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glibc  2.9
iofgets_u.c
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00001 /* Copyright (C) 1993,1995-1998,2002,2005 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.
00018 
00019    As a special exception, if you link the code in this file with
00020    files compiled with a GNU compiler to produce an executable,
00021    that does not cause the resulting executable to be covered by
00022    the GNU Lesser General Public License.  This exception does not
00023    however invalidate any other reasons why the executable file
00024    might be covered by the GNU Lesser General Public License.
00025    This exception applies to code released by its copyright holders
00026    in files containing the exception.  */
00027 
00028 #include "libioP.h"
00029 #include <stdio.h>
00030 
00031 char *
00032 fgets_unlocked (buf, n, fp)
00033      char *buf;
00034      int n;
00035      _IO_FILE *fp;
00036 {
00037   _IO_size_t count;
00038   char *result;
00039   int old_error;
00040   CHECK_FILE (fp, NULL);
00041   if (n <= 0)
00042     return NULL;
00043   if (__builtin_expect (n == 1, 0))
00044     {
00045       /* Another irregular case: since we have to store a NUL byte and
00046         there is only room for exactly one byte, we don't have to
00047         read anything.  */
00048       buf[0] = '\0';
00049       return buf;
00050     }
00051   /* This is very tricky since a file descriptor may be in the
00052      non-blocking mode. The error flag doesn't mean much in this
00053      case. We return an error only when there is a new error. */
00054   old_error = fp->_IO_file_flags & _IO_ERR_SEEN;
00055   fp->_IO_file_flags &= ~_IO_ERR_SEEN;
00056   count = INTUSE(_IO_getline) (fp, buf, n - 1, '\n', 1);
00057   /* If we read in some bytes and errno is EAGAIN, that error will
00058      be reported for next read. */
00059   if (count == 0 || ((fp->_IO_file_flags & _IO_ERR_SEEN)
00060                    && errno != EAGAIN))
00061     result = NULL;
00062   else
00063     {
00064       buf[count] = '\0';
00065       result = buf;
00066     }
00067   fp->_IO_file_flags |= old_error;
00068   return result;
00069 }
00070 libc_hidden_def (fgets_unlocked)