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 <sys/types.h>
31 #include <sys/wait.h>
32 #include <unistd.h>
33
34 #include "pager.h"
35
36 static pid_t pager_pid;
37
38
39 static void
pager_death(int n)40 pager_death(int n)
41 {
42 exit(0);
43 }
44
45 void
pager_open(void)46 pager_open(void)
47 {
48 int fd[2];
49
50 if (pipe(fd) < 0) {
51 fprintf(stderr, "Failed to create pager pipe: %m\n");
52 exit(-1);
53 }
54
55 pager_pid = fork();
56 if (pager_pid < 0) {
57 fprintf(stderr, "Failed to fork pager: %m\n");
58 exit(-1);
59 }
60
61 if (pager_pid == 0) {
62 const char* less_opts;
63
64 dup2(fd[0], STDIN_FILENO);
65 close(fd[0]);
66 close(fd[1]);
67
68 less_opts = "FRSMKX";
69 setenv("LESS", less_opts, 1);
70
71 execlp("less", "less", NULL);
72
73 } else {
74 /* we want to kill the parent process when pager exits: */
75 signal(SIGCHLD, pager_death);
76 dup2(fd[1], STDOUT_FILENO);
77 close(fd[0]);
78 close(fd[1]);
79 }
80 }
81
82 int
pager_close(void)83 pager_close(void)
84 {
85 siginfo_t status;
86
87 close(STDOUT_FILENO);
88
89 while (true) {
90 memset(&status, 0, sizeof(status));
91 if (waitid(P_PID, pager_pid, &status, WEXITED) < 0) {
92 if (errno == EINTR)
93 continue;
94 return -errno;
95 }
96
97 return 0;
98 }
99 }
100