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glibc  2.9
iofgets.c
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00001 /* Copyright (C) 1993, 1995, 1996, 1997, 1998, 1999, 2002, 2003, 2005
00002    Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.
00019 
00020    As a special exception, if you link the code in this file with
00021    files compiled with a GNU compiler to produce an executable,
00022    that does not cause the resulting executable to be covered by
00023    the GNU Lesser General Public License.  This exception does not
00024    however invalidate any other reasons why the executable file
00025    might be covered by the GNU Lesser General Public License.
00026    This exception applies to code released by its copyright holders
00027    in files containing the exception.  */
00028 
00029 #include "libioP.h"
00030 #include <stdio.h>
00031 
00032 char *
00033 _IO_fgets (buf, n, fp)
00034      char *buf;
00035      int n;
00036      _IO_FILE *fp;
00037 {
00038   _IO_size_t count;
00039   char *result;
00040   int old_error;
00041   CHECK_FILE (fp, NULL);
00042   if (n <= 0)
00043     return NULL;
00044   if (__builtin_expect (n == 1, 0))
00045     {
00046       /* Another irregular case: since we have to store a NUL byte and
00047         there is only room for exactly one byte, we don't have to
00048         read anything.  */
00049       buf[0] = '\0';
00050       return buf;
00051     }
00052   _IO_acquire_lock (fp);
00053   /* This is very tricky since a file descriptor may be in the
00054      non-blocking mode. The error flag doesn't mean much in this
00055      case. We return an error only when there is a new error. */
00056   old_error = fp->_IO_file_flags & _IO_ERR_SEEN;
00057   fp->_IO_file_flags &= ~_IO_ERR_SEEN;
00058   count = INTUSE(_IO_getline) (fp, buf, n - 1, '\n', 1);
00059   /* If we read in some bytes and errno is EAGAIN, that error will
00060      be reported for next read. */
00061   if (count == 0 || ((fp->_IO_file_flags & _IO_ERR_SEEN)
00062                    && errno != EAGAIN))
00063     result = NULL;
00064   else
00065     {
00066       buf[count] = '\0';
00067       result = buf;
00068     }
00069   fp->_IO_file_flags |= old_error;
00070   _IO_release_lock (fp);
00071   return result;
00072 }
00073 
00074 #ifdef weak_alias
00075 weak_alias (_IO_fgets, fgets)
00076 
00077 # ifndef _IO_MTSAFE_IO
00078 weak_alias (_IO_fgets, fgets_unlocked)
00079 libc_hidden_weak (fgets_unlocked)
00080 # endif
00081 #endif