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1968a360 LP |
1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2010 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
5430f7f2 LP |
9 | under the terms of the GNU Lesser General Public License as published by |
10 | the Free Software Foundation; either version 2.1 of the License, or | |
1968a360 LP |
11 | (at your option) any later version. |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
5430f7f2 | 16 | Lesser General Public License for more details. |
1968a360 | 17 | |
5430f7f2 | 18 | You should have received a copy of the GNU Lesser General Public License |
1968a360 LP |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
20 | ***/ | |
21 | ||
22 | #include <sys/types.h> | |
4a8e40eb | 23 | #include <fcntl.h> |
1968a360 LP |
24 | #include <stdlib.h> |
25 | #include <unistd.h> | |
26 | #include <string.h> | |
27 | #include <sys/prctl.h> | |
28 | ||
29 | #include "pager.h" | |
30 | #include "util.h" | |
31 | #include "macro.h" | |
32 | ||
33 | static pid_t pager_pid = 0; | |
34 | ||
adda7d8b | 35 | _noreturn_ static void pager_fallback(void) { |
4a8e40eb MS |
36 | ssize_t n; |
37 | do { | |
38 | n = splice(STDIN_FILENO, NULL, STDOUT_FILENO, NULL, 64*1024, 0); | |
39 | } while (n > 0); | |
40 | if (n < 0) { | |
41 | log_error("Internal pager failed: %m"); | |
42 | _exit(EXIT_FAILURE); | |
43 | } | |
44 | _exit(EXIT_SUCCESS); | |
45 | } | |
46 | ||
1b12a7b5 | 47 | int pager_open(bool jump_to_end) { |
1968a360 LP |
48 | int fd[2]; |
49 | const char *pager; | |
50 | pid_t parent_pid; | |
f89a3b6f | 51 | int r; |
1968a360 LP |
52 | |
53 | if (pager_pid > 0) | |
f89a3b6f | 54 | return 1; |
1968a360 | 55 | |
1968a360 LP |
56 | if ((pager = getenv("SYSTEMD_PAGER")) || (pager = getenv("PAGER"))) |
57 | if (!*pager || streq(pager, "cat")) | |
f89a3b6f | 58 | return 0; |
1968a360 | 59 | |
8481248b | 60 | if (!on_tty()) |
f89a3b6f | 61 | return 0; |
729e3769 | 62 | |
1968a360 LP |
63 | /* Determine and cache number of columns before we spawn the |
64 | * pager so that we get the value from the actual tty */ | |
65 | columns(); | |
66 | ||
67 | if (pipe(fd) < 0) { | |
68 | log_error("Failed to create pager pipe: %m"); | |
f89a3b6f | 69 | return -errno; |
1968a360 LP |
70 | } |
71 | ||
72 | parent_pid = getpid(); | |
73 | ||
74 | pager_pid = fork(); | |
75 | if (pager_pid < 0) { | |
f89a3b6f | 76 | r = -errno; |
1968a360 LP |
77 | log_error("Failed to fork pager: %m"); |
78 | close_pipe(fd); | |
f89a3b6f | 79 | return r; |
1968a360 LP |
80 | } |
81 | ||
82 | /* In the child start the pager */ | |
83 | if (pager_pid == 0) { | |
84 | ||
85 | dup2(fd[0], STDIN_FILENO); | |
86 | close_pipe(fd); | |
87 | ||
1b12a7b5 | 88 | if (jump_to_end) |
b47ef6a0 | 89 | setenv("LESS", "FRSXMK+G", 1); |
1b12a7b5 | 90 | else |
b47ef6a0 | 91 | setenv("LESS", "FRSXMK", 1); |
1968a360 LP |
92 | |
93 | /* Make sure the pager goes away when the parent dies */ | |
94 | if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0) | |
95 | _exit(EXIT_FAILURE); | |
96 | ||
97 | /* Check whether our parent died before we were able | |
98 | * to set the death signal */ | |
99 | if (getppid() != parent_pid) | |
100 | _exit(EXIT_SUCCESS); | |
101 | ||
102 | if (pager) { | |
103 | execlp(pager, pager, NULL); | |
104 | execl("/bin/sh", "sh", "-c", pager, NULL); | |
105 | } | |
106 | ||
107 | /* Debian's alternatives command for pagers is | |
108 | * called 'pager'. Note that we do not call | |
109 | * sensible-pagers here, since that is just a | |
110 | * shell script that implements a logic that | |
111 | * is similar to this one anyway, but is | |
112 | * Debian-specific. */ | |
113 | execlp("pager", "pager", NULL); | |
114 | ||
115 | execlp("less", "less", NULL); | |
116 | execlp("more", "more", NULL); | |
1968a360 | 117 | |
4a8e40eb MS |
118 | pager_fallback(); |
119 | /* not reached */ | |
1968a360 LP |
120 | } |
121 | ||
122 | /* Return in the parent */ | |
fafb6ecc | 123 | if (dup2(fd[1], STDOUT_FILENO) < 0) { |
1968a360 | 124 | log_error("Failed to duplicate pager pipe: %m"); |
f89a3b6f | 125 | return -errno; |
fafb6ecc | 126 | } |
1968a360 LP |
127 | |
128 | close_pipe(fd); | |
f89a3b6f | 129 | return 1; |
1968a360 LP |
130 | } |
131 | ||
132 | void pager_close(void) { | |
133 | ||
134 | if (pager_pid <= 0) | |
135 | return; | |
136 | ||
137 | /* Inform pager that we are done */ | |
138 | fclose(stdout); | |
139 | kill(pager_pid, SIGCONT); | |
140 | wait_for_terminate(pager_pid, NULL); | |
141 | pager_pid = 0; | |
142 | } | |
f89a3b6f LP |
143 | |
144 | bool pager_have(void) { | |
145 | return pager_pid > 0; | |
146 | } |