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/*

 * tmpname.c

 * Original Author:     G. Haley

 */

/*

FUNCTION

<<tmpnam>>, <<tempnam>>---name for a temporary file

INDEX

        tmpnam

INDEX

        tempnam

INDEX

        _tmpnam_r

INDEX

        _tempnam_r

ANSI_SYNOPSIS

        #include <stdio.h>

        char *tmpnam(char *<[s]>);

        char *tempnam(char *<[dir]>, char *<[pfx]>);

        char *_tmpnam_r(struct _reent *<[reent]>, char *<[s]>);

        char *_tempnam_r(struct _reent *<[reent]>, char *<[dir]>, char *<[pfx]>);

TRAD_SYNOPSIS

        #include <stdio.h>

        char *tmpnam(<[s]>)

        char *<[s]>;

        char *tempnam(<[dir]>, <[pfx]>)

        char *<[dir]>;

        char *<[pfx]>;

        char *_tmpnam_r(<[reent]>, <[s]>)

        struct _reent *<[reent]>;

        char *<[s]>;

        char *_tempnam_r(<[reent]>, <[dir]>, <[pfx]>)

        struct *<[reent]>;

        char *<[dir]>;

        char *<[pfx]>;

DESCRIPTION

Use either of these functions to generate a name for a temporary file.

The generated name is guaranteed to avoid collision with other files

(for up to <<TMP_MAX>> calls of either function).

<<tmpnam>> generates file names with the value of <<P_tmpdir>>

(defined in `<<stdio.h>>') as the leading directory component of the path.

You can use the <<tmpnam>> argument <[s]> to specify a suitable area

of memory for the generated filename; otherwise, you can call

<<tmpnam(NULL)>> to use an internal static buffer.

<<tempnam>> allows you more control over the generated filename: you

can use the argument <[dir]> to specify the path to a directory for

temporary files, and you can use the argument <[pfx]> to specify a

prefix for the base filename.

If <[dir]> is <<NULL>>, <<tempnam>> will attempt to use the value of

environment variable <<TMPDIR>> instead; if there is no such value,

<<tempnam>> uses the value of <<P_tmpdir>> (defined in `<<stdio.h>>').

If you don't need any particular prefix to the basename of temporary

files, you can pass <<NULL>> as the <[pfx]> argument to <<tempnam>>.

<<_tmpnam_r>> and <<_tempnam_r>> are reentrant versions of <<tmpnam>>

and <<tempnam>> respectively.  The extra argument <[reent]> is a

pointer to a reentrancy structure.

WARNINGS

The generated filenames are suitable for temporary files, but do not

in themselves make files temporary.  Files with these names must still

be explicitly removed when you no longer want them.

If you supply your own data area <[s]> for <<tmpnam>>, you must ensure

that it has room for at least <<L_tmpnam>> elements of type <<char>>.

RETURNS

Both <<tmpnam>> and <<tempnam>> return a pointer to the newly

generated filename.

PORTABILITY

ANSI C requires <<tmpnam>>, but does not specify the use of

<<P_tmpdir>>.  The System V Interface Definition (Issue 2) requires

both <<tmpnam>> and <<tempnam>>.

Supporting OS subroutines required: <<close>>,  <<fstat>>, <<getpid>>,

<<isatty>>, <<lseek>>, <<open>>, <<read>>, <<sbrk>>, <<write>>.

The global pointer <<environ>> is also required.

*/

#include <_ansi.h>

#include <reent.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <fcntl.h>

#include <reent.h>

#include <errno.h>

/* Try to open the file specified, if it can't be opened then try

   another one.  Return nonzero if successful, otherwise zero.  */

static int

_DEFUN(worker, (ptr, result, part1, part2, part3, part4),

       struct _reent *ptr _AND

       char *result       _AND

       _CONST char *part1 _AND

       _CONST char *part2 _AND

       int part3          _AND

       int *part4)

{

  /*  Generate the filename and make sure that there isn't one called

      it already.  */

  while (1)

    {

      int t;

      _sprintf_r (ptr, result, "%s/%s%x.%x", part1, part2, part3, *part4);

      (*part4)++;

      t = _open_r (ptr, result, O_RDONLY, 0);

      if (t == -1)

        {

          if (ptr->_errno == ENOSYS)

            {

              result[0] = '\0';

              return 0;

            }

          break;

        }

      _close_r (ptr, t);

    }

  return 1;

}

char *

_DEFUN(_tmpnam_r, (p, s),

       struct _reent *p _AND

       char *s)

{

  char *result;

  int pid;

  if (s == NULL)

    {

      /* ANSI states we must use an internal static buffer if s is NULL */

      _REENT_CHECK_EMERGENCY(p);

      result = _REENT_EMERGENCY(p);

    }

  else

    {

      result = s;

    }

  pid = _getpid_r (p);

  if (worker (p, result, P_tmpdir, "t", pid, &p->_inc))

    {

      p->_inc++;

      return result;

    }

  return NULL;

}

char *

_DEFUN(_tempnam_r, (p, dir, pfx),

       struct _reent *p _AND

       _CONST char *dir _AND

       _CONST char *pfx)

{

  char *filename;

  int length;

  _CONST char *prefix = (pfx) ? pfx : "";

  if (dir == NULL && (dir = getenv ("TMPDIR")) == NULL)

    dir = P_tmpdir;

  /* two 8 digit numbers + . / */

  length = strlen (dir) + strlen (prefix) + (4 * sizeof (int)) + 2 + 1;

  filename = _malloc_r (p, length);

  if (filename)

    {

      if (! worker (p, filename, dir, prefix,

                    _getpid_r (p) ^ (int) (_POINTER_INT) p, &p->_inc))

        return NULL;

    }

  return filename;

}

#ifndef _REENT_ONLY

char *

_DEFUN(tempnam, (dir, pfx),

       _CONST char *dir _AND

       _CONST char *pfx)

{

  return _tempnam_r (_REENT, dir, pfx);

}

char *

_DEFUN(tmpnam, (s),

       char *s)

{

  return _tmpnam_r (_REENT, s);

}

#endif