/* $Id: term_tag.c,v 1.6 2021/03/30 17:16:55 schwarze Exp $ */
/*
 * Copyright (c) 2015,2016,2018,2019,2020 Ingo Schwarze <schwarze@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Functions to write a ctags(1) file.
 * For use by the mandoc(1) ASCII and UTF-8 formatters only.
 */
#include "config.h"

#include <sys/types.h>

#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "mandoc.h"
#include "roff.h"
#include "roff_int.h"
#include "tag.h"
#include "term_tag.h"

static void tag_signal(int) __attribute__((__noreturn__));

static struct tag_files tag_files;


/*
 * Prepare for using a pager.
 * Not all pagers are capable of using a tag file,
 * but for simplicity, create it anyway.
 */
struct tag_files *
term_tag_init(const char *outfilename, const char *suffix,
    const char *tagfilename)
{
        struct sigaction         sa;
        int                      ofd;   /* In /tmp/, dup(2)ed to stdout. */
        int                      tfd;

        ofd = tfd = -1;
        tag_files.tfs = NULL;
        tag_files.tcpgid = -1;

        /* Clean up when dying from a signal. */

        memset(&sa, 0, sizeof(sa));
        sigfillset(&sa.sa_mask);
        sa.sa_handler = tag_signal;
        sigaction(SIGHUP, &sa, NULL);
        sigaction(SIGINT, &sa, NULL);
        sigaction(SIGTERM, &sa, NULL);

        /*
         * POSIX requires that a process calling tcsetpgrp(3)
         * from the background gets a SIGTTOU signal.
         * In that case, do not stop.
         */

        sa.sa_handler = SIG_IGN;
        sigaction(SIGTTOU, &sa, NULL);

        /* Save the original standard output for use by the pager. */

        if ((tag_files.ofd = dup(STDOUT_FILENO)) == -1) {
                mandoc_msg(MANDOCERR_DUP, 0, 0, "%s", strerror(errno));
                goto fail;
        }

        /* Create both temporary output files. */

        if (outfilename == NULL) {
                (void)snprintf(tag_files.ofn, sizeof(tag_files.ofn),
                    "/tmp/man.XXXXXXXXXX%s", suffix);
                if ((ofd = mkstemps(tag_files.ofn, strlen(suffix))) == -1) {
                        mandoc_msg(MANDOCERR_MKSTEMP, 0, 0,
                            "%s: %s", tag_files.ofn, strerror(errno));
                        goto fail;
                }
        } else {
                (void)strlcpy(tag_files.ofn, outfilename,
                   sizeof(tag_files.ofn));
                unlink(outfilename);
                ofd = open(outfilename, O_WRONLY | O_CREAT | O_EXCL, 0644);
                if (ofd == -1) {
                        mandoc_msg(MANDOCERR_OPEN, 0, 0,
                            "%s: %s", outfilename, strerror(errno));
                        goto fail;
                }
        }
        if (tagfilename == NULL) {
                (void)strlcpy(tag_files.tfn, "/tmp/man.XXXXXXXXXX",
                    sizeof(tag_files.tfn));
                if ((tfd = mkstemp(tag_files.tfn)) == -1) {
                        mandoc_msg(MANDOCERR_MKSTEMP, 0, 0,
                            "%s: %s", tag_files.tfn, strerror(errno));
                        goto fail;
                }
        } else {
                (void)strlcpy(tag_files.tfn, tagfilename,
                    sizeof(tag_files.tfn));
                unlink(tagfilename);
                tfd = open(tagfilename, O_WRONLY | O_CREAT | O_EXCL, 0644);
                if (tfd == -1) {
                        mandoc_msg(MANDOCERR_OPEN, 0, 0,
                            "%s: %s", tagfilename, strerror(errno));
                        goto fail;
                }
        }
        if ((tag_files.tfs = fdopen(tfd, "w")) == NULL) {
                mandoc_msg(MANDOCERR_FDOPEN, 0, 0, "%s", strerror(errno));
                goto fail;
        }
        tfd = -1;
        if (dup2(ofd, STDOUT_FILENO) == -1) {
                mandoc_msg(MANDOCERR_DUP, 0, 0, "%s", strerror(errno));
                goto fail;
        }
        close(ofd);
        return &tag_files;

fail:
        term_tag_unlink();
        if (ofd != -1)
                close(ofd);
        if (tfd != -1)
                close(tfd);
        if (tag_files.ofd != -1) {
                close(tag_files.ofd);
                tag_files.ofd = -1;
        }
        return NULL;
}

void
term_tag_write(struct roff_node *n, size_t line)
{
        const char      *cp;
        int              len;

        if (tag_files.tfs == NULL)
                return;
        cp = n->tag == NULL ? n->child->string : n->tag;
        if (cp[0] == '\\' && (cp[1] == '&' || cp[1] == 'e'))
                cp += 2;
        len = strcspn(cp, " \t\\");
        fprintf(tag_files.tfs, "%.*s %s %zu\n",
            len, cp, tag_files.ofn, line);
}

/*
 * Close both output files and restore the original standard output
 * to the terminal.  In the unlikely case that the latter fails,
 * trying to start a pager would be useless, so report the failure
 * to the main program.
 */
int
term_tag_close(void)
{
        int irc = 0;

        if (tag_files.tfs != NULL) {
                fclose(tag_files.tfs);
                tag_files.tfs = NULL;
        }
        if (tag_files.ofd != -1) {
                fflush(stdout);
                if ((irc = dup2(tag_files.ofd, STDOUT_FILENO)) == -1)
                        mandoc_msg(MANDOCERR_DUP, 0, 0, "%s", strerror(errno));
                close(tag_files.ofd);
                tag_files.ofd = -1;
        }
        return irc;
}

void
term_tag_unlink(void)
{
        pid_t    tc_pgid;

        if (tag_files.tcpgid != -1) {
                tc_pgid = tcgetpgrp(STDOUT_FILENO);
                if (tc_pgid == tag_files.pager_pid ||
                    tc_pgid == getpgid(0) ||
                    getpgid(tc_pgid) == -1)
                        (void)tcsetpgrp(STDOUT_FILENO, tag_files.tcpgid);
        }
        if (strncmp(tag_files.ofn, "/tmp/man.", 9) == 0) {
                unlink(tag_files.ofn);
                *tag_files.ofn = '\0';
        }
        if (strncmp(tag_files.tfn, "/tmp/man.", 9) == 0) {
                unlink(tag_files.tfn);
                *tag_files.tfn = '\0';
        }
}

static void
tag_signal(int signum)
{
        struct sigaction         sa;

        term_tag_unlink();
        memset(&sa, 0, sizeof(sa));
        sigemptyset(&sa.sa_mask);
        sa.sa_handler = SIG_DFL;
        sigaction(signum, &sa, NULL);
        kill(getpid(), signum);
        /* NOTREACHED */
        _exit(1);
}