From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 27 Jun 2016 16:56:48 +0000 (-0700)
Subject: Merge branch 'jk/avoid-unbounded-alloca'
X-Git-Tag: v2.10.0-rc0~180
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/269085e16e26d5096b5458ae89d63eb27de26eb7?ds=inline;hp=-c

Merge branch 'jk/avoid-unbounded-alloca'

* jk/avoid-unbounded-alloca:
tree-diff: avoid alloca for large allocations
---

269085e16e26d5096b5458ae89d63eb27de26eb7
diff --combined tree-diff.c
index edb4de9b72,286cab8177..e164e532b2
--- a/tree-diff.c
+++ b/tree-diff.c
@@@ -14,6 -14,16 +14,16 @@@
   */
  #define S_IFXMIN_NEQ	S_DIFFTREE_IFXMIN_NEQ
  
+ #define FAST_ARRAY_ALLOC(x, nr) do { \
+ 	if ((nr) <= 2) \
+ 		(x) = xalloca((nr) * sizeof(*(x))); \
+ 	else \
+ 		ALLOC_ARRAY((x), nr); \
+ } while(0)
+ #define FAST_ARRAY_FREE(x, nr) do { \
+ 	if ((nr) > 2) \
+ 		free((x)); \
+ } while(0)
  
  static struct combine_diff_path *ll_diff_tree_paths(
  	struct combine_diff_path *p, const unsigned char *sha1,
@@@ -64,7 -74,7 +74,7 @@@ static int emit_diff_first_parent_only(
  {
  	struct combine_diff_parent *p0 = &p->parent[0];
  	if (p->mode && p0->mode) {
 -		opt->change(opt, p0->mode, p->mode, p0->sha1, p->sha1,
 +		opt->change(opt, p0->mode, p->mode, p0->oid.hash, p->oid.hash,
  			1, 1, p->path, 0, 0);
  	}
  	else {
@@@ -74,11 -84,11 +84,11 @@@
  
  		if (p->mode) {
  			addremove = '+';
 -			sha1 = p->sha1;
 +			sha1 = p->oid.hash;
  			mode = p->mode;
  		} else {
  			addremove = '-';
 -			sha1 = p0->sha1;
 +			sha1 = p0->oid.hash;
  			mode = p0->mode;
  		}
  
@@@ -151,7 -161,7 +161,7 @@@ static struct combine_diff_path *path_a
  	memcpy(p->path + base->len, path, pathlen);
  	p->path[len] = 0;
  	p->mode = mode;
 -	hashcpy(p->sha1, sha1 ? sha1 : null_sha1);
 +	hashcpy(p->oid.hash, sha1 ? sha1 : null_sha1);
  
  	return p;
  }
@@@ -183,7 -193,7 +193,7 @@@ static struct combine_diff_path *emit_p
  
  	if (t) {
  		/* path present in resulting tree */
 -		sha1 = tree_entry_extract(t, &path, &mode);
 +		sha1 = tree_entry_extract(t, &path, &mode)->hash;
  		pathlen = tree_entry_len(&t->entry);
  		isdir = S_ISDIR(mode);
  	} else {
@@@ -229,7 -239,7 +239,7 @@@
  						DIFF_STATUS_ADDED;
  
  			if (tpi_valid) {
 -				sha1_i = tp[i].entry.sha1;
 +				sha1_i = tp[i].entry.oid->hash;
  				mode_i = tp[i].entry.mode;
  			}
  			else {
@@@ -238,7 -248,7 +248,7 @@@
  			}
  
  			p->parent[i].mode = mode_i;
 -			hashcpy(p->parent[i].sha1, sha1_i ? sha1_i : null_sha1);
 +			hashcpy(p->parent[i].oid.hash, sha1_i ? sha1_i : null_sha1);
  		}
  
  		keep = 1;
@@@ -265,19 -275,19 +275,19 @@@
  	if (recurse) {
  		const unsigned char **parents_sha1;
  
- 		parents_sha1 = xalloca(nparent * sizeof(parents_sha1[0]));
+ 		FAST_ARRAY_ALLOC(parents_sha1, nparent);
  		for (i = 0; i < nparent; ++i) {
  			/* same rule as in emitthis */
  			int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);
  
 -			parents_sha1[i] = tpi_valid ? tp[i].entry.sha1
 +			parents_sha1[i] = tpi_valid ? tp[i].entry.oid->hash
  						    : NULL;
  		}
  
  		strbuf_add(base, path, pathlen);
  		strbuf_addch(base, '/');
  		p = ll_diff_tree_paths(p, sha1, parents_sha1, nparent, base, opt);
- 		xalloca_free(parents_sha1);
+ 		FAST_ARRAY_FREE(parents_sha1, nparent);
  	}
  
  	strbuf_setlen(base, old_baselen);
@@@ -402,8 -412,8 +412,8 @@@ static struct combine_diff_path *ll_dif
  	void *ttree, **tptree;
  	int i;
  
- 	tp     = xalloca(nparent * sizeof(tp[0]));
- 	tptree = xalloca(nparent * sizeof(tptree[0]));
+ 	FAST_ARRAY_ALLOC(tp, nparent);
+ 	FAST_ARRAY_ALLOC(tptree, nparent);
  
  	/*
  	 * load parents first, as they are probably already cached.
@@@ -482,7 -492,7 +492,7 @@@
  						continue;
  
  					/* diff(t,pi) != ø */
 -					if (hashcmp(t.entry.sha1, tp[i].entry.sha1) ||
 +					if (oidcmp(t.entry.oid, tp[i].entry.oid) ||
  					    (t.entry.mode != tp[i].entry.mode))
  						continue;
  
@@@ -531,8 -541,8 +541,8 @@@
  	free(ttree);
  	for (i = nparent-1; i >= 0; i--)
  		free(tptree[i]);
- 	xalloca_free(tptree);
- 	xalloca_free(tp);
+ 	FAST_ARRAY_FREE(tptree, nparent);
+ 	FAST_ARRAY_FREE(tp, nparent);
  
  	return p;
  }
@@@ -607,7 -617,7 +617,7 @@@ static void try_to_follow_renames(cons
  	diff_setup_done(&diff_opts);
  	ll_diff_tree_sha1(old, new, base, &diff_opts);
  	diffcore_std(&diff_opts);
 -	free_pathspec(&diff_opts.pathspec);
 +	clear_pathspec(&diff_opts.pathspec);
  
  	/* Go through the new set of filepairing, and see if we find a more interesting one */
  	opt->found_follow = 0;
@@@ -630,7 -640,7 +640,7 @@@
  			/* Update the path we use from now on.. */
  			path[0] = p->one->path;
  			path[1] = NULL;
 -			free_pathspec(&opt->pathspec);
 +			clear_pathspec(&opt->pathspec);
  			parse_pathspec(&opt->pathspec,
  				       PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
  				       PATHSPEC_LITERAL_PATH, "", path);