/*-
 * Copyright (c) 2002 John Rochester
 * Copyright (c) 2013-2014 Franco Fichtner <franco@lastsummer.de>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer,
 *    in this position and unchanged.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $FreeBSD: src/usr.bin/makewhatis/makewhatis.c,v 1.9 2002/09/04 23:29:04 dwmalone Exp $
 */

#include <sys/tree.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/stat.h>

#include <ctype.h>
#include <dirent.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stringlist.h>
#include <unistd.h>
#include <zlib.h>

#define DEFAULT_MANPATH		"/usr/share/man"
#define LINE_ALLOC		4096

static char blank[] = 		"";

/*
 * Information collected about each man page alias.
 */
struct page_alias {
	RB_ENTRY(page_alias) entry;
	char *filename;
	char *name;
	char *suffix;
	int gzipped;
};

/*
 * Information collected about each unique man page.
 */
struct page_info {
	RB_HEAD(page_alias_tree, page_alias) head;
	RB_ENTRY(page_info) entry;
	ino_t inode;
};

static RB_HEAD(page_info_tree, page_info) page_head = RB_INITIALIZER(&page_head);

/*
 * Sorts page info by inode number.
 */
static int
infosort(const struct page_info *a, const struct page_info *b)
{
	return (memcmp(&a->inode, &b->inode, sizeof(a->inode)));
}

RB_PROTOTYPE(page_info_tree, page_info, entry, infosort);
RB_GENERATE(page_info_tree, page_info, entry, infosort);

/*
 * Sorts page alias first by suffix, then name.
 */
static int
aliassort(const struct page_alias *a, const struct page_alias *b)
{
	int ret = strcmp(a->suffix, b->suffix);
	if (ret) {
		return (ret);
	}

	return (strcmp(a->name, b->name));
}

RB_PROTOTYPE(page_alias_tree, page_alias, entry, aliassort);
RB_GENERATE(page_alias_tree, page_alias, entry, aliassort);

/*
 * An entry kept for each visited directory.
 */
struct visited_dir {
	dev_t		device;
	ino_t		inode;
	SLIST_ENTRY(visited_dir)	next;
};

/*
 * an expanding string
 */
struct sbuf {
	char *	content;		/* the start of the buffer */
	char *	end;			/* just past the end of the content */
	char *	last;			/* the last allocated character */
};

/*
 * Removes the last amount characters from the sbuf.
 */
#define sbuf_retract(sbuf, amount)	\
	((sbuf)->end -= (amount))
/*
 * Returns the length of the sbuf content.
 */
#define sbuf_length(sbuf)		\
	((sbuf)->end - (sbuf)->content)

typedef char *edited_copy(char *from, char *to, int length);

static int append;			/* -a flag: append to existing whatis */
static int verbose;			/* -v flag: be verbose with warnings */
static int indent = 24;			/* -i option: description indentation */
static const char *whatis_name="whatis";/* -n option: the name */
static char *common_output;		/* -o option: the single output file */
static char *locale;			/* user's locale if -L is used */
static char *lang_locale;		/* short form of locale */
static const char *machine;

static int exit_code;			/* exit code to use when finished */
static SLIST_HEAD(, visited_dir) visited_dirs =
    SLIST_HEAD_INITIALIZER(visited_dirs);

/*
 * While the whatis line is being formed, it is stored in whatis_proto.
 * When finished, it is reformatted into whatis_final and then appended
 * to whatis_lines.
 */
static struct sbuf *whatis_proto;
static struct sbuf *whatis_final;
static StringList *whatis_lines;	/* collected output lines */

static char tmp_file[MAXPATHLEN];	/* path of temporary file, if any */

/* A set of possible names for the NAME man page section */
static const char *name_section_titles[] = {
	"NAME", "Name", "NAMN", "BEZEICHNUNG", "\xcc\xbe\xbe\xce",
	"\xee\xe1\xfa\xf7\xe1\xee\xe9\xe5", NULL
};

/* A subset of the mdoc(7) commands to ignore */
static char mdoc_commands[] = "ArDvErEvFlLiNmPa";

/*
 * Frees a struct page_info and its content.
 */
static void
free_page_info(struct page_info *info)
{
	struct page_alias *alias;

	while ((alias = RB_ROOT(&info->head))) {
		RB_REMOVE(page_alias_tree, &info->head, alias);
		free(alias->filename);
		free(alias->suffix);
		free(alias->name);
		free(alias);
	}

	free(info);
}

/*
 * Allocates and fills in a new struct page_alias given the
 * full file name of the man page and its dirent.
 * If the file is not a man page, nothing is added.
 */
static void
new_page_alias(struct page_info *info, char *filename, struct dirent *dirent)
{
	int basename_length;
	struct page_alias *alias;
	char *suffix;
	int gzipped;

	basename_length = strlen(dirent->d_name);
	suffix = &dirent->d_name[basename_length];
	gzipped = basename_length >= 4 &&
	    strcmp(&dirent->d_name[basename_length - 3], ".gz") == 0;
	if (gzipped) {
		suffix -= 3;
		*suffix = '\0';
	}
	for (;;) {
		if (--suffix == dirent->d_name || !isalnum(*suffix)) {
			if (*suffix == '.')
				break;
			if (verbose)
				warnx("%s: invalid man page name",
				    filename);
			return;
		}
	}

	*suffix++ = '\0';

	alias = malloc(sizeof(*alias));
	if (alias == NULL) {
		err(1, "malloc");
	}

	alias->name = strdup(dirent->d_name);
	alias->filename = strdup(filename);
	alias->suffix = strdup(suffix);
	alias->gzipped = gzipped;

	if (!alias->name || !alias->filename || !alias->suffix) {
		err(1, "strdup");
	}

	RB_INSERT(page_alias_tree, &info->head, alias);
}

/*
 * Reset an sbuf's length to 0.
 */
static void
sbuf_clear(struct sbuf *sbuf)
{
	sbuf->end = sbuf->content;
}

/*
 * Allocate a new sbuf.
 */
static struct sbuf *
new_sbuf(void)
{
	struct sbuf *sbuf = (struct sbuf *) malloc(sizeof(struct sbuf));
	sbuf->content = malloc(LINE_ALLOC);
	sbuf->last = sbuf->content + LINE_ALLOC - 1;
	sbuf_clear(sbuf);
	return(sbuf);
}

/*
 * Ensure that there is enough room in the sbuf for nchars more characters.
 */
static void
sbuf_need(struct sbuf *sbuf, int nchars)
{
	char *new_content;
	size_t size, cntsize;

	/* double the size of the allocation until the buffer is big enough */
	while (sbuf->end + nchars > sbuf->last) {
		size = sbuf->last + 1 - sbuf->content;
		size *= 2;
		cntsize = sbuf->end - sbuf->content;

		new_content = malloc(size);
		memcpy(new_content, sbuf->content, cntsize);
		free(sbuf->content);
		sbuf->content = new_content;
		sbuf->end = new_content + cntsize;
		sbuf->last = new_content + size - 1;
	}
}

/*
 * Appends a string of a given length to the sbuf.
 */
static void
sbuf_append(struct sbuf *sbuf, const char *text, int length)
{
	if (length > 0) {
		sbuf_need(sbuf, length);
		memcpy(sbuf->end, text, length);
		sbuf->end += length;
	}
}

/*
 * Appends a null-terminated string to the sbuf.
 */
static void
sbuf_append_str(struct sbuf *sbuf, char *text)
{
	sbuf_append(sbuf, text, strlen(text));
}

/*
 * Appends an edited null-terminated string to the sbuf.
 */
static void
sbuf_append_edited(struct sbuf *sbuf, char *text, edited_copy copy)
{
	int length = strlen(text);
	if (length > 0) {
		sbuf_need(sbuf, length);
		sbuf->end = copy(text, sbuf->end, length);
	}
}

/*
 * Strips any of a set of chars from the end of the sbuf.
 */
static void
sbuf_strip(struct sbuf *sbuf, const char *set)
{
	while (sbuf->end > sbuf->content && strchr(set, sbuf->end[-1]) != NULL)
		sbuf->end--;
}

/*
 * Returns the null-terminated string built by the sbuf.
 */
static char *
sbuf_content(struct sbuf *sbuf)
{
	*sbuf->end = '\0';
	return(sbuf->content);
}

static void
trap_signal(int sig __unused)
{
	if (tmp_file[0] != '\0')
		unlink(tmp_file);
	exit(1);
}

/*
 * Attempts to open an output file.  Returns NULL if unsuccessful.
 */
static FILE *
open_output(char *name)
{
	FILE *output;

	whatis_lines = sl_init();
	if (append) {
		char line[LINE_ALLOC];

		output = fopen(name, "r");
		if (output == NULL) {
			warn("%s", name);
			exit_code = 1;
			return(NULL);
		}
		while (fgets(line, sizeof line, output) != NULL) {
			line[strlen(line) - 1] = '\0';
			sl_add(whatis_lines, strdup(line));
		}
	}
	if (common_output == NULL) {
		snprintf(tmp_file, sizeof tmp_file, "%s.tmp", name);
		name = tmp_file;
	}
	output = fopen(name, "w");
	if (output == NULL) {
		warn("%s", name);
		exit_code = 1;
		return(NULL);
	}
	return(output);
}

static int
linesort(const void *a, const void *b)
{
	return(strcmp((*(const char * const *)a), (*(const char * const *)b)));
}

/*
 * Writes the unique sorted lines to the output file.
 */
static void
finish_output(FILE *output, char *name)
{
	size_t i;
	char *prev = NULL;

	qsort(whatis_lines->sl_str, whatis_lines->sl_cur, sizeof(char *),
	      linesort);
	for (i = 0; i < whatis_lines->sl_cur; i++) {
		char *line = whatis_lines->sl_str[i];
		if (i > 0 && strcmp(line, prev) == 0)
			continue;
		prev = line;
		fputs(line, output);
		putc('\n', output);
	}
	fclose(output);
	sl_free(whatis_lines, 1);
	if (common_output == NULL) {
		rename(tmp_file, name);
		unlink(tmp_file);
	}
}

static FILE *
open_whatis(char *mandir)
{
	char filename[MAXPATHLEN];

	snprintf(filename, sizeof filename, "%s/%s", mandir, whatis_name);
	return(open_output(filename));
}

static void
finish_whatis(FILE *output, char *mandir)
{
	char filename[MAXPATHLEN];

	snprintf(filename, sizeof filename, "%s/%s", mandir, whatis_name);
	finish_output(output, filename);
}

/*
 * Tests to see if the given directory has already been visited.
 */
static int
already_visited(char *dir)
{
	struct stat st;
	struct visited_dir *visit;

	if (stat(dir, &st) < 0) {
		warn("%s", dir);
		exit_code = 1;
		return(1);
	}
	SLIST_FOREACH(visit, &visited_dirs, next) {
		if (visit->inode == st.st_ino &&
		    visit->device == st.st_dev) {
			warnx("already visited %s", dir);
			return(1);
		}
	}
	visit = (struct visited_dir *) malloc(sizeof(struct visited_dir));
	visit->device = st.st_dev;
	visit->inode = st.st_ino;
	SLIST_INSERT_HEAD(&visited_dirs, visit, next);
	return(0);
}

/*
 * Removes trailing spaces from a string, returning a pointer to just
 * beyond the new last character.
 */
static char *
trim_rhs(char *str)
{
	char *rhs = &str[strlen(str)];
	while (--rhs > str && isspace(*rhs))
		;
	*++rhs = '\0';
	return(rhs);
}

/*
 * Returns a pointer to the next non-space character in the string.
 */
static char *
skip_spaces(char *s)
{
	while (*s != '\0' && isspace(*s))
		s++;
	return(s);
}

/*
 * Returns whether the string contains only digits.
 */
static int
only_digits(char *line)
{
	if (!isdigit(*line++))
		return(0);
	while (isdigit(*line))
		line++;
	return(*line == '\0');
}

/*
 * Returns whether the line is of one of the forms:
 *	.Sh NAME
 *	.Sh "NAME"
 *	etc.
 * assuming that section_start is ".Sh".
 */
static int
name_section_line(char *line, const char *section_start)
{
	char *rhs;
	const char **title;

	if (strncmp(line, section_start, 3) != 0)
		return(0);
	line = skip_spaces(line + 3);
	rhs = trim_rhs(line);
	if (*line == '"') {
		line++;
		if (*--rhs == '"')
			*rhs = '\0';
	}
	for (title = name_section_titles; *title != NULL; title++)
		if (strcmp(*title, line) == 0)
			return(1);
	return(0);
}

/*
 * Copies characters while removing the most common nroff/troff
 * markup:
 *	\(em, \(mi, \s[+-N], \&
 *	\fF, \f(fo, \f[font]
 *	\*s, \*(st, \*[stringvar]
 */
static char *
de_nroff_copy(char *from, char *to, int fromlen)
{
	char *from_end = &from[fromlen];
	while (from < from_end) {
		switch (*from) {
		case '\\':
			switch (*++from) {
			case '(':
				if (strncmp(&from[1], "em", 2) == 0 ||
				    strncmp(&from[1], "mi", 2) == 0) {
					from += 3;
					continue;
				}
				break;
			case 's':
				if (*++from == '-')
					from++;
				while (isdigit(*from))
					from++;
				continue;
			case 'f':
			case '*':
				if (*++from == '(')
					from += 3;
				else if (*from == '[') {
					while (*++from != ']' && from < from_end)
						;
					from++;
				} else
					from++;
				continue;
			case '&':
				from++;
				continue;
			}
			break;
		}
		*to++ = *from++;
	}
	return(to);
}

/*
 * Appends a string with the nroff formatting removed.
 */
static void
add_nroff(char *text)
{
	sbuf_append_edited(whatis_proto, text, de_nroff_copy);
}

/*
 * Appends "name(suffix), " to whatis_final.
 */
static void
add_whatis_name(char *name, char *suffix)
{
	if (*name != '\0') {
		sbuf_append_str(whatis_final, name);
		sbuf_append(whatis_final, "(", 1);
		sbuf_append_str(whatis_final, suffix);
		sbuf_append(whatis_final, "), ", 3);
	}
}

/*
 * Processes an old-style man(7) line.  This ignores commands with only
 * a single number argument.
 */
static void
process_man_line(char *line)
{
	if (*line == '.') {
		while (isalpha(*++line))
			;
		line = skip_spaces(line);
		if (only_digits(line))
			return;
	} else
		line = skip_spaces(line);
	if (*line != '\0') {
		add_nroff(line);
		sbuf_append(whatis_proto, " ", 1);
	}
}

struct mdoc_text {
	const char *mdoc;
	const char *text;
};

static int
process_mdoc_macro(char *line)
{
	static const struct mdoc_text list[] = {
		{ ".At", "AT&T UNIX" },
		{ ".Bsx", "BSD/OS" },
		{ ".Bx", "BSD" },
		{ ".Dx", "DragonFly" },
		{ ".Fx", "FreeBSD" },
		{ ".Nx", "NetBSD" },
		{ ".Ox", "OpenBSD" },
		{ ".Ux", "UNIX" },
	};
	unsigned int i;

	for (i = 0; i < sizeof(list) / sizeof(list[0]); ++i) {
		if (!strcmp(line, list[i].mdoc)) {
			sbuf_append(whatis_proto, list[i].text,
			    strlen(list[i].text));
			sbuf_append(whatis_proto, " ", 1);
			return (1);
		}
	}

	return (0);
}

/*
 * Processes a new-style mdoc(7) line.
 */
static void
process_mdoc_line(char *line)
{
	int xref;
	int arg = 0;
	char *line_end = &line[strlen(line)];
	int orig_length = sbuf_length(whatis_proto);
	char *next;

	if (*line == '\0')
		return;
	if (line[0] != '.' || !isupper(line[1]) || !islower(line[2])) {
		add_nroff(skip_spaces(line));
		sbuf_append(whatis_proto, " ", 1);
		return;
	}
	if (process_mdoc_macro(line)) {
		return;
	}
	xref = strncmp(line, ".Xr", 3) == 0;
	line += 3;
	while ((line = skip_spaces(line)) < line_end) {
		if (*line == '"') {
			next = ++line;
			for (;;) {
				next = strchr(next, '"');
				if (next == NULL)
					break;
				memmove(next, next + 1, strlen(next));
				line_end--;
				if (*next != '"')
					break;
				next++;
			}
		} else
			next = strpbrk(line, " \t");
		if (next != NULL)
			*next++ = '\0';
		else
			next = line_end;
		if (isupper(*line) && islower(line[1]) && line[2] == '\0') {
			if (strcmp(line, "Ns") == 0) {
				arg = 0;
				line = next;
				continue;
			}
			if (strstr(mdoc_commands, line) != NULL) {
				line = next;
				continue;
			}
		}
		if (arg > 0 && strchr(",.:;?!)]", *line) == 0) {
			if (xref) {
				sbuf_append(whatis_proto, "(", 1);
				add_nroff(line);
				sbuf_append(whatis_proto, ")", 1);
				xref = 0;
				line = blank;
			} else
				sbuf_append(whatis_proto, " ", 1);
		}
		add_nroff(line);
		arg++;
		line = next;
	}
	if (sbuf_length(whatis_proto) > orig_length)
		sbuf_append(whatis_proto, " ", 1);
}

enum { STATE_UNKNOWN, STATE_MANSTYLE, STATE_MDOCNAME, STATE_MDOCDESC };

/*
 * Processes a man page source into a single whatis line and adds it
 * to whatis_lines.
 */
static void
process_page(struct page_info *info)
{
	gzFile in;
	char buffer[4096];
	char *line;
	char *descr;
	int state = STATE_UNKNOWN;
	struct page_alias *alias;

	/*
	 * Only read the page once for each inode.  It's
	 * safe to assume that page->list is set.
	 */
	alias = RB_MIN(page_alias_tree, &info->head);

	if (verbose) {
		fprintf(stderr, "\treading %s\n", alias->filename);
	}

	sbuf_clear(whatis_proto);
	if ((in = gzopen(alias->filename, "r")) == NULL) {
		warn("%s", alias->filename);
		exit_code = 1;
		return;
	}
	while (gzgets(in, buffer, sizeof buffer) != NULL) {
		line = buffer;
		if (strncmp(line, ".\\\"", 3) == 0)	/* ignore comments */
			continue;
		switch (state) {
		/*
		 * haven't reached the NAME section yet.
		 */
		case STATE_UNKNOWN:
			if (name_section_line(line, ".SH"))
				state = STATE_MANSTYLE;
			else if (name_section_line(line, ".Sh"))
				state = STATE_MDOCNAME;
			continue;
		/*
		 * Inside an old-style .SH NAME section.
		 */
		case STATE_MANSTYLE:
			if (strncmp(line, ".SH", 3) == 0)
				break;
			if (strncmp(line, ".SS", 3) == 0)
				break;
			trim_rhs(line);
			if (strcmp(line, ".") == 0)
				continue;
			if (strncmp(line, ".IX", 3) == 0) {
				line += 3;
				line = skip_spaces(line);
			}
			process_man_line(line);
			continue;
		/*
		 * Inside a new-style .Sh NAME section (the .Nm part).
		 */
		case STATE_MDOCNAME:
			trim_rhs(line);
			if (strncmp(line, ".Nm", 3) == 0) {
				process_mdoc_line(line);
				continue;
			} else {
				if (strcmp(line, ".") == 0)
					continue;
				sbuf_append(whatis_proto, "- ", 2);
				state = STATE_MDOCDESC;
			}
			/* fall through */
		/*
		 * Inside a new-style .Sh NAME section (after the .Nm-s).
		 */
		case STATE_MDOCDESC:
			if (strncmp(line, ".Sh", 3) == 0)
				break;
			trim_rhs(line);
			if (strcmp(line, ".") == 0)
				continue;
			process_mdoc_line(line);
			continue;
		}
		break;
	}
	gzclose(in);
	sbuf_strip(whatis_proto, " \t.-");
	line = sbuf_content(whatis_proto);
	/*
	 * line now contains the appropriate data, but without
	 * the proper indentation or the section appended to each name.
	 */
	descr = strstr(line, " - ");
	if (descr == NULL) {
		descr = strchr(line, ' ');
		if (descr == NULL) {
			if (verbose)
				fprintf(stderr,
					"\tignoring junk description \"%s\"\n",
					line);
			return;
		}
		*descr++ = '\0';
	} else {
		*descr = '\0';
		descr += 3;
	}
	sbuf_clear(whatis_final);
	RB_FOREACH(alias, page_alias_tree, &info->head) {
		/*
		 * This won't append names stored in `line'.
		 * The reason for that is that we cannot be sure
		 * which section they belong to unless we have
		 * a real alias (via MLINKS) in this list.
		 */
		add_whatis_name(alias->name, alias->suffix);
	}
	if (verbose) {
		char *arg, *text = line;
		StringList *names;

		names = sl_init();

		/*
		 * See if there are names in the manual that
		 * are not in the alias list provided by the
		 * MLINKS.  We may want to add those as well.
		 */
		RB_FOREACH(alias, page_alias_tree, &info->head)
			sl_add(names, alias->name);

		for (;;) {
			arg = text;
			text = strchr(text, ',');
			if (text != NULL)
				*text++ = '\0';
			if (!sl_find(names, arg)) {
				fprintf(stderr, "\tpage alias \"%s\" "
				    "may be missing\n", arg);
			}
			if (text  == NULL)
				break;
			if (*text == ' ')
				text++;
		}

		sl_free(names, 0);
	}
	sbuf_retract(whatis_final, 2);		/* remove last ", " */
	while (sbuf_length(whatis_final) < indent)
		sbuf_append(whatis_final, " ", 1);
	sbuf_append(whatis_final, " - ", 3);
	sbuf_append_str(whatis_final, skip_spaces(descr));
	sl_add(whatis_lines, strdup(sbuf_content(whatis_final)));
}

/*
 * Processes a single man section.
 */
static void
process_section(char *section_dir)
{
	struct dirent **entries;
	struct page_info *info;
	int nentries;
	int i;

	if (verbose)
		fprintf(stderr, "  %s\n", section_dir);

	/*
	 * scan the man section directory for pages
	 */
	nentries = scandir(section_dir, &entries, NULL, alphasort);
	if (nentries < 0) {
		warn("%s", section_dir);
		exit_code = 1;
		return;
	}

	/*
	 * collect information about man pages
	 */
	for (i = 0; i < nentries; i++) {
		struct page_info ref;
		char *filename;
		struct stat st;

		if (asprintf(&filename, "%s/%s", section_dir,
		    entries[i]->d_name) < 0) {
			err(1, "malloc");
		}

		if (stat(filename, &st) < 0) {
			warn("%s", filename);
			goto process_section_next;
		}

		if (!S_ISREG(st.st_mode)) {
			if (verbose && !S_ISDIR(st.st_mode))
			    warnx("%s: not a regular file", filename);
			goto process_section_next;
		}

		ref.inode = st.st_ino;

		info = RB_FIND(page_info_tree, &page_head, &ref);
		if (info == NULL) {
			info = malloc(sizeof(*info));
			if (info == NULL) {
				err(1, "malloc");
			}

			bzero(info, sizeof(*info));
			info->inode = st.st_ino;
			RB_INIT(&info->head);

			RB_INSERT(page_info_tree, &page_head, info);
		}

		new_page_alias(info, filename, entries[i]);

process_section_next:

		free(entries[i]);
		free(filename);
	}
	free(entries);
}

/*
 * Returns whether the directory entry is a man page section.
 */
static int
select_sections(const struct dirent *entry)
{
	const char *p = &entry->d_name[3];

	if (strncmp(entry->d_name, "man", 3) != 0)
		return(0);
	while (*p != '\0') {
		if (!isalnum(*p++))
			return(0);
	}
	return(1);
}

/*
 * Processes a single top-level man directory by finding all the
 * sub-directories named man* and processing each one in turn.
 */
static void
process_mandir(char *dir_name)
{
	struct dirent **entries;
	struct page_info *info;
	int nsections;
	FILE *fp = NULL;
	int i;
	struct stat st;

	if (already_visited(dir_name))
		return;
	if (verbose)
		fprintf(stderr, "man directory %s\n", dir_name);
	nsections = scandir(dir_name, &entries, select_sections, alphasort);
	if (nsections < 0) {
		warn("%s", dir_name);
		exit_code = 1;
		return;
	}
	if (common_output == NULL && (fp = open_whatis(dir_name)) == NULL)
		return;
	for (i = 0; i < nsections; i++) {
		char section_dir[MAXPATHLEN];
		snprintf(section_dir, sizeof section_dir, "%s/%s", dir_name,
			 entries[i]->d_name);
		process_section(section_dir);
		snprintf(section_dir, sizeof section_dir, "%s/%s/%s", dir_name,
			 entries[i]->d_name, machine);
		if (stat(section_dir, &st) == 0 && S_ISDIR(st.st_mode))
			process_section(section_dir);
		free(entries[i]);
	}
	free(entries);

	/*
	 * process and free all pages
	 */
	while ((info = RB_ROOT(&page_head))) {
		RB_REMOVE(page_info_tree, &page_head, info);
		process_page(info);
		free_page_info(info);
	}

	if (common_output == NULL)
		finish_whatis(fp, dir_name);
}

/*
 * Processes one argument, which may be a colon-separated list of
 * directories.
 */
static void
process_argument(const char *arg)
{
	char *dir;
	char *mandir;
	char *parg;

	parg = strdup(arg);
	if (parg == NULL)
		err(1, "out of memory");
	while ((dir = strsep(&parg, ":")) != NULL) {
		if (locale != NULL) {
			asprintf(&mandir, "%s/%s", dir, locale);
			process_mandir(mandir);
			free(mandir);
			if (lang_locale != NULL) {
				asprintf(&mandir, "%s/%s", dir, lang_locale);
				process_mandir(mandir);
				free(mandir);
			}
		} else {
			process_mandir(dir);
		}
	}
	free(parg);
}


int
main(int argc, char **argv)
{
	int opt;
	FILE *fp = NULL;

	while ((opt = getopt(argc, argv, "ai:n:o:vL")) != -1) {
		switch (opt) {
		case 'a':
			append++;
			break;
		case 'i':
			indent = atoi(optarg);
			break;
		case 'n':
			whatis_name = optarg;
			break;
		case 'o':
			common_output = optarg;
			break;
		case 'v':
			verbose++;
			break;
		case 'L':
			locale = getenv("LC_ALL");
			if (locale == NULL)
				locale = getenv("LC_CTYPE");
			if (locale == NULL)
				locale = getenv("LANG");
			if (locale != NULL) {
				char *sep = strchr(locale, '_');
				if (sep != NULL && isupper(sep[1]) &&
				    isupper(sep[2])) {
					asprintf(&lang_locale, "%.*s%s",
					    (int)(sep - locale),
					    locale, &sep[3]);
				}
			}
			break;
		default:
			fprintf(stderr, "usage: %s [-a] [-i indent] [-n name] [-o output_file] [-v] [-L] [directories...]\n", argv[0]);
			exit(1);
		}
	}

	signal(SIGINT, trap_signal);
	signal(SIGHUP, trap_signal);
	signal(SIGQUIT, trap_signal);
	signal(SIGTERM, trap_signal);
	SLIST_INIT(&visited_dirs);
	whatis_proto = new_sbuf();
	whatis_final = new_sbuf();

	if ((machine = getenv("MACHINE")) == NULL)
		machine = MACHINE;

	if (common_output != NULL && (fp = open_output(common_output)) == NULL)
		err(1, "%s", common_output);
	if (optind == argc) {
		const char *manpath = getenv("MANPATH");
		if (manpath == NULL)
			manpath = DEFAULT_MANPATH;
		process_argument(manpath);
	} else {
		while (optind < argc)
			process_argument(argv[optind++]);
	}
	if (common_output != NULL)
		finish_output(fp, common_output);
	exit(exit_code);
}