libexplain  1.4.D001
libexplain/vfork_on_error.c
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00001 /*
00002  * libexplain - Explain errno values returned by libc functions
00003  * Copyright (C) 2009, 2010, 2012, 2013 Peter Miller
00004  *
00005  * This program is free software; you can redistribute it and/or modify it
00006  * under the terms of the GNU Lesser General Public License as published by
00007  * the Free Software Foundation; either version 3 of the License, or (at
00008  * your option) any later version.
00009  *
00010  * This program is distributed in the hope that it will be useful,but
00011  * WITHOUT ANY WARRANTY; without even the implied warranty
00012  * ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNULesser
00013  * General Public License for more details.
00014  *
00015  * You should have received a copy of the GNU Lesser General Public License
00016  * along with this program. If not, see <http://www.gnu.org/licenses/>.
00017  */
00018 
00019 #include <libexplain/ac/errno.h>
00020 #include <libexplain/ac/sys/types.h>
00021 #include <libexplain/ac/unistd.h>
00022 
00023 #include <libexplain/vfork.h>
00024 #include <libexplain/output.h>
00025 
00026 
00027 pid_t
00028 explain_vfork_on_error(void)
00029 {
00030     pid_t           result;
00031 
00032     /*
00033      * Note: we can't use vfork(2), we have to use fork(2).
00034      *
00035      * From the vfork(2) man page:
00036      *
00037      *     "The vfork() function has the same effect as fork(2), except
00038      *     that the behavior is undefined if the process created by
00039      *     vfork() either modifies any data other than a variable of
00040      *     type pid_t used to store the return value from vfork(), or
00041      *     returns from the function in which vfork() was called, or
00042      *     calls any other function before successfully calling _exit(2)
00043      *     or one of the exec(3) family of functions."
00044      *
00045      * since we can't satisfy these requirements, we must use fork(2)
00046      * instead.  Mind you, this only happens if they are using GCC with
00047      * version < 3.0.
00048      */
00049     result = fork();
00050     if (result < 0)
00051     {
00052         int             hold_errno;
00053 
00054         hold_errno = errno;
00055         explain_output_error("%s", explain_errno_vfork(hold_errno));
00056         errno = hold_errno;
00057     }
00058     return result;
00059 }
00060 
00061 
00062 /* vim: set ts=8 sw=4 et : */