newlib/libc/stdio/tmpfile.c

   1 /*
   2 FUNCTION
   3 <<tmpfile>>---create a temporary file
   4
   5 INDEX
   6         tmpfile
   7 INDEX
   8         _tmpfile_r
   9
  10 SYNOPSIS
  11         #include <stdio.h>
  12         FILE *tmpfile(void);
  13
  14         FILE *_tmpfile_r(struct _reent *<[reent]>);
  15
  16 DESCRIPTION
  17 Create a temporary file (a file which will be deleted automatically),
  18 using a name generated by <<tmpnam>>.  The temporary file is opened with
  19 the mode <<"wb+">>, permitting you to read and write anywhere in it
  20 as a binary file (without any data transformations the host system may
  21 perform for text files).
  22
  23 The alternate function <<_tmpfile_r>> is a reentrant version.  The
  24 argument <[reent]> is a pointer to a reentrancy structure.
  25
  26 RETURNS
  27 <<tmpfile>> normally returns a pointer to the temporary file.  If no
  28 temporary file could be created, the result is NULL, and <<errno>>
  29 records the reason for failure.
  30
  31 PORTABILITY
  32 Both ANSI C and the System V Interface Definition (Issue 2) require
  33 <<tmpfile>>.
  34
  35 Supporting OS subroutines required: <<close>>, <<fstat>>, <<getpid>>,
  36 <<isatty>>, <<lseek>>, <<open>>, <<read>>, <<sbrk>>, <<write>>.
  37
  38 <<tmpfile>> also requires the global pointer <<environ>>.
  39 */
  40
  41 #include <_ansi.h>
  42 #include <reent.h>
  43 #include <stdio.h>
  44 #include <errno.h>
  45 #include <fcntl.h>
  46 #include <sys/stat.h>
  47
  48 #ifndef O_BINARY
  49 # define O_BINARY 0
  50 #endif
  51
  52 FILE *
  53 _tmpfile_r (struct _reent *ptr)
  54 {
  55   FILE *fp;
  56   int e;
  57   char *f;
  58   char buf[L_tmpnam];
  59   int fd;
  60
  61   do
  62     {
  63       if ((f = _tmpnam_r (ptr, buf)) == NULL)
  64         return NULL;
  65       fd = _open_r (ptr, f, O_RDWR | O_CREAT | O_EXCL | O_BINARY,
  66                     S_IRUSR | S_IWUSR);
  67     }
  68   while (fd < 0 && _REENT_ERRNO(ptr) == EEXIST);
  69   if (fd < 0)
  70     return NULL;
  71   fp = _fdopen_r (ptr, fd, "wb+");
  72   e = _REENT_ERRNO(ptr);
  73   if (!fp)
  74     _close_r (ptr, fd);
  75   (void) _remove_r (ptr, f);
  76   _REENT_ERRNO(ptr) = e;
  77   return fp;
  78 }
  79
  80 #ifndef _REENT_ONLY
  81
  82 FILE *
  83 tmpfile (void)
  84 {
  85   return _tmpfile_r (_REENT);
  86 }
  87
  88 #endif