1/*
2 * Copyright (c) 2018 Rob Clark <robdclark@gmail.com>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 * SOFTWARE.
22 */
23
24#include <errno.h>
25#include <signal.h>
26#include <stdbool.h>
27#include <stdio.h>
28#include <stdlib.h>
29#include <string.h>
30#include <unistd.h>
31#include <sys/types.h>
32#include <sys/wait.h>
33
34#include "pager.h"
35
36static pid_t pager_pid;
37
38static void
39pager_death(int n)
40{
41   exit(0);
42}
43
44void
45pager_open(void)
46{
47   int fd[2];
48
49   if (pipe(fd) < 0) {
50      fprintf(stderr, "Failed to create pager pipe: %m\n");
51      exit(-1);
52   }
53
54   pager_pid = fork();
55   if (pager_pid < 0) {
56      fprintf(stderr, "Failed to fork pager: %m\n");
57      exit(-1);
58   }
59
60   if (pager_pid == 0) {
61      const char *less_opts;
62
63      dup2(fd[0], STDIN_FILENO);
64      close(fd[0]);
65      close(fd[1]);
66
67      less_opts = "FRSMKX";
68      setenv("LESS", less_opts, 1);
69
70      execlp("less", "less", NULL);
71
72   } else {
73      /* we want to kill the parent process when pager exits: */
74      signal(SIGCHLD, pager_death);
75      dup2(fd[1], STDOUT_FILENO);
76      close(fd[0]);
77      close(fd[1]);
78   }
79}
80
81int
82pager_close(void)
83{
84   siginfo_t status;
85
86   close(STDOUT_FILENO);
87
88   while (true) {
89      memset(&status, 0, sizeof(status));
90      if (waitid(P_PID, pager_pid, &status, WEXITED) < 0) {
91         if (errno == EINTR)
92            continue;
93         return -errno;
94      }
95
96      return 0;
97   }
98}
99