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
  13 #include "libbb.h"
  14 #include "common_bufsiz.h"
  15
  16 enum {
  17         OPT_a = 1, /* all */
  18         OPT_w = 2, /* print path */
  19 };
  20
  21 /* This is what I see on my desktop system being executed:
  22 (
  23 echo ".ll 12.4i"
  24 echo ".nr LL 12.4i"
  25 echo ".pl 1100i"
  26 gunzip -c '/usr/man/man1/bzip2.1.gz'
  27 echo ".\\\""
  28 echo ".pl \n(nlu+10"
  29 ) | gtbl | nroff -Tlatin1 -mandoc | less
  30
  31 On another system I see this:
  32
  33 ... | tbl | nroff -mandoc -rLL=<NNN>n -rLT=<NNN>n -Tutf8 | less
  34
  35 where <NNN> is screen width minus 5.
  36 Replacing "DEFINE nroff nroff -mandoc" in /etc/man_db.conf
  37 changes "nroff -mandoc" part; -rLL=<NNN>n, -rLT=<NNN>n and -Tutf8 parts are
  38 appended to the user-specified command.
  39
  40 Redirecting to a pipe or file sets GROFF_NO_SGR=1 to prevent color escapes,
  41 and uses "col -b -p -x" instead of pager, this filters out backspace
  42 and underscore tricks.
  43 */
  44
  45 struct globals {
  46         const char *col;
  47         const char *tbl;
  48         const char *nroff;
  49         const char *pager;
  50 } FIX_ALIASING;
  51 #define G (*(struct globals*)bb_common_bufsiz1)
  52 #define INIT_G() do { \
  53         setup_common_bufsiz(); \
  54         G.col = "col"; \
  55         G.tbl = "tbl"; \
  56         /* replaced -Tlatin1 with -Tascii for non-UTF8 displays */; \
  57         G.nroff = "nroff -mandoc -Tascii"; \
  58         G.pager = ENABLE_LESS ? "less" : "more"; \
  59 } while (0)
  60
  61 static int show_manpage(char *man_filename, int man, int level);
  62
  63 static int run_pipe(char *man_filename, int man, int level)
  64 {
  65         char *cmd;
  66
  67         /* Prevent man page link loops */
  68         if (level > 10)
  69                 return 0;
  70
  71         if (access(man_filename, R_OK) != 0)
  72                 return 0;
  73
  74         if (option_mask32 & OPT_w) {
  75                 puts(man_filename);
  76                 return 1;
  77         }
  78
  79         if (man) { /* man page, not cat page */
  80                 /* Is this a link to another manpage? */
  81                 /* The link has the following on the first line: */
  82                 /* ".so another_man_page" */
  83
  84                 struct stat sb;
  85                 char *line;
  86                 char *linkname, *p;
  87
  88                 /* On my system:
  89                  * man1/genhostid.1.gz: 203 bytes - smallest real manpage
  90                  * man2/path_resolution.2.gz: 114 bytes - largest link
  91                  */
  92                 xstat(man_filename, &sb);
  93                 if (sb.st_size > 300) /* err on the safe side */
  94                         goto ordinary_manpage;
  95
  96                 line = xmalloc_open_zipped_read_close(man_filename, NULL);
  97                 if (!line || !is_prefixed_with(line, ".so ")) {
  98                         free(line);
  99                         goto ordinary_manpage;
 100                 }
 101                 /* Example: man2/path_resolution.2.gz contains
 102                  * ".so man7/path_resolution.7\n<junk>"
 103                  */
 104                 *strchrnul(line, '\n') = '\0';
 105                 linkname = skip_whitespace(&line[4]);
 106
 107                 /* If link has no slashes, we just replace man page name.
 108                  * If link has slashes (however many), we go back *once*.
 109                  * ".so zzz/ggg/page.3" does NOT go back two levels. */
 110                 p = strrchr(man_filename, '/');
 111                 if (!p)
 112                         goto ordinary_manpage;
 113                 *p = '\0';
 114                 if (strchr(linkname, '/')) {
 115                         p = strrchr(man_filename, '/');
 116                         if (!p)
 117                                 goto ordinary_manpage;
 118                         *p = '\0';
 119                 }
 120
 121                 /* Links do not have .gz extensions, even if manpage
 122                  * is compressed */
 123                 man_filename = xasprintf("%s/%s", man_filename, linkname);
 124                 free(line);
 125                 /* Note: we leak "new" man_filename string as well... */
 126                 if (show_manpage(man_filename, man, level + 1))
 127                         return 1;
 128                 /* else: show the link, it's better than nothing */
 129         }
 130
 131  ordinary_manpage:
 132         close(STDIN_FILENO);
 133         open_zipped(man_filename, /*fail_if_not_compressed:*/ 0); /* guaranteed to use fd 0 (STDIN_FILENO) */
 134         if (man) {
 135                 /* "man man" formats to screen width.
 136                  * "man man >file" formats to default 80 columns.
 137                  * "man man | cat" formats to default 80 columns.
 138                  */
 139                 int w = get_terminal_width(STDOUT_FILENO);
 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                 cmd = xasprintf("%s | %s -rLL=%un -rLT=%un 2>&1 | %s",
 145                                 G.tbl, G.nroff, w, w,
 146                                 G.pager);
 147         } else {
 148                 cmd = xstrdup(G.pager);
 149         }
 150         system(cmd);
 151         free(cmd);
 152         return 1;
 153 }
 154
 155 /* man_filename is of the form "/dir/dir/dir/name.s" */
 156 static int show_manpage(char *man_filename, int man, int level)
 157 {
 158 #if SEAMLESS_COMPRESSION
 159         /* We leak this allocation... */
 160         char *filename_with_zext = xasprintf("%s.lzma", man_filename);
 161         char *ext = strrchr(filename_with_zext, '.') + 1;
 162 #endif
 163
 164 #if ENABLE_FEATURE_SEAMLESS_LZMA
 165         if (run_pipe(filename_with_zext, man, level))
 166                 return 1;
 167 #endif
 168 #if ENABLE_FEATURE_SEAMLESS_XZ
 169         strcpy(ext, "xz");
 170         if (run_pipe(filename_with_zext, man, level))
 171                 return 1;
 172 #endif
 173 #if ENABLE_FEATURE_SEAMLESS_BZ2
 174         strcpy(ext, "bz2");
 175         if (run_pipe(filename_with_zext, man, level))
 176                 return 1;
 177 #endif
 178 #if ENABLE_FEATURE_SEAMLESS_GZ
 179         strcpy(ext, "gz");
 180         if (run_pipe(filename_with_zext, man, level))
 181                 return 1;
 182 #endif
 183
 184         return run_pipe(man_filename, man, level);
 185 }
 186
 187 static char **add_MANPATH(char **man_path_list, int *count_mp, char *path)
 188 {
 189         if (path) while (*path) {
 190                 char *next_path;
 191                 char **path_element;
 192
 193                 next_path = strchr(path, ':');
 194                 if (next_path) {
 195                         if (next_path == path) /* "::"? */
 196                                 goto next;
 197                         *next_path = '\0';
 198                 }
 199                 /* Do we already have path? */
 200                 path_element = man_path_list;
 201                 if (path_element) while (*path_element) {
 202                         if (strcmp(*path_element, path) == 0)
 203                                 goto skip;
 204                         path_element++;
 205                 }
 206                 man_path_list = xrealloc_vector(man_path_list, 4, *count_mp);
 207                 man_path_list[*count_mp] = xstrdup(path);
 208                 (*count_mp)++;
 209                 /* man_path_list is NULL terminated */
 210                 /* man_path_list[*count_mp] = NULL; - xrealloc_vector did it */
 211  skip:
 212                 if (!next_path)
 213                         break;
 214                 /* "path" may be a result of getenv(), be nice and don't mangle it */
 215                 *next_path = ':';
 216  next:
 217                 path = next_path + 1;
 218         }
 219         return man_path_list;
 220 }
 221
 222 static const char *if_redefined(const char *var, const char *key, const char *line)
 223 {
 224         if (!is_prefixed_with(line, key))
 225                 return var;
 226         line += strlen(key);
 227         if (!isspace(line[0]))
 228                 return var;
 229         return xstrdup(skip_whitespace(line));
 230 }
 231
 232 int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 233 int man_main(int argc UNUSED_PARAM, char **argv)
 234 {
 235         parser_t *parser;
 236         char *sec_list;
 237         char *cur_path, *cur_sect;
 238         char **man_path_list;
 239         int count_mp;
 240         int cur_mp;
 241         int opt, not_found;
 242         char *token[2];
 243
 244         INIT_G();
 245
 246         opt_complementary = "-1"; /* at least one argument */
 247         opt = getopt32(argv, "+aw");
 248         argv += optind;
 249
 250         sec_list = xstrdup("0p:1:1p:2:3:3p:4:5:6:7:8:9");
 251
 252         count_mp = 0;
 253         man_path_list = add_MANPATH(NULL, &count_mp,
 254                         getenv("MANDATORY_MANPATH"+10) /* "MANPATH" */
 255         );
 256         if (!man_path_list) {
 257                 /* default, may be overridden by /etc/man.conf */
 258                 man_path_list = xzalloc(2 * sizeof(man_path_list[0]));
 259                 man_path_list[0] = (char*)"/usr/man";
 260                 /* count_mp stays 0.
 261                  * Thus, man.conf will overwrite man_path_list[0]
 262                  * if a path is defined there.
 263                  */
 264         }
 265
 266         /* Parse man.conf[ig] or man_db.conf */
 267         /* man version 1.6f uses man.config */
 268         /* man-db implementation of man uses man_db.conf */
 269         parser = config_open2("/etc/man.config", fopen_for_read);
 270         if (!parser)
 271                 parser = config_open2("/etc/man.conf", fopen_for_read);
 272         if (!parser)
 273                 parser = config_open2("/etc/man_db.conf", fopen_for_read);
 274
 275         while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 276                 if (!token[1])
 277                         continue;
 278                 if (strcmp("DEFINE", token[0]) == 0) {
 279                         G.col   = if_redefined(G.tbl  , "col",   token[1]);
 280                         G.tbl   = if_redefined(G.tbl  , "tbl",   token[1]);
 281                         G.nroff = if_redefined(G.nroff, "nroff", token[1]);
 282                         G.pager = if_redefined(G.pager, "pager", token[1]);
 283                 } else
 284                 if (strcmp("MANDATORY_MANPATH"+10, token[0]) == 0 /* "MANPATH"? */
 285                  || strcmp("MANDATORY_MANPATH", token[0]) == 0
 286                 ) {
 287                         man_path_list = add_MANPATH(man_path_list, &count_mp, token[1]);
 288                 }
 289                 if (strcmp("MANSECT", token[0]) == 0) {
 290                         free(sec_list);
 291                         sec_list = xstrdup(token[1]);
 292                 }
 293         }
 294         config_close(parser);
 295
 296         {
 297                 /* environment overrides setting from man.config */
 298                 char *env_pager = getenv("MANPAGER");
 299                 if (!env_pager)
 300                         env_pager = getenv("PAGER");
 301                 if (env_pager)
 302                         G.pager = env_pager;
 303         }
 304
 305         if (!isatty(STDOUT_FILENO)) {
 306                 putenv((char*)"GROFF_NO_SGR=1");
 307                 G.pager = xasprintf("%s -b -p -x", G.col);
 308         }
 309
 310         not_found = 0;
 311         do { /* for each argv[] */
 312                 int found = 0;
 313                 cur_mp = 0;
 314
 315                 if (strchr(*argv, '/')) {
 316                         found = show_manpage(*argv, /*man:*/ 1, 0);
 317                         goto check_found;
 318                 }
 319                 while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 320                         /* for each MANPATH */
 321                         cur_sect = sec_list;
 322                         do { /* for each section */
 323                                 char *next_sect = strchrnul(cur_sect, ':');
 324                                 int sect_len = next_sect - cur_sect;
 325                                 char *man_filename;
 326                                 int cat0man1 = 0;
 327
 328                                 /* Search for cat, then man page */
 329                                 while (cat0man1 < 2) {
 330                                         int found_here;
 331                                         man_filename = xasprintf("%s/%s%.*s/%s.%.*s",
 332                                                         cur_path,
 333                                                         "cat\0man" + (cat0man1 * 4),
 334                                                         sect_len, cur_sect,
 335                                                         *argv,
 336                                                         sect_len, cur_sect);
 337                                         found_here = show_manpage(man_filename, cat0man1, 0);
 338                                         found |= found_here;
 339                                         cat0man1 += found_here + 1;
 340                                         free(man_filename);
 341                                 }
 342
 343                                 if (found && !(opt & OPT_a))
 344                                         goto next_arg;
 345                                 cur_sect = next_sect;
 346                                 while (*cur_sect == ':')
 347                                         cur_sect++;
 348                         } while (*cur_sect);
 349                 }
 350  check_found:
 351                 if (!found) {
 352                         bb_error_msg("no manual entry for '%s'", *argv);
 353                         not_found = 1;
 354                 }
 355  next_arg:
 356                 argv++;
 357         } while (*argv);
 358
 359         return not_found;
 360 }