         G.nroff = "nroff -mandoc"; \
  62         G.pager = ENABLE_LESS ? "less" : "more"; \
  63 } while (0)
  64
  65 static int show_manpage(char *man_filename, int man, int level);
  66
  67 static int run_pipe(char *man_filename, int man, int level)
  68 {
  69         char *cmd;
  70
  71         /* Prevent man page link loops */
  72         if (level > 10)
  73                 return 0;
  74
  75         if (access(man_filename, R_OK) != 0)
  76                 return 0;
  77
  78         if (option_mask32 & OPT_w) {
  79                 puts(man_filename);
  80                 return 1;
  81         }
  82
  83         if (man) { /* man page, not cat page */
  84                 /* Is this a link to another manpage? */
  85                 /* The link has the following on the first line: */
  86                 /* ".so another_man_page" */
  87
  88                 struct stat sb;
  89                 char *line;
  90                 char *linkname, *p;
  91
  92                 /* On my system:
  93                  * man1/genhostid.1.gz: 203 bytes - smallest real manpage
  94                  * man2/path_resolution.2.gz: 114 bytes - largest link
  95                  */
  96                 xstat(man_filename, &sb);
  97                 if (sb.st_size > 300) /* err on the safe side */
  98                         goto ordinary_manpage;
  99
 100                 line = xmalloc_open_zipped_read_close(man_filename, NULL);
 101                 if (!line || !is_prefixed_with(line, ".so ")) {
 102                         free(line);
 103                         goto ordinary_manpage;
 104                 }
 105                 /* Example: man2/path_resolution.2.gz contains
 106                  * ".so man7/path_resolution.7\n<junk>"
 107                  */
 108                 *strchrnul(line, '\n') = '\0';
 109                 linkname = skip_whitespace(&line[4]);
 110
 111                 /* If link has no slashes, we just replace man page name.
 112                  * If link has slashes (however many), we go back *once*.
 113                  * ".so zzz/ggg/page.3" does NOT go back two levels. */
 114                 p = strrchr(man_filename, '/');
 115                 if (!p)
 116                         goto ordinary_manpage;
 117                 *p = '\0';
 118                 if (strchr(linkname, '/')) {
 119                         p = strrchr(man_filename, '/');
 120                         if (!p)
 121                                 goto ordinary_manpage;
 122                         *p = '\0';
 123                 }
 124
 125                 /* Links do not have .gz extensions, even if manpage
 126                  * is compressed */
 127                 man_filename = xasprintf("%s/%s", man_filename, linkname);
 128                 free(line);
 129                 /* Note: we leak "new" man_filename string as well... */
 130                 if (show_manpage(man_filename, man, level + 1))
 131                         return 1;
 132                 /* else: show the link, it's better than nothing */
 133         }
 134
 135  ordinary_manpage:
 136         close(STDIN_FILENO);
 137         open_zipped(man_filename, /*fail_if_not_compressed:*/ 0); /* guaranteed to use fd 0 (STDIN_FILENO) */
 138         if (man) {
 139                 int w = get_terminal_width(-1);
 140                 if (w > 10)
 141                         w -= 2;
 142                 /* "2>&1" is added so that nroff errors are shown in pager too.
 143                  * Otherwise it may show just empty screen.
 144                  */
 145                 cmd = xasprintf("%s | %s -rLL=%un -rLT=%un 2>&1 | %s",
 146                                 G.tbl, G.nroff, w, w,
 147                                 G.pager);
 148         } else {
 149                 cmd = xstrdup(G.pager);
 150         }
 151         system(cmd);
 152         free(cmd);
 153         return 1;
 154 }
 155
 156 /* man_filename is of the form "/dir/dir/dir/name.s" */
 157 static int show_manpage(char *man_filename, int man, int level)
 158 {
 159 #if SEAMLESS_COMPRESSION
 160         /* We leak this allocation... */
 161         char *filename_with_zext = xasprintf("%s.lzma", man_filename);
 162         char *ext = strrchr(filename_with_zext, '.') + 1;
 163 #endif
 164
 165 #if ENABLE_FEATURE_SEAMLESS_LZMA
 166         if (run_pipe(filename_with_zext, man, level))
 167                 return 1;
 168 #endif
 169 #if ENABLE_FEATURE_SEAMLESS_XZ
 170         strcpy(ext, "xz");
 171         if (run_pipe(filename_with_zext, man, level))
 172                 return 1;
 173 #endif
 174 #if ENABLE_FEATURE_SEAMLESS_BZ2
 175         strcpy(ext, "bz2");
 176         if (run_pipe(filename_with_zext, man, level))
 177                 return 1;
 178 #endif
 179 #if ENABLE_FEATURE_SEAMLESS_GZ
 180         strcpy(ext, "gz");
 181         if (run_pipe(filename_with_zext, man, level))
 182                 return 1;
 183 #endif
 184
 185         return run_pipe(man_filename, man, level);
 186 }
 187
 188 static char **add_MANPATH(char **man_path_list, int *count_mp, char *path)
 189 {
 190         if (path) while (*path) {
 191                 char *next_path;
 192                 char **path_element;
 193
 194                 next_path = strchr(path, ':');
 195                 if (next_path) {
 196                         if (next_path == path) /* "::"? */
 197                                 goto next;
 198                         *next_path = '\0';
 199                 }
 200                 /* Do we already have path? */
 201                 path_element = man_path_list;
 202                 if (path_element) while (*path_element) {
 203                         if (strcmp(*path_element, path) == 0)
 204                                 goto skip;
 205                         path_element++;
 206                 }
 207                 man_path_list = xrealloc_vector(man_path_list, 4, *count_mp);
 208                 man_path_list[*count_mp] = xstrdup(path);
 209                 (*count_mp)++;
 210                 /* man_path_list is NULL terminated */
 211                 /* man_path_list[*count_mp] = NULL; - xrealloc_vector did it */
 212  skip:
 213                 if (!next_path)
 214                         break;
 215                 /* "path" may be a result of getenv(), be nice and don't mangle it */
 216                 *next_path = ':';
 217  next:
 218                 path = next_path + 1;
 219         }
 220         return man_path_list;
 221 }
 222
 223 static const char *if_redefined(const char *var, const char *key, const char *line)
 224 {
 225         if (!is_prefixed_with(line, key))
 226                 return var;
 227         line += strlen(key);
 228         if (!isspace(line[0]))
 229                 return var;
 230         return xstrdup(skip_whitespace(line));
 231 }
 232
 233 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 234 int man_main(int argc UNUSED_PARAM, char **argv)
 235 {
 236         parser_t *parser;
 237         char *sec_list;
 238         char *cur_path, *cur_sect;
 239         char **man_path_list;
 240         int count_mp;
 241         int cur_mp;
 242         int opt, not_found;
 243         char *token[2];
 244
 245         INIT_G();
 246
 247         opt_complementary = "-1"; /* at least one argument */
 248         opt = getopt32(argv, "+aw");
 249         argv += optind;
 250
 251         sec_list = xstrdup("0p:1:1p:2:3:3p:4:5:6:7:8:9");
 252
 253         count_mp = 0;
 254         man_path_list = add_MANPATH(NULL, &count_mp,
 255                         getenv("MANDATORY_MANPATH"+10) /* "MANPATH" */
 256         );
 257         if (!man_path_list) {
 258                 /* default, may be overridden by /etc/man.conf */
 259                 man_path_list = xzalloc(2 * sizeof(man_path_list[0]));
 260                 man_path_list[0] = (char*)"/usr/man";
 261                 /* count_mp stays 0.
 262                  * Thus, man.conf will overwrite man_path_list[0]
 263                  * if a path is defined there.
 264                  */
 265         }
 266
 267         /* Parse man.conf[ig] or man_db.conf */
 268         /* man version 1.6f uses man.config */
 269         /* man-db implementation of man uses man_db.conf */
 270         parser = config_open2("/etc/man.config", fopen_for_read);
 271         if (!parser)
 272                 parser = config_open2("/etc/man.conf", fopen_for_read);
 273         if (!parser)
 274                 parser = config_open2("/etc/man_db.conf", fopen_for_read);
 275
 276         while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 277                 if (!token[1])
 278                         continue;
 279                 if (strcmp("DEFINE", token[0]) == 0) {
 280                         G.col   = if_redefined(G.tbl  , "col",   token[1]);
 281                         G.tbl   = if_redefined(G.tbl  , "tbl",   token[1]);
 282                         G.nroff = if_redefined(G.nroff, "nroff", token[1]);
 283                         G.pager = if_redefined(G.pager, "pager", token[1]);
 284                 } else
 285                 if (strcmp("MANDATORY_MANPATH"+10, token[0]) == 0 /* "MANPATH"? */
 286                  || strcmp("MANDATORY_MANPATH", token[0]) == 0
 287                 ) {
 288                         man_path_list = add_MANPATH(man_path_list, &count_mp, token[1]);
 289                 }
 290                 if (strcmp("MANSECT", token[0]) == 0) {
 291                         free(sec_list);
 292                         sec_list = xstrdup(token[1]);
 293                 }
 294         }
 295         config_close(parser);
 296
 297         {
 298                 /* environment overrides setting from man.config */
 299                 char *env_pager = getenv("MANPAGER");
 300                 if (!env_pager)
 301                         env_pager = getenv("PAGER");
 302                 if (env_pager)
 303                         G.pager = env_pager;
 304         }
 305
 306         if (!isatty(STDOUT_FILENO)) {
 307                 putenv((char*)"GROFF_NO_SGR=1");
 308                 G.pager = xasprintf("%s -b -p -x", G.col);
 309         }
 310
 311         not_found = 0;
 312         do { /* for each argv[] */
 313                 int found = 0;
 314                 cur_mp = 0;
 315
 316                 if (strchr(*argv, '/')) {
 317                         found = show_manpage(*argv, /*man:*/ 1, 0);
 318                         goto check_found;
 319                 }
 320                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 321                         /* for each MANPATH */
 322                         cur_sect = sec_list;
 323                         do { /* for each section */
 324                                 char *next_sect = strchrnul(cur_sect, ':');
 325                                 int sect_len = next_sect - cur_sect;
 326                                 char *man_filename;
 327                                 int cat0man1 = 0;
 328
 329                                 /* Search for cat, then man page */
 330                                 while (cat0man1 < 2) {
 331                                         int found_here;
 332                                         man_filename = xasprintf("%s/%s%.*s/%s.%.*s",
 333                                                         cur_path,
 334                                                         "cat\0man" + (cat0man1 * 4),
 335                                                         sect_len, cur_sect,
 336                                                         *argv,
 337                                                         sect_len, cur_sect);
 338                                         found_here = show_manpage(man_filename, cat0man1, 0);
 339                                         found |= found_here;
 340                                         cat0man1 += found_here + 1;
 341                                         free(man_filename);
 342                                 }
 343
 344                                 if (found && !(opt & OPT_a))
 345                                         goto next_arg;
 346                                 cur_sect = next_sect;
 347                                 while (*cur_sect == ':')
 348                                         cur_sect++;
 349                         } while (*cur_sect);
 350                 }
 351  check_found:
 352                 if (!found) {
 353                         bb_error_msg("no manual entry for '%s'", *argv);
 354                         not_found = 1;
 355                 }
 356  next_arg:
 357                 argv++;
 358         } while (*argv);
 359
 360         return not_found;
 361 }