1  /* posix.c -- POSIX file I/O routines for the backtrace library.
       2     Copyright (C) 2012-2023 Free Software Foundation, Inc.
       3     Written by Ian Lance Taylor, Google.
       4  
       5  Redistribution and use in source and binary forms, with or without
       6  modification, are permitted provided that the following conditions are
       7  met:
       8  
       9      (1) Redistributions of source code must retain the above copyright
      10      notice, this list of conditions and the following disclaimer.
      11  
      12      (2) Redistributions in binary form must reproduce the above copyright
      13      notice, this list of conditions and the following disclaimer in
      14      the documentation and/or other materials provided with the
      15      distribution.
      16  
      17      (3) The name of the author may not be used to
      18      endorse or promote products derived from this software without
      19      specific prior written permission.
      20  
      21  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
      22  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
      23  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
      24  DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
      25  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
      26  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
      27  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
      28  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
      29  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
      30  IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
      31  POSSIBILITY OF SUCH DAMAGE.  */
      32  
      33  #include "config.h"
      34  
      35  #include <errno.h>
      36  #include <sys/types.h>
      37  #include <sys/stat.h>
      38  #include <fcntl.h>
      39  #include <unistd.h>
      40  
      41  #include "backtrace.h"
      42  #include "internal.h"
      43  
      44  #ifndef O_BINARY
      45  #define O_BINARY 0
      46  #endif
      47  
      48  #ifndef O_CLOEXEC
      49  #define O_CLOEXEC 0
      50  #endif
      51  
      52  #ifndef FD_CLOEXEC
      53  #define FD_CLOEXEC 1
      54  #endif
      55  
      56  /* Open a file for reading.  */
      57  
      58  int
      59  backtrace_open (const char *filename, backtrace_error_callback error_callback,
      60  		void *data, int *does_not_exist)
      61  {
      62    int descriptor;
      63  
      64    if (does_not_exist != NULL)
      65      *does_not_exist = 0;
      66  
      67    descriptor = open (filename, (int) (O_RDONLY | O_BINARY | O_CLOEXEC));
      68    if (descriptor < 0)
      69      {
      70        /* If DOES_NOT_EXIST is not NULL, then don't call ERROR_CALLBACK
      71  	 if the file does not exist.  We treat lacking permission to
      72  	 open the file as the file not existing; this case arises when
      73  	 running the libgo syscall package tests as root.  */
      74        if (does_not_exist != NULL && (errno == ENOENT || errno == EACCES))
      75  	*does_not_exist = 1;
      76        else
      77  	error_callback (data, filename, errno);
      78        return -1;
      79      }
      80  
      81  #ifdef HAVE_FCNTL
      82    /* Set FD_CLOEXEC just in case the kernel does not support
      83       O_CLOEXEC. It doesn't matter if this fails for some reason.
      84       FIXME: At some point it should be safe to only do this if
      85       O_CLOEXEC == 0.  */
      86    fcntl (descriptor, F_SETFD, FD_CLOEXEC);
      87  #endif
      88  
      89    return descriptor;
      90  }
      91  
      92  /* Close DESCRIPTOR.  */
      93  
      94  int
      95  backtrace_close (int descriptor, backtrace_error_callback error_callback,
      96  		 void *data)
      97  {
      98    if (close (descriptor) < 0)
      99      {
     100        error_callback (data, "close", errno);
     101        return 0;
     102      }
     103    return 1;
     104  }