From 8e0f4a293e0264b0bfdb0b3e8751418b7eaedbb2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dag-Erling=20Sm=C3=B8rgrav?= <des@des.no>
Date: Wed, 10 May 2017 23:45:56 +0200
Subject: [PATCH] Determine the default for CRYB_LEAKTEST at run-time.

When cryb-test is used as a framework for another project, the compile-time test is useless since cryb-test itself will have been built with coverage disabled.  Besides, it is not a reliable indicator of whether leak detection will work.  Instead, check if the heap is already dirty when we first gain control.
---
 include/cryb/test.h      |  1 +
 lib/test/cryb_t_main.c   | 17 ++++++++++-------
 lib/test/cryb_t_malloc.c | 27 +++++++++++++++++++--------
 3 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/include/cryb/test.h b/include/cryb/test.h
index a511287..340d7f8 100644
--- a/include/cryb/test.h
+++ b/include/cryb/test.h
@@ -146,6 +146,7 @@ size_t t_malloc_snapshot(void *, size_t);
 #if CRYB_TEST_HAVE_STDIO
 void t_malloc_printstats(FILE *);
 #endif
+unsigned long t_malloc_outstanding(void);
 extern struct t_test t_memory_leak;
 
 /*
diff --git a/lib/test/cryb_t_main.c b/lib/test/cryb_t_main.c
index b1f2a6a..3a4f528 100644
--- a/lib/test/cryb_t_main.c
+++ b/lib/test/cryb_t_main.c
@@ -251,6 +251,16 @@ t_main(t_prepare_func t_prepare, t_cleanup_func t_cleanup,
 	size_t nt;
 	int opt;
 
+	/*
+	 * Enable memory leak detection by default if and only if the heap
+	 * is empty at the start of main(), since otherwise we have no
+	 * reason to trust that it will be empty after we've run the tests
+	 * and cleaned up what we could.
+	 */
+	leaktest = t_malloc_outstanding() ?
+	    t_str_is_true(getenv("CRYB_LEAKTEST")) :
+	    !t_str_is_false(getenv("CRYB_LEAKTEST"));
+
 	/* make all unintentional allocation failures fatal */
 	t_malloc_fatal = 1;
 
@@ -266,13 +276,6 @@ t_main(t_prepare_func t_prepare, t_cleanup_func t_cleanup,
 	else
 		t_progname = argv[0];
 
-	/* check for leaks, unless doing coverage analysis */
-#if CRYB_COVERAGE
-	leaktest = t_str_is_true(getenv("CRYB_LEAKTEST"));
-#else
-	leaktest = !t_str_is_false(getenv("CRYB_LEAKTEST"));
-#endif
-
 	/* parse command line options */
 	while ((opt = getopt(argc, argv, "Llv")) != -1)
 		switch (opt) {
diff --git a/lib/test/cryb_t_malloc.c b/lib/test/cryb_t_malloc.c
index 8059815..4cdd7ec 100644
--- a/lib/test/cryb_t_malloc.c
+++ b/lib/test/cryb_t_malloc.c
@@ -534,22 +534,33 @@ t_malloc_printstats(FILE *f)
 		    nmapalloc, nmapfree, nmapalloc - nmapfree);
 }
 
+/*
+ * Return number of outstanding allocations
+ */
+unsigned long
+t_malloc_outstanding(void)
+{
+	struct bucket *b;
+	unsigned int shift;
+	unsigned long n;
+
+	n = nmapalloc - nmapfree;
+	for (shift = BUCKET_MIN_SHIFT; shift <= BUCKET_MAX_SHIFT; ++shift) {
+		b = &buckets[shift];
+		n += b->nalloc - b->nfree;
+	}
+	return (n);
+}
+
 /*
  * Test that fails if we leaked memory
  */
 static int
 t_malloc_leaked(char **desc, void *arg CRYB_UNUSED)
 {
-	struct bucket *b;
-	unsigned int shift;
 	unsigned long nleaked;
 
-	nleaked = 0;
-	for (shift = BUCKET_MIN_SHIFT; shift <= BUCKET_MAX_SHIFT; ++shift) {
-		b = &buckets[shift];
-		nleaked += b->nalloc - b->nfree;
-	}
-	nleaked += nmapalloc - nmapfree;
+	nleaked = t_malloc_outstanding();
 	if (nleaked > 0)
 		(void)asprintf(desc, "%lu allocation(s) leaked", nleaked);
 	else