Everhart, Glenn (FUSA)
From:	Boris Gubenko [Boris.Gubenko@digital.com]
Sent:	Wednesday, April 14, 1999 3:19 PM
To:	Info-VAX@Mvb.Saic.Com
Cc:	Boris.Gubenko@digital.com
Subject:	Re: access() odd behavior
Richard Levitte - VMS Whacker wrote:
> 
> It seems that when you do an access check on a directory with mode
> bits including X_OK, access() will fail (return -1) unconditionally (I
> tried giving myself all permissions, including adding an ACL).
> 
> So far, I've tested this on VMS 7.2 with DEC C 5.7 and VAX C 3.2.
> 
> This is the code that I used to check this:
> 
> ------------------------------- snip ------------------------------
> #include <stdio.h>
> #include <stdlib.h>
> #ifdef __DECC
> #include <unistd.h>
> #else
> #define  F_OK      0
> #define  X_OK      1
> #define  W_OK      2
> #define  R_OK      4
> #endif
> #include <string.h>
> #include <errno.h>
> 
> int states[]={F_OK, X_OK, R_OK, W_OK};
> char *staten[]={"F_OK", "X_OK", "R_OK", "W_OK"};
> 
> main()
> {
>   int i;
>   int status;
> 
>   for(i = 0; i < 4; i++) {
>     errno = 0;
>     printf("%s %d ", staten[i],
>            status = access("USER1:[LEVITTE.TEST]",states[i]));
>     if (status < 0)
>       printf("%d \"%s\"\n", errno, strerror(errno,vaxc$errno));
>     else
>       printf("OK!\n");
>   }
> }
> ------------------------------- snip ------------------------------
> 
> Of course, when I change the test string to "USER1:[LEVITTE]TEST.DIR",
> I get the results I expected (X_OK also makes access() return 0).
> 
> Personally, I find this behavior insane.  The work-around would be to
> hack the file spec. as soon as you detect it to be a directory spec.
> It can be done, but it is a pain in my lower parts (having done so
> just too damn many times).
> 
[...]

-- 

I'm not sure why it fails for you. I could not reproduce
the problem using your (slightly modified) program example
on OpenVMS Alpha V7.2.

This is what I get:

$ cc/ver _nl0:
DEC C V5.5-002 on OpenVMS Alpha V7.2
$ show log work5 /full
   "WORK5" [exec] = "_$64$DUA1240:" [concealed] (LNM$SYSTEM_TABLE)
$ show log boris$root /full
   "BORIS$ROOT" [super] = "_$64$DUA1240:[BORIS.]" [concealed,terminal]
(LNM$JOB_
81071180)
$ r x

testing work5:[boris.tmp.tmp]
F_OK 0 OK!
X_OK 0 OK!
R_OK 0 OK!
W_OK -1 "permission denied"

testing work5:[boris.tmp]tmp.dir
F_OK 0 OK!
X_OK 0 OK!
R_OK 0 OK!
W_OK -1 "permission denied"

testing boris$root:[tmp.tmp]
F_OK 0 OK!
X_OK 0 OK!
R_OK 0 OK!
W_OK -1 "permission denied"

testing boris$root:[tmp]tmp.dir
F_OK 0 OK!
X_OK 0 OK!
R_OK 0 OK!
W_OK -1 "permission denied"
$

Failure of access(W_OK) for a directory file is expected. It fails
because on VMS W_OK implies both Write and Delete privilege. There
is no Delete protection bit on Unix, so access() was implemented on
VMS to map W_OK to Write + Delete which is as reasonable as
implementing it the other way ignoring Delete privilege at all,
for example. This is documented in the DEC C RTL Reference Manual.

How USER1 is defined on your system? $show log/full USER1 ?

x.c
===
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

#define DIM(_s) (sizeof(_s) / sizeof(_s[0]))

int states[]={F_OK, X_OK, R_OK, W_OK};
char *staten[]={"F_OK", "X_OK", "R_OK", "W_OK"};

char *filename[] = { "work5:[boris.tmp.tmp]",
                     "work5:[boris.tmp]tmp.dir",
                     "boris$root:[tmp.tmp]",
                     "boris$root:[tmp]tmp.dir" };

main()
{
  int i, j;
  int status;

  for(j=0; j < DIM(filename); ++j) {
    printf("\ntesting %s\n", filename[j]);
    for(i = 0; i < 4; i++) {
      errno = 0;
      printf("%s %d ", staten[i],
           status = access(filename[j],states[i]));
      if (status < 0)
        printf("\"%s\"\n", strerror(errno));
      else
        printf("OK!\n");
    }
  }
}


+--------------------------------------------------------+
| Boris Gubenko. Compaq Computer Corporarion. Nashua, NH.|
| DEC C RTL / C++ libraries. Boris.Gubenko@digital.com   |
|========================================================|
| All the opinions voiced are mine alone and do not      |
| reflect anyone else's opinion, including my employer's.|
+--------------------------------------------------------+