merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

2 files changed, 19 insertions, 4 deletions

diff --git a/third_party/git/ewah/bitmap.c b/third_party/git/ewah/bitmap.c
index 52f1178db4ce..d8cec585af97 100644
--- a/third_party/git/ewah/bitmap.c
+++ b/third_party/git/ewah/bitmap.c
@@ -22,21 +22,26 @@
 #define EWAH_MASK(x) ((eword_t)1 << (x % BITS_IN_EWORD))
 #define EWAH_BLOCK(x) (x / BITS_IN_EWORD)
 
-struct bitmap *bitmap_new(void)
+struct bitmap *bitmap_word_alloc(size_t word_alloc)
 {
 	struct bitmap *bitmap = xmalloc(sizeof(struct bitmap));
-	bitmap->words = xcalloc(32, sizeof(eword_t));
-	bitmap->word_alloc = 32;
+	bitmap->words = xcalloc(word_alloc, sizeof(eword_t));
+	bitmap->word_alloc = word_alloc;
 	return bitmap;
 }
 
+struct bitmap *bitmap_new(void)
+{
+	return bitmap_word_alloc(32);
+}
+
 void bitmap_set(struct bitmap *self, size_t pos)
 {
 	size_t block = EWAH_BLOCK(pos);
 
 	if (block >= self->word_alloc) {
 		size_t old_size = self->word_alloc;
-		self->word_alloc = block * 2;
+		self->word_alloc = block ? block * 2 : 1;
 		REALLOC_ARRAY(self->words, self->word_alloc);
 		memset(self->words + old_size, 0x0,
 			(self->word_alloc - old_size) * sizeof(eword_t));
@@ -45,6 +50,14 @@ void bitmap_set(struct bitmap *self, size_t pos)
 	self->words[block] |= EWAH_MASK(pos);
 }
 
+void bitmap_unset(struct bitmap *self, size_t pos)
+{
+	size_t block = EWAH_BLOCK(pos);
+
+	if (block < self->word_alloc)
+		self->words[block] &= ~EWAH_MASK(pos);
+}
+
 int bitmap_get(struct bitmap *self, size_t pos)
 {
 	size_t block = EWAH_BLOCK(pos);
diff --git a/third_party/git/ewah/ewok.h b/third_party/git/ewah/ewok.h
index 84b2a29faa0c..011852bef179 100644
--- a/third_party/git/ewah/ewok.h
+++ b/third_party/git/ewah/ewok.h
@@ -172,7 +172,9 @@ struct bitmap {
 };
 
 struct bitmap *bitmap_new(void);
+struct bitmap *bitmap_word_alloc(size_t word_alloc);
 void bitmap_set(struct bitmap *self, size_t pos);
+void bitmap_unset(struct bitmap *self, size_t pos);
 int bitmap_get(struct bitmap *self, size_t pos);
 void bitmap_reset(struct bitmap *self);
 void bitmap_free(struct bitmap *self);