busybox/miscutils/man.c

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/* mini man implementation for busybox
* Copyright (C) 2008 Denys Vlasenko <vda.linux@googlemail.com>
* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
//usage:#define man_trivial_usage
//usage: "[-aw] [MANPAGE]..."
//usage:#define man_full_usage "\n\n"
//usage: "Format and display manual page\n"
//usage: "\n -a Display all pages"
//usage: "\n -w Show page locations"
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#include "libbb.h"
enum {
OPT_a = 1, /* all */
OPT_w = 2, /* print path */
};
/* This is what I see on my desktop system being executed:
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(
echo ".ll 12.4i"
echo ".nr LL 12.4i"
echo ".pl 1100i"
gunzip -c '/usr/man/man1/bzip2.1.gz'
echo ".\\\""
echo ".pl \n(nlu+10"
) | gtbl | nroff -Tlatin1 -mandoc | less
*/
static int show_manpage(const char *pager, char *man_filename, int man, int level);
static int run_pipe(const char *pager, char *man_filename, int man, int level)
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{
char *cmd;
/* Prevent man page link loops */
if (level > 10)
return 0;
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if (access(man_filename, R_OK) != 0)
return 0;
if (option_mask32 & OPT_w) {
puts(man_filename);
return 1;
}
if (man) { /* man page, not cat page */
/* Is this a link to another manpage? */
/* The link has the following on the first line: */
/* ".so another_man_page" */
struct stat sb;
char *line;
char *linkname, *p;
/* On my system:
* man1/genhostid.1.gz: 203 bytes - smallest real manpage
* man2/path_resolution.2.gz: 114 bytes - largest link
*/
xstat(man_filename, &sb);
if (sb.st_size > 300) /* err on the safe side */
goto ordinary_manpage;
line = xmalloc_open_zipped_read_close(man_filename, NULL);
if (!line || strncmp(line, ".so ", 4) != 0) {
free(line);
goto ordinary_manpage;
}
/* Example: man2/path_resolution.2.gz contains
* ".so man7/path_resolution.7\n<junk>"
*/
*strchrnul(line, '\n') = '\0';
linkname = skip_whitespace(&line[4]);
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/* If link has no slashes, we just replace man page name.
* If link has slashes (however many), we go back *once*.
* ".so zzz/ggg/page.3" does NOT go back two levels. */
p = strrchr(man_filename, '/');
if (!p)
goto ordinary_manpage;
*p = '\0';
if (strchr(linkname, '/')) {
p = strrchr(man_filename, '/');
if (!p)
goto ordinary_manpage;
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*p = '\0';
}
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/* Links do not have .gz extensions, even if manpage
* is compressed */
man_filename = xasprintf("%s/%s", man_filename, linkname);
free(line);
/* Note: we leak "new" man_filename string as well... */
if (show_manpage(pager, man_filename, man, level + 1))
return 1;
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/* else: show the link, it's better than nothing */
}
ordinary_manpage:
close(STDIN_FILENO);
open_zipped(man_filename, /*fail_if_not_compressed:*/ 0); /* guaranteed to use fd 0 (STDIN_FILENO) */
/* "2>&1" is added so that nroff errors are shown in pager too.
* Otherwise it may show just empty screen */
cmd = xasprintf(
man ? "gtbl | nroff -Tlatin1 -mandoc 2>&1 | %s"
: "%s",
pager);
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system(cmd);
free(cmd);
return 1;
}
/* man_filename is of the form "/dir/dir/dir/name.s" */
static int show_manpage(const char *pager, char *man_filename, int man, int level)
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{
#if SEAMLESS_COMPRESSION
/* We leak this allocation... */
char *filename_with_zext = xasprintf("%s.lzma", man_filename);
char *ext = strrchr(filename_with_zext, '.') + 1;
#endif
#if ENABLE_FEATURE_SEAMLESS_LZMA
if (run_pipe(pager, filename_with_zext, man, level))
return 1;
#endif
#if ENABLE_FEATURE_SEAMLESS_XZ
strcpy(ext, "xz");
if (run_pipe(pager, filename_with_zext, man, level))
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return 1;
#endif
#if ENABLE_FEATURE_SEAMLESS_BZ2
strcpy(ext, "bz2");
if (run_pipe(pager, filename_with_zext, man, level))
return 1;
#endif
#if ENABLE_FEATURE_SEAMLESS_GZ
strcpy(ext, "gz");
if (run_pipe(pager, filename_with_zext, man, level))
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return 1;
#endif
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return run_pipe(pager, man_filename, man, level);
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}
int man_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int man_main(int argc UNUSED_PARAM, char **argv)
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{
parser_t *parser;
const char *pager = ENABLE_LESS ? "less" : "more";
char **man_path_list;
char *sec_list;
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char *cur_path, *cur_sect;
int count_mp, cur_mp;
int opt, not_found;
char *token[2];
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opt_complementary = "-1"; /* at least one argument */
opt = getopt32(argv, "+aw");
argv += optind;
sec_list = xstrdup("0p:1:1p:2:3:3p:4:5:6:7:8:9");
/* Last valid man_path_list[] is [0x10] */
count_mp = 0;
man_path_list = xzalloc(0x11 * sizeof(man_path_list[0]));
man_path_list[0] = getenv("MANPATH");
if (!man_path_list[0]) /* default, may be overridden by /etc/man.conf */
man_path_list[0] = (char*)"/usr/man";
else
count_mp++;
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/* Parse man.conf[ig] or man_db.conf */
/* man version 1.6f uses man.config */
/* man-db implementation of man uses man_db.conf */
parser = config_open2("/etc/man.config", fopen_for_read);
if (!parser)
parser = config_open2("/etc/man.conf", fopen_for_read);
if (!parser)
parser = config_open2("/etc/man_db.conf", fopen_for_read);
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while (config_read(parser, token, 2, 0, "# \t", PARSE_NORMAL)) {
if (!token[1])
continue;
if (strcmp("DEFINE", token[0]) == 0) {
if (strncmp("pager", token[1], 5) == 0) {
pager = xstrdup(skip_whitespace(token[1]) + 5);
}
} else
if (strcmp("MANDATORY_MANPATH"+10, token[0]) == 0 /* "MANPATH"? */
|| strcmp("MANDATORY_MANPATH", token[0]) == 0
) {
char *path = token[1];
while (*path) {
char *next_path;
char **path_element;
next_path = strchr(path, ':');
if (next_path) {
*next_path = '\0';
if (next_path++ == path) /* "::"? */
goto next;
}
/* Do we already have path? */
path_element = man_path_list;
while (*path_element) {
if (strcmp(*path_element, path) == 0)
goto skip;
path_element++;
}
man_path_list = xrealloc_vector(man_path_list, 4, count_mp);
man_path_list[count_mp] = xstrdup(path);
count_mp++;
/* man_path_list is NULL terminated */
/*man_path_list[count_mp] = NULL; - xrealloc_vector did it */
skip:
if (!next_path)
break;
next:
path = next_path;
}
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}
if (strcmp("MANSECT", token[0]) == 0) {
free(sec_list);
sec_list = xstrdup(token[1]);
}
}
config_close(parser);
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{
/* environment overrides setting from man.config */
char *env_pager = getenv("MANPAGER");
if (!env_pager)
env_pager = getenv("PAGER");
if (env_pager)
pager = env_pager;
}
not_found = 0;
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do { /* for each argv[] */
int found = 0;
cur_mp = 0;
if (strchr(*argv, '/')) {
found = show_manpage(pager, *argv, /*man:*/ 1, 0);
goto check_found;
}
while ((cur_path = man_path_list[cur_mp++]) != NULL) {
/* for each MANPATH */
cur_sect = sec_list;
do { /* for each section */
char *next_sect = strchrnul(cur_sect, ':');
int sect_len = next_sect - cur_sect;
char *man_filename;
int cat0man1 = 0;
/* Search for cat, then man page */
while (cat0man1 < 2) {
int found_here;
man_filename = xasprintf("%s/%s%.*s/%s.%.*s",
cur_path,
"cat\0man" + (cat0man1 * 4),
sect_len, cur_sect,
*argv,
sect_len, cur_sect);
found_here = show_manpage(pager, man_filename, cat0man1, 0);
found |= found_here;
cat0man1 += found_here + 1;
free(man_filename);
}
if (found && !(opt & OPT_a))
goto next_arg;
cur_sect = next_sect;
while (*cur_sect == ':')
cur_sect++;
} while (*cur_sect);
}
check_found:
if (!found) {
bb_error_msg("no manual entry for '%s'", *argv);
not_found = 1;
}
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next_arg:
argv++;
} while (*argv);
return not_found;
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}