[3611] | 1 | /* Close standard output and standard error, exiting with a diagnostic on error.
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| 2 |
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| 3 | Copyright (C) 1998-2002, 2004, 2006, 2008-2022 Free Software Foundation,
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| 4 | Inc.
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| 5 |
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| 6 | This program is free software: you can redistribute it and/or modify
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| 7 | it under the terms of the GNU General Public License as published by
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| 8 | the Free Software Foundation, either version 3 of the License, or
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| 9 | (at your option) any later version.
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| 10 |
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| 11 | This program is distributed in the hope that it will be useful,
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | GNU General Public License for more details.
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| 15 |
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| 16 | You should have received a copy of the GNU General Public License
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| 17 | along with this program. If not, see <https://www.gnu.org/licenses/>. */
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| 18 |
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| 19 | #include <config.h>
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| 20 |
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| 21 | #include "closeout.h"
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| 22 |
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| 23 | #include <errno.h>
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| 24 | #include <stdio.h>
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| 25 | #include <unistd.h>
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| 26 |
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| 27 | #include "gettext.h"
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| 28 | #define _(msgid) gettext (msgid)
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| 29 |
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| 30 | #include "close-stream.h"
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| 31 | #include "error.h"
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| 32 | #include "exitfail.h"
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| 33 | #include "quotearg.h"
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| 34 |
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| 35 | #ifndef __has_feature
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| 36 | # define __has_feature(a) false
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| 37 | #endif
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| 38 |
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| 39 | #if defined __SANITIZE_ADDRESS__ || __has_feature (address_sanitizer)
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| 40 | enum { SANITIZE_ADDRESS = true };
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| 41 | #else
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| 42 | enum { SANITIZE_ADDRESS = false };
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| 43 | #endif
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| 44 |
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| 45 | static const char *file_name;
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| 46 |
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| 47 | /* Set the file name to be reported in the event an error is detected
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| 48 | by close_stdout. */
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| 49 | void
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| 50 | close_stdout_set_file_name (const char *file)
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| 51 | {
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| 52 | file_name = file;
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| 53 | }
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| 54 |
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| 55 | static bool ignore_EPIPE /* = false */;
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| 56 |
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| 57 | /* Specify the reaction to an EPIPE error during the closing of stdout:
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| 58 | - If ignore = true, it shall be ignored.
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| 59 | - If ignore = false, it shall evoke a diagnostic, along with a nonzero
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| 60 | exit status.
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| 61 | The default is ignore = false.
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| 62 |
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| 63 | This setting matters only if the SIGPIPE signal is ignored (i.e. its
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| 64 | handler set to SIG_IGN) or blocked. Only particular programs need to
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| 65 | temporarily ignore SIGPIPE. If SIGPIPE is ignored or blocked because
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| 66 | it was ignored or blocked in the parent process when it created the
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| 67 | child process, it usually is a bug in the parent process: It is bad
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| 68 | practice to have SIGPIPE ignored or blocked while creating a child
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| 69 | process.
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| 70 |
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| 71 | EPIPE occurs when writing to a pipe or socket that has no readers now,
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| 72 | when SIGPIPE is ignored or blocked.
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| 73 |
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| 74 | The ignore = false setting is suitable for a scenario where it is normally
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| 75 | guaranteed that the pipe writer terminates before the pipe reader. In
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| 76 | this case, an EPIPE is an indication of a premature termination of the
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| 77 | pipe reader and should lead to a diagnostic and a nonzero exit status.
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| 78 |
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| 79 | The ignore = true setting is suitable for a scenario where you don't know
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| 80 | ahead of time whether the pipe writer or the pipe reader will terminate
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| 81 | first. In this case, an EPIPE is an indication that the pipe writer can
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| 82 | stop doing useless write() calls; this is what close_stdout does anyway.
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| 83 | EPIPE is part of the normal pipe/socket shutdown protocol in this case,
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| 84 | and should not lead to a diagnostic message. */
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| 85 |
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| 86 | void
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| 87 | close_stdout_set_ignore_EPIPE (bool ignore)
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| 88 | {
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| 89 | ignore_EPIPE = ignore;
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| 90 | }
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| 91 |
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| 92 | /* Close standard output. On error, issue a diagnostic and _exit
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| 93 | with status 'exit_failure'.
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| 94 |
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| 95 | Also close standard error. On error, _exit with status 'exit_failure'.
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| 96 |
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| 97 | Since close_stdout is commonly registered via 'atexit', POSIX
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| 98 | and the C standard both say that it should not call 'exit',
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| 99 | because the behavior is undefined if 'exit' is called more than
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| 100 | once. So it calls '_exit' instead of 'exit'. If close_stdout
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| 101 | is registered via atexit before other functions are registered,
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| 102 | the other functions can act before this _exit is invoked.
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| 103 |
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| 104 | Applications that use close_stdout should flush any streams
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| 105 | other than stdout and stderr before exiting, since the call to
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| 106 | _exit will bypass other buffer flushing. Applications should
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| 107 | be flushing and closing other streams anyway, to check for I/O
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| 108 | errors. Also, applications should not use tmpfile, since _exit
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| 109 | can bypass the removal of these files.
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| 110 |
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| 111 | It's important to detect such failures and exit nonzero because many
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| 112 | tools (most notably 'make' and other build-management systems) depend
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| 113 | on being able to detect failure in other tools via their exit status. */
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| 114 |
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| 115 | void
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| 116 | close_stdout (void)
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| 117 | {
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| 118 | if (close_stream (stdout) != 0
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| 119 | && !(ignore_EPIPE && errno == EPIPE))
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| 120 | {
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| 121 | char const *write_error = _("write error");
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| 122 | if (file_name)
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| 123 | error (0, errno, "%s: %s", quotearg_colon (file_name),
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| 124 | write_error);
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| 125 | else
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| 126 | error (0, errno, "%s", write_error);
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| 127 |
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| 128 | _exit (exit_failure);
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| 129 | }
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| 130 |
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| 131 | /* Close stderr only if not sanitizing, as sanitizers may report to
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| 132 | stderr after this function returns. */
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| 133 | if (!SANITIZE_ADDRESS && close_stream (stderr) != 0)
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| 134 | _exit (exit_failure);
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| 135 | }
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