apply: introduce macro and function to init images

We're about to convert the `struct image` to gain a `struct strbuf`
member, which requires more careful initialization than just memsetting
it to zeros. Introduce the `IMAGE_INIT` macro and `image_init()`
function to prepare for this change.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/apply.c b/apply.c
index ac21c21297e39c08aa320bfee4ca3a0b03221837..76f7777d4c625e780cd3105145c5be2b203e254f 100644 (file)
--- a/apply.c
+++ b/apply.c
@@ -284,11 +284,19 @@ struct image {
        struct line *line_allocated;
        struct line *line;
 };
+#define IMAGE_INIT { 0 }
+
+static void image_init(struct image *image)
+{
+       struct image empty = IMAGE_INIT;
+       memcpy(image, &empty, sizeof(*image));
+}
 
 static void image_clear(struct image *image)
 {
        free(image->buf);
        free(image->line_allocated);
+       image_init(image);
 }
 
 static uint32_t hash_line(const char *cp, size_t len)
@@ -322,7 +330,7 @@ static void image_prepare(struct image *image, char *buf, size_t len,
 {
        const char *cp, *ep;
 
-       memset(image, 0, sizeof(*image));
+       image_clear(image);
        image->buf = buf;
        image->len = len;
 
@@ -2314,7 +2322,7 @@ static void update_pre_post_images(struct image *preimage,
 {
        int i, ctx, reduced;
        char *new_buf, *old_buf, *fixed;
-       struct image fixed_preimage;
+       struct image fixed_preimage = IMAGE_INIT;
 
        /*
         * Update the preimage with whitespace fixes.  Note that we
@@ -2910,11 +2918,9 @@ static int apply_one_fragment(struct apply_state *state,
        int hunk_linenr = frag->linenr;
        unsigned long leading, trailing;
        int pos, applied_pos;
-       struct image preimage;
-       struct image postimage;
+       struct image preimage = IMAGE_INIT;
+       struct image postimage = IMAGE_INIT;
 
-       memset(&preimage, 0, sizeof(preimage));
-       memset(&postimage, 0, sizeof(postimage));
        oldlines = xmalloc(size);
        strbuf_init(&newlines, size);
 
@@ -3650,7 +3656,7 @@ static int try_threeway(struct apply_state *state,
        size_t len;
        int status;
        char *img;
-       struct image tmp_image;
+       struct image tmp_image = IMAGE_INIT;
 
        /* No point falling back to 3-way merge in these cases */
        if (patch->is_delete ||
@@ -3727,7 +3733,7 @@ static int try_threeway(struct apply_state *state,
 static int apply_data(struct apply_state *state, struct patch *patch,
                      struct stat *st, const struct cache_entry *ce)
 {
-       struct image image;
+       struct image image = IMAGE_INIT;
 
        if (load_preimage(state, &image, patch, st, ce) < 0)
                return -1;