prefer memcpy to strcpy

When we already know the length of a string (e.g., because
we just malloc'd to fit it), it's nicer to use memcpy than
strcpy, as it makes it more obvious that we are not going to
overflow the buffer (because the size we pass matches the
size in the allocation).

This also eliminates calls to strcpy, which make auditing
the code base harder.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 7 insertions, 5 deletions

diff --git a/compat/nedmalloc/nedmalloc.c b/compat/nedmalloc/nedmalloc.c
index 609ebba125..a0a16eb1bb 100644
--- a/compat/nedmalloc/nedmalloc.c
+++ b/compat/nedmalloc/nedmalloc.c
@@ -957,8 +957,9 @@ char *strdup(const char *s1)
 {
 	char *s2 = 0;
 	if (s1) {
-		s2 = malloc(strlen(s1) + 1);
-		strcpy(s2, s1);
+		size_t len = strlen(s1) + 1;
+		s2 = malloc(len);
+		memcpy(s2, s1, len);
 	}
 	return s2;
 }
diff --git a/fast-import.c b/fast-import.c
index 895c6b4a7e..cf6d8bc0ce 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -644,8 +644,9 @@ static void *pool_calloc(size_t count, size_t size)
 
 static char *pool_strdup(const char *s)
 {
-	char *r = pool_alloc(strlen(s) + 1);
-	strcpy(r, s);
+	size_t len = strlen(s) + 1;
+	char *r = pool_alloc(len);
+	memcpy(r, s, len);
 	return r;
 }
 
diff --git a/revision.c b/revision.c
index af2a18ed74..22364636d1 100644
--- a/revision.c
+++ b/revision.c
@@ -38,7 +38,7 @@ char *path_name(const struct name_path *path, const char *name)
 	}
 	n = xmalloc(len);
 	m = n + len - (nlen + 1);
-	strcpy(m, name);
+	memcpy(m, name, nlen + 1);
 	for (p = path; p; p = p->up) {
 		if (p->elem_len) {
 			m -= p->elem_len + 1;