Merge branch 'jk/avoid-unbounded-alloca'

diff --git a/xdiff/xdiffi.c b/xdiff/xdiffi.c
index 2358a2d6326e54308413cb8a5e6b61eba06324e9..b3c684887502c3c473a614114e4acdfbc57ea094 100644 (file)
--- a/xdiff/xdiffi.c
+++ b/xdiff/xdiffi.c
@@ -400,9 +400,23 @@ static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1,
 }
 
 
+static int is_blank_line(xrecord_t **recs, long ix, long flags)
+{
+       return xdl_blankline(recs[ix]->ptr, recs[ix]->size, flags);
+}
+
+static int recs_match(xrecord_t **recs, long ixs, long ix, long flags)
+{
+       return (recs[ixs]->ha == recs[ix]->ha &&
+               xdl_recmatch(recs[ixs]->ptr, recs[ixs]->size,
+                            recs[ix]->ptr, recs[ix]->size,
+                            flags));
+}
+
 int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
        long ix, ixo, ixs, ixref, grpsiz, nrec = xdf->nrec;
        char *rchg = xdf->rchg, *rchgo = xdfo->rchg;
+       unsigned int blank_lines;
        xrecord_t **recs = xdf->recs;
 
        /*
@@ -436,14 +450,14 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
 
                do {
                        grpsiz = ix - ixs;
+                       blank_lines = 0;
 
                        /*
                         * If the line before the current change group, is equal to
                         * the last line of the current change group, shift backward
                         * the group.
                         */
-                       while (ixs > 0 && recs[ixs - 1]->ha == recs[ix - 1]->ha &&
-                              xdl_recmatch(recs[ixs - 1]->ptr, recs[ixs - 1]->size, recs[ix - 1]->ptr, recs[ix - 1]->size, flags)) {
+                       while (ixs > 0 && recs_match(recs, ixs - 1, ix - 1, flags)) {
                                rchg[--ixs] = 1;
                                rchg[--ix] = 0;
 
@@ -470,8 +484,9 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
                         * the line next of the current change group, shift forward
                         * the group.
                         */
-                       while (ix < nrec && recs[ixs]->ha == recs[ix]->ha &&
-                              xdl_recmatch(recs[ixs]->ptr, recs[ixs]->size, recs[ix]->ptr, recs[ix]->size, flags)) {
+                       while (ix < nrec && recs_match(recs, ixs, ix, flags)) {
+                               blank_lines += is_blank_line(recs, ix, flags);
+
                                rchg[ixs++] = 0;
                                rchg[ix++] = 1;
 
@@ -498,6 +513,23 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
                        rchg[--ix] = 0;
                        while (rchgo[--ixo]);
                }
+
+               /*
+                * If a group can be moved back and forth, see if there is a
+                * blank line in the moving space. If there is a blank line,
+                * make sure the last blank line is the end of the group.
+                *
+                * As we already shifted the group forward as far as possible
+                * in the earlier loop, we need to shift it back only if at all.
+                */
+               if ((flags & XDF_COMPACTION_HEURISTIC) && blank_lines) {
+                       while (ixs > 0 &&
+                              !is_blank_line(recs, ix - 1, flags) &&
+                              recs_match(recs, ixs - 1, ix - 1, flags)) {
+                               rchg[--ixs] = 1;
+                               rchg[--ix] = 0;
+                       }
+               }
        }
 
        return 0;