Re: Race conditions

[jsa () alv teli se (Jonas Sandberg)]

The race condition seems to work at ULTRIX 4.1
palantir% ls -l
total 46
-rwxr-xr-x  1 jonte       43860 Dec  9 08:18 race*
-rw-r--r--  1 jonte         359 Dec  9 08:17 racetest.c
-rw-r--r--  1 jonte           8 Dec  9 08:19 symlink
What i didn't get was if the 'symlink' really should be a link or a plain
file, as it was in 4.1. I tried to gcc the 'noddy little program'.

/jonas
      In message <199412080339.OAA10567 () huon melb cpr itg telecom com au>, 
        Luke Mewburn <lm () melb cpr itg telecom com au> writes:
      
      > After checking the man pages in Solaris 2.x and NetBSD, and confirming
                        -----deleted-------      
      > 
      > Unfortunately, it appears that older systems (possibly including SunOS 4
      > and Ultrix) don't have this check.
      
      I've just checked this out with a noddy program and built the
      following table up (appended at the end of this post along with the
      program). The most suprising part of this exercise for me was that I
      could only find *one* OS that failed the check and created the file
      pointed to be the symlink!  Must be the pessimist in me.. :)
      
      Notes:
      
      1) The program was run as a normal user, not root.
      2) The ls output looks like:
      
      -rw-r--r--   1 chris    cs2           359 Dec  8 13:46 tst.c
      lrwxrwxrwx   1 chris    cs2             3 Dec  8 14:49 symlink -> ./a
      -rwxr-xr-x   1 chris    cs2          5492 Dec  8 14:50 tst*
      
      
      Happy hunting, folks!
      Chris
      --
       Christopher Samuel     Phone:  +44 1684 894644       chris () rivers dra hmg gb
       N-115, Defence Research Agency,  St Andrews Road, Great Malvern, England, UK
       postmaster () rivers dra hmg gb                        usenet () rivers dra hmg gb
      
      ----------------------------------------------------------
      BAD - creates file with "open succeded (fh=3)":
      
      HP-UX V7.05
      ----------------------------------------------------------
      OK - fails with "open: File exists"
      
      Ultrix 4.4
      Ultrix 4.2
      SunOS 4.1.3_U1
      SunOS 4.1.3
      SunOS 4.1.1
      Solaris 2.1
      Solaris 2.3
      USL SVR4.2
      Unixware 1.1.2
      SCO 3.2 (ODT3)
      Irix 5.2
      HP-UX 9.05
      NeXTstep 3.2
      DRS/NX 6000 SVR4 Version 7  Level 2  Increment 2
      Linux 1.1.64
      ----------------------------------------------------------
      #include <stdio.h>
      #include <fcntl.h>
      
      static char message[]="testing";
      
      int main(void)
      {
        int fh,retval;
      
        fh=open("./symlink",O_RDWR|O_EXCL|O_CREAT,0644);
        
        if(fh < 0)
        {
                perror("open");
        }
        else
        {
                printf("open succeded (fh=%d)\n",fh);
      
                retval = write(fh,message,sizeof(message));
      
                if( retval == -1 )
                {
                        perror("write");
                }
                close(fh);
        }
      }
      ----------------------------------------------------------
      
      

/jonas
--
Jonas Sandberg                  jsa () alv teli se
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Disclaimer: I'm innocent, I haven't done anything ...