Merge pull request #354 from libgit2/cmn/panic-threading

Add Feature query support & panic if libgit2 is not thread-aware

2 files changed, 39 insertions, 0 deletions

diff --git a/features.go b/features.go
new file mode 100644
index 0000000..f6474a0
--- /dev/null
+++ b/features.go
@@ -0,0 +1,30 @@
+package git
+
+/*
+#include <git2.h>
+*/
+import "C"
+
+type Feature int
+
+const (
+	// libgit2 was built with threading support
+	FeatureThreads Feature = C.GIT_FEATURE_THREADS
+
+	// libgit2 was built with HTTPS support built-in
+	FeatureHttps Feature = C.GIT_FEATURE_HTTPS
+
+	// libgit2 was build with SSH support built-in
+	FeatureSsh Feature = C.GIT_FEATURE_SSH
+
+	// libgit2 was built with nanosecond support for files
+	FeatureNSec Feature = C.GIT_FEATURE_NSEC
+)
+
+// Features returns a bit-flag of Feature values indicating which features the
+// loaded libgit2 library has.
+func Features() Feature {
+	features := C.git_libgit2_features()
+
+	return Feature(features)
+}
diff --git a/git.go b/git.go
index a3c40e3..53b1a12 100644
--- a/git.go
+++ b/git.go
@@ -124,6 +124,15 @@ func init() {
 
 	C.git_libgit2_init()
 
+	// Due to the multithreaded nature of Go and its interaction with
+	// calling C functions, we cannot work with a library that was not built
+	// with multi-threading support. The most likely outcome is a segfault
+	// or panic at an incomprehensible time, so let's make it easy by
+	// panicking right here.
+	if Features()&FeatureThreads == 0 {
+		panic("libgit2 was not built with threading support")
+	}
+
 	// This is not something we should be doing, as we may be
 	// stomping all over someone else's setup. The user should do
 	// this themselves or use some binding/wrapper which does it