[Bug libc/6700] New: utmpname(3) returns interger but man page says void and doesnot returns with failure if file not found.

[Bug libc/6700] New: utmpname(3) returns interger but man page says void and doesnot returns with failure if file not found.

[halesh dot s at gmail dot com]

Hi,

In glibc 2.7 I found, Man page of utmpname(3) says its prototype as...

            void utmpname(const char *file);

But if we check the source in login/utmpname.c
int
__utmpname (const char *file)
{
....
....
}

This is conflicting one, so man page needs to be fixed.

And utmpname(3) does not reports failure if the file that we pass and
it does not exists.

The testcase is...
$ ls -l utmp1
ls: utmp1: No such file or directory

$ cat test.c
#include <stdio.h>
#include <utmp.h>

int main()
{
     printf("%d\n", utmpname("./utmp1"));
}

$ gcc test.c -o test
$ ./test
0

This intern affecting the other commands like who (1).

$ who ./utmp1
$ echo $?
0

**Even utmp1 file not exists, its exit status is zero.

Fixing the issue in utmp will fix the other dependencies.

Patch to fix the issue
=======================

--- utmpname.c.old      2008-06-24 16:36:27.000000000 +0530
+++ utmpname.c  2008-06-24 16:37:12.000000000 +0530
@@ -21,6 +21,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <utmp.h>
+#include <sys/stat.h>

 #include "utmp-private.h"

@@ -39,6 +40,12 @@
 __utmpname (const char *file)
 {
  int result = -1;
+ struct stat buf;
+
+  if (stat(file, &buf) != 0)
+   {
+        return result;
+   }

 __libc_lock_lock (__libc_utmp_lock);


Thanks,
Halesh

-- 
           Summary: utmpname(3) returns interger but man page says void and
                    doesnot returns with failure if file not found.
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: minor
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: halesh dot s at gmail dot com
                CC: glibc-bugs at sources dot redhat dot com


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[Bug libc/6700] utmpname(3) returns interger but man page says void and doesnot returns with failure if file not found.

[halesh dot s at gmail dot com]

------- Additional Comments From halesh dot s at gmail dot com  2008-06-27 12:37 -------
Hi Ulrich,

In the link 
http://www.gnu.org/software/libtool/manual/libc/Manipulating-the-Database.html

It has mentioned that 
"The utmpname function returns a value of 0 if the new name was successfully 
stored, and a value of -1 to indicate an error. Note that utmpname does not try 
to open the database, and that therefore the return value does not say anything 
about whether the database can be successfully opened."

This means utmpname(3) never reports faiure if database doesnot exists.

In readutmp.c of coreutils it has mentioned 
"Solaris' utmpname returns 1 upon success -- which is contrary to what the GNU 
libc version does.  In addition, older GNU libc versions are actually void."

But GNU libc utmpname returns -1 on failure, May it returns differen values on 
success I think it does not causes any contrary with Solaris utmpname failure.

Even we did not open database can we include the database existance checking, 
Will it causes any effects. 

As mentioned above this may resolve who(1) problem, and which helps in 
processing other commands based on who(1) o/p.

Thanks,
Halesh

-- 


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[Bug libc/6700] utmpname(3) returns interger but man page says void and doesnot returns with failure if file not found.

[pasky at suse dot cz]

------- Additional Comments From pasky at suse dot cz  2008-06-28 23:19 -------
Note that the manpage does not come from libc but linux-manpages: 
http://www.kernel.org/doc/man-pages/

-- 


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[Bug libc/6700] utmpname(3) returns interger but man page says void and doesnot returns with failure if file not found.

[halesh dot s at gmail dot com]

------- Additional Comments From halesh dot s at gmail dot com  2008-06-30 07:10 -------

Thanks Petr Baudis.

I have raised a bug for the manpage after refering your mentione link.
http://bugzilla.kernel.org/show_bug.cgi?id=11011

Can you please verfiy the second part of this defect, about the return value 
when file not found?





-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pasky at suse dot cz


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[Bug libc/6700] utmpname(3) returns interger but man page says void and doesnot returns with failure if file not found.

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2008-08-13 04:31 -------
It makes no sense for utmpname to check whether the file exists.  It does not
open the file so the file might not yet exist at the time of the call or it
might disappear before it is actually used.  The code is fine.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


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