builtin-apply.c: mark common context lines in lineinfo structure.

This updates the way preimage and postimage in a patch hunk is
parsed and prepared for applying.  By looking at image->line[n].flag,
the code can tell if it is a common context line that is the
same between the preimage and the postimage.

This matters when we actually start applying a patch with
contexts that have whitespace breakages that have already been
fixed in the target file.

diff --git a/builtin-apply.c b/builtin-apply.c
index dc650f16f65663586a078dbf63580f13107b0e9f..acd84f988aae230752b296381f3325a251fc3558 100644 (file)
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -170,6 +170,7 @@ struct line {
        size_t len;
        unsigned hash : 24;
        unsigned flag : 8;
+#define LINE_COMMON     1
 };
 
 /*
@@ -179,6 +180,7 @@ struct image {
        char *buf;
        size_t len;
        size_t nr;
+       size_t alloc;
        struct line *line_allocated;
        struct line *line;
 };
@@ -195,49 +197,39 @@ static uint32_t hash_line(const char *cp, size_t len)
        return h;
 }
 
+static void add_line_info(struct image *img, const char *bol, size_t len, unsigned flag)
+{
+       ALLOC_GROW(img->line_allocated, img->nr + 1, img->alloc);
+       img->line_allocated[img->nr].len = len;
+       img->line_allocated[img->nr].hash = hash_line(bol, len);
+       img->line_allocated[img->nr].flag = flag;
+       img->nr++;
+}
+
 static void prepare_image(struct image *image, char *buf, size_t len,
                          int prepare_linetable)
 {
        const char *cp, *ep;
-       int n;
 
+       memset(image, 0, sizeof(*image));
        image->buf = buf;
        image->len = len;
 
-       if (!prepare_linetable) {
-               image->line = NULL;
-               image->line_allocated = NULL;
-               image->nr = 0;
+       if (!prepare_linetable)
                return;
-       }
 
        ep = image->buf + image->len;
-
-       /* First count lines */
        cp = image->buf;
-       n = 0;
-       while (cp < ep) {
-               cp = strchrnul(cp, '\n');
-               n++;
-               cp++;
-       }
-
-       image->line_allocated = xcalloc(n, sizeof(struct line));
-       image->line = image->line_allocated;
-       image->nr = n;
-       cp = image->buf;
-       n = 0;
        while (cp < ep) {
                const char *next;
                for (next = cp; next < ep && *next != '\n'; next++)
                        ;
                if (next < ep)
                        next++;
-               image->line[n].len = next - cp;
-               image->line[n].hash = hash_line(cp, next - cp);
+               add_line_info(image, cp, next - cp, 0);
                cp = next;
-               n++;
        }
+       image->line = image->line_allocated;
 }
 
 static void clear_image(struct image *image)
@@ -1822,6 +1814,9 @@ static int apply_one_fragment(struct image *img, struct fragment *frag,
        struct image preimage;
        struct image postimage;
 
+       memset(&preimage, 0, sizeof(preimage));
+       memset(&postimage, 0, sizeof(postimage));
+
        while (size > 0) {
                char first;
                int len = linelen(patch, size);
@@ -1857,10 +1852,14 @@ static int apply_one_fragment(struct image *img, struct fragment *frag,
                                break;
                        old[oldsize++] = '\n';
                        new[newsize++] = '\n';
+                       add_line_info(&preimage, "\n", 1, LINE_COMMON);
+                       add_line_info(&postimage, "\n", 1, LINE_COMMON);
                        break;
                case ' ':
                case '-':
                        memcpy(old + oldsize, patch + 1, plen);
+                       add_line_info(&preimage, old + oldsize, plen,
+                                     (first == ' ' ? LINE_COMMON : 0));
                        oldsize += plen;
                        if (first == '-')
                                break;
@@ -1869,6 +1868,9 @@ static int apply_one_fragment(struct image *img, struct fragment *frag,
                        if (first != '+' || !no_add) {
                                int added = apply_line(new + newsize, patch,
                                                       plen, ws_rule);
+                               add_line_info(&postimage, new + newsize, added,
+                                             (first == '+' ? 0 : LINE_COMMON));
+
                                newsize += added;
                                if (first == '+' &&
                                    added == 1 && new[newsize-1] == '\n')
@@ -1921,8 +1923,13 @@ static int apply_one_fragment(struct image *img, struct fragment *frag,
        }
 
        pos = frag->newpos ? (frag->newpos - 1) : 0;
-       prepare_image(&preimage, oldlines, oldsize, 1);
-       prepare_image(&postimage, newlines, newsize, 1);
+       preimage.buf = old;
+       preimage.len = oldsize;
+       postimage.buf = new;
+       postimage.len = newsize;
+       preimage.line = preimage.line_allocated;
+       postimage.line = postimage.line_allocated;
+
        for (;;) {
 
                applied_pos = find_pos(img, &preimage, &postimage,