[tor-commits] [tor/maint-0.3.0] Fix build warnings from Coverity related to our BUG macro

[nickm at torproject.org]

commit 32b9edeb91a7d9b9752083622d1ce400f45e42ea
Author: Nick Mathewson <nickm at torproject.org>
Date:   Tue Jul 25 10:14:24 2017 -0400

    Fix build warnings from Coverity related to our BUG macro
    
    In the Linux kernel, the BUG() macro causes an instant panic.  Our
    BUG() macro is different, however: it generates a nonfatal assertion
    failure, and is usable as an expression.
    
    Additionally, this patch tells util_bug.h to make all assertion
    failures into fatal conditions when we're building with a static
    analysis tool, so that the analysis tool can look for instances
    where they're reachable.
    
    Fixes bug 23030.
---
 changes/bug23030_029  |  7 +++++++
 src/common/util_bug.h | 13 +++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/changes/bug23030_029 b/changes/bug23030_029
new file mode 100644
index 000000000..89a1b507d
--- /dev/null
+++ b/changes/bug23030_029
@@ -0,0 +1,7 @@
+  o Minor bugfixes (coverity builds):
+    - Avoid Coverity build warnings related to our BUG() macro. By
+      default, Coverity treats BUG() as the Linux kernel does: an
+      instant abort(). We need to override that so our BUG() macro
+      doesn't prevent Coverity from analyzing functions that use it.
+      Fixes bug 23030; bugfix on 0.2.9.1-alpha.
+
diff --git a/src/common/util_bug.h b/src/common/util_bug.h
index e02778110..069580691 100644
--- a/src/common/util_bug.h
+++ b/src/common/util_bug.h
@@ -58,6 +58,19 @@
  *     return -1;
  */
 
+#ifdef __COVERITY__
+#undef BUG
+// Coverity defines this in global headers; let's override it.  This is a
+// magic coverity-only preprocessor thing.
+#nodef BUG(x) ((x)?(__coverity_panic__(),1):0)
+#endif
+
+#if defined(__COVERITY__) || defined(__clang_analyzer__)
+// We're running with a static analysis tool: let's treat even nonfatal
+// assertion failures as something that we need to avoid.
+#define ALL_BUGS_ARE_FATAL
+#endif
+
 #ifdef ALL_BUGS_ARE_FATAL
 #define tor_assert_nonfatal_unreached() tor_assert(0)
 #define tor_assert_nonfatal(cond) tor_assert((cond))