lutil_detach()

[Hallvard B Furuseth <h.b.furuseth@usit.uio.no>]

Is there any reason why lutil_detach() closes stdin/out/err before
doing dup2() to them?  dup2() closes the destination descriptor
anyway, at least in the Unixes I know.  Closing them has the slight
problem that if they were already closed so 'sd' (the /dev/null
descriptor) is 0, 1, or 2, 'sd' is closed.

If there are no protests, I'll apply this patch.

It skips closing the descriptors, tries to open /dev/null and then /
in read-only mode if opening /dev/null failed, and skips the dup2()s
as well if open() failed.

--- libraries/liblutil/detach.c	19 Apr 2000 11:35:43 -0000	1.12
+++ libraries/liblutil/detach.c	23 Jan 2003 13:00:59 -0000
@@ -73,13 +73,10 @@
 		}
 
-		if ( (sd = open( "/dev/null", O_RDWR )) == -1 ) {
+		if ( (sd = open( "/dev/null", O_RDWR   )) == -1 &&
+		     (sd = open( "/dev/null", O_RDONLY )) == -1 &&
+		     /* Panic -- open *something* */
+		     (sd = open( "/",         O_RDONLY )) == -1    ) {
 			perror("/dev/null");
-		}
-
-		/* close stdin, stdout, stderr */
-		close( STDIN_FILENO );
-		close( STDOUT_FILENO );
-		close( STDERR_FILENO );
-
+		} else {
 		/* redirect stdin, stdout, stderr to /dev/null */
 		dup2( sd, STDIN_FILENO );
@@ -87,5 +84,13 @@
 		dup2( sd, STDERR_FILENO );
 
+			switch( sd ) {
+			default:
		 		close( sd );
+			case STDIN_FILENO:
+			case STDOUT_FILENO:
+			case STDERR_FILENO:
+				break;
+			}
+		}
 
 		if ( do_close ) {