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-rw-r--r--contrib/coccinelle/swap.cocci28
-rw-r--r--git-compat-util.h10
2 files changed, 38 insertions, 0 deletions
diff --git a/contrib/coccinelle/swap.cocci b/contrib/coccinelle/swap.cocci
new file mode 100644
index 000000000..a0934d1fd
--- /dev/null
+++ b/contrib/coccinelle/swap.cocci
@@ -0,0 +1,28 @@
+@ swap_with_declaration @
+type T;
+identifier tmp;
+T a, b;
+@@
+- T tmp = a;
++ T tmp;
++ tmp = a;
+ a = b;
+ b = tmp;
+
+@ swap @
+type T;
+T tmp, a, b;
+@@
+- tmp = a;
+- a = b;
+- b = tmp;
++ SWAP(a, b);
+
+@ extends swap @
+identifier unused;
+@@
+ {
+ ...
+- T unused;
+ ... when != unused
+ }
diff --git a/git-compat-util.h b/git-compat-util.h
index 87237b092..66cd466ee 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -527,6 +527,16 @@ static inline int ends_with(const char *str, const char *suffix)
return strip_suffix(str, suffix, &len);
}
+#define SWAP(a, b) do { \
+ void *_swap_a_ptr = &(a); \
+ void *_swap_b_ptr = &(b); \
+ unsigned char _swap_buffer[sizeof(a)]; \
+ memcpy(_swap_buffer, _swap_a_ptr, sizeof(a)); \
+ memcpy(_swap_a_ptr, _swap_b_ptr, sizeof(a) + \
+ BUILD_ASSERT_OR_ZERO(sizeof(a) == sizeof(b))); \
+ memcpy(_swap_b_ptr, _swap_buffer, sizeof(a)); \
+} while (0)
+
#if defined(NO_MMAP) || defined(USE_WIN32_MMAP)
#ifndef PROT_READ