tmpfile(3C)

NAME

     tmpfile - create a temporary file

SYNOPSIS

     #include <stdio.h>

     FILE *tmpfile(void);

DESCRIPTION

     The tmpfile() function creates a temporary file and opens  a
     corresponding   stream.   The  file  will  automatically  be
     deleted when all references to the  file  are  closed.   The
     file is opened as in fopen(3C) for update (w+).

     The largest value that can be represented  correctly  in  an
     object  of type off_t will be established as the offset max-
     imum in the open file description.

RETURN VALUES

     Upon successful completion, tmpfile() returns a  pointer  to
     the  stream  of  the  file  that  is  created. Otherwise, it
     returns a null pointer and sets errno to indicate the error.

ERRORS

     The tmpfile() function will fail if:

     EINTR A signal was caught during the execution of tmpfile().

     EMFILE
           There are OPEN_MAX file descriptors currently open  in
           the calling process.

     ENFILE
           The maximum allowable number  of  files  is  currently
           open in the system.

     ENOSPC
           The directory or file system which would  contain  the
           new file cannot be expanded.

     The tmpfile() function may fail if:

     EMFILE
           There are FOPEN_MAX streams currently open in the cal-
           ling process.

     ENOMEM
           Insufficient storage space is available.

USAGE

     The stream refers to a file which is unlinked.  If the  pro-
     cess  is  killed  in  the  period  between file creation and
     unlinking, a permanent file may be left behind.

     The tmpfile() function has a transitional interface for  64-
     bit file offsets. See lf64(5).

     When a UFS file system is mounted with logging enabled, file
     system  transactions  that  free blocks from files might not
     actually add those freed blocks to the  file  system's  free
     list  until  some  unspecified  time  in  the  future.  This
     behavior improves file system performance but does not  con-
     form  to the POSIX, Single UNIX Specification, SPARC Confor-
     mance Definition, System  V  Application  Binary  Interface,
     System  V Interface Definition, and X/Open Portability Guide
     Standards, which  require  that  freed  space  be  available
     immediately.  To enable standards conformance regarding file
     deletions or to address the problem of  not  being  able  to
     grow  files  on a relatively full UFS file system even after
     files  have  been  deleted,   disable   UFS   logging   (see
     mount_ufs(1M).

SEE ALSO

     mount_ufs(1M), unlink(2), fopen(3C), tmpnam(3C), lf64(5)