text: /* posix.c -- POSIX file I/O routines for the backtrace library.
     Copyright (C) 2012-2020 Free Software Foundation, Inc.
     Written by Ian Lance Taylor, Google.
  
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are
  met:
  
      (1) Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
  
      (2) Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in
      the documentation and/or other materials provided with the
      distribution.
  
      (3) The name of the author may not be used to
      endorse or promote products derived from this software without
      specific prior written permission.
  
  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  POSSIBILITY OF SUCH DAMAGE.  */
  
  #include "config.h"
  
  #include <errno.h>
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  #include <unistd.h>
  
  #include "backtrace.h"
  #include "internal.h"
  
  #ifndef O_BINARY
  #define O_BINARY 0
  #endif
  
  #ifndef O_CLOEXEC
  #define O_CLOEXEC 0
  #endif
  
  #ifndef FD_CLOEXEC
  #define FD_CLOEXEC 1
  #endif
  
  /* Open a file for reading.  */
  
  int
  backtrace_open (const char *filename, backtrace_error_callback error_callback,
  		void *data, int *does_not_exist)
  {
    int descriptor;
  
    if (does_not_exist != NULL)
      *does_not_exist = 0;
  
    descriptor = open (filename, (int) (O_RDONLY | O_BINARY | O_CLOEXEC));
    if (descriptor < 0)
      {
        if (does_not_exist != NULL && errno == ENOENT)
  	*does_not_exist = 1;
        else
  	error_callback (data, filename, errno);
        return -1;
      }
  
  #ifdef HAVE_FCNTL
    /* Set FD_CLOEXEC just in case the kernel does not support
       O_CLOEXEC. It doesn't matter if this fails for some reason.
       FIXME: At some point it should be safe to only do this if
       O_CLOEXEC == 0.  */
    fcntl (descriptor, F_SETFD, FD_CLOEXEC);
  #endif
  
    return descriptor;
  }
  
  /* Close DESCRIPTOR.  */
  
  int
  backtrace_close (int descriptor, backtrace_error_callback error_callback,
  		 void *data)
  {
    if (close (descriptor) < 0)
      {
        error_callback (data, "close", errno);
        return 0;
      }
    return 1;
  }
  