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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 | ||
919ce0b7 | 35 | noreturn static void pager_fallback(void) { |
4a8e40eb | 36 | ssize_t n; |
46e65dcc | 37 | |
4a8e40eb MS |
38 | do { |
39 | n = splice(STDIN_FILENO, NULL, STDOUT_FILENO, NULL, 64*1024, 0); | |
40 | } while (n > 0); | |
46e65dcc | 41 | |
4a8e40eb MS |
42 | if (n < 0) { |
43 | log_error("Internal pager failed: %m"); | |
44 | _exit(EXIT_FAILURE); | |
45 | } | |
46e65dcc | 46 | |
4a8e40eb MS |
47 | _exit(EXIT_SUCCESS); |
48 | } | |
49 | ||
1b12a7b5 | 50 | int pager_open(bool jump_to_end) { |
1968a360 LP |
51 | int fd[2]; |
52 | const char *pager; | |
53 | pid_t parent_pid; | |
f89a3b6f | 54 | int r; |
1968a360 LP |
55 | |
56 | if (pager_pid > 0) | |
f89a3b6f | 57 | return 1; |
1968a360 | 58 | |
1968a360 LP |
59 | if ((pager = getenv("SYSTEMD_PAGER")) || (pager = getenv("PAGER"))) |
60 | if (!*pager || streq(pager, "cat")) | |
f89a3b6f | 61 | return 0; |
1968a360 | 62 | |
8481248b | 63 | if (!on_tty()) |
f89a3b6f | 64 | return 0; |
729e3769 | 65 | |
1968a360 LP |
66 | /* Determine and cache number of columns before we spawn the |
67 | * pager so that we get the value from the actual tty */ | |
68 | columns(); | |
69 | ||
70 | if (pipe(fd) < 0) { | |
71 | log_error("Failed to create pager pipe: %m"); | |
f89a3b6f | 72 | return -errno; |
1968a360 LP |
73 | } |
74 | ||
75 | parent_pid = getpid(); | |
76 | ||
77 | pager_pid = fork(); | |
78 | if (pager_pid < 0) { | |
f89a3b6f | 79 | r = -errno; |
1968a360 LP |
80 | log_error("Failed to fork pager: %m"); |
81 | close_pipe(fd); | |
f89a3b6f | 82 | return r; |
1968a360 LP |
83 | } |
84 | ||
85 | /* In the child start the pager */ | |
86 | if (pager_pid == 0) { | |
87 | ||
88 | dup2(fd[0], STDIN_FILENO); | |
89 | close_pipe(fd); | |
90 | ||
1b12a7b5 | 91 | if (jump_to_end) |
b47ef6a0 | 92 | setenv("LESS", "FRSXMK+G", 1); |
1b12a7b5 | 93 | else |
b47ef6a0 | 94 | setenv("LESS", "FRSXMK", 1); |
1968a360 LP |
95 | |
96 | /* Make sure the pager goes away when the parent dies */ | |
97 | if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0) | |
98 | _exit(EXIT_FAILURE); | |
99 | ||
100 | /* Check whether our parent died before we were able | |
101 | * to set the death signal */ | |
102 | if (getppid() != parent_pid) | |
103 | _exit(EXIT_SUCCESS); | |
104 | ||
105 | if (pager) { | |
106 | execlp(pager, pager, NULL); | |
107 | execl("/bin/sh", "sh", "-c", pager, NULL); | |
108 | } | |
109 | ||
110 | /* Debian's alternatives command for pagers is | |
111 | * called 'pager'. Note that we do not call | |
112 | * sensible-pagers here, since that is just a | |
113 | * shell script that implements a logic that | |
114 | * is similar to this one anyway, but is | |
115 | * Debian-specific. */ | |
116 | execlp("pager", "pager", NULL); | |
117 | ||
118 | execlp("less", "less", NULL); | |
119 | execlp("more", "more", NULL); | |
1968a360 | 120 | |
4a8e40eb MS |
121 | pager_fallback(); |
122 | /* not reached */ | |
1968a360 LP |
123 | } |
124 | ||
125 | /* Return in the parent */ | |
fafb6ecc | 126 | if (dup2(fd[1], STDOUT_FILENO) < 0) { |
1968a360 | 127 | log_error("Failed to duplicate pager pipe: %m"); |
f89a3b6f | 128 | return -errno; |
fafb6ecc | 129 | } |
1968a360 LP |
130 | |
131 | close_pipe(fd); | |
f89a3b6f | 132 | return 1; |
1968a360 LP |
133 | } |
134 | ||
135 | void pager_close(void) { | |
136 | ||
137 | if (pager_pid <= 0) | |
138 | return; | |
139 | ||
140 | /* Inform pager that we are done */ | |
141 | fclose(stdout); | |
142 | kill(pager_pid, SIGCONT); | |
143 | wait_for_terminate(pager_pid, NULL); | |
144 | pager_pid = 0; | |
145 | } | |
f89a3b6f LP |
146 | |
147 | bool pager_have(void) { | |
148 | return pager_pid > 0; | |
149 | } |