libbacktrace/posix.c

   1 /* posix.c -- POSIX file I/O routines for the backtrace library.
   2    Copyright (C) 2012-2021 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 }