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
36 static pid_t pager_pid;
37
38 static void
pager_death(int n)39 pager_death(int n)
40 {
41 exit(0);
42 }
43
44 void
pager_open(void)45 pager_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
81 int
pager_close(void)82 pager_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