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 2-Apr-90 16:48:35-PDT,2748;000000000005
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Date: 02 Apr 90 17:06:56 EDT
From: <[email protected]>
To: <[email protected]>
Subject: tmpnam()
Message-Id: <"CSI 5715-6078"@CompuServe.COM>

Hi Ken,
    Someone for some reason looked at the names generated by tmpnam(),
and discovered that they were sometimes longer than 6 characters.  This
probably doesn't cause any harm, as the system will truncate them to six,
but it may cause some funny-ness in searching the 100-name space for one
that doesn't already exist: some names will be generated more often than
others.  Also, the constant TMP_MAX is defined as 512, which is 5 times
more than the naming scheme actually will generate.  This may cause us
to search for a free name longer than necessary, if in fact they're all
used up.
     Here's a copy of tmpnam.c which does a modulo 100 on the discreet-
name count, instead of anding it with 0177 (which is frequently more than
the 2 digits allowed).  I also redefined TMP_MAX to 100, which might be
more properly done in STDDEF.H;  what do you think?
					Michael
/*
**	TMPNAM - create a unique temporary file name
**
**	(c) Copyright Ken Harrenstien 1989
**		for all changes after v.6, 13-Apr-1988
**	(c) Copyright Ian Macky, SRI International 1986
**
**	This code conforms with the description of the tmpnam()
**	function in the ANSI X3J11 C language standard, section
**	4.9.4.4
**
*/

#include <c-env.h>
#if SYS_T20+SYS_10X+SYS_T10+SYS_CSI+SYS_WTS+SYS_ITS	/* Systems supported */

#include <stdio.h>
#include <time.h>
#include <sys/file.h>		/* For access() */

extern int getpid(), access();	/* Syscalls */

#if SYS_T20+SYS_10X
#define TMPFMT(pid, ver) "TMPNAM-%o.TMP.%d", pid, ver
#else				/* nnnCmm.TMP */
#define TMPFMT(pid, ver) "%03.3dC%02.02d.TMP", pid, (ver)%100
	/* can only have 100 unique names... */
#undef  TMP_MAX
#define TMP_MAX 100
#endif

char *
tmpnam(s)
char *s;
{
    static char tmpbuf[L_tmpnam];	/* storage for filename */
    static int newver = 0;
    int i;
    int pid = getpid();

    if (!s) s = tmpbuf;		/* if they didn't supply a buf, use ours */
    if (newver == 0)
	newver = (int)time(0) & 0777;	/* Get random non-neg start seed */

    for (i = 0; i < TMP_MAX; ++i) {	/* Avoid infinite loop */
	sprintf(s, TMPFMT(pid, ++newver));	/* Make a filename */
	if (access(s, F_OK) != 0)	/* Check for existence */
	    return s;			/* Doesn't exist, win. */
    }
    return NULL;		/* Failed... */
}

#endif /* T20+10X+T10+CSI+WAITS+ITS */