cmd/cgo: fix handling of defs_linux.go

Instead of including <sys/types.h> to get size_t, instead include
the ISO C standard <stddef.h> header, which defines fewer additional
types at risk of colliding with the user code.  In particular, this
prevents collisions between <sys/types.h>'s userspace definitions with
the kernel definitions needed by defs_linux.go.

Also, -cdefs mode uses #pragma pack, so we can keep misaligned fields.

Fixes issue 8477.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://codereview.appspot.com/120610043

Committer: Ian Lance Taylor <iant@golang.org>

3 files changed, 42 insertions, 0 deletions

diff --git a/misc/cgo/testcdefs/cdefstest.c b/misc/cgo/testcdefs/cdefstest.c
index 10cdd66b6..ce670e729 100644
--- a/misc/cgo/testcdefs/cdefstest.c
+++ b/misc/cgo/testcdefs/cdefstest.c
@@ -6,3 +6,4 @@
 #include "cdefstest.h"
 
 struct CdefsTest test;
+struct PackedTest packed;
diff --git a/misc/cgo/testcdefs/cdefstest.go b/misc/cgo/testcdefs/cdefstest.go
index e6305b77d..0804083a0 100644
--- a/misc/cgo/testcdefs/cdefstest.go
+++ b/misc/cgo/testcdefs/cdefstest.go
@@ -35,7 +35,25 @@ struct cdefsTest {
 	// Correct: -> Array [20][20]**int8 -> int8 **array[20][20]
 	char **array5[20][20];
 };
+
+// Test that packed structures can be translated to C correctly too.
+// See issue 8477.
+
+struct packedTest {
+	char first;
+	int second;
+	long long third;
+} __attribute__((packed));
+
+// Test that conflicting type definitions don't cause problems with cgo.
+// See issue 8477.
+
+typedef struct timespec {
+	double bogus;
+} pid_t;
+
 */
 import "C"
 
 type CdefsTest C.struct_cdefsTest
+type PackedTest C.struct_packedTest
diff --git a/misc/cgo/testcdefs/main.c b/misc/cgo/testcdefs/main.c
index 2d3ee4dbe..c13a80430 100644
--- a/misc/cgo/testcdefs/main.c
+++ b/misc/cgo/testcdefs/main.c
@@ -17,11 +17,22 @@ struct CdefsOrig {
 	int8 **array5[20][20];
 };
 
+typedef struct PackedOrig PackedOrig;
+#pragma pack on
+struct PackedOrig {
+	int8 first;
+	int32 second;
+	int64 third;
+};
+#pragma pack off
+
 void
 main·test(int32 ret)
 {
 	CdefsOrig o;
 	CdefsTest t;
+	PackedOrig po;
+	PackedTest pt;
 	
 	ret = 0;
 	if(sizeof(t.array1) != sizeof(o.array1) || offsetof(CdefsTest, array1[0]) != offsetof(CdefsOrig, array1[0])) {
@@ -44,5 +55,17 @@ main·test(int32 ret)
 		runtime·printf("array5: size, offset = %d, %d, want %d, %d\n", sizeof(t.array5), offsetof(CdefsTest, array5[0][0]), sizeof(o.array5), offsetof(CdefsOrig, array5[0][0]));
 		ret = 1;
 	}
+	if(sizeof(pt.first) != sizeof(po.first) || offsetof(PackedTest, first) != offsetof(PackedOrig, first)) {
+		runtime·printf("first: size, offset = %d, %d, want %d, %d\n", sizeof(pt.first), offsetof(PackedTest, first), sizeof(po.first), offsetof(PackedOrig, first));
+		ret = 1;
+	}
+	if(sizeof(pt.second) != sizeof(po.second) || offsetof(PackedTest, second) != offsetof(PackedOrig, second)) {
+		runtime·printf("second: size, offset = %d, %d, want %d, %d\n", sizeof(pt.second), offsetof(PackedTest, second), sizeof(po.second), offsetof(PackedOrig, second));
+		ret = 1;
+	}
+	if(sizeof(pt.third) != sizeof(po.third) || offsetof(PackedTest, third) != offsetof(PackedOrig, third)) {
+		runtime·printf("third: size, offset = %d, %d, want %d, %d\n", sizeof(pt.third), offsetof(PackedTest, third), sizeof(po.third), offsetof(PackedOrig, third));
+		ret = 1;
+	}
 	FLUSH(&ret); // flush return value
 }