libexplain  1.4.D001
libexplain/fclose_or_die.c
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00001 /*
00002  * libexplain - Explain errno values returned by libc functions
00003  * Copyright (C) 2008-2010, 2012, 2013 Peter Miller
00004  * Written by Peter Miller <pmiller@opensource.org.au>
00005  *
00006  * This program is free software; you can redistribute it and/or modify
00007  * it under the terms of the GNU Lesser General Public License as
00008  * published by the Free Software Foundation; either version 3 of the
00009  * License, or (at your option) any later version.
00010  *
00011  * This program is distributed in the hope that it will be useful,
00012  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014  * Lesser General Public License for more details.
00015  *
00016  * You should have received a copy of the GNU Lesser General Public License
00017  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
00018  */
00019 
00020 #include <libexplain/ac/errno.h>
00021 #include <libexplain/ac/fcntl.h>
00022 #include <libexplain/ac/stdio.h>
00023 
00024 #include <libexplain/fclose.h>
00025 #include <libexplain/fflush.h>
00026 #include <libexplain/output.h>
00027 #include <libexplain/stream_to_fildes.h>
00028 
00029 
00030 static int
00031 open_for_writing(FILE *fp)
00032 {
00033     int             fildes;
00034     int             flags;
00035 
00036     fildes = explain_stream_to_fildes(fp);
00037     flags = fcntl(fildes, F_GETFL);
00038     if (flags < 0)
00039         return 0;
00040     switch (flags & O_ACCMODE)
00041     {
00042     case O_WRONLY:
00043     case O_RDWR:
00044         return 1;
00045 
00046     default:
00047         break;
00048     }
00049     return 0;
00050 }
00051 
00052 
00053 int
00054 explain_fclose_on_error(FILE *fp)
00055 {
00056     int             result;
00057 
00058     if (open_for_writing(fp))
00059     {
00060         /* only flush output streams */
00061         result = explain_fflush_on_error(fp);
00062         if (result < 0)
00063         {
00064             int             hold_errno;
00065 
00066             /*
00067              * FIXME: it would be better if we could nominate a different
00068              * syscall_name for this error message, rather than surprising
00069              * the user (or developer reading the bug report) with "fflush".
00070              */
00071             hold_errno = errno;
00072             explain_output_error("%s", explain_errno_fflush(hold_errno, fp));
00073             fclose(fp);
00074             errno = hold_errno;
00075             return result;
00076         }
00077     }
00078 
00079     result = fclose(fp);
00080     if (result < 0)
00081     {
00082         int             hold_errno;
00083 
00084         hold_errno = errno;
00085         explain_output_error("%s", explain_errno_fclose(hold_errno, fp));
00086         errno = hold_errno;
00087     }
00088     return result;
00089 }
00090 
00091 
00092 void
00093 explain_fclose_or_die(FILE *fp)
00094 {
00095     if (explain_fclose_on_error(fp))
00096     {
00097         explain_output_exit_failure();
00098     }
00099 }
00100 
00101 
00102 /* vim: set ts=8 sw=4 et : */