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Commit | Line | Data |
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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
1968a360 | 2 | |
a8fbdf54 TA |
3 | #include <errno.h> |
4 | #include <signal.h> | |
5 | #include <stddef.h> | |
6 | #include <stdint.h> | |
7 | #include <stdio.h> | |
1968a360 | 8 | #include <stdlib.h> |
1968a360 LP |
9 | #include <string.h> |
10 | #include <sys/prctl.h> | |
07630cea | 11 | #include <unistd.h> |
1968a360 | 12 | |
07630cea | 13 | #include "copy.h" |
3ffd4af2 | 14 | #include "fd-util.h" |
6432da6a ZJS |
15 | #include "fileio.h" |
16 | #include "io-util.h" | |
8752c575 | 17 | #include "locale-util.h" |
a8fbdf54 | 18 | #include "log.h" |
1968a360 | 19 | #include "macro.h" |
3ffd4af2 | 20 | #include "pager.h" |
07630cea | 21 | #include "process-util.h" |
595225af | 22 | #include "rlimit-util.h" |
ce30c8dc | 23 | #include "signal-util.h" |
07630cea | 24 | #include "string-util.h" |
57c9e047 | 25 | #include "strv.h" |
07630cea | 26 | #include "terminal-util.h" |
1968a360 LP |
27 | |
28 | static pid_t pager_pid = 0; | |
29 | ||
3f603952 LP |
30 | static int stored_stdout = -1; |
31 | static int stored_stderr = -1; | |
32 | static bool stdout_redirected = false; | |
33 | static bool stderr_redirected = false; | |
34 | ||
848e863a | 35 | _noreturn_ static void pager_fallback(void) { |
6a7c676c | 36 | int r; |
46e65dcc | 37 | |
1c876927 | 38 | r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, (uint64_t) -1, 0); |
6a7c676c LP |
39 | if (r < 0) { |
40 | log_error_errno(r, "Internal pager failed: %m"); | |
4a8e40eb MS |
41 | _exit(EXIT_FAILURE); |
42 | } | |
46e65dcc | 43 | |
4a8e40eb MS |
44 | _exit(EXIT_SUCCESS); |
45 | } | |
46 | ||
6432da6a ZJS |
47 | static int no_quit_on_interrupt(int exe_name_fd, const char *less_opts) { |
48 | _cleanup_fclose_ FILE *file = NULL; | |
49 | _cleanup_free_ char *line = NULL; | |
50 | int r; | |
51 | ||
52 | assert(exe_name_fd >= 0); | |
53 | assert(less_opts); | |
54 | ||
55 | /* This takes ownership of exe_name_fd */ | |
56 | file = fdopen(exe_name_fd, "r"); | |
57 | if (!file) { | |
58 | safe_close(exe_name_fd); | |
1d788908 | 59 | return log_error_errno(errno, "Failed to create FILE object: %m"); |
6432da6a ZJS |
60 | } |
61 | ||
62 | /* Find the last line */ | |
63 | for (;;) { | |
64 | _cleanup_free_ char *t = NULL; | |
65 | ||
66 | r = read_line(file, LONG_LINE_MAX, &t); | |
67 | if (r < 0) | |
1d788908 | 68 | return log_error_errno(r, "Failed to read from socket: %m"); |
6432da6a ZJS |
69 | if (r == 0) |
70 | break; | |
71 | ||
72 | free_and_replace(line, t); | |
73 | } | |
74 | ||
75 | /* We only treat "less" specially. | |
76 | * Return true whenever option K is *not* set. */ | |
77 | r = streq_ptr(line, "less") && !strchr(less_opts, 'K'); | |
78 | ||
79 | log_debug("Pager executable is \"%s\", options \"%s\", quit_on_interrupt: %s", | |
80 | strnull(line), less_opts, yes_no(!r)); | |
81 | return r; | |
82 | } | |
83 | ||
0221d68a | 84 | int pager_open(PagerFlags flags) { |
6432da6a | 85 | _cleanup_close_pair_ int fd[2] = { -1, -1 }, exe_name_pipe[2] = { -1, -1 }; |
43942e80 | 86 | _cleanup_strv_free_ char **pager_args = NULL; |
6432da6a | 87 | const char *pager, *less_opts; |
4c253ed1 | 88 | int r; |
1968a360 | 89 | |
0221d68a | 90 | if (flags & PAGER_DISABLE) |
ea4b98e6 AK |
91 | return 0; |
92 | ||
1968a360 | 93 | if (pager_pid > 0) |
f89a3b6f | 94 | return 1; |
1968a360 | 95 | |
ac96418b | 96 | if (terminal_is_dumb()) |
f89a3b6f | 97 | return 0; |
729e3769 | 98 | |
85afeae8 | 99 | if (!is_main_thread()) |
1d788908 | 100 | return log_error_errno(SYNTHETIC_ERRNO(EPERM), "Pager invoked from wrong thread."); |
85afeae8 | 101 | |
bcbd61db LP |
102 | pager = getenv("SYSTEMD_PAGER"); |
103 | if (!pager) | |
104 | pager = getenv("PAGER"); | |
105 | ||
43942e80 YW |
106 | if (pager) { |
107 | pager_args = strv_split(pager, WHITESPACE); | |
108 | if (!pager_args) | |
1d788908 | 109 | return log_oom(); |
43942e80 YW |
110 | |
111 | /* If the pager is explicitly turned off, honour it */ | |
112 | if (strv_isempty(pager_args) || strv_equal(pager_args, STRV_MAKE("cat"))) | |
113 | return 0; | |
114 | } | |
bcbd61db | 115 | |
d13b5227 LP |
116 | /* Determine and cache number of columns/lines before we spawn the pager so that we get the value from the |
117 | * actual tty */ | |
bcbd61db | 118 | (void) columns(); |
d13b5227 | 119 | (void) lines(); |
1968a360 | 120 | |
d262e99e | 121 | if (pipe2(fd, O_CLOEXEC) < 0) |
4a62c710 | 122 | return log_error_errno(errno, "Failed to create pager pipe: %m"); |
1968a360 | 123 | |
6432da6a ZJS |
124 | /* This is a pipe to feed the name of the executed pager binary into the parent */ |
125 | if (pipe2(exe_name_pipe, O_CLOEXEC) < 0) | |
126 | return log_error_errno(errno, "Failed to create exe_name pipe: %m"); | |
127 | ||
128 | /* Initialize a good set of less options */ | |
129 | less_opts = getenv("SYSTEMD_LESS"); | |
130 | if (!less_opts) | |
131 | less_opts = "FRSXMK"; | |
132 | if (flags & PAGER_JUMP_TO_END) | |
133 | less_opts = strjoina(less_opts, " +G"); | |
134 | ||
a81921e4 | 135 | r = safe_fork("(pager)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pager_pid); |
4c253ed1 | 136 | if (r < 0) |
b6e1fff1 | 137 | return r; |
4c253ed1 | 138 | if (r == 0) { |
6432da6a | 139 | const char *less_charset, *exe; |
1968a360 | 140 | |
4c253ed1 | 141 | /* In the child start the pager */ |
ce30c8dc | 142 | |
1d788908 LP |
143 | if (dup2(fd[0], STDIN_FILENO) < 0) { |
144 | log_error_errno(errno, "Failed to duplicate file descriptor to STDIN: %m"); | |
145 | _exit(EXIT_FAILURE); | |
146 | } | |
147 | ||
3d94f76c | 148 | safe_close_pair(fd); |
1968a360 | 149 | |
1d788908 LP |
150 | if (setenv("LESS", less_opts, 1) < 0) { |
151 | log_error_errno(errno, "Failed to set environment variable LESS: %m"); | |
0357fa0d | 152 | _exit(EXIT_FAILURE); |
1d788908 | 153 | } |
1968a360 | 154 | |
a1b4e6e9 LP |
155 | /* Initialize a good charset for less. This is |
156 | * particularly important if we output UTF-8 | |
157 | * characters. */ | |
158 | less_charset = getenv("SYSTEMD_LESSCHARSET"); | |
159 | if (!less_charset && is_locale_utf8()) | |
160 | less_charset = "utf-8"; | |
0357fa0d | 161 | if (less_charset && |
1d788908 LP |
162 | setenv("LESSCHARSET", less_charset, 1) < 0) { |
163 | log_error_errno(errno, "Failed to set environment variable LESSCHARSET: %m"); | |
0357fa0d | 164 | _exit(EXIT_FAILURE); |
1d788908 | 165 | } |
a1b4e6e9 | 166 | |
6432da6a | 167 | if (pager_args) { |
1d788908 LP |
168 | r = loop_write(exe_name_pipe[1], pager_args[0], strlen(pager_args[0]) + 1, false); |
169 | if (r < 0) { | |
170 | log_error_errno(r, "Failed to write pager name to socket: %m"); | |
6432da6a | 171 | _exit(EXIT_FAILURE); |
1d788908 | 172 | } |
6432da6a | 173 | |
43942e80 | 174 | execvp(pager_args[0], pager_args); |
1d788908 | 175 | log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno, |
118dccc9 | 176 | "Failed to execute '%s', using fallback pagers: %m", pager_args[0]); |
6432da6a | 177 | } |
1968a360 LP |
178 | |
179 | /* Debian's alternatives command for pagers is | |
180 | * called 'pager'. Note that we do not call | |
181 | * sensible-pagers here, since that is just a | |
182 | * shell script that implements a logic that | |
183 | * is similar to this one anyway, but is | |
184 | * Debian-specific. */ | |
6432da6a | 185 | FOREACH_STRING(exe, "pager", "less", "more") { |
1d788908 LP |
186 | r = loop_write(exe_name_pipe[1], exe, strlen(exe) + 1, false); |
187 | if (r < 0) { | |
188 | log_error_errno(r, "Failed to write pager name to socket: %m"); | |
6432da6a | 189 | _exit(EXIT_FAILURE); |
1d788908 | 190 | } |
6432da6a | 191 | execlp(exe, exe, NULL); |
1d788908 | 192 | log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno, |
118dccc9 | 193 | "Failed to execute '%s', using next fallback pager: %m", exe); |
6432da6a | 194 | } |
1968a360 | 195 | |
1d788908 LP |
196 | r = loop_write(exe_name_pipe[1], "(built-in)", strlen("(built-in") + 1, false); |
197 | if (r < 0) { | |
198 | log_error_errno(r, "Failed to write pager name to socket: %m"); | |
6432da6a | 199 | _exit(EXIT_FAILURE); |
1d788908 | 200 | } |
4a8e40eb MS |
201 | pager_fallback(); |
202 | /* not reached */ | |
1968a360 LP |
203 | } |
204 | ||
205 | /* Return in the parent */ | |
a45e7bb4 MS |
206 | stored_stdout = fcntl(STDOUT_FILENO, F_DUPFD_CLOEXEC, 3); |
207 | if (dup2(fd[1], STDOUT_FILENO) < 0) { | |
208 | stored_stdout = safe_close(stored_stdout); | |
4a62c710 | 209 | return log_error_errno(errno, "Failed to duplicate pager pipe: %m"); |
a45e7bb4 MS |
210 | } |
211 | stdout_redirected = true; | |
212 | ||
213 | stored_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3); | |
214 | if (dup2(fd[1], STDERR_FILENO) < 0) { | |
215 | stored_stderr = safe_close(stored_stderr); | |
8b5264aa | 216 | return log_error_errno(errno, "Failed to duplicate pager pipe: %m"); |
a45e7bb4 MS |
217 | } |
218 | stderr_redirected = true; | |
1968a360 | 219 | |
6432da6a ZJS |
220 | exe_name_pipe[1] = safe_close(exe_name_pipe[1]); |
221 | ||
222 | r = no_quit_on_interrupt(TAKE_FD(exe_name_pipe[0]), less_opts); | |
223 | if (r < 0) | |
224 | return r; | |
225 | if (r > 0) | |
226 | (void) ignore_signals(SIGINT, -1); | |
227 | ||
f89a3b6f | 228 | return 1; |
1968a360 LP |
229 | } |
230 | ||
231 | void pager_close(void) { | |
232 | ||
233 | if (pager_pid <= 0) | |
234 | return; | |
235 | ||
236 | /* Inform pager that we are done */ | |
a45e7bb4 | 237 | (void) fflush(stdout); |
77018a8c MS |
238 | if (stdout_redirected) |
239 | if (stored_stdout < 0 || dup2(stored_stdout, STDOUT_FILENO) < 0) | |
240 | (void) close(STDOUT_FILENO); | |
a45e7bb4 MS |
241 | stored_stdout = safe_close(stored_stdout); |
242 | (void) fflush(stderr); | |
77018a8c MS |
243 | if (stderr_redirected) |
244 | if (stored_stderr < 0 || dup2(stored_stderr, STDERR_FILENO) < 0) | |
245 | (void) close(STDERR_FILENO); | |
a45e7bb4 MS |
246 | stored_stderr = safe_close(stored_stderr); |
247 | stdout_redirected = stderr_redirected = false; | |
8b5264aa | 248 | |
74ca738f | 249 | (void) kill(pager_pid, SIGCONT); |
c73d180d | 250 | (void) wait_for_terminate(pager_pid, NULL); |
1968a360 LP |
251 | pager_pid = 0; |
252 | } | |
f89a3b6f LP |
253 | |
254 | bool pager_have(void) { | |
255 | return pager_pid > 0; | |
256 | } | |
78002a67 ZJS |
257 | |
258 | int show_man_page(const char *desc, bool null_stdio) { | |
259 | const char *args[4] = { "man", NULL, NULL, NULL }; | |
260 | char *e = NULL; | |
261 | pid_t pid; | |
262 | size_t k; | |
263 | int r; | |
78002a67 ZJS |
264 | |
265 | k = strlen(desc); | |
266 | ||
267 | if (desc[k-1] == ')') | |
268 | e = strrchr(desc, '('); | |
269 | ||
270 | if (e) { | |
271 | char *page = NULL, *section = NULL; | |
272 | ||
273 | page = strndupa(desc, e - desc); | |
274 | section = strndupa(e + 1, desc + k - e - 2); | |
275 | ||
276 | args[1] = section; | |
277 | args[2] = page; | |
278 | } else | |
279 | args[1] = desc; | |
280 | ||
0672e2c6 | 281 | r = safe_fork("(man)", FORK_RESET_SIGNALS|FORK_DEATHSIG|(null_stdio ? FORK_NULL_STDIO : 0)|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pid); |
4c253ed1 | 282 | if (r < 0) |
b6e1fff1 | 283 | return r; |
4c253ed1 | 284 | if (r == 0) { |
78002a67 | 285 | /* Child */ |
78002a67 | 286 | execvp(args[0], (char**) args); |
56f64d95 | 287 | log_error_errno(errno, "Failed to execute man: %m"); |
78002a67 ZJS |
288 | _exit(EXIT_FAILURE); |
289 | } | |
290 | ||
2e87a1fd | 291 | return wait_for_terminate_and_check(NULL, pid, 0); |
78002a67 | 292 | } |