[PATCH] login-utils: use getdtablesize() correctly in login.c

[PATCH] login-utils: use getdtablesize() correctly in login.c

[chas williams - CONTRACTOR]

while it might seem harmless to close a non-existent descriptor, we have
a local configuration that protects a certain descriptor by lowering
rlim_cur to prevent child processes from closing said descriptor. this
descriptor points to a ticket cache which we need later for the user.

Author: chas williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Date:   Fri Apr 20 10:49:51 2012 -0400

    login-utils: use getdtablesize() correctly in login.c
    
    getdtablesize() is the number of descriptors and since decriptors start
    at 0, its value isnt the largest descriptors possible.  One should use
    getdtablesize() - 1 instead.
    
    Signed-off-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>

diff --git a/login-utils/login.c b/login-utils/login.c
index 6c3b6f7..026c72b 100644
--- a/login-utils/login.c
+++ b/login-utils/login.c
@@ -1290,7 +1290,7 @@ int main(int argc, char **argv)
 			*p++ = ' ';
 	}
 
-	for (cnt = getdtablesize(); cnt > 2; cnt--)
+	for (cnt = (getdtablesize() - 1); cnt > 2; cnt--)
 		close(cnt);
 
 	setpgrp();	 /* set pgid to pid this means that setsid() will fail */

Re: [PATCH] login-utils: use getdtablesize() correctly in login.c

[Karel Zak]

On Fri, Apr 20, 2012 at 10:58:28AM -0400, chas williams - CONTRACTOR wrote:
>     login-utils: use getdtablesize() correctly in login.c
>     
>     getdtablesize() is the number of descriptors and since decriptors start
>     at 0, its value isnt the largest descriptors possible.  One should use
>     getdtablesize() - 1 instead.

 Applied, thanks.

 I have also added fallback for the getdtablesize() to lib/fileutils.c, it
 seems that the function is not too portable.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com