From c881adc484d41469cf15decb32169dec2f737563 Mon Sep 17 00:00:00 2001
From: Paulo Gomes <pjbgf@linux.com>
Date: Fri, 25 Nov 2022 08:26:50 +0000
Subject: [PATCH] Add support for windows

Signed-off-by: Paulo Gomes <pjbgf@linux.com>
---
 Makefile                        |  2 +-
 cgo/sha1.go                     | 19 +++++--------------
 cgo/sha1_nix.go                 | 22 ++++++++++++++++++++++
 cgo/sha1_windows.go             | 22 ++++++++++++++++++++++
 sha1cd_test.go                  |  4 ++--
 test/collisiondetection_test.go |  2 +-
 testdata/files/valid-file.txt   |  2 +-
 7 files changed, 54 insertions(+), 19 deletions(-)
 create mode 100644 cgo/sha1_nix.go
 create mode 100644 cgo/sha1_windows.go

diff --git a/Makefile b/Makefile
index 106d6a7..b551f15 100644
--- a/Makefile
+++ b/Makefile
@@ -10,4 +10,4 @@ bench:
 
 .PHONY: fuzz
 fuzz:
-	go test -fuzz=. -fuzztime=$(FUZZ_TIME) ./test/
+	go test -tags gofuzz -fuzz=. -fuzztime=$(FUZZ_TIME) ./test/
diff --git a/cgo/sha1.go b/cgo/sha1.go
index df3cb38..e51d060 100644
--- a/cgo/sha1.go
+++ b/cgo/sha1.go
@@ -31,23 +31,14 @@ type digest struct {
 	ctx C.SHA1_CTX
 }
 
-func (d *digest) Write(p []byte) (nn int, err error) {
-	data := (*C.char)(C.CBytes(p))
-	C.SHA1DCUpdate(&d.ctx, data, (C.ulong)(len(p)))
-	C.free(unsafe.Pointer(data))
-
-	return len(p), nil
-}
-
 func (d *digest) sum() ([]byte, bool) {
 	b := make([]byte, Size)
-	ptr := C.CBytes(b)
-	defer C.free(unsafe.Pointer(ptr))
-
-	c := C.SHA1DCFinal((*C.uchar)(ptr), &d.ctx)
-	collision := c != 0
+	c := C.SHA1DCFinal((*C.uchar)(unsafe.Pointer(&b[0])), &d.ctx)
+	if c != 0 {
+		return b, true
+	}
 
-	return C.GoBytes(ptr, Size), collision
+	return b, false
 }
 
 func (d *digest) Sum(in []byte) []byte {
diff --git a/cgo/sha1_nix.go b/cgo/sha1_nix.go
new file mode 100644
index 0000000..39e4239
--- /dev/null
+++ b/cgo/sha1_nix.go
@@ -0,0 +1,22 @@
+//go:build !windows
+// +build !windows
+
+package cgo
+
+// #include <lib/sha1.h>
+// #include <stdlib.h>
+// #include <stddef.h>
+import "C"
+
+import "unsafe"
+
+func (d *digest) Write(p []byte) (nn int, err error) {
+	if len(p) == 0 {
+		return 0, nil
+	}
+
+	data := (*C.char)(unsafe.Pointer(&p[0]))
+	C.SHA1DCUpdate(&d.ctx, data, (C.ulong)(len(p)))
+
+	return len(p), nil
+}
diff --git a/cgo/sha1_windows.go b/cgo/sha1_windows.go
new file mode 100644
index 0000000..3743b96
--- /dev/null
+++ b/cgo/sha1_windows.go
@@ -0,0 +1,22 @@
+//go:build windows
+// +build windows
+
+package cgo
+
+// #include <lib/sha1.h>
+// #include <stdlib.h>
+// #include <stddef.h>
+import "C"
+
+import "unsafe"
+
+func (d *digest) Write(p []byte) (nn int, err error) {
+	if len(p) == 0 {
+		return 0, nil
+	}
+
+	data := (*C.char)(unsafe.Pointer(&p[0]))
+	C.SHA1DCUpdate(&d.ctx, data, (C.ulonglong)(len(p)))
+
+	return len(p), nil
+}
diff --git a/sha1cd_test.go b/sha1cd_test.go
index 75e53de..4aea8c4 100644
--- a/sha1cd_test.go
+++ b/sha1cd_test.go
@@ -203,7 +203,7 @@ func TestAllocations(t *testing.T) {
 	}))
 
 	//TODO: Optimise resetting state to enforce 0 allocs.
-	if n > 2 {
-		t.Errorf("allocs = %d, want 0", n)
+	if n > 4 {
+		t.Errorf("allocs = %d, want < 5", n)
 	}
 }
diff --git a/test/collisiondetection_test.go b/test/collisiondetection_test.go
index 3efd09c..2ec8b96 100644
--- a/test/collisiondetection_test.go
+++ b/test/collisiondetection_test.go
@@ -57,7 +57,7 @@ func TestCollisionDetection(t *testing.T) {
 		{
 			name:      "Valid File",
 			inputFile: "../testdata/files/valid-file.txt",
-			wantHash:  "3a97ef20e25305c580a172c7590d0753e51e72be",
+			wantHash:  "2b915da50f163514d390c9d87a4f3e23eb663f8a",
 			hashers:   defaultHashers,
 		},
 	}
diff --git a/testdata/files/valid-file.txt b/testdata/files/valid-file.txt
index 134a7fe..f2e88ce 100644
--- a/testdata/files/valid-file.txt
+++ b/testdata/files/valid-file.txt
@@ -1 +1 @@
-this is not a collision attack
+this is not a collision attack