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/* Close a stream, with nicer error checking than fclose's.
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Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2006 Free
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Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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#include "close-stream.h"
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#include "__fpending.h"
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# include "unlocked-io.h"
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/* Close STREAM. Return 0 if successful, EOF (setting errno)
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otherwise. A failure might set errno to 0 if the error number
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If a program writes *anything* to STREAM, that program should close
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STREAM and make sure that it succeeds before exiting. Otherwise,
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suppose that you go to the extreme of checking the return status
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of every function that does an explicit write to STREAM. The last
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printf can succeed in writing to the internal stream buffer, and yet
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the fclose(STREAM) could still fail (due e.g., to a disk full error)
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when it tries to write out that buffered data. Thus, you would be
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left with an incomplete output file and the offending program would
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exit successfully. Even calling fflush is not always sufficient,
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since some file systems (NFS and CODA) buffer written/flushed data
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until an actual close call.
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Besides, it's wasteful to check the return value from every call
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that writes to STREAM -- just let the internal stream state record
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the failure. That's what the ferror test is checking below. */
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close_stream (FILE *stream)
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bool some_pending = (__fpending (stream) != 0);
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bool prev_fail = (ferror (stream) != 0);
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bool fclose_fail = (fclose (stream) != 0);
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/* Return an error indication if there was a previous failure or if
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fclose failed, with one exception: ignore an fclose failure if
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there was no previous error, no data remains to be flushed, and
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fclose failed with EBADF. That can happen when a program like cp
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is invoked like this `cp a b >&-' (i.e., with standard output
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closed) and doesn't generate any output (hence no previous error
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and nothing to be flushed). */
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if (prev_fail || (fclose_fail && (some_pending || errno != EBADF)))