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 (27 kb)"
   7 //config:       default y
   8 //config:       help
   9 //config:       Format and display manual pages.
  10
  11 //applet:IF_MAN(APPLET(man, BB_DIR_USR_BIN, BB_SUID_DROP))
  12
  13 //kbuild:lib-$(CONFIG_MAN) += man.o
  14
  15 //usage:#define man_trivial_usage
  16 //usage:       "[-aw] [MANPAGE]..."
  17 //usage:#define man_full_usage "\n\n"
  18 //usage:       "Format and display manual page\n"
  19 //usage:     "\n        -a      Display all pages"
  20 //usage:     "\n        -w      Show page locations"
  21 //usage:     "\n"
  22 //usage:     "\n$COLUMNS overrides output width"
  23
  24 #include "libbb.h"
  25 #include "common_bufsiz.h"
  26
  27 enum {
  28         OPT_a = 1, /* all */
  29         OPT_w = 2, /* print path */
  30 };
  31
  32 /* This is what I see on my desktop system being executed:
  33 (
  34 echo ".ll 12.4i"
  35 echo ".nr LL 12.4i"
  36 echo ".pl 1100i"
  37 gunzip -c '/usr/man/man1/bzip2.1.gz'
  38 echo ".\\\""
  39 echo ".pl \n(nlu+10"
  40 ) | gtbl | nroff -Tlatin1 -mandoc | less
  41
  42 Some systems use -Tascii.
  43
  44 On another system I see this:
  45
  46 ... | tbl | nroff -mandoc -rLL=<NNN>n -rLT=<NNN>n -Tutf8 | less
  47
  48 where <NNN> is screen width minus 5.
  49 Replacing "DEFINE nroff nroff -mandoc" in /etc/man_db.conf
  50 changes "nroff -mandoc" part; -rLL=<NNN>n, -rLT=<NNN>n and -Tutf8 parts are
  51 appended to the user-specified command.
  52
  53 Redirecting to a pipe or file sets GROFF_NO_SGR=1 to prevent color escapes,
  54 and uses "col -b -p -x" instead of pager, this filters out backspace
  55 and underscore tricks.
  56 */
  57
  58 struct globals {
  59         const char *col;
  60         const char *tbl;
  61         const char *nroff;
  62         const char *pager;
  63 } FIX_ALIASING;
  64 #define G (*(struct globals*)bb_common_bufsiz1)
  65 #define INIT_G() do { \
  66         setup_common_bufsiz(); \
  67         G.col = "col"; \
  68         G.tbl = "tbl"; \
  69         /* Removed -Tlatin1. Assuming system nroff has suitable default */ \
  70         G.nroff = "nroff -mandoc"; \
  71         G.pager = ENABLE_LESS ? "less" : "more"; \
  72 } while (0)
  73
  74 static int show_manpage(char *man_filename, int man, int level);
  75
  76 static int run_pipe(char *man_filename, int man, int level)
  77 {
  78         char *cmd;
  79
  80         /* Prevent man page link loops */
  81         if (level > 10)
  82                 return 0;
  83
  84         if (access(man_filename, R_OK) != 0)
  85                 return 0;
  86
  87         if (option_mask32 & OPT_w) {
  88                 puts(man_filename);
  89                 return 1;
  90         }
  91
  92         if (man) { /* man page, not cat page */
  93                 /* Is this a link to another manpage? */
  94                 /* The link has the following on the first line: */
  95                 /* ".so another_man_page" */
  96
  97                 struct stat sb;
  98                 char *line;
  99                 char *linkname, *p;
 100
 101                 /* On my system:
 102                  * man1/genhostid.1.gz: 203 bytes - smallest real manpage
 103                  * man2/path_resolution.2.gz: 114 bytes - largest link
 104                  */
 105                 xstat(man_filename, &sb);
 106                 if (sb.st_size > 300) /* err on the safe side */
 107                         goto ordinary_manpage;
 108
 109                 line = xmalloc_open_zipped_read_close(man_filename, NULL);
 110                 if (!line || !is_prefixed_with(line, ".so ")) {
 111                         free(line);
 112                         goto ordinary_manpage;
 113                 }
 114                 /* Example: man2/path_resolution.2.gz contains
 115                  * ".so man7/path_resolution.7\n<junk>"
 116                  */
 117                 *strchrnul(line, '\n') = '\0';
 118                 linkname = skip_whitespace(&line[4]);
 119
 120                 /* If link has no slashes, we just replace man page name.
 121                  * If link has slashes (however many), we go back *once*.
 122                  * ".so zzz/ggg/page.3" does NOT go back two levels. */
 123                 p = strrchr(man_filename, '/');
 124                 if (!p)
 125                         goto ordinary_manpage;
 126                 *p = '\0';
 127                 if (strchr(linkname, '/')) {
 128                         p = strrchr(man_filename, '/');
 129                         if (!p)
 130                                 goto ordinary_manpage;
 131                         *p = '\0';
 132                 }
 133
 134                 /* Links do not have .gz extensions, even if manpage
 135                  * is compressed */
 136                 man_filename = xasprintf("%s/%s", man_filename, linkname);
 137                 free(line);
 138                 /* Note: we leak "new" man_filename string as well... */
 139                 if (show_manpage(man_filename, man, level + 1))
 140                         return 1;
 141                 /* else: show the link, it's better than nothing */
 142         }
 143
 144  ordinary_manpage:
 145         close(STDIN_FILENO);
 146         open_zipped(man_filename, /*fail_if_not_compressed:*/ 0); /* guaranteed to use fd 0 (STDIN_FILENO) */
 147         if (man) {
 148                 int w = get_terminal_width(-1);
 149                 if (w > 10)
 150                         w -= 2;
 151                 /* "2>&1" is added so that nroff errors are shown in pager too.
 152                  * Otherwise it may show just empty screen.
 153                  */
 154                 cmd = xasprintf("%s | %s -rLL=%un -rLT=%un 2>&1 | %s",
 155                                 G.tbl, G.nroff, w, w,
 156                                 G.pager);
 157         } else {
 158                 cmd = xstrdup(G.pager);
 159         }
 160         system(cmd);
 161         free(cmd);
 162         return 1;
 163 }
 164
 165 /* man_filename is of the form "/dir/dir/dir/name.s" */
 166 static int show_manpage(char *man_filename, int man, int level)
 167 {
 168 #if SEAMLESS_COMPRESSION
 169         /* We leak this allocation... */
 170         char *filename_with_zext = xasprintf("%s.lzma", man_filename);
 171         char *ext = strrchr(filename_with_zext, '.') + 1;
 172 #endif
 173
 174 #if ENABLE_FEATURE_SEAMLESS_LZMA
 175         if (run_pipe(filename_with_zext, man, level))
 176                 return 1;
 177 #endif
 178 #if ENABLE_FEATURE_SEAMLESS_XZ
 179         strcpy(ext, "xz");
 180         if (run_pipe(filename_with_zext, man, level))
 181                 return 1;
 182 #endif
 183 #if ENABLE_FEATURE_SEAMLESS_BZ2
 184         strcpy(ext, "bz2");
 185         if (run_pipe(filename_with_zext, man, level))
 186                 return 1;
 187 #endif
 188 #if ENABLE_FEATURE_SEAMLESS_GZ
 189         strcpy(ext, "gz");
 190         if (run_pipe(filename_with_zext, man, level))
 191                 return 1;
 192 #endif
 193
 194         return run_pipe(man_filename, man, level);
 195 }
 196
 197 static char **add_MANPATH(char **man_path_list, int *count_mp, char *path)
 198 {
 199         if (path) while (*path) {
 200                 char *next_path;
 201                 char **path_element;
 202
 203                 next_path = strchr(path, ':');
 204                 if (next_path) {
 205                         if (next_path == path) /* "::"? */
 206                                 goto next;
 207                         *next_path = '\0';
 208                 }
 209                 /* Do we already have path? */
 210                 path_element = man_path_list;
 211                 if (path_element) while (*path_element) {
 212                         if (strcmp(*path_element, path) == 0)
 213                                 goto skip;
 214                         path_element++;
 215                 }
 216                 man_path_list = xrealloc_vector(man_path_list, 4, *count_mp);
 217                 man_path_list[*count_mp] = xstrdup(path);
 218                 (*count_mp)++;
 219                 /* man_path_list is NULL terminated */
 220                 /* man_path_list[*count_mp] = NULL; - xrealloc_vector did it */
 221  skip:
 222                 if (!next_path)
 223                         break;
 224                 /* "path" may be a result of getenv(), be nice and don't mangle it */
 225                 *next_path = ':';
 226  next:
 227                 path = next_path + 1;
 228         }
 229         return man_path_list;
 230 }
 231
 232 static const char *if_redefined(const char *var, const char *key, const char *line)
 233 {
 234         if (!is_prefixed_with(line, key))
 235                 return var;
 236         line += strlen(key);
 237         if (!isspace(line[0]))
 238                 return var;
 239         return xstrdup(skip_whitespace(line));
 240 }
 241
 242 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 243 int man_main(int argc UNUSED_PARAM, char **argv)
 244 {
 245         parser_t *parser;
 246         char *sec_list;
 247         char *cur_path, *cur_sect;
 248         char **man_path_list;
 249         int count_mp;
 250         int cur_mp;
 251         int opt, not_found;
 252         char *token[2];
 253
 254         INIT_G();
 255
 256         opt = getopt32(argv, "^+" "aw" "\0" "-1"/*at least one arg*/);
 257         argv += optind;
 258
 259         sec_list = xstrdup("0p:1:1p:2:3:3p:4:5:6:7:8:9");
 260
 261         count_mp = 0;
 262         man_path_list = add_MANPATH(NULL, &count_mp,
 263                         getenv("MANDATORY_MANPATH"+10) /* "MANPATH" */
 264         );
 265         if (!man_path_list) {
 266                 /* default, may be overridden by /etc/man.conf */
 267                 man_path_list = xzalloc(2 * sizeof(man_path_list[0]));
 268                 man_path_list[0] = (char*)"/usr/man";
 269                 /* count_mp stays 0.
 270                  * Thus, man.conf will overwrite man_path_list[0]
 271                  * if a path is defined there.
 272                  */
 273         }
 274
 275         /* Parse man.conf[ig] or man_db.conf */
 276         /* man version 1.6f uses man.config */
 277         /* man-db implementation of man uses man_db.conf */
 278         parser = config_open2("/etc/man.config", fopen_for_read);
 279         if (!parser)
 280                 parser = config_open2("/etc/man.conf", fopen_for_read);
 281         if (!parser)
 282                 parser = config_open2("/etc/man_db.conf", fopen_for_read);
 283
 284         while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 285                 if (!token[1])
 286                         continue;
 287                 if (strcmp("DEFINE", token[0]) == 0) {
 288                         G.col   = if_redefined(G.tbl  , "col",   token[1]);
 289                         G.tbl   = if_redefined(G.tbl  , "tbl",   token[1]);
 290                         G.nroff = if_redefined(G.nroff, "nroff", token[1]);
 291                         G.pager = if_redefined(G.pager, "pager", token[1]);
 292                 } else
 293                 if (strcmp("MANDATORY_MANPATH"+10, token[0]) == 0 /* "MANPATH"? */
 294                  || strcmp("MANDATORY_MANPATH", token[0]) == 0
 295                 ) {
 296                         man_path_list = add_MANPATH(man_path_list, &count_mp, token[1]);
 297                 }
 298                 if (strcmp("MANSECT", token[0]) == 0) {
 299                         free(sec_list);
 300                         sec_list = xstrdup(token[1]);
 301                 }
 302         }
 303         config_close(parser);
 304
 305         {
 306                 /* environment overrides setting from man.config */
 307                 char *env_pager = getenv("MANPAGER");
 308                 if (!env_pager)
 309                         env_pager = getenv("PAGER");
 310                 if (env_pager)
 311                         G.pager = env_pager;
 312         }
 313
 314         if (!isatty(STDOUT_FILENO)) {
 315                 putenv((char*)"GROFF_NO_SGR=1");
 316                 G.pager = xasprintf("%s -b -p -x", G.col);
 317         }
 318
 319         not_found = 0;
 320         do { /* for each argv[] */
 321                 int found = 0;
 322                 cur_mp = 0;
 323
 324                 if (strchr(*argv, '/')) {
 325                         found = show_manpage(*argv, /*man:*/ 1, 0);
 326                         goto check_found;
 327                 }
 328                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 329                         /* for each MANPATH */
 330                         cur_sect = sec_list;
 331                         do { /* for each section */
 332                                 char *next_sect = strchrnul(cur_sect, ':');
 333                                 int sect_len = next_sect - cur_sect;
 334                                 char *man_filename;
 335                                 int cat0man1 = 0;
 336
 337                                 /* Search for cat, then man page */
 338                                 while (cat0man1 < 2) {
 339                                         int found_here;
 340                                         man_filename = xasprintf("%s/%s%.*s/%s.%.*s",
 341                                                         cur_path,
 342                                                         "cat\0man" + (cat0man1 * 4),
 343                                                         sect_len, cur_sect,
 344                                                         *argv,
 345                                                         sect_len, cur_sect);
 346                                         found_here = show_manpage(man_filename, cat0man1, 0);
 347                                         found |= found_here;
 348                                         cat0man1 += found_here + 1;
 349                                         free(man_filename);
 350                                 }
 351
 352                                 if (found && !(opt & OPT_a))
 353                                         goto next_arg;
 354                                 cur_sect = next_sect;
 355                                 while (*cur_sect == ':')
 356                                         cur_sect++;
 357                         } while (*cur_sect);
 358                 }
 359  check_found:
 360                 if (!found) {
 361                         bb_error_msg("no manual entry for '%s'", *argv);
 362                         not_found = 1;
 363                 }
 364  next_arg:
 365                 argv++;
 366         } while (*argv);
 367
 368         return not_found;
 369 }