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 //config:config MAN
   6 //config:       bool "man"
   7 //config:       default y
   8 //config:       help
   9 //config:         Format and display manual pages.
  10
  11 //usage:#define man_trivial_usage
  12 //usage:       "[-aw] [MANPAGE]..."
  13 //usage:#define man_full_usage "\n\n"
  14 //usage:       "Format and display manual page\n"
  15 //usage:     "\n        -a      Display all pages"
  16 //usage:     "\n        -w      Show page locations"
  17 //usage:     "\n"
  18 //usage:     "\n$COLUMNS overrides output width"
  19
  20 #include "libbb.h"
  21 #include "common_bufsiz.h"
  22
  23 enum {
  24         OPT_a = 1, /* all */
  25         OPT_w = 2, /* print path */
  26 };
  27
  28 /* This is what I see on my desktop system being executed:
  29 (
  30 echo ".ll 12.4i"
  31 echo ".nr LL 12.4i"
  32 echo ".pl 1100i"
  33 gunzip -c '/usr/man/man1/bzip2.1.gz'
  34 echo ".\\\""
  35 echo ".pl \n(nlu+10"
  36 ) | gtbl | nroff -Tlatin1 -mandoc | less
  37
  38 Some systems use -Tascii.
  39
  40 On another system I see this:
  41
  42 ... | tbl | nroff -mandoc -rLL=<NNN>n -rLT=<NNN>n -Tutf8 | less
  43
  44 where <NNN> is screen width minus 5.
  45 Replacing "DEFINE nroff nroff -mandoc" in /etc/man_db.conf
  46 changes "nroff -mandoc" part; -rLL=<NNN>n, -rLT=<NNN>n and -Tutf8 parts are
  47 appended to the user-specified command.
  48
  49 Redirecting to a pipe or file sets GROFF_NO_SGR=1 to prevent color escapes,
  50 and uses "col -b -p -x" instead of pager, this filters out backspace
  51 and underscore tricks.
  52 */
  53
  54 struct globals {
  55         const char *col;
  56         const char *tbl;
  57         const char *nroff;
  58         const char *pager;
  59 } FIX_ALIASING;
  60 #define G (*(struct globals*)bb_common_bufsiz1)
  61 #define INIT_G() do { \
  62         setup_common_bufsiz(); \
  63         G.col = "col"; \
  64         G.tbl = "tbl"; \
  65         /* Removed -Tlatin1. Assuming system nroff has suitable default */ \
  66         G.nroff = "nroff -mandoc"; \
  67         G.pager = ENABLE_LESS ? "less" : "more"; \
  68 } while (0)
  69
  70 static int show_manpage(char *man_filename, int man, int level);
  71
  72 static int run_pipe(char *man_filename, int man, int level)
  73 {
  74         char *cmd;
  75
  76         /* Prevent man page link loops */
  77         if (level > 10)
  78                 return 0;
  79
  80         if (access(man_filename, R_OK) != 0)
  81                 return 0;
  82
  83         if (option_mask32 & OPT_w) {
  84                 puts(man_filename);
  85                 return 1;
  86         }
  87
  88         if (man) { /* man page, not cat page */
  89                 /* Is this a link to another manpage? */
  90                 /* The link has the following on the first line: */
  91                 /* ".so another_man_page" */
  92
  93                 struct stat sb;
  94                 char *line;
  95                 char *linkname, *p;
  96
  97                 /* On my system:
  98                  * man1/genhostid.1.gz: 203 bytes - smallest real manpage
  99                  * man2/path_resolution.2.gz: 114 bytes - largest link
 100                  */
 101                 xstat(man_filename, &sb);
 102                 if (sb.st_size > 300) /* err on the safe side */
 103                         goto ordinary_manpage;
 104
 105                 line = xmalloc_open_zipped_read_close(man_filename, NULL);
 106                 if (!line || !is_prefixed_with(line, ".so ")) {
 107                         free(line);
 108                         goto ordinary_manpage;
 109                 }
 110                 /* Example: man2/path_resolution.2.gz contains
 111                  * ".so man7/path_resolution.7\n<junk>"
 112                  */
 113                 *strchrnul(line, '\n') = '\0';
 114                 linkname = skip_whitespace(&line[4]);
 115
 116                 /* If link has no slashes, we just replace man page name.
 117                  * If link has slashes (however many), we go back *once*.
 118                  * ".so zzz/ggg/page.3" does NOT go back two levels. */
 119                 p = strrchr(man_filename, '/');
 120                 if (!p)
 121                         goto ordinary_manpage;
 122                 *p = '\0';
 123                 if (strchr(linkname, '/')) {
 124                         p = strrchr(man_filename, '/');
 125                         if (!p)
 126                                 goto ordinary_manpage;
 127                         *p = '\0';
 128                 }
 129
 130                 /* Links do not have .gz extensions, even if manpage
 131                  * is compressed */
 132                 man_filename = xasprintf("%s/%s", man_filename, linkname);
 133                 free(line);
 134                 /* Note: we leak "new" man_filename string as well... */
 135                 if (show_manpage(man_filename, man, level + 1))
 136                         return 1;
 137                 /* else: show the link, it's better than nothing */
 138         }
 139
 140  ordinary_manpage:
 141         close(STDIN_FILENO);
 142         open_zipped(man_filename, /*fail_if_not_compressed:*/ 0); /* guaranteed to use fd 0 (STDIN_FILENO) */
 143         if (man) {
 144                 int w = get_terminal_width(-1);
 145                 if (w > 10)
 146                         w -= 2;
 147                 /* "2>&1" is added so that nroff errors are shown in pager too.
 148                  * Otherwise it may show just empty screen.
 149                  */
 150                 cmd = xasprintf("%s | %s -rLL=%un -rLT=%un 2>&1 | %s",
 151                                 G.tbl, G.nroff, w, w,
 152                                 G.pager);
 153         } else {
 154                 cmd = xstrdup(G.pager);
 155         }
 156         system(cmd);
 157         free(cmd);
 158         return 1;
 159 }
 160
 161 /* man_filename is of the form "/dir/dir/dir/name.s" */
 162 static int show_manpage(char *man_filename, int man, int level)
 163 {
 164 #if SEAMLESS_COMPRESSION
 165         /* We leak this allocation... */
 166         char *filename_with_zext = xasprintf("%s.lzma", man_filename);
 167         char *ext = strrchr(filename_with_zext, '.') + 1;
 168 #endif
 169
 170 #if ENABLE_FEATURE_SEAMLESS_LZMA
 171         if (run_pipe(filename_with_zext, man, level))
 172                 return 1;
 173 #endif
 174 #if ENABLE_FEATURE_SEAMLESS_XZ
 175         strcpy(ext, "xz");
 176         if (run_pipe(filename_with_zext, man, level))
 177                 return 1;
 178 #endif
 179 #if ENABLE_FEATURE_SEAMLESS_BZ2
 180         strcpy(ext, "bz2");
 181         if (run_pipe(filename_with_zext, man, level))
 182                 return 1;
 183 #endif
 184 #if ENABLE_FEATURE_SEAMLESS_GZ
 185         strcpy(ext, "gz");
 186         if (run_pipe(filename_with_zext, man, level))
 187                 return 1;
 188 #endif
 189
 190         return run_pipe(man_filename, man, level);
 191 }
 192
 193 static char **add_MANPATH(char **man_path_list, int *count_mp, char *path)
 194 {
 195         if (path) while (*path) {
 196                 char *next_path;
 197                 char **path_element;
 198
 199                 next_path = strchr(path, ':');
 200                 if (next_path) {
 201                         if (next_path == path) /* "::"? */
 202                                 goto next;
 203                         *next_path = '\0';
 204                 }
 205                 /* Do we already have path? */
 206                 path_element = man_path_list;
 207                 if (path_element) while (*path_element) {
 208                         if (strcmp(*path_element, path) == 0)
 209                                 goto skip;
 210                         path_element++;
 211                 }
 212                 man_path_list = xrealloc_vector(man_path_list, 4, *count_mp);
 213                 man_path_list[*count_mp] = xstrdup(path);
 214                 (*count_mp)++;
 215                 /* man_path_list is NULL terminated */
 216                 /* man_path_list[*count_mp] = NULL; - xrealloc_vector did it */
 217  skip:
 218                 if (!next_path)
 219                         break;
 220                 /* "path" may be a result of getenv(), be nice and don't mangle it */
 221                 *next_path = ':';
 222  next:
 223                 path = next_path + 1;
 224         }
 225         return man_path_list;
 226 }
 227
 228 static const char *if_redefined(const char *var, const char *key, const char *line)
 229 {
 230         if (!is_prefixed_with(line, key))
 231                 return var;
 232         line += strlen(key);
 233         if (!isspace(line[0]))
 234                 return var;
 235         return xstrdup(skip_whitespace(line));
 236 }
 237
 238 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 239 int man_main(int argc UNUSED_PARAM, char **argv)
 240 {
 241         parser_t *parser;
 242         char *sec_list;
 243         char *cur_path, *cur_sect;
 244         char **man_path_list;
 245         int count_mp;
 246         int cur_mp;
 247         int opt, not_found;
 248         char *token[2];
 249
 250         INIT_G();
 251
 252         opt_complementary = "-1"; /* at least one argument */
 253         opt = getopt32(argv, "+aw");
 254         argv += optind;
 255
 256         sec_list = xstrdup("0p:1:1p:2:3:3p:4:5:6:7:8:9");
 257
 258         count_mp = 0;
 259         man_path_list = add_MANPATH(NULL, &count_mp,
 260                         getenv("MANDATORY_MANPATH"+10) /* "MANPATH" */
 261         );
 262         if (!man_path_list) {
 263                 /* default, may be overridden by /etc/man.conf */
 264                 man_path_list = xzalloc(2 * sizeof(man_path_list[0]));
 265                 man_path_list[0] = (char*)"/usr/man";
 266                 /* count_mp stays 0.
 267                  * Thus, man.conf will overwrite man_path_list[0]
 268                  * if a path is defined there.
 269                  */
 270         }
 271
 272         /* Parse man.conf[ig] or man_db.conf */
 273         /* man version 1.6f uses man.config */
 274         /* man-db implementation of man uses man_db.conf */
 275         parser = config_open2("/etc/man.config", fopen_for_read);
 276         if (!parser)
 277                 parser = config_open2("/etc/man.conf", fopen_for_read);
 278         if (!parser)
 279                 parser = config_open2("/etc/man_db.conf", fopen_for_read);
 280
 281         while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 282                 if (!token[1])
 283                         continue;
 284                 if (strcmp("DEFINE", token[0]) == 0) {
 285                         G.col   = if_redefined(G.tbl  , "col",   token[1]);
 286                         G.tbl   = if_redefined(G.tbl  , "tbl",   token[1]);
 287                         G.nroff = if_redefined(G.nroff, "nroff", token[1]);
 288                         G.pager = if_redefined(G.pager, "pager", token[1]);
 289                 } else
 290                 if (strcmp("MANDATORY_MANPATH"+10, token[0]) == 0 /* "MANPATH"? */
 291                  || strcmp("MANDATORY_MANPATH", token[0]) == 0
 292                 ) {
 293                         man_path_list = add_MANPATH(man_path_list, &count_mp, token[1]);
 294                 }
 295                 if (strcmp("MANSECT", token[0]) == 0) {
 296                         free(sec_list);
 297                         sec_list = xstrdup(token[1]);
 298                 }
 299         }
 300         config_close(parser);
 301
 302         {
 303                 /* environment overrides setting from man.config */
 304                 char *env_pager = getenv("MANPAGER");
 305                 if (!env_pager)
 306                         env_pager = getenv("PAGER");
 307                 if (env_pager)
 308                         G.pager = env_pager;
 309         }
 310
 311         if (!isatty(STDOUT_FILENO)) {
 312                 putenv((char*)"GROFF_NO_SGR=1");
 313                 G.pager = xasprintf("%s -b -p -x", G.col);
 314         }
 315
 316         not_found = 0;
 317         do { /* for each argv[] */
 318                 int found = 0;
 319                 cur_mp = 0;
 320
 321                 if (strchr(*argv, '/')) {
 322                         found = show_manpage(*argv, /*man:*/ 1, 0);
 323                         goto check_found;
 324                 }
 325                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 326                         /* for each MANPATH */
 327                         cur_sect = sec_list;
 328                         do { /* for each section */
 329                                 char *next_sect = strchrnul(cur_sect, ':');
 330                                 int sect_len = next_sect - cur_sect;
 331                                 char *man_filename;
 332                                 int cat0man1 = 0;
 333
 334                                 /* Search for cat, then man page */
 335                                 while (cat0man1 < 2) {
 336                                         int found_here;
 337                                         man_filename = xasprintf("%s/%s%.*s/%s.%.*s",
 338                                                         cur_path,
 339                                                         "cat\0man" + (cat0man1 * 4),
 340                                                         sect_len, cur_sect,
 341                                                         *argv,
 342                                                         sect_len, cur_sect);
 343                                         found_here = show_manpage(man_filename, cat0man1, 0);
 344                                         found |= found_here;
 345                                         cat0man1 += found_here + 1;
 346                                         free(man_filename);
 347                                 }
 348
 349                                 if (found && !(opt & OPT_a))
 350                                         goto next_arg;
 351                                 cur_sect = next_sect;
 352                                 while (*cur_sect == ':')
 353                                         cur_sect++;
 354                         } while (*cur_sect);
 355                 }
 356  check_found:
 357                 if (!found) {
 358                         bb_error_msg("no manual entry for '%s'", *argv);
 359                         not_found = 1;
 360                 }
 361  next_arg:
 362                 argv++;
 363         } while (*argv);
 364
 365         return not_found;
 366 }