On Wed, 20 Jun 2012, Eitan Adler wrote:

Log:
 Don't close an uninitialized descriptor. [1]
 Add a sanity check for the validity of the passed fd.

Library functions shouldn't use assert() or abort().

The fd is not passed, but is a static variable under syslog()'s control.

In libc, only the following use assert.h:
- stdio/xprintf*.c.  Very nonstd.
- rpc/*.c (perhaps not everything)
- db/*.c (but partly under DEBUG.  Not the standard use where assert() is
  controlled by NDEBUG)
- nameser/ns_print.c
- ia64/gen/unwind.c (but under SANITY.  The standard NDEBUG is too hard to
  use here too)
- gen/getgrent.c. - regex/grot/main.c (test program. Not part of libc)
- regex/regex/utils.h (but ifdefed, and I think turned off in production.
  Spencer knows how to use NDEBUG)
- regex/regcomp.c (ifdefed)
- include/isc/list.h
- net/*.c (just 2 files)
- posix1e/acl*.c (perhaps not everything)
- inet/inet_net_pton.c
- iconv/*.c (perhaps not everything).

The list was only short enough to be described by "only" in not very old
versions of FreeBSD.  posix1e and iconv doubled the number of files.

Modified: head/lib/libc/gen/syslog.c
==============================================================================
--- head/lib/libc/gen/syslog.c  Wed Jun 20 04:11:34 2012        (r237285)
+++ head/lib/libc/gen/syslog.c  Wed Jun 20 06:38:41 2012        (r237286)
@@ -41,6 +41,7 @@ __FBSDID("$FreeBSD$");
#include <sys/un.h>
#include <netdb.h>

+#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
@@ -413,8 +414,11 @@ void
closelog(void)
{
        THREAD_LOCK();
-       (void)_close(LogFile);
-       LogFile = -1;
+       assert(LogFile >= -1);

Since this assert() can't fail (unless the CPU has a parity error or
or the memory behind Logfile has a parity error or another memory error
or was clobbered by a buffer overrun), this assert() doesn't break the
library but just wastes space.

+       if (LogFile != -1) {
+               (void)_close(LogFile);
+               LogFile = -1;
+       }
        LogTag = NULL;
        status = NOCONN;
        THREAD_UNLOCK();

Bruce
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