summaryrefslogtreecommitdiff
path: root/read-tree.c
diff options
context:
space:
mode:
Diffstat (limited to 'read-tree.c')
-rw-r--r--read-tree.c137
1 files changed, 132 insertions, 5 deletions
diff --git a/read-tree.c b/read-tree.c
index ecd40cc..d86cc02 100644
--- a/read-tree.c
+++ b/read-tree.c
@@ -143,7 +143,72 @@ static int deleted_entry(struct cache_entry *ce, struct cache_entry *old, struct
return 1;
}
-static int threeway_merge(struct cache_entry *stages[4], struct cache_entry **dst)
+static int causes_df_conflict(struct cache_entry *ce, int stage,
+ struct cache_entry **dst_,
+ struct cache_entry **next_,
+ int tail)
+{
+ /* This is called during the merge operation and walking
+ * the active_cache[] array is messy, because it is in the
+ * middle of overlapping copy operation. The invariants
+ * are:
+ * (1) active_cache points at the first (zeroth) entry.
+ * (2) up to dst pointer are resolved entries.
+ * (3) from the next pointer (head-inclusive) to the tail
+ * of the active_cache array have the remaining paths
+ * to be processed. There can be a gap between dst
+ * and next. Note that next is called "src" in the
+ * merge_cache() function, and tail is the original
+ * end of active_cache array when merge_cache() started.
+ * (4) the path corresponding to *ce is not found in (2)
+ * or (3). It is in the gap.
+ *
+ * active_cache -----......+++++++++++++.
+ * ^dst ^next ^tail
+ */
+ int i, next, dst;
+ const char *path = ce->name;
+ int namelen = ce_namelen(ce);
+
+ next = next_ - active_cache;
+ dst = dst_ - active_cache;
+
+ for (i = 0; i < tail; i++) {
+ int entlen, len;
+ const char *one, *two;
+ if (dst <= i && i < next)
+ continue;
+ ce = active_cache[i];
+ if (ce_stage(ce) != stage)
+ continue;
+ /* If ce->name is a prefix of path, then path is a file
+ * that hangs underneath ce->name, which is bad.
+ * If path is a prefix of ce->name, then it is the
+ * other way around which also is bad.
+ */
+ entlen = ce_namelen(ce);
+ if (namelen == entlen)
+ continue;
+ if (namelen < entlen) {
+ len = namelen;
+ one = path;
+ two = ce->name;
+ } else {
+ len = entlen;
+ one = ce->name;
+ two = path;
+ }
+ if (memcmp(one, two, len))
+ continue;
+ if (two[len] == '/')
+ return 1;
+ }
+ return 0;
+}
+
+static int threeway_merge(struct cache_entry *stages[4],
+ struct cache_entry **dst,
+ struct cache_entry **next, int tail)
{
struct cache_entry *old = stages[0];
struct cache_entry *a = stages[1], *b = stages[2], *c = stages[3];
@@ -156,6 +221,65 @@ static int threeway_merge(struct cache_entry *stages[4], struct cache_entry **ds
return -1;
return merged_entry_allow_dirty(b, old, dst);
}
+ /* #2ALT and #3ALT */
+ if (!a && (!!b != !!c)) {
+ /*
+ * The reason we need to worry about directory/file
+ * conflicts only in #2ALT and #3ALT case is this:
+ *
+ * (1) For all other cases that read-tree internally
+ * resolves a path, we always have such a path in
+ * *both* stage2 and stage3 when we begin.
+ * Traditionally, the behaviour has been even
+ * stricter and we did not resolve a path without
+ * initially being in all of stage1, 2, and 3.
+ *
+ * (2) When read-tree finishes, all resolved paths (i.e.
+ * the paths that are in stage0) must have come from
+ * either stage2 or stage3. It is not possible to
+ * have a stage0 path as a result of a merge if
+ * neither stage2 nor stage3 had that path.
+ *
+ * (3) It is guaranteed that just after reading the
+ * stages, each stage cannot have directory/file
+ * conflicts on its own, because they are populated
+ * by reading hierarchy of a tree. Combined with
+ * (1) and (2) above, this means that no matter what
+ * combination of paths we take from stage2 and
+ * stage3 as a result of a merge, they cannot cause
+ * a directory/file conflict situation (otherwise
+ * the "guilty" path would have already had such a
+ * conflict in the original stage, either stage2
+ * or stage3). Although its stage2 is synthesized
+ * by overlaying the current index on top of "our
+ * head" tree, --emu23 case also has this guarantee,
+ * by calling add_cache_entry() to create such stage2
+ * entries.
+ *
+ * (4) Only #2ALT and #3ALT lack the guarantee (1).
+ * They resolve paths that exist only in stage2
+ * or stage3. The stage2 tree may have a file DF
+ * while stage3 tree may have a file DF/DF. If
+ * #2ALT and #3ALT rules happen to apply to both
+ * of them, we would end up having DF (coming from
+ * stage2) and DF/DF (from stage3) in the result.
+ * When we attempt to resolve a path that exists
+ * only in stage2, we need to make sure there is
+ * no path that would conflict with it in stage3
+ * and vice versa.
+ */
+ if (c) { /* #2ALT */
+ if (!causes_df_conflict(c, 2, dst, next, tail) &&
+ (!old || same(c, old)))
+ return merged_entry_allow_dirty(c, old, dst);
+ }
+ else { /* #3ALT */
+ if (!causes_df_conflict(b, 3, dst, next, tail) &&
+ (!old || same(b, old)))
+ return merged_entry_allow_dirty(b, old, dst);
+ }
+ /* otherwise we will apply the original rule */
+ }
/*
* If we have an entry in the index cache ("old"), then we want
* to make sure that it matches any entries in stage 2 ("first
@@ -186,7 +310,8 @@ static int threeway_merge(struct cache_entry *stages[4], struct cache_entry **ds
* "carry forward" rule, please see <Documentation/git-read-tree.txt>.
*
*/
-static int twoway_merge(struct cache_entry **src, struct cache_entry **dst)
+static int twoway_merge(struct cache_entry **src, struct cache_entry **dst,
+ struct cache_entry **next, int tail)
{
struct cache_entry *current = src[0];
struct cache_entry *oldtree = src[1], *newtree = src[2];
@@ -283,7 +408,8 @@ static void setup_emu23(void)
* The rule is:
* - take the stat information from stage0, take the data from stage1
*/
-static int oneway_merge(struct cache_entry **src, struct cache_entry **dst)
+static int oneway_merge(struct cache_entry **src, struct cache_entry **dst,
+ struct cache_entry **next, int tail)
{
struct cache_entry *old = src[0];
struct cache_entry *a = src[1];
@@ -324,11 +450,12 @@ static void check_updates(struct cache_entry **src, int nr)
}
}
-typedef int (*merge_fn_t)(struct cache_entry **, struct cache_entry **);
+typedef int (*merge_fn_t)(struct cache_entry **, struct cache_entry **, struct cache_entry **, int);
static void merge_cache(struct cache_entry **src, int nr, merge_fn_t fn)
{
struct cache_entry **dst = src;
+ int tail = nr;
while (nr) {
int entries;
@@ -346,7 +473,7 @@ static void merge_cache(struct cache_entry **src, int nr, merge_fn_t fn)
break;
}
- entries = fn(stages, dst);
+ entries = fn(stages, dst, src, tail);
if (entries < 0)
reject_merge(name);
dst += entries;