lib: fix backtraces broken by 837d16c...

837d16c ("*: use array_size() helper macro") accidentally changed one of
the expressions in the backtrace code, which afterwards read:

zlog_backtrace_sigsafe():
  if (((size = backtrace(array,array_size(array)) <= 0) ||

which boils down to: (size = backtrace(...)  <= 0).  The braces were
intended to go:      (size = backtrace(...)) <= 0.

All in all, this makes a nice textbook example of the original author
being too clever (trying to save a single line by pulling the assignment
into the condition) and the next person touching the code tripping over
it...

This code occurs another time in zlog_backtrace() where it is actually
correct.  Pulling out the assignment nonetheless.  Also, new test
program.

Cc: Andrew J. Schorr <ajschorr@alumni.princeton.edu>
Cc: Balaji.G <balajig81@gmail.com>
Cc: Scott Feldman <sfeldma@cumulusnetworks.com>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/lib/log.c b/lib/log.c
index e4ec7c22..55a3b052 100644
--- a/lib/log.c
+++ b/lib/log.c
@@ -443,8 +443,8 @@ zlog_backtrace_sigsafe(int priority, void *program_counter)
 #define LOC s,buf+sizeof(buf)-s
 
 #ifdef HAVE_GLIBC_BACKTRACE
-  if (((size = backtrace(array,array_size(array)) <= 0) ||
-      ((size_t)size > array_size(array))))
+  size = backtrace(array, array_size(array));
+  if (size <= 0 || (size_t)size > array_size(array))
     return;
 
 #define DUMP(FD) { \
@@ -526,8 +526,8 @@ zlog_backtrace(int priority)
   int size, i;
   char **strings;
 
-  if (((size = backtrace(array,array_size(array))) <= 0) ||
-      ((size_t)size > array_size(array)))
+  size = backtrace(array, array_size(array));
+  if (size <= 0 || (size_t)size > array_size(array))
     {
       zlog_err("Cannot get backtrace, returned invalid # of frames %d "
 	       "(valid range is between 1 and %lu)",