Use common "revision.h" header for both fsck and rev-tree.

It's really a very generic thing: the notion of one sha1 revision
referring to another one. "fsck" uses it for all nodes, and "rev-tree"
only tracks commit-node relationships, but the code was already
the same - now we just make that explicit by moving it to a common
header file.

fsck-cache.c

@@ -3,120 +3,11 @@
 #include <sys/types.h>
 #include <dirent.h>
 
-/*
- * The low 16 bits of the "flags" field shows whether
- * a commit is part of the path to the root for that
- * parent.
- *
- * Bit 16 is an internal flag that we've seen the
- * definition for this rev, and not just seen it as
- * a parent target.
- */
-#define MAX_COMMITS (16)
-#define marked(rev)	((rev)->flags & 0xffff)
-#define SEEN 0x10000
-#define USED 0x20000
-#define REACHABLE 0x40000
+#include "revision.h"
 
 static int show_unreachable = 0;
 static unsigned char head_sha1[20];
 
-struct parent {
-	struct revision *parent;
-	struct parent *next;
-};
-
-struct revision {
-	unsigned int flags;
-	unsigned char sha1[20];
-	unsigned long date;
-	struct parent *parent;
-};
-
-static struct revision **revs;
-static int nr_revs, rev_allocs;
-
-static int find_rev(unsigned char *sha1)
-{
-	int first = 0, last = nr_revs;
-
-	while (first < last) {
-		int next = (first + last) / 2;
-		struct revision *rev = revs[next];
-		int cmp;
-
-		cmp = memcmp(sha1, rev->sha1, 20);
-		if (!cmp)
-			return next;
-		if (cmp < 0) {
-			last = next;
-			continue;
-		}
-		first = next+1;
-	}
-	return -first-1;
-}
-
-static struct revision *lookup_rev(unsigned char *sha1)
-{
-	int pos = find_rev(sha1);
-	struct revision *n;
-
-	if (pos >= 0)
-		return revs[pos];
-	
-	pos = -pos-1;
-
-	if (rev_allocs == nr_revs) {
-		rev_allocs = alloc_nr(rev_allocs);
-		revs = realloc(revs, rev_allocs * sizeof(struct revision *));
-	}
-	n = malloc(sizeof(struct revision));
-
-	n->flags = 0;
-	memcpy(n->sha1, sha1, 20);
-	n->parent = NULL;
-
-	/* Insert it into the right place */
-	memmove(revs + pos + 1, revs + pos, (nr_revs - pos) * sizeof(struct revision *));
-	revs[pos] = n;
-	nr_revs++;
-
-	return n;
-}
-
-static struct revision *add_relationship(struct revision *rev, unsigned char *needs)
-{
-	struct revision *parent_rev = lookup_rev(needs);
-	struct parent **pp = &rev->parent, *p;
-
-	while ((p = *pp) != NULL) {
-		if (p->parent == parent_rev)
-			return parent_rev;
-		pp = &p->next;
-	}
-
-	p = malloc(sizeof(*p));
-	p->parent = parent_rev;
-	p->next = NULL;
-	*pp = p;
-	return parent_rev;
-}
-
-static void mark_reachable(struct revision *rev)
-{
-	struct parent *p = rev->parent;
-
-	/* If we've been here already, don't bother */
-	if (rev->flags & REACHABLE)
-		return;
-	rev->flags |= REACHABLE | USED;
-	while (p) {
-		mark_reachable(p->parent);
-		p = p->next;
-	}
-}
-
 static void check_connectivity(void)
 {
 	int i;

rev-tree.c

 #define _XOPEN_SOURCE /* glibc2 needs this */
 #include <time.h>
 #include <ctype.h>
+
 #include "cache.h"
+#include "revision.h"
 
 /*
- * The low 16 bits of the "flags" field shows whether
- * a commit is part of the path to the root for that
- * parent.
- *
- * Bit 16 is an internal flag that we've seen the
- * definition for this rev, and not just seen it as
- * a parent target.
+ * revision.h leaves the low 16 bits of the "flags" field of the
+ * revision data structure unused. We use it for a "reachable from
+ * this commit <N>" bitmask.
  */
-#define MAX_COMMITS (16)
-#define marked(rev)	((rev)->flags & 0xffff)
-#define SEEN 0x10000
+#define MAX_COMMITS 16
 
 static int show_edges = 0;
 static int basemask = 0;
 
-struct parent {
-	struct revision *parent;
-	struct parent *next;
-};
-
-struct revision {
-	unsigned int flags;
-	unsigned char sha1[20];
-	unsigned long date;
-	struct parent *parent;
-};
-
-static struct revision **revs;
-static int nr_revs, rev_allocs;
-
-static int find_rev(unsigned char *sha1)
-{
-	int first = 0, last = nr_revs;
-
-	while (first < last) {
-		int next = (first + last) / 2;
-		struct revision *rev = revs[next];
-		int cmp;
-
-		cmp = memcmp(sha1, rev->sha1, 20);
-		if (!cmp)
-			return next;
-		if (cmp < 0) {
-			last = next;
-			continue;
-		}
-		first = next+1;
-	}
-	return -first-1;
-}
-
-static struct revision *lookup_rev(unsigned char *sha1)
-{
-	int pos = find_rev(sha1);
-	struct revision *n;
-
-	if (pos >= 0)
-		return revs[pos];
-	
-	pos = -pos-1;
-
-	if (rev_allocs == nr_revs) {
-		rev_allocs = alloc_nr(rev_allocs);
-		revs = realloc(revs, rev_allocs * sizeof(struct revision *));
-	}
-	n = malloc(sizeof(struct revision));
-
-	n->flags = 0;
-	memcpy(n->sha1, sha1, 20);
-	n->parent = NULL;
-
-	/* Insert it into the right place */
-	memmove(revs + pos + 1, revs + pos, (nr_revs - pos) * sizeof(struct revision *));
-	revs[pos] = n;
-	nr_revs++;
-
-	return n;
-}
-
-static int add_relationship(struct revision *rev, unsigned char *parent_sha)
-{
-	struct revision *parent_rev = lookup_rev(parent_sha);
-	struct parent **pp = &rev->parent, *p;
-
-	while ((p = *pp) != NULL) {
-		if (p->parent == parent_rev)
-			return 0;
-		pp = &p->next;
-	}
-
-	p = malloc(sizeof(*p));
-	p->parent = parent_rev;
-	p->next = NULL;
-	*pp = p;
-	return 1;
-}
-
 static unsigned long parse_time(const char *buf)
 {
 	char c, *p;

revision.h

+#ifndef REVISION_H
+#define REVISION_H
+
+/*
+ * The low 16 bits of the "flags" field shows whether
+ * a commit is part of the path to the root for that
+ * parent.
+ *
+ * Bit 16 is an internal flag that we've seen the
+ * definition for this rev, and not just seen it as
+ * a parent target.
+ */
+#define marked(rev)	((rev)->flags & 0xffff)
+#define SEEN 0x10000
+#define USED 0x20000
+#define REACHABLE 0x40000
+
+struct parent {
+	struct revision *parent;
+	struct parent *next;
+};
+
+struct revision {
+	unsigned int flags;
+	unsigned char sha1[20];
+	unsigned long date;
+	struct parent *parent;
+};
+
+static struct revision **revs;
+static int nr_revs, rev_allocs;
+
+static int find_rev(unsigned char *sha1)
+{
+	int first = 0, last = nr_revs;
+
+	while (first < last) {
+		int next = (first + last) / 2;
+		struct revision *rev = revs[next];
+		int cmp;
+
+		cmp = memcmp(sha1, rev->sha1, 20);
+		if (!cmp)
+			return next;
+		if (cmp < 0) {
+			last = next;
+			continue;
+		}
+		first = next+1;
+	}
+	return -first-1;
+}
+
+static struct revision *lookup_rev(unsigned char *sha1)
+{
+	int pos = find_rev(sha1);
+	struct revision *n;
+
+	if (pos >= 0)
+		return revs[pos];
+	
+	pos = -pos-1;
+
+	if (rev_allocs == nr_revs) {
+		rev_allocs = alloc_nr(rev_allocs);
+		revs = realloc(revs, rev_allocs * sizeof(struct revision *));
+	}
+	n = malloc(sizeof(struct revision));
+
+	n->flags = 0;
+	memcpy(n->sha1, sha1, 20);
+	n->parent = NULL;
+
+	/* Insert it into the right place */
+	memmove(revs + pos + 1, revs + pos, (nr_revs - pos) * sizeof(struct revision *));
+	revs[pos] = n;
+	nr_revs++;
+
+	return n;
+}
+
+static struct revision *add_relationship(struct revision *rev, unsigned char *needs)
+{
+	struct revision *parent_rev = lookup_rev(needs);
+	struct parent **pp = &rev->parent, *p;
+
+	while ((p = *pp) != NULL) {
+		if (p->parent == parent_rev)
+			return parent_rev;
+		pp = &p->next;
+	}
+
+	p = malloc(sizeof(*p));
+	p->parent = parent_rev;
+	p->next = NULL;
+	*pp = p;
+	return parent_rev;
+}
+
+static void mark_reachable(struct revision *rev)
+{
+	struct parent *p = rev->parent;
+
+	/* If we've been here already, don't bother */
+	if (rev->flags & REACHABLE)
+		return;
+	rev->flags |= REACHABLE | USED;
+	while (p) {
+		mark_reachable(p->parent);
+		p = p->next;
+	}
+}
+
+#endif /* REVISION_H */