LXR busybox/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#include "libbb.h"
   7
   8enum {
   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(
  16echo ".ll 12.4i"
  17echo ".nr LL 12.4i"
  18echo ".pl 1100i"
  19gunzip -c '/usr/man/man1/bzip2.1.gz'
  20echo ".\\\""
  21echo ".pl \n(nlu+10"
  22) | gtbl | nroff -Tlatin1 -mandoc | less
  23
  24*/
  25
  26#if ENABLE_FEATURE_SEAMLESS_LZMA
  27#define Z_SUFFIX ".lzma"
  28#elif ENABLE_FEATURE_SEAMLESS_BZ2
  29#define Z_SUFFIX ".bz2"
  30#elif ENABLE_FEATURE_SEAMLESS_GZ
  31#define Z_SUFFIX ".gz"
  32#else
  33#define Z_SUFFIX ""
  34#endif
  35
  36static int show_manpage(const char *pager, char *man_filename, int man, int level);
  37
  38static int run_pipe(const char *pager, char *man_filename, int man, int level)
  39{
  40        char *cmd;
  41
  42        /* Prevent man page link loops */
  43        if (level > 10)
  44                return 0;
  45
  46        if (access(man_filename, R_OK) != 0)
  47                return 0;
  48
  49        if (option_mask32 & OPT_w) {
  50                puts(man_filename);
  51                return 1;
  52        }
  53
  54        if (man) { /* man page, not cat page */
  55                /* Is this a link to another manpage? */
  56                /* The link has the following on the first line: */
  57                /* ".so another_man_page" */
  58
  59                struct stat sb;
  60                char *line;
  61                char *linkname, *p;
  62
  63                /* On my system:
  64                 * man1/genhostid.1.gz: 203 bytes - smallest real manpage
  65                 * man2/path_resolution.2.gz: 114 bytes - largest link
  66                 */
  67                xstat(man_filename, &sb);
  68                if (sb.st_size > 300) /* err on the safe side */
  69                        goto ordinary_manpage;
  70
  71                line = xmalloc_open_zipped_read_close(man_filename, NULL);
  72                if (!line || strncmp(line, ".so ", 4) != 0) {
  73                        free(line);
  74                        goto ordinary_manpage;
  75                }
  76                /* Example: man2/path_resolution.2.gz contains
  77                 * ".so man7/path_resolution.7\n<junk>"
  78                 */
  79                *strchrnul(line, '\n') = '\0';
  80                linkname = skip_whitespace(&line[4]);
  81
  82                /* If link has no slashes, we just replace man page name.
  83                 * If link has slashes (however many), we go back *once*.
  84                 * ".so zzz/ggg/page.3" does NOT go back two levels. */
  85                p = strrchr(man_filename, '/');
  86                if (!p)
  87                        goto ordinary_manpage;
  88                *p = '\0';
  89                if (strchr(linkname, '/')) {
  90                        p = strrchr(man_filename, '/');
  91                        if (!p)
  92                                goto ordinary_manpage;
  93                        *p = '\0';
  94                }
  95
  96                /* Links do not have .gz extensions, even if manpage
  97                 * is compressed */
  98                man_filename = xasprintf("%s/%s" Z_SUFFIX, man_filename, linkname);
  99                free(line);
 100                /* Note: we leak "new" man_filename string as well... */
 101                if (show_manpage(pager, man_filename, man, level + 1))
 102                        return 1;
 103                /* else: show the link, it's better than nothing */
 104        }
 105
 106 ordinary_manpage:
 107        close(STDIN_FILENO);
 108        open_zipped(man_filename); /* guaranteed to use fd 0 (STDIN_FILENO) */
 109        /* "2>&1" is added so that nroff errors are shown in pager too.
 110         * Otherwise it may show just empty screen */
 111        cmd = xasprintf(
 112                man ? "gtbl | nroff -Tlatin1 -mandoc 2>&1 | %s"
 113                    : "%s",
 114                pager);
 115        system(cmd);
 116        free(cmd);
 117        return 1;
 118}
 119
 120/* man_filename is of the form "/dir/dir/dir/name.s" Z_SUFFIX */
 121static int show_manpage(const char *pager, char *man_filename, int man, int level)
 122{
 123#if ENABLE_FEATURE_SEAMLESS_LZMA
 124        if (run_pipe(pager, man_filename, man, level))
 125                return 1;
 126#endif
 127
 128#if ENABLE_FEATURE_SEAMLESS_BZ2
 129#if ENABLE_FEATURE_SEAMLESS_LZMA
 130        strcpy(strrchr(man_filename, '.') + 1, "bz2");
 131#endif
 132        if (run_pipe(pager, man_filename, man, level))
 133                return 1;
 134#endif
 135
 136#if ENABLE_FEATURE_SEAMLESS_GZ
 137#if ENABLE_FEATURE_SEAMLESS_LZMA || ENABLE_FEATURE_SEAMLESS_BZ2
 138        strcpy(strrchr(man_filename, '.') + 1, "gz");
 139#endif
 140        if (run_pipe(pager, man_filename, man, level))
 141                return 1;
 142#endif
 143
 144#if ENABLE_FEATURE_SEAMLESS_LZMA || ENABLE_FEATURE_SEAMLESS_BZ2 || ENABLE_FEATURE_SEAMLESS_GZ
 145        *strrchr(man_filename, '.') = '\0';
 146#endif
 147        if (run_pipe(pager, man_filename, man, level))
 148                return 1;
 149
 150        return 0;
 151}
 152
 153int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 154int man_main(int argc UNUSED_PARAM, char **argv)
 155{
 156        parser_t *parser;
 157        const char *pager;
 158        char **man_path_list;
 159        char *sec_list;
 160        char *cur_path, *cur_sect;
 161        int count_mp, cur_mp;
 162        int opt, not_found;
 163        char *token[2];
 164
 165        opt_complementary = "-1"; /* at least one argument */
 166        opt = getopt32(argv, "+aw");
 167        argv += optind;
 168
 169        sec_list = xstrdup("1:2:3:4:5:6:7:8:9");
 170        /* Last valid man_path_list[] is [0x10] */
 171        count_mp = 0;
 172        man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
 173        man_path_list[0] = getenv("MANPATH");
 174        if (!man_path_list[0]) /* default, may be overridden by /etc/man.conf */
 175                man_path_list[0] = (char*)"/usr/man";
 176        else
 177                count_mp++;
 178        pager = getenv("MANPAGER");
 179        if (!pager) {
 180                pager = getenv("PAGER");
 181                if (!pager)
 182                        pager = "more";
 183        }
 184
 185        /* Parse man.conf[ig] or man_db.conf */
 186        /* man version 1.6f uses man.config */
 187        /* man-db implementation of man uses man_db.conf */
 188        parser = config_open2("/etc/man.config", fopen_for_read);
 189        if (!parser)
 190                parser = config_open2("/etc/man.conf", fopen_for_read);
 191        if (!parser)
 192                parser = config_open2("/etc/man_db.conf", fopen_for_read);
 193
 194        while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 195                if (!token[1])
 196                        continue;
 197                if (strcmp("MANDATORY_MANPATH"+10, token[0]) == 0 /* "MANPATH"? */
 198                 || strcmp("MANDATORY_MANPATH", token[0]) == 0
 199                ) {
 200                        char *path = token[1];
 201                        while (*path) {
 202                                char *next_path;
 203                                char **path_element;
 204
 205                                next_path = strchr(path, ':');
 206                                if (next_path) {
 207                                        *next_path = '\0';
 208                                        if (next_path++ == path) /* "::"? */
 209                                                goto next;
 210                                }
 211                                /* Do we already have path? */
 212                                path_element = man_path_list;
 213                                while (*path_element) {
 214                                        if (strcmp(*path_element, path) == 0)
 215                                                goto skip;
 216                                        path_element++;
 217                                }
 218                                man_path_list = xrealloc_vector(man_path_list, 4, count_mp);
 219                                man_path_list[count_mp] = xstrdup(path);
 220                                count_mp++;
 221                                /* man_path_list is NULL terminated */
 222                                /*man_path_list[count_mp] = NULL; - xrealloc_vector did it */
 223 skip:
 224                                if (!next_path)
 225                                        break;
 226 next:
 227                                path = next_path;
 228                        }
 229                }
 230                if (strcmp("MANSECT", token[0]) == 0) {
 231                        free(sec_list);
 232                        sec_list = xstrdup(token[1]);
 233                }
 234        }
 235        config_close(parser);
 236
 237        not_found = 0;
 238        do { /* for each argv[] */
 239                int found = 0;
 240                cur_mp = 0;
 241
 242                if (strchr(*argv, '/')) {
 243                        found = show_manpage(pager, *argv, /*man:*/ 1, 0);
 244                        goto check_found;
 245                }
 246                while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 247                        /* for each MANPATH */
 248                        cur_sect = sec_list;
 249                        do { /* for each section */
 250                                char *next_sect = strchrnul(cur_sect, ':');
 251                                int sect_len = next_sect - cur_sect;
 252                                char *man_filename;
 253                                int cat0man1 = 0;
 254
 255                                /* Search for cat, then man page */
 256                                while (cat0man1 < 2) {
 257                                        int found_here;
 258                                        man_filename = xasprintf("%s/%s%.*s/%s.%.*s" Z_SUFFIX,
 259                                                        cur_path,
 260                                                        "cat\0man" + (cat0man1 * 4),
 261                                                        sect_len, cur_sect,
 262                                                        *argv,
 263                                                        sect_len, cur_sect);
 264                                        found_here = show_manpage(pager, man_filename, cat0man1, 0);
 265                                        found |= found_here;
 266                                        cat0man1 += found_here + 1;
 267                                        free(man_filename);
 268                                }
 269
 270                                if (found && !(opt & OPT_a))
 271                                        goto next_arg;
 272                                cur_sect = next_sect;
 273                                while (*cur_sect == ':')
 274                                        cur_sect++;
 275                        } while (*cur_sect);
 276                }
 277 check_found:
 278                if (!found) {
 279                        bb_error_msg("no manual entry for '%s'", *argv);
 280                        not_found = 1;
 281                }
 282 next_arg:
 283                argv++;
 284        } while (*argv);
 285
 286        return not_found;
 287}
 288