1 | /* Close standard output and standard error, exiting with a diagnostic on error. |
2 | |
3 | Copyright (C) 1998-2002, 2004, 2006, 2008-2019 Free Software Foundation, |
4 | Inc. |
5 | |
6 | This program is free software: you can redistribute it and/or modify |
7 | it under the terms of the GNU General Public License as published by |
8 | the Free Software Foundation; either version 3 of the License, or |
9 | (at your option) any later version. |
10 | |
11 | This program is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | GNU General Public License for more details. |
15 | |
16 | You should have received a copy of the GNU General Public License |
17 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <config.h> |
20 | |
21 | #include "closeout.h" |
22 | |
23 | #include <errno.h> |
24 | #include <stdbool.h> |
25 | #include <stdio.h> |
26 | #include <unistd.h> |
27 | |
28 | #include "gettext.h" |
29 | #define _(msgid) gettext (msgid) |
30 | |
31 | #include "close-stream.h" |
32 | #include "error.h" |
33 | #include "exitfail.h" |
34 | #include "quotearg.h" |
35 | |
36 | #ifndef __has_feature |
37 | # define __has_feature(a) false |
38 | #endif |
39 | |
40 | #if defined __SANITIZE_ADDRESS__ || __has_feature (address_sanitizer) |
41 | enum { SANITIZE_ADDRESS = true }; |
42 | #else |
43 | enum { SANITIZE_ADDRESS = false }; |
44 | #endif |
45 | |
46 | static const char *file_name; |
47 | |
48 | /* Set the file name to be reported in the event an error is detected |
49 | by close_stdout. */ |
50 | void |
51 | close_stdout_set_file_name (const char *file) |
52 | { |
53 | file_name = file; |
54 | } |
55 | |
56 | static bool ignore_EPIPE /* = false */; |
57 | |
58 | /* Specify the reaction to an EPIPE error during the closing of stdout: |
59 | - If ignore = true, it shall be ignored. |
60 | - If ignore = false, it shall evoke a diagnostic, along with a nonzero |
61 | exit status. |
62 | The default is ignore = false. |
63 | |
64 | This setting matters only if the SIGPIPE signal is ignored (i.e. its |
65 | handler set to SIG_IGN) or blocked. Only particular programs need to |
66 | temporarily ignore SIGPIPE. If SIGPIPE is ignored or blocked because |
67 | it was ignored or blocked in the parent process when it created the |
68 | child process, it usually is a bug in the parent process: It is bad |
69 | practice to have SIGPIPE ignored or blocked while creating a child |
70 | process. |
71 | |
72 | EPIPE occurs when writing to a pipe or socket that has no readers now, |
73 | when SIGPIPE is ignored or blocked. |
74 | |
75 | The ignore = false setting is suitable for a scenario where it is normally |
76 | guaranteed that the pipe writer terminates before the pipe reader. In |
77 | this case, an EPIPE is an indication of a premature termination of the |
78 | pipe reader and should lead to a diagnostic and a nonzero exit status. |
79 | |
80 | The ignore = true setting is suitable for a scenario where you don't know |
81 | ahead of time whether the pipe writer or the pipe reader will terminate |
82 | first. In this case, an EPIPE is an indication that the pipe writer can |
83 | stop doing useless write() calls; this is what close_stdout does anyway. |
84 | EPIPE is part of the normal pipe/socket shutdown protocol in this case, |
85 | and should not lead to a diagnostic message. */ |
86 | |
87 | void |
88 | close_stdout_set_ignore_EPIPE (bool ignore) |
89 | { |
90 | ignore_EPIPE = ignore; |
91 | } |
92 | |
93 | /* Close standard output. On error, issue a diagnostic and _exit |
94 | with status 'exit_failure'. |
95 | |
96 | Also close standard error. On error, _exit with status 'exit_failure'. |
97 | |
98 | Since close_stdout is commonly registered via 'atexit', POSIX |
99 | and the C standard both say that it should not call 'exit', |
100 | because the behavior is undefined if 'exit' is called more than |
101 | once. So it calls '_exit' instead of 'exit'. If close_stdout |
102 | is registered via atexit before other functions are registered, |
103 | the other functions can act before this _exit is invoked. |
104 | |
105 | Applications that use close_stdout should flush any streams |
106 | other than stdout and stderr before exiting, since the call to |
107 | _exit will bypass other buffer flushing. Applications should |
108 | be flushing and closing other streams anyway, to check for I/O |
109 | errors. Also, applications should not use tmpfile, since _exit |
110 | can bypass the removal of these files. |
111 | |
112 | It's important to detect such failures and exit nonzero because many |
113 | tools (most notably 'make' and other build-management systems) depend |
114 | on being able to detect failure in other tools via their exit status. */ |
115 | |
116 | void |
117 | close_stdout (void) |
118 | { |
119 | if (close_stream (stdout) != 0 |
120 | && !(ignore_EPIPE && errno == EPIPE)) |
121 | { |
122 | char const *write_error = _("write error" ); |
123 | if (file_name) |
124 | error (0, errno, "%s: %s" , quotearg_colon (file_name), |
125 | write_error); |
126 | else |
127 | error (0, errno, "%s" , write_error); |
128 | |
129 | _exit (exit_failure); |
130 | } |
131 | |
132 | /* Close stderr only if not sanitizing, as sanitizers may report to |
133 | stderr after this function returns. */ |
134 | if (!SANITIZE_ADDRESS && close_stream (stderr) != 0) |
135 | _exit (exit_failure); |
136 | } |
137 | |