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//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
  15enum {
  16        OPT_a = 1, /* all */
  17        OPT_w = 2, /* print path */
  18};
  19
  20/* This is what I see on my desktop system being executed:
  21
  22(
  23echo ".ll 12.4i"
  24echo ".nr LL 12.4i"
  25echo ".pl 1100i"
  26gunzip -c '/usr/man/man1/bzip2.1.gz'
  27echo ".\\\""
  28echo ".pl \n(nlu+10"
  29) | gtbl | nroff -Tlatin1 -mandoc | less
  30
  31*/
  32
  33#if ENABLE_FEATURE_SEAMLESS_LZMA
  34#define Z_SUFFIX ".lzma"
  35#elif ENABLE_FEATURE_SEAMLESS_BZ2
  36#define Z_SUFFIX ".bz2"
  37#elif ENABLE_FEATURE_SEAMLESS_GZ
  38#define Z_SUFFIX ".gz"
  39#else
  40#define Z_SUFFIX ""
  41#endif
  42
  43static int show_manpage(const char *pager, char *man_filename, int man, int level);
  44
  45static int run_pipe(const char *pager, char *man_filename, int man, int level)
  46{
  47        char *cmd;
  48
  49        /* Prevent man page link loops */
  50        if (level > 10)
  51                return 0;
  52
  53        if (access(man_filename, R_OK) != 0)
  54                return 0;
  55
  56        if (option_mask32 & OPT_w) {
  57                puts(man_filename);
  58                return 1;
  59        }
  60
  61        if (man) { /* man page, not cat page */
  62                /* Is this a link to another manpage? */
  63                /* The link has the following on the first line: */
  64                /* ".so another_man_page" */
  65
  66                struct stat sb;
  67                char *line;
  68                char *linkname, *p;
  69
  70                /* On my system:
  71                 * man1/genhostid.1.gz: 203 bytes - smallest real manpage
  72                 * man2/path_resolution.2.gz: 114 bytes - largest link
  73                 */
  74                xstat(man_filename, &sb);
  75                if (sb.st_size > 300) /* err on the safe side */
  76                        goto ordinary_manpage;
  77
  78                line = xmalloc_open_zipped_read_close(man_filename, NULL);
  79                if (!line || strncmp(line, ".so ", 4) != 0) {
  80                        free(line);
  81                        goto ordinary_manpage;
  82                }
  83                /* Example: man2/path_resolution.2.gz contains
  84                 * ".so man7/path_resolution.7\n<junk>"
  85                 */
  86                *strchrnul(line, '\n') = '\0';
  87                linkname = skip_whitespace(&line[4]);
  88
  89                /* If link has no slashes, we just replace man page name.
  90                 * If link has slashes (however many), we go back *once*.
  91                 * ".so zzz/ggg/page.3" does NOT go back two levels. */
  92                p = strrchr(man_filename, '/');
  93                if (!p)
  94                        goto ordinary_manpage;
  95                *p = '\0';
  96                if (strchr(linkname, '/')) {
  97                        p = strrchr(man_filename, '/');
  98                        if (!p)
  99                                goto ordinary_manpage;
 100                        *p = '\0';
 101                }
 102
 103                /* Links do not have .gz extensions, even if manpage
 104                 * is compressed */
 105                man_filename = xasprintf("%s/%s" Z_SUFFIX, man_filename, linkname);
 106                free(line);
 107                /* Note: we leak "new" man_filename string as well... */
 108                if (show_manpage(pager, man_filename, man, level + 1))
 109                        return 1;
 110                /* else: show the link, it's better than nothing */
 111        }
 112
 113 ordinary_manpage:
 114        close(STDIN_FILENO);
 115        open_zipped(man_filename); /* guaranteed to use fd 0 (STDIN_FILENO) */
 116        /* "2>&1" is added so that nroff errors are shown in pager too.
 117         * Otherwise it may show just empty screen */
 118        cmd = xasprintf(
 119                man ? "gtbl | nroff -Tlatin1 -mandoc 2>&1 | %s"
 120                    : "%s",
 121                pager);
 122        system(cmd);
 123        free(cmd);
 124        return 1;
 125}
 126
 127/* man_filename is of the form "/dir/dir/dir/name.s" Z_SUFFIX */
 128static int show_manpage(const char *pager, char *man_filename, int man, int level)
 129{
 130#if ENABLE_FEATURE_SEAMLESS_LZMA
 131        if (run_pipe(pager, man_filename, man, level))
 132                return 1;
 133#endif
 134
 135#if ENABLE_FEATURE_SEAMLESS_BZ2
 136#if ENABLE_FEATURE_SEAMLESS_LZMA
 137        strcpy(strrchr(man_filename, '.') + 1, "bz2");
 138#endif
 139        if (run_pipe(pager, man_filename, man, level))
 140                return 1;
 141#endif
 142
 143#if ENABLE_FEATURE_SEAMLESS_GZ
 144#if ENABLE_FEATURE_SEAMLESS_LZMA || ENABLE_FEATURE_SEAMLESS_BZ2
 145        strcpy(strrchr(man_filename, '.') + 1, "gz");
 146#endif
 147        if (run_pipe(pager, man_filename, man, level))
 148                return 1;
 149#endif
 150
 151#if ENABLE_FEATURE_SEAMLESS_LZMA || ENABLE_FEATURE_SEAMLESS_BZ2 || ENABLE_FEATURE_SEAMLESS_GZ
 152        *strrchr(man_filename, '.') = '\0';
 153#endif
 154        if (run_pipe(pager, man_filename, man, level))
 155                return 1;
 156
 157        return 0;
 158}
 159
 160int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 161int man_main(int argc UNUSED_PARAM, char **argv)
 162{
 163        parser_t *parser;
 164        const char *pager;
 165        char **man_path_list;
 166        char *sec_list;
 167        char *cur_path, *cur_sect;
 168        int count_mp, cur_mp;
 169        int opt, not_found;
 170        char *token[2];
 171
 172        opt_complementary = "-1"; /* at least one argument */
 173        opt = getopt32(argv, "+aw");
 174        argv += optind;
 175
 176        sec_list = xstrdup("1:2:3:4:5:6:7:8:9");
 177        /* Last valid man_path_list[] is [0x10] */
 178        count_mp = 0;
 179        man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
 180        man_path_list[0] = getenv("MANPATH");
 181        if (!man_path_list[0]) /* default, may be overridden by /etc/man.conf */
 182                man_path_list[0] = (char*)"/usr/man";
 183        else
 184                count_mp++;
 185        pager = getenv("MANPAGER");
 186        if (!pager) {
 187                pager = getenv("PAGER");
 188                if (!pager)
 189                        pager = "more";
 190        }
 191
 192        /* Parse man.conf[ig] or man_db.conf */
 193        /* man version 1.6f uses man.config */
 194        /* man-db implementation of man uses man_db.conf */
 195        parser = config_open2("/etc/man.config", fopen_for_read);
 196        if (!parser)
 197                parser = config_open2("/etc/man.conf", fopen_for_read);
 198        if (!parser)
 199                parser = config_open2("/etc/man_db.conf", fopen_for_read);
 200
 201        while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
 202                if (!token[1])
 203                        continue;
 204                if (strcmp("MANDATORY_MANPATH"+10, token[0]) == 0 /* "MANPATH"? */
 205                 || strcmp("MANDATORY_MANPATH", token[0]) == 0
 206                ) {
 207                        char *path = token[1];
 208                        while (*path) {
 209                                char *next_path;
 210                                char **path_element;
 211
 212                                next_path = strchr(path, ':');
 213                                if (next_path) {
 214                                        *next_path = '\0';
 215                                        if (next_path++ == path) /* "::"? */
 216                                                goto next;
 217                                }
 218                                /* Do we already have path? */
 219                                path_element = man_path_list;
 220                                while (*path_element) {
 221                                        if (strcmp(*path_element, path) == 0)
 222                                                goto skip;
 223                                        path_element++;
 224                                }
 225                                man_path_list = xrealloc_vector(man_path_list, 4, count_mp);
 226                                man_path_list[count_mp] = xstrdup(path);
 227                                count_mp++;
 228                                /* man_path_list is NULL terminated */
 229                                /*man_path_list[count_mp] = NULL; - xrealloc_vector did it */
 230 skip:
 231                                if (!next_path)
 232                                        break;
 233 next:
 234                                path = next_path;
 235                        }
 236                }
 237                if (strcmp("MANSECT", token[0]) == 0) {
 238                        free(sec_list);
 239                        sec_list = xstrdup(token[1]);
 240                }
 241        }
 242        config_close(parser);
 243
 244        not_found = 0;
 245        do { /* for each argv[] */
 246                int found = 0;
 247                cur_mp = 0;
 248
 249                if (strchr(*argv, '/')) {
 250                        found = show_manpage(pager, *argv, /*man:*/ 1, 0);
 251                        goto check_found;
 252                }
 253                while ((cur_path = man_path_list[cur_mp++]) != NULL) {
 254                        /* for each MANPATH */
 255                        cur_sect = sec_list;
 256                        do { /* for each section */
 257                                char *next_sect = strchrnul(cur_sect, ':');
 258                                int sect_len = next_sect - cur_sect;
 259                                char *man_filename;
 260                                int cat0man1 = 0;
 261
 262                                /* Search for cat, then man page */
 263                                while (cat0man1 < 2) {
 264                                        int found_here;
 265                                        man_filename = xasprintf("%s/%s%.*s/%s.%.*s" Z_SUFFIX,
 266                                                        cur_path,
 267                                                        "cat\0man" + (cat0man1 * 4),
 268                                                        sect_len, cur_sect,
 269                                                        *argv,
 270                                                        sect_len, cur_sect);
 271                                        found_here = show_manpage(pager, man_filename, cat0man1, 0);
 272                                        found |= found_here;
 273                                        cat0man1 += found_here + 1;
 274                                        free(man_filename);
 275                                }
 276
 277                                if (found && !(opt & OPT_a))
 278                                        goto next_arg;
 279                                cur_sect = next_sect;
 280                                while (*cur_sect == ':')
 281                                        cur_sect++;
 282                        } while (*cur_sect);
 283                }
 284 check_found:
 285                if (!found) {
 286                        bb_error_msg("no manual entry for '%s'", *argv);
 287                        not_found = 1;
 288                }
 289 next_arg:
 290                argv++;
 291        } while (*argv);
 292
 293        return not_found;
 294}
 295