1/*	$Id: tag.c,v 1.21 2018/11/22 11:30:23 schwarze Exp $ */
2/*
3 * Copyright (c) 2015, 2016, 2018 Ingo Schwarze <schwarze@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17#include "config.h"
18
19#include <sys/types.h>
20
21#if HAVE_ERR
22#include <err.h>
23#endif
24#include <limits.h>
25#include <signal.h>
26#include <stddef.h>
27#include <stdint.h>
28#include <stdio.h>
29#include <stdlib.h>
30#include <string.h>
31#include <unistd.h>
32
33#include "mandoc_aux.h"
34#include "mandoc_ohash.h"
35#include "tag.h"
36
37struct tag_entry {
38	size_t	*lines;
39	size_t	 maxlines;
40	size_t	 nlines;
41	int	 prio;
42	char	 s[];
43};
44
45static	void	 tag_signal(int) __attribute__((__noreturn__));
46
47static struct ohash	 tag_data;
48static struct tag_files	 tag_files;
49
50
51/*
52 * Prepare for using a pager.
53 * Not all pagers are capable of using a tag file,
54 * but for simplicity, create it anyway.
55 */
56struct tag_files *
57tag_init(void)
58{
59	struct sigaction	 sa;
60	int			 ofd;
61
62	ofd = -1;
63	tag_files.tfd = -1;
64	tag_files.tcpgid = -1;
65
66	/* Clean up when dying from a signal. */
67
68	memset(&sa, 0, sizeof(sa));
69	sigfillset(&sa.sa_mask);
70	sa.sa_handler = tag_signal;
71	sigaction(SIGHUP, &sa, NULL);
72	sigaction(SIGINT, &sa, NULL);
73	sigaction(SIGTERM, &sa, NULL);
74
75	/*
76	 * POSIX requires that a process calling tcsetpgrp(3)
77	 * from the background gets a SIGTTOU signal.
78	 * In that case, do not stop.
79	 */
80
81	sa.sa_handler = SIG_IGN;
82	sigaction(SIGTTOU, &sa, NULL);
83
84	/* Save the original standard output for use by the pager. */
85
86	if ((tag_files.ofd = dup(STDOUT_FILENO)) == -1)
87		goto fail;
88
89	/* Create both temporary output files. */
90
91	(void)strlcpy(tag_files.ofn, "/tmp/man.XXXXXXXXXX",
92	    sizeof(tag_files.ofn));
93	(void)strlcpy(tag_files.tfn, "/tmp/man.XXXXXXXXXX",
94	    sizeof(tag_files.tfn));
95	if ((ofd = mkstemp(tag_files.ofn)) == -1)
96		goto fail;
97	if ((tag_files.tfd = mkstemp(tag_files.tfn)) == -1)
98		goto fail;
99	if (dup2(ofd, STDOUT_FILENO) == -1)
100		goto fail;
101	close(ofd);
102
103	/*
104	 * Set up the ohash table to collect output line numbers
105	 * where various marked-up terms are documented.
106	 */
107
108	mandoc_ohash_init(&tag_data, 4, offsetof(struct tag_entry, s));
109	return &tag_files;
110
111fail:
112	tag_unlink();
113	if (ofd != -1)
114		close(ofd);
115	if (tag_files.ofd != -1)
116		close(tag_files.ofd);
117	if (tag_files.tfd != -1)
118		close(tag_files.tfd);
119	*tag_files.ofn = '\0';
120	*tag_files.tfn = '\0';
121	tag_files.ofd = -1;
122	tag_files.tfd = -1;
123	return NULL;
124}
125
126/*
127 * Set the line number where a term is defined,
128 * unless it is already defined at a lower priority.
129 */
130void
131tag_put(const char *s, int prio, size_t line)
132{
133	struct tag_entry	*entry;
134	const char		*se;
135	size_t			 len;
136	unsigned int		 slot;
137
138	if (tag_files.tfd <= 0)
139		return;
140
141	if (s[0] == '\\' && (s[1] == '&' || s[1] == 'e'))
142		s += 2;
143
144	/*
145	 * Skip whitespace and whatever follows it,
146	 * and if there is any, downgrade the priority.
147	 */
148
149	len = strcspn(s, " \t");
150	if (len == 0)
151		return;
152
153	se = s + len;
154	if (*se != '\0')
155		prio = INT_MAX;
156
157	slot = ohash_qlookupi(&tag_data, s, &se);
158	entry = ohash_find(&tag_data, slot);
159
160	if (entry == NULL) {
161
162		/* Build a new entry. */
163
164		entry = mandoc_malloc(sizeof(*entry) + len + 1);
165		memcpy(entry->s, s, len);
166		entry->s[len] = '\0';
167		entry->lines = NULL;
168		entry->maxlines = entry->nlines = 0;
169		ohash_insert(&tag_data, slot, entry);
170
171	} else {
172
173		/*
174		 * Lower priority numbers take precedence,
175		 * but 0 is special.
176		 * A tag with priority 0 is only used
177		 * if the tag occurs exactly once.
178		 */
179
180		if (prio == 0) {
181			if (entry->prio == 0)
182				entry->prio = -1;
183			return;
184		}
185
186		/* A better entry is already present, ignore the new one. */
187
188		if (entry->prio > 0 && entry->prio < prio)
189			return;
190
191		/* The existing entry is worse, clear it. */
192
193		if (entry->prio < 1 || entry->prio > prio)
194			entry->nlines = 0;
195	}
196
197	/* Remember the new line. */
198
199	if (entry->maxlines == entry->nlines) {
200		entry->maxlines += 4;
201		entry->lines = mandoc_reallocarray(entry->lines,
202		    entry->maxlines, sizeof(*entry->lines));
203	}
204	entry->lines[entry->nlines++] = line;
205	entry->prio = prio;
206}
207
208/*
209 * Write out the tags file using the previously collected
210 * information and clear the ohash table while going along.
211 */
212void
213tag_write(void)
214{
215	FILE			*stream;
216	struct tag_entry	*entry;
217	size_t			 i;
218	unsigned int		 slot;
219
220	if (tag_files.tfd <= 0)
221		return;
222	if (tag_files.tagname != NULL && ohash_find(&tag_data,
223            ohash_qlookup(&tag_data, tag_files.tagname)) == NULL) {
224		warnx("%s: no such tag", tag_files.tagname);
225		tag_files.tagname = NULL;
226	}
227	stream = fdopen(tag_files.tfd, "w");
228	entry = ohash_first(&tag_data, &slot);
229	while (entry != NULL) {
230		if (stream != NULL && entry->prio >= 0)
231			for (i = 0; i < entry->nlines; i++)
232				fprintf(stream, "%s %s %zu\n",
233				    entry->s, tag_files.ofn, entry->lines[i]);
234		free(entry->lines);
235		free(entry);
236		entry = ohash_next(&tag_data, &slot);
237	}
238	ohash_delete(&tag_data);
239	if (stream != NULL)
240		fclose(stream);
241	else
242		close(tag_files.tfd);
243	tag_files.tfd = -1;
244}
245
246void
247tag_unlink(void)
248{
249	pid_t	 tc_pgid;
250
251	if (tag_files.tcpgid != -1) {
252		tc_pgid = tcgetpgrp(tag_files.ofd);
253		if (tc_pgid == tag_files.pager_pid ||
254		    tc_pgid == getpgid(0) ||
255		    getpgid(tc_pgid) == -1)
256			(void)tcsetpgrp(tag_files.ofd, tag_files.tcpgid);
257	}
258	if (*tag_files.ofn != '\0')
259		unlink(tag_files.ofn);
260	if (*tag_files.tfn != '\0')
261		unlink(tag_files.tfn);
262}
263
264static void
265tag_signal(int signum)
266{
267	struct sigaction	 sa;
268
269	tag_unlink();
270	memset(&sa, 0, sizeof(sa));
271	sigemptyset(&sa.sa_mask);
272	sa.sa_handler = SIG_DFL;
273	sigaction(signum, &sa, NULL);
274	kill(getpid(), signum);
275	/* NOTREACHED */
276	_exit(1);
277}
278