tree/diff header cleanup.

Introduce tree-walk.[ch] and move "struct tree_desc" and
associated functions from various places.

Rename DIFF_FILE_CANON_MODE(mode) macro to canon_mode(mode) and
move it to cache.h.  This macro returns the canonicalized
st_mode value in the host byte order for files, symlinks and
directories -- to be compared with a tree_desc entry.
create_ce_mode(mode) in cache.h is similar but is intended to be
used for index entries (so it does not work for directories) and
returns the value in the network byte order.

Signed-off-by: Junio C Hamano <junkio@cox.net>

13 files changed, 156 insertions, 143 deletions

diff --git a/Makefile b/Makefile
index d945546eb..d78298ae6 100644
--- a/Makefile
+++ b/Makefile
@@ -193,7 +193,8 @@ XDIFF_LIB=xdiff/lib.a
 LIB_H = \
 	blob.h cache.h commit.h csum-file.h delta.h \
 	diff.h object.h pack.h pkt-line.h quote.h refs.h \
-	run-command.h strbuf.h tag.h tree.h git-compat-util.h revision.h
+	run-command.h strbuf.h tag.h tree.h git-compat-util.h revision.h \
+	tree-walk.h
 
 DIFF_OBJS = \
 	diff.o diffcore-break.o diffcore-order.o diffcore-pathspec.o \
@@ -207,7 +208,7 @@ LIB_OBJS = \
 	quote.o read-cache.o refs.o run-command.o \
 	server-info.o setup.o sha1_file.o sha1_name.o strbuf.o \
 	tag.o tree.o usage.o config.o environment.o ctype.o copy.o \
-	fetch-clone.o revision.o pager.o \
+	fetch-clone.o revision.o pager.o tree-walk.o \
 	$(DIFF_OBJS)
 
 GITLIBS = $(LIB_FILE) $(XDIFF_LIB)
diff --git a/cache.h b/cache.h
index 255e6b5cc..69801b02d 100644
--- a/cache.h
+++ b/cache.h
@@ -106,6 +106,9 @@ static inline unsigned int create_ce_mode(unsigned int mode)
 		return htonl(S_IFLNK);
 	return htonl(S_IFREG | ce_permissions(mode));
 }
+#define canon_mode(mode) \
+	(S_ISREG(mode) ? (S_IFREG | ce_permissions(mode)) : \
+	S_ISLNK(mode) ? S_IFLNK : S_IFDIR)
 
 #define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
 
diff --git a/combine-diff.c b/combine-diff.c
index a23894d86..f17aab33f 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -649,7 +649,7 @@ static int show_patch_diff(struct combine_diff_path *elem, int num_parent,
 			int len = st.st_size;
 			int cnt = 0;
 
-			elem->mode = DIFF_FILE_CANON_MODE(st.st_mode);
+			elem->mode = canon_mode(st.st_mode);
 			size = len;
 			result = xmalloc(len + 1);
 			while (cnt < len) {
diff --git a/diff-files.c b/diff-files.c
index b1c05b325..3e7f5f105 100644
--- a/diff-files.c
+++ b/diff-files.c
@@ -149,7 +149,7 @@ int main(int argc, const char **argv)
 					memcpy(combine.p.parent[stage-2].sha1,
 					       nce->sha1, 20);
 					combine.p.parent[stage-2].mode =
-						DIFF_FILE_CANON_MODE(mode);
+						canon_mode(mode);
 					combine.p.parent[stage-2].status =
 						DIFF_STATUS_MODIFIED;
 				}
@@ -198,7 +198,7 @@ int main(int argc, const char **argv)
 			continue;
 		oldmode = ntohl(ce->ce_mode);
 
-		newmode = DIFF_FILE_CANON_MODE(st.st_mode);
+		newmode = canon_mode(st.st_mode);
 		if (!trust_executable_bit &&
 		    S_ISREG(newmode) && S_ISREG(oldmode) &&
 		    ((newmode ^ oldmode) == 0111))
diff --git a/diff.c b/diff.c
index 8b37477af..e496905ba 100644
--- a/diff.c
+++ b/diff.c
@@ -300,7 +300,7 @@ void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
 		   unsigned short mode)
 {
 	if (mode) {
-		spec->mode = DIFF_FILE_CANON_MODE(mode);
+		spec->mode = canon_mode(mode);
 		memcpy(spec->sha1, sha1, 20);
 		spec->sha1_valid = !!memcmp(sha1, null_sha1, 20);
 	}
diff --git a/diff.h b/diff.h
index 8fac465a9..a268d16ff 100644
--- a/diff.h
+++ b/diff.h
@@ -4,17 +4,7 @@
 #ifndef DIFF_H
 #define DIFF_H
 
-#define DIFF_FILE_CANON_MODE(mode) \
-	(S_ISREG(mode) ? (S_IFREG | ce_permissions(mode)) : \
-	S_ISLNK(mode) ? S_IFLNK : S_IFDIR)
-
-struct tree_desc {
-	void *buf;
-	unsigned long size;
-};
-
-extern void update_tree_entry(struct tree_desc *);
-extern const unsigned char *tree_entry_extract(struct tree_desc *, const char **, unsigned int *);
+#include "tree-walk.h"
 
 struct diff_options;
 
diff --git a/merge-tree.c b/merge-tree.c
index 768d83a7c..50528d5e4 100644
--- a/merge-tree.c
+++ b/merge-tree.c
@@ -1,51 +1,11 @@
 #include "cache.h"
-#include "diff.h"
+#include "tree-walk.h"
 
 static const char merge_tree_usage[] = "git-merge-tree <base-tree> <branch1> <branch2>";
 static int resolve_directories = 1;
 
 static void merge_trees(struct tree_desc t[3], const char *base);
 
-static void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1)
-{
-	unsigned long size = 0;
-	void *buf = NULL;
-
-	if (sha1) {
-		buf = read_object_with_reference(sha1, "tree", &size, NULL);
-		if (!buf)
-			die("unable to read tree %s", sha1_to_hex(sha1));
-	}
-	desc->size = size;
-	desc->buf = buf;
-	return buf;
-}
-
-struct name_entry {
-	const unsigned char *sha1;
-	const char *path;
-	unsigned int mode;
-	int pathlen;
-};
-
-static void entry_clear(struct name_entry *a)
-{
-	memset(a, 0, sizeof(*a));
-}
-
-static int entry_compare(struct name_entry *a, struct name_entry *b)
-{
-	return base_name_compare(
-			a->path, a->pathlen, a->mode,
-			b->path, b->pathlen, b->mode);
-}
-
-static void entry_extract(struct tree_desc *t, struct name_entry *a)
-{
-	a->sha1 = tree_entry_extract(t, &a->path, &a->mode);
-	a->pathlen = strlen(a->path);
-}
-
 /* An empty entry never compares same, not even to another empty entry */
 static int same_entry(struct name_entry *a, struct name_entry *b)
 {
@@ -125,60 +85,6 @@ static void unresolved(const char *base, struct name_entry n[3])
 		printf("3 %06o %s %s%s\n", n[2].mode, sha1_to_hex(n[2].sha1), base, n[2].path);
 }
 
-typedef void (*traverse_callback_t)(int n, unsigned long mask, struct name_entry *entry, const char *base);
-
-static void traverse_trees(int n, struct tree_desc *t, const char *base, traverse_callback_t callback)
-{
-	struct name_entry *entry = xmalloc(n*sizeof(*entry));
-
-	for (;;) {
-		struct name_entry entry[3];
-		unsigned long mask = 0;
-		int i, last;
-
-		last = -1;
-		for (i = 0; i < n; i++) {
-			if (!t[i].size)
-				continue;
-			entry_extract(t+i, entry+i);
-			if (last >= 0) {
-				int cmp = entry_compare(entry+i, entry+last);
-
-				/*
-				 * Is the new name bigger than the old one?
-				 * Ignore it
-				 */
-				if (cmp > 0)
-					continue;
-				/*
-				 * Is the new name smaller than the old one?
-				 * Ignore all old ones
-				 */
-				if (cmp < 0)
-					mask = 0;
-			}
-			mask |= 1ul << i;
-			last = i;
-		}
-		if (!mask)
-			break;
-
-		/*
-		 * Update the tree entries we've walked, and clear
-		 * all the unused name-entries.
-		 */
-		for (i = 0; i < n; i++) {
-			if (mask & (1ul << i)) {
-				update_tree_entry(t+i);
-				continue;
-			}
-			entry_clear(entry + i);
-		}
-		callback(n, mask, entry, base);
-	}
-	free(entry);
-}
-
 /*
  * Merge two trees together (t[1] and t[2]), using a common base (t[0])
  * as the origin.
diff --git a/pack-objects.c b/pack-objects.c
index 49357c673..ccfaa5f60 100644
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -3,7 +3,7 @@
 #include "delta.h"
 #include "pack.h"
 #include "csum-file.h"
-#include "diff.h"
+#include "tree-walk.h"
 #include <sys/time.h>
 #include <signal.h>
 
diff --git a/rev-list.c b/rev-list.c
index f3a989cce..ee88f567a 100644
--- a/rev-list.c
+++ b/rev-list.c
@@ -4,7 +4,7 @@
 #include "commit.h"
 #include "tree.h"
 #include "blob.h"
-#include "diff.h"
+#include "tree-walk.h"
 #include "revision.h"
 
 /* bits #0-5 in revision.h */
diff --git a/tar-tree.c b/tar-tree.c
index 8d9e31c20..705b8fa1c 100644
--- a/tar-tree.c
+++ b/tar-tree.c
@@ -3,7 +3,7 @@
  */
 #include <time.h>
 #include "cache.h"
-#include "diff.h"
+#include "tree-walk.h"
 #include "commit.h"
 #include "strbuf.h"
 #include "tar.h"
diff --git a/tree-diff.c b/tree-diff.c
index d97842891..7bb610911 100644
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -9,34 +9,6 @@ static int nr_paths = 0;
 static const char **paths = NULL;
 static int *pathlens = NULL;
 
-void update_tree_entry(struct tree_desc *desc)
-{
-	void *buf = desc->buf;
-	unsigned long size = desc->size;
-	int len = strlen(buf) + 1 + 20;
-
-	if (size < len)
-		die("corrupt tree file");
-	desc->buf = buf + len;
-	desc->size = size - len;
-}
-
-const unsigned char *tree_entry_extract(struct tree_desc *desc, const char **pathp, unsigned int *modep)
-{
-	void *tree = desc->buf;
-	unsigned long size = desc->size;
-	int len = strlen(tree)+1;
-	const unsigned char *sha1 = tree + len;
-	const char *path = strchr(tree, ' ');
-	unsigned int mode;
-
-	if (!path || size < len + 20 || sscanf(tree, "%o", &mode) != 1)
-		die("corrupt tree file");
-	*pathp = path+1;
-	*modep = DIFF_FILE_CANON_MODE(mode);
-	return sha1;
-}
-
 static char *malloc_base(const char *base, const char *path, int pathlen)
 {
 	int baselen = strlen(base);
diff --git a/tree-walk.c b/tree-walk.c
new file mode 100644
index 000000000..0735f4046
--- /dev/null
+++ b/tree-walk.c
@@ -0,0 +1,116 @@
+#include "cache.h"
+#include "tree-walk.h"
+
+void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1)
+{
+	unsigned long size = 0;
+	void *buf = NULL;
+
+	if (sha1) {
+		buf = read_object_with_reference(sha1, "tree", &size, NULL);
+		if (!buf)
+			die("unable to read tree %s", sha1_to_hex(sha1));
+	}
+	desc->size = size;
+	desc->buf = buf;
+	return buf;
+}
+
+static int entry_compare(struct name_entry *a, struct name_entry *b)
+{
+	return base_name_compare(
+			a->path, a->pathlen, a->mode,
+			b->path, b->pathlen, b->mode);
+}
+
+static void entry_clear(struct name_entry *a)
+{
+	memset(a, 0, sizeof(*a));
+}
+
+static void entry_extract(struct tree_desc *t, struct name_entry *a)
+{
+	a->sha1 = tree_entry_extract(t, &a->path, &a->mode);
+	a->pathlen = strlen(a->path);
+}
+
+void update_tree_entry(struct tree_desc *desc)
+{
+	void *buf = desc->buf;
+	unsigned long size = desc->size;
+	int len = strlen(buf) + 1 + 20;
+
+	if (size < len)
+		die("corrupt tree file");
+	desc->buf = buf + len;
+	desc->size = size - len;
+}
+
+const unsigned char *tree_entry_extract(struct tree_desc *desc, const char **pathp, unsigned int *modep)
+{
+	void *tree = desc->buf;
+	unsigned long size = desc->size;
+	int len = strlen(tree)+1;
+	const unsigned char *sha1 = tree + len;
+	const char *path = strchr(tree, ' ');
+	unsigned int mode;
+
+	if (!path || size < len + 20 || sscanf(tree, "%o", &mode) != 1)
+		die("corrupt tree file");
+	*pathp = path+1;
+	*modep = canon_mode(mode);
+	return sha1;
+}
+
+void traverse_trees(int n, struct tree_desc *t, const char *base, traverse_callback_t callback)
+{
+	struct name_entry *entry = xmalloc(n*sizeof(*entry));
+
+	for (;;) {
+		struct name_entry entry[3];
+		unsigned long mask = 0;
+		int i, last;
+
+		last = -1;
+		for (i = 0; i < n; i++) {
+			if (!t[i].size)
+				continue;
+			entry_extract(t+i, entry+i);
+			if (last >= 0) {
+				int cmp = entry_compare(entry+i, entry+last);
+
+				/*
+				 * Is the new name bigger than the old one?
+				 * Ignore it
+				 */
+				if (cmp > 0)
+					continue;
+				/*
+				 * Is the new name smaller than the old one?
+				 * Ignore all old ones
+				 */
+				if (cmp < 0)
+					mask = 0;
+			}
+			mask |= 1ul << i;
+			last = i;
+		}
+		if (!mask)
+			break;
+
+		/*
+		 * Update the tree entries we've walked, and clear
+		 * all the unused name-entries.
+		 */
+		for (i = 0; i < n; i++) {
+			if (mask & (1ul << i)) {
+				update_tree_entry(t+i);
+				continue;
+			}
+			entry_clear(entry + i);
+		}
+		callback(n, mask, entry, base);
+	}
+	free(entry);
+}
+
diff --git a/tree-walk.h b/tree-walk.h
new file mode 100644
index 000000000..76893e36c
--- /dev/null
+++ b/tree-walk.h
@@ -0,0 +1,25 @@
+#ifndef TREE_WALK_H
+#define TREE_WALK_H
+
+struct tree_desc {
+	void *buf;
+	unsigned long size;
+};
+
+struct name_entry {
+	const unsigned char *sha1;
+	const char *path;
+	unsigned int mode;
+	int pathlen;
+};
+
+void update_tree_entry(struct tree_desc *);
+const unsigned char *tree_entry_extract(struct tree_desc *, const char **, unsigned int *);
+
+void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1);
+
+typedef void (*traverse_callback_t)(int n, unsigned long mask, struct name_entry *entry, const char *base);
+
+void traverse_trees(int n, struct tree_desc *t, const char *base, traverse_callback_t callback);
+
+#endif