From 463acbe1c60fc5009dac9d033df6c2b9c5037a91 Mon Sep 17 00:00:00 2001
From: "Shawn O. Pearce" <spearce@spearce.org>
Date: Mon, 14 Aug 2006 00:58:19 -0400
Subject: [PATCH] Added tree and commit writing to fast-import.

The tree of the current commit can be altered by file_change commands
before the commit gets written to the pack.  The file changes are
rather primitive as they simply allow removal of a tree entry or
setting/adding a tree entry.

Currently trees and commits aren't being deltafied when written to
the pack and branch reloading from the current pack doesn't work,
so at most 5 branches can be worked with at any one time.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
---
 fast-import.c | 906 ++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 729 insertions(+), 177 deletions(-)

diff --git a/fast-import.c b/fast-import.c
index 98c5d1cbd..4605b7469 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1,9 +1,70 @@
+/*
+Format of STDIN stream:
+
+  stream ::= cmd*;
+
+  cmd ::= new_blob
+        | new_commit
+        | new_branch
+        | new_tag
+        ;
+
+  new_blob ::= 'blob' blob_data;
+
+  new_commit ::= 'comt' ref_name author_committer_msg
+    file_change*
+    '0';
+
+  new_branch ::= 'brch' dst_ref_name src_ref_name;
+  dst_ref_name ::= ref_name;
+  src_ref_name ::= ref_name | sha1_exp;
+
+  new_tag ::= 'tagg' ref_name tag_name tagger_msg;
+
+  file_change ::= 'M' path_name hexsha1
+                | 'D' path_name
+                ;
+
+  author_committer_msg ::= len32
+    'author' sp name '<' email '>' ts tz lf
+    'committer' sp name '<' email '>' ts tz lf
+    lf
+    binary_data;
+
+  tagger_msg ::= len32
+    'tagger' sp name '<' email '>' ts tz lf
+    lf
+    binary_data;
+
+  blob_data ::= len32 binary_data; # max len is 2^32-1
+  path_name ::= len32 path;        # max len is PATH_MAX-1
+  ref_name  ::= len32 ref;         # max len is PATH_MAX-1
+  tag_name  ::= len32 tag;         # max len is PATH_MAX-1
+  sha1_exp  ::= len32 sha1exp;     # max len is PATH_MAX-1
+
+  len32 ::= # unsigned 32 bit value, native format;
+  binary_data ::= # file content, not interpreted;
+  sp ::= # ASCII space character;
+  lf ::= # ASCII newline (LF) character;
+  path ::= # GIT style file path, e.g. "a/b/c";
+  ref ::= # GIT ref name, e.g. "refs/heads/MOZ_GECKO_EXPERIMENT";
+  tag ::= # GIT tag name, e.g. "FIREFOX_1_5";
+  sha1exp ::= # Any valid GIT SHA1 expression;
+  hexsha1 ::= # SHA1 in hexadecimal format;
+  name ::= # valid GIT author/committer name;
+  email ::= # valid GIT author/committer email;
+  ts ::= # time since the epoch in seconds, ascii decimal;
+  tz ::= # GIT style timezone;
+*/
+
 #include "builtin.h"
 #include "cache.h"
 #include "object.h"
 #include "blob.h"
+#include "tree.h"
 #include "delta.h"
 #include "pack.h"
+#include "refs.h"
 #include "csum-file.h"
 
 struct object_entry
@@ -13,9 +74,9 @@ struct object_entry
 	unsigned char sha1[20];
 };
 
-struct object_entry_block
+struct object_entry_pool
 {
-	struct object_entry_block *next_block;
+	struct object_entry_pool *next_pool;
 	struct object_entry *next_free;
 	struct object_entry *end;
 	struct object_entry entries[FLEX_ARRAY]; /* more */
@@ -29,31 +90,55 @@ struct last_object
 	unsigned char sha1[20];
 };
 
-struct tree;
+struct mem_pool
+{
+	struct mem_pool *next_pool;
+	char *next_free;
+	char *end;
+	char space[FLEX_ARRAY]; /* more */
+};
+
+struct atom_str
+{
+	struct atom_str *next_atom;
+	int str_len;
+	char str_dat[FLEX_ARRAY]; /* more */
+};
+
+struct tree_content;
 struct tree_entry
 {
-	struct tree *tree;
-	mode_t mode;
+	struct tree_content *tree;
+	struct atom_str* name;
+	unsigned int mode;
 	unsigned char sha1[20];
-	char name[FLEX_ARRAY]; /* more */
 };
 
-struct tree
+struct tree_content
 {
-	struct last_object last_tree;
-	unsigned long entry_count;
-	struct tree_entry **entries;
+	unsigned int entry_capacity; /* must match avail_tree_content */
+	unsigned int entry_count;
+	struct tree_entry *entries[FLEX_ARRAY]; /* more */
+};
+
+struct avail_tree_content
+{
+	unsigned int entry_capacity; /* must match tree_content */
+	struct avail_tree_content *next_avail;
 };
 
 struct branch
 {
-	struct branch *next_branch;
-	struct tree_entry tree;
-	unsigned char sha1[20];
+	struct branch *table_next_branch;
+	struct branch *active_next_branch;
 	const char *name;
+	unsigned long last_commit;
+	struct tree_entry branch_tree;
+	unsigned char sha1[20];
 };
 
-/* Stats and misc. counters. */
+
+/* Stats and misc. counters */
 static int max_depth = 10;
 static unsigned long alloc_count;
 static unsigned long branch_count;
@@ -62,29 +147,50 @@ static unsigned long duplicate_count;
 static unsigned long object_count_by_type[9];
 static unsigned long duplicate_count_by_type[9];
 
-/* The .pack file */
+/* Memory pools */
+static size_t mem_pool_alloc = 2*1024*1024 - sizeof(struct mem_pool);
+static size_t total_allocd;
+static struct mem_pool *mem_pool;
+
+/* atom management */
+static unsigned int atom_table_sz = 4451;
+static unsigned int atom_cnt;
+static struct atom_str **atom_table;
+
+/* The .pack file being generated */
 static int pack_fd;
 static unsigned long pack_offset;
 static unsigned char pack_sha1[20];
 
 /* Table of objects we've written. */
-struct object_entry_block *blocks;
-struct object_entry *object_table[1 << 16];
+static unsigned int object_entry_alloc = 1000;
+static struct object_entry_pool *blocks;
+static struct object_entry *object_table[1 << 16];
 
 /* Our last blob */
-struct last_object last_blob;
+static struct last_object last_blob;
+
+/* Tree management */
+static unsigned int tree_entry_alloc = 1000;
+static void *avail_tree_entry;
+static unsigned int avail_tree_table_sz = 100;
+static struct avail_tree_content **avail_tree_table;
 
 /* Branch data */
-struct branch *branches;
-struct branch *current_branch;
+static unsigned int max_active_branches = 5;
+static unsigned int cur_active_branches;
+static unsigned int branch_table_sz = 1039;
+static struct branch **branch_table;
+static struct branch *active_branches;
+
 
 static void alloc_objects(int cnt)
 {
-	struct object_entry_block *b;
+	struct object_entry_pool *b;
 
-	b = xmalloc(sizeof(struct object_entry_block)
+	b = xmalloc(sizeof(struct object_entry_pool)
 		+ cnt * sizeof(struct object_entry));
-	b->next_block = blocks;
+	b->next_pool = blocks;
 	b->next_free = b->entries;
 	b->end = b->entries + cnt;
 	blocks = b;
@@ -96,18 +202,28 @@ static struct object_entry* new_object(unsigned char *sha1)
 	struct object_entry *e;
 
 	if (blocks->next_free == blocks->end)
-		alloc_objects(1000);
+		alloc_objects(object_entry_alloc);
 
 	e = blocks->next_free++;
 	memcpy(e->sha1, sha1, sizeof(e->sha1));
 	return e;
 }
 
+static struct object_entry* find_object(unsigned char *sha1)
+{
+	unsigned int h = sha1[0] << 8 | sha1[1];
+	struct object_entry *e;
+	for (e = object_table[h]; e; e = e->next)
+		if (!memcmp(sha1, e->sha1, sizeof(e->sha1)))
+			return e;
+	return NULL;
+}
+
 static struct object_entry* insert_object(unsigned char *sha1)
 {
 	unsigned int h = sha1[0] << 8 | sha1[1];
 	struct object_entry *e = object_table[h];
-	struct object_entry *p = 0;
+	struct object_entry *p = NULL;
 
 	while (e) {
 		if (!memcmp(sha1, e->sha1, sizeof(e->sha1)))
@@ -117,7 +233,7 @@ static struct object_entry* insert_object(unsigned char *sha1)
 	}
 
 	e = new_object(sha1);
-	e->next = 0;
+	e->next = NULL;
 	e->offset = 0;
 	if (p)
 		p->next = e;
@@ -126,64 +242,240 @@ static struct object_entry* insert_object(unsigned char *sha1)
 	return e;
 }
 
-static ssize_t yread(int fd, void *buffer, size_t length)
+static unsigned int hc_str(const char *s, size_t len)
+{
+	unsigned int r = 0;
+	while (len-- > 0)
+		r = r * 31 + *s++;
+	return r;
+}
+
+static void* pool_alloc(size_t len)
+{
+	struct mem_pool *p;
+	void *r;
+
+	for (p = mem_pool; p; p = p->next_pool)
+		if ((p->end - p->next_free >= len))
+			break;
+
+	if (!p) {
+		if (len >= (mem_pool_alloc/2)) {
+			total_allocd += len;
+			return xmalloc(len);
+		}
+		total_allocd += sizeof(struct mem_pool) + mem_pool_alloc;
+		p = xmalloc(sizeof(struct mem_pool) + mem_pool_alloc);
+		p->next_pool = mem_pool;
+		p->next_free = p->space;
+		p->end = p->next_free + mem_pool_alloc;
+		mem_pool = p;
+	}
+
+	r = p->next_free;
+	p->next_free += len;
+	return r;
+}
+
+static void* pool_calloc(size_t count, size_t size)
+{
+	size_t len = count * size;
+	void *r = pool_alloc(len);
+	memset(r, 0, len);
+	return r;
+}
+
+static char* pool_strdup(const char *s)
+{
+	char *r = pool_alloc(strlen(s) + 1);
+	strcpy(r, s);
+	return r;
+}
+
+static struct atom_str* to_atom(const char *s, size_t len)
+{
+	unsigned int hc = hc_str(s, len) % atom_table_sz;
+	struct atom_str *c;
+
+	for (c = atom_table[hc]; c; c = c->next_atom)
+		if (c->str_len == len && !strncmp(s, c->str_dat, len))
+			return c;
+
+	c = pool_alloc(sizeof(struct atom_str) + len + 1);
+	c->str_len = len;
+	strncpy(c->str_dat, s, len);
+	c->str_dat[len] = 0;
+	c->next_atom = atom_table[hc];
+	atom_table[hc] = c;
+	atom_cnt++;
+	return c;
+}
+
+static struct branch* lookup_branch(const char *name)
+{
+	unsigned int hc = hc_str(name, strlen(name)) % branch_table_sz;
+	struct branch *b;
+
+	for (b = branch_table[hc]; b; b = b->table_next_branch)
+		if (!strcmp(name, b->name))
+			return b;
+	return NULL;
+}
+
+static struct branch* new_branch(const char *name)
+{
+	unsigned int hc = hc_str(name, strlen(name)) % branch_table_sz;
+	struct branch* b = lookup_branch(name);
+
+	if (b)
+		die("Invalid attempt to create duplicate branch: %s", name);
+
+	b = pool_calloc(1, sizeof(struct branch));
+	b->name = pool_strdup(name);
+	b->table_next_branch = branch_table[hc];
+	branch_table[hc] = b;
+	branch_count++;
+	return b;
+}
+
+static unsigned int hc_entries(unsigned int cnt)
+{
+	cnt = cnt & 7 ? (cnt / 8) + 1 : cnt / 8;
+	return cnt < avail_tree_table_sz ? cnt : avail_tree_table_sz - 1;
+}
+
+static struct tree_content* new_tree_content(unsigned int cnt)
+{
+	struct avail_tree_content *f, *l = NULL;
+	struct tree_content *t;
+	unsigned int hc = hc_entries(cnt);
+
+	for (f = avail_tree_table[hc]; f; l = f, f = f->next_avail)
+		if (f->entry_capacity >= cnt)
+			break;
+
+	if (f) {
+		if (l)
+			l->next_avail = f->next_avail;
+		else
+			avail_tree_table[hc] = f->next_avail;
+	} else {
+		cnt = cnt & 7 ? ((cnt / 8) + 1) * 8 : cnt;
+		f = pool_alloc(sizeof(*t) + sizeof(t->entries[0]) * cnt);
+		f->entry_capacity = cnt;
+	}
+
+	t = (struct tree_content*)f;
+	t->entry_count = 0;
+	return t;
+}
+
+static void release_tree_entry(struct tree_entry *e);
+static void release_tree_content(struct tree_content *t)
+{
+	struct avail_tree_content *f = (struct avail_tree_content*)t;
+	unsigned int hc = hc_entries(f->entry_capacity);
+	unsigned int i;
+	for (i = 0; i < t->entry_count; i++)
+		release_tree_entry(t->entries[i]);
+	f->next_avail = avail_tree_table[hc];
+	avail_tree_table[hc] = f;
+}
+
+static struct tree_content* grow_tree_content(
+	struct tree_content *t,
+	int amt)
+{
+	struct tree_content *r = new_tree_content(t->entry_count + amt);
+	r->entry_count = t->entry_count;
+	memcpy(r->entries,t->entries,t->entry_count*sizeof(t->entries[0]));
+	release_tree_content(t);
+	return r;
+}
+
+static struct tree_entry* new_tree_entry()
+{
+	struct tree_entry *e;
+
+	if (!avail_tree_entry) {
+		unsigned int n = tree_entry_alloc;
+		avail_tree_entry = e = xmalloc(n * sizeof(struct tree_entry));
+		while (n--) {
+			*((void**)e) = e + 1;
+			e++;
+		}
+	}
+
+	e = avail_tree_entry;
+	avail_tree_entry = *((void**)e);
+	return e;
+}
+
+static void release_tree_entry(struct tree_entry *e)
+{
+	if (e->tree)
+		release_tree_content(e->tree);
+	*((void**)e) = avail_tree_entry;
+	avail_tree_entry = e;
+}
+
+static void yread(int fd, void *buffer, size_t length)
 {
 	ssize_t ret = 0;
 	while (ret < length) {
 		ssize_t size = xread(fd, (char *) buffer + ret, length - ret);
-		if (size < 0) {
-			return size;
-		}
-		if (size == 0) {
-			return ret;
-		}
+		if (!size)
+			die("Read from descriptor %i: end of stream", fd);
+		if (size < 0)
+			die("Read from descriptor %i: %s", fd, strerror(errno));
+		ret += size;
+	}
+}
+
+static int optional_read(int fd, void *buffer, size_t length)
+{
+	ssize_t ret = 0;
+	while (ret < length) {
+		ssize_t size = xread(fd, (char *) buffer + ret, length - ret);
+		if (!size && !ret)
+			return 1;
+		if (!size)
+			die("Read from descriptor %i: end of stream", fd);
+		if (size < 0)
+			die("Read from descriptor %i: %s", fd, strerror(errno));
 		ret += size;
 	}
-	return ret;
+	return 0;
 }
 
-static ssize_t ywrite(int fd, void *buffer, size_t length)
+static void ywrite(int fd, void *buffer, size_t length)
 {
 	ssize_t ret = 0;
 	while (ret < length) {
 		ssize_t size = xwrite(fd, (char *) buffer + ret, length - ret);
-		if (size < 0) {
-			return size;
-		}
-		if (size == 0) {
-			return ret;
-		}
+		if (!size)
+			die("Write to descriptor %i: end of file", fd);
+		if (size < 0)
+			die("Write to descriptor %i: %s", fd, strerror(errno));
 		ret += size;
 	}
-	return ret;
 }
 
-static const char* read_string()
+static const char* read_path()
 {
 	static char sn[PATH_MAX];
 	unsigned long slen;
 
-	if (yread(0, &slen, 4) != 4)
-		die("Can't obtain string");
+	yread(0, &slen, 4);
 	if (!slen)
-		return 0;
+		die("Expected string command parameter, didn't find one");
 	if (slen > (PATH_MAX - 1))
 		die("Can't handle excessive string length %lu", slen);
-
-	if (yread(0, sn, slen) != slen)
-		die("Can't obtain string of length %lu", slen);
+	yread(0, sn, slen);
 	sn[slen] = 0;
 	return sn;
 }
 
-static const char* read_required_string()
-{
-	const char *r = read_string();
-	if (!r)
-		die("Expected string command parameter, didn't find one");
-	return r;
-}
-
 static unsigned long encode_header(
 	enum object_type type,
 	unsigned long size,
@@ -234,13 +526,13 @@ static int store_object(
 	if (e->offset) {
 		duplicate_count++;
 		duplicate_count_by_type[type]++;
-		return 0;
+		return 1;
 	}
 	e->offset = pack_offset;
 	object_count++;
 	object_count_by_type[type]++;
 
-	if (last->data && last->depth < max_depth)
+	if (last && last->data && last->depth < max_depth)
 		delta = diff_delta(last->data, last->len,
 			dat, datlen,
 			&deltalen, 0);
@@ -255,18 +547,16 @@ static int store_object(
 		s.next_in = delta;
 		s.avail_in = deltalen;
 		hdrlen = encode_header(OBJ_DELTA, deltalen, hdr);
-		if (ywrite(pack_fd, hdr, hdrlen) != hdrlen)
-			die("Can't write object header: %s", strerror(errno));
-		if (ywrite(pack_fd, last->sha1, sizeof(sha1)) != sizeof(sha1))
-			die("Can't write object base: %s", strerror(errno));
+		ywrite(pack_fd, hdr, hdrlen);
+		ywrite(pack_fd, last->sha1, sizeof(sha1));
 		pack_offset += hdrlen + sizeof(sha1);
 	} else {
-		last->depth = 0;
+		if (last)
+			last->depth = 0;
 		s.next_in = dat;
 		s.avail_in = datlen;
 		hdrlen = encode_header(type, datlen, hdr);
-		if (ywrite(pack_fd, hdr, hdrlen) != hdrlen)
-			die("Can't write object header: %s", strerror(errno));
+		ywrite(pack_fd, hdr, hdrlen);
 		pack_offset += hdrlen;
 	}
 
@@ -276,18 +566,220 @@ static int store_object(
 		/* nothing */;
 	deflateEnd(&s);
 
-	if (ywrite(pack_fd, out, s.total_out) != s.total_out)
-		die("Failed writing compressed data %s", strerror(errno));
+	ywrite(pack_fd, out, s.total_out);
 	pack_offset += s.total_out;
 
 	free(out);
 	if (delta)
 		free(delta);
-	if (last->data)
-		free(last->data);
-	last->data = dat;
-	last->len = datlen;
-	memcpy(last->sha1, sha1, sizeof(sha1));
+	if (last) {
+		if (last->data)
+			free(last->data);
+		last->data = dat;
+		last->len = datlen;
+		memcpy(last->sha1, sha1, sizeof(sha1));
+	}
+	return 0;
+}
+
+static const char *get_mode(const char *str, unsigned int *modep)
+{
+	unsigned char c;
+	unsigned int mode = 0;
+
+	while ((c = *str++) != ' ') {
+		if (c < '0' || c > '7')
+			return NULL;
+		mode = (mode << 3) + (c - '0');
+	}
+	*modep = mode;
+	return str;
+}
+
+static void load_tree(struct tree_entry *root)
+{
+	struct object_entry *myoe;
+	struct tree_content *t;
+	unsigned long size;
+	char *buf;
+	const char *c;
+	char type[20];
+
+	root->tree = t = new_tree_content(8);
+	if (!memcmp(root->sha1, null_sha1, 20))
+		return;
+
+	myoe = find_object(root->sha1);
+	if (myoe) {
+		die("FIXME");
+	} else {
+		buf = read_sha1_file(root->sha1, type, &size);
+		if (!buf || strcmp(type, tree_type))
+			die("Can't load existing tree %s", sha1_to_hex(root->sha1));
+	}
+
+	c = buf;
+	while (c != (buf + size)) {
+		struct tree_entry *e = new_tree_entry();
+
+		if (t->entry_count == t->entry_capacity)
+			root->tree = t = grow_tree_content(t, 8);
+		t->entries[t->entry_count++] = e;
+
+		e->tree = NULL;
+		c = get_mode(c, &e->mode);
+		if (!c)
+			die("Corrupt mode in %s", sha1_to_hex(root->sha1));
+		e->name = to_atom(c, strlen(c));
+		c += e->name->str_len + 1;
+		memcpy(e->sha1, c, sizeof(e->sha1));
+		c += 20;
+	}
+	free(buf);
+}
+
+static int tecmp (const void *_a, const void *_b)
+{
+	struct tree_entry *a = *((struct tree_entry**)_a);
+	struct tree_entry *b = *((struct tree_entry**)_b);
+	return base_name_compare(
+		a->name->str_dat, a->name->str_len, a->mode,
+		b->name->str_dat, b->name->str_len, b->mode);
+}
+
+static void store_tree(struct tree_entry *root)
+{
+	struct tree_content *t = root->tree;
+	unsigned int i;
+	size_t maxlen;
+	char *buf, *c;
+
+	if (memcmp(root->sha1, null_sha1, 20))
+		return;
+
+	maxlen = 0;
+	for (i = 0; i < t->entry_count; i++) {
+		maxlen += t->entries[i]->name->str_len + 34;
+		if (t->entries[i]->tree)
+			store_tree(t->entries[i]);
+	}
+
+	qsort(t->entries, t->entry_count, sizeof(t->entries[0]), tecmp);
+	buf = c = xmalloc(maxlen);
+	for (i = 0; i < t->entry_count; i++) {
+		struct tree_entry *e = t->entries[i];
+		c += sprintf(c, "%o", e->mode);
+		*c++ = ' ';
+		strcpy(c, e->name->str_dat);
+		c += e->name->str_len + 1;
+		memcpy(c, e->sha1, 20);
+		c += 20;
+	}
+	store_object(OBJ_TREE, buf, c - buf, NULL, root->sha1);
+	free(buf);
+}
+
+static int tree_content_set(
+	struct tree_entry *root,
+	const char *p,
+	const unsigned char *sha1,
+	const unsigned int mode)
+{
+	struct tree_content *t = root->tree;
+	const char *slash1;
+	unsigned int i, n;
+	struct tree_entry *e;
+
+	slash1 = strchr(p, '/');
+	if (slash1)
+		n = slash1 - p;
+	else
+		n = strlen(p);
+
+	for (i = 0; i < t->entry_count; i++) {
+		e = t->entries[i];
+		if (e->name->str_len == n && !strncmp(p, e->name->str_dat, n)) {
+			if (!slash1) {
+				if (e->mode == mode && !memcmp(e->sha1, sha1, 20))
+					return 0;
+				e->mode = mode;
+				memcpy(e->sha1, sha1, 20);
+				if (e->tree) {
+					release_tree_content(e->tree);
+					e->tree = NULL;
+				}
+				memcpy(root->sha1, null_sha1, 20);
+				return 1;
+			}
+			if (!S_ISDIR(e->mode)) {
+				e->tree = new_tree_content(8);
+				e->mode = 040000;
+			}
+			if (!e->tree)
+				load_tree(e);
+			if (tree_content_set(e, slash1 + 1, sha1, mode)) {
+				memcpy(root->sha1, null_sha1, 20);
+				return 1;
+			}
+			return 0;
+		}
+	}
+
+	if (t->entry_count == t->entry_capacity)
+		root->tree = t = grow_tree_content(t, 8);
+	e = new_tree_entry();
+	e->name = to_atom(p, n);
+	t->entries[t->entry_count++] = e;
+	if (slash1) {
+		e->tree = new_tree_content(8);
+		e->mode = 040000;
+		tree_content_set(e, slash1 + 1, sha1, mode);
+	} else {
+		e->tree = NULL;
+		e->mode = mode;
+		memcpy(e->sha1, sha1, 20);
+	}
+	memcpy(root->sha1, null_sha1, 20);
+	return 1;
+}
+
+static int tree_content_remove(struct tree_entry *root, const char *p)
+{
+	struct tree_content *t = root->tree;
+	const char *slash1;
+	unsigned int i, n;
+	struct tree_entry *e;
+
+	slash1 = strchr(p, '/');
+	if (slash1)
+		n = slash1 - p;
+	else
+		n = strlen(p);
+
+	for (i = 0; i < t->entry_count; i++) {
+		e = t->entries[i];
+		if (e->name->str_len == n && !strncmp(p, e->name->str_dat, n)) {
+			if (!slash1 || !S_ISDIR(e->mode))
+				goto del_entry;
+			if (!e->tree)
+				load_tree(e);
+			if (tree_content_remove(e, slash1 + 1)) {
+				if (!e->tree->entry_count)
+					goto del_entry;
+				memcpy(root->sha1, null_sha1, 20);
+				return 1;
+			}
+			return 0;
+		}
+	}
+	return 0;
+
+del_entry:
+	for (i++; i < t->entry_count; i++)
+		t->entries[i-1] = t->entries[i];
+	t->entry_count--;
+	release_tree_entry(e);
+	memcpy(root->sha1, null_sha1, 20);
 	return 1;
 }
 
@@ -298,13 +790,9 @@ static void init_pack_header()
 	unsigned long zero = 0;
 
 	version = htonl(version);
-
-	if (ywrite(pack_fd, (char*)magic, 4) != 4)
-		die("Can't write pack magic: %s", strerror(errno));
-	if (ywrite(pack_fd, &version, 4) != 4)
-		die("Can't write pack version: %s", strerror(errno));
-	if (ywrite(pack_fd, &zero, 4) != 4)
-		die("Can't write 0 object count: %s", strerror(errno));
+	ywrite(pack_fd, (char*)magic, 4);
+	ywrite(pack_fd, &version, 4);
+	ywrite(pack_fd, &zero, 4);
 	pack_offset = 4 * 3;
 }
 
@@ -320,14 +808,12 @@ static void fixup_header_footer()
 		die("Failed seeking to start: %s", strerror(errno));
 
 	SHA1_Init(&c);
-	if (yread(pack_fd, hdr, 8) != 8)
-		die("Failed reading header: %s", strerror(errno));
+	yread(pack_fd, hdr, 8);
 	SHA1_Update(&c, hdr, 8);
 
 	cnt = htonl(object_count);
 	SHA1_Update(&c, &cnt, 4);
-	if (ywrite(pack_fd, &cnt, 4) != 4)
-		die("Failed writing object count: %s", strerror(errno));
+	ywrite(pack_fd, &cnt, 4);
 
 	buf = xmalloc(128 * 1024);
 	for (;;) {
@@ -339,8 +825,7 @@ static void fixup_header_footer()
 	free(buf);
 
 	SHA1_Final(pack_sha1, &c);
-	if (ywrite(pack_fd, pack_sha1, sizeof(pack_sha1)) != sizeof(pack_sha1))
-		die("Failed writing pack checksum: %s", strerror(errno));
+	ywrite(pack_fd, pack_sha1, sizeof(pack_sha1));
 }
 
 static int oecmp (const void *_a, const void *_b)
@@ -355,14 +840,14 @@ static void write_index(const char *idx_name)
 	struct sha1file *f;
 	struct object_entry **idx, **c, **last;
 	struct object_entry *e;
-	struct object_entry_block *o;
+	struct object_entry_pool *o;
 	unsigned int array[256];
 	int i;
 
 	/* Build the sorted table of object IDs. */
 	idx = xmalloc(object_count * sizeof(struct object_entry*));
 	c = idx;
-	for (o = blocks; o; o = o->next_block)
+	for (o = blocks; o; o = o->next_pool)
 		for (e = o->entries; e != o->next_free; e++)
 			*c++ = e;
 	last = idx + object_count;
@@ -393,118 +878,175 @@ static void write_index(const char *idx_name)
 	free(idx);
 }
 
-static void new_blob()
+static void dump_branches()
+{
+	static const char *msg = "fast-import";
+	unsigned int i;
+	struct branch *b;
+	struct ref_lock *lock;
+
+	for (i = 0; i < branch_table_sz; i++) {
+		for (b = branch_table[i]; b; b = b->table_next_branch) {
+			lock = lock_any_ref_for_update(b->name, NULL, 0);
+			if (!lock || write_ref_sha1(lock, b->sha1, msg) < 0)
+				die("Can't write %s", b->name);
+		}
+	}
+}
+
+static void cmd_new_blob()
 {
 	unsigned long datlen;
+	unsigned char sha1[20];
 	void *dat;
 
-	if (yread(0, &datlen, 4) != 4)
-		die("Can't obtain blob length");
-
+	yread(0, &datlen, 4);
 	dat = xmalloc(datlen);
-	if (yread(0, dat, datlen) != datlen)
-		die("Con't obtain %lu bytes of blob data", datlen);
-
-	if (!store_object(OBJ_BLOB, dat, datlen, &last_blob, 0))
+	yread(0, dat, datlen);
+	if (store_object(OBJ_BLOB, dat, datlen, &last_blob, sha1))
 		free(dat);
 }
 
-static struct branch* lookup_branch(const char *name)
+static void unload_one_branch()
 {
-	struct branch *b;
-	for (b = branches; b; b = b->next_branch) {
-		if (!strcmp(name, b->name))
-			return b;
+	while (cur_active_branches >= max_active_branches) {
+		unsigned long min_commit = ULONG_MAX;
+		struct branch *e, *l = NULL, *p = NULL;
+
+		for (e = active_branches; e; e = e->active_next_branch) {
+			if (e->last_commit < min_commit) {
+				p = l;
+				min_commit = e->last_commit;
+			}
+			l = e;
+		}
+
+		if (p) {
+			e = p->active_next_branch;
+			p->active_next_branch = e->active_next_branch;
+		} else {
+			e = active_branches;
+			active_branches = e->active_next_branch;
+		}
+		e->active_next_branch = NULL;
+		if (e->branch_tree.tree) {
+			release_tree_content(e->branch_tree.tree);
+			e->branch_tree.tree = NULL;
+		}
+		cur_active_branches--;
 	}
-	die("No branch named '%s' has been declared", name);
 }
 
-static struct tree* deep_copy_tree (struct tree *t)
+static void load_branch(struct branch *b)
 {
-	struct tree *r = xmalloc(sizeof(struct tree));
-	unsigned long i;
-
-	if (t->last_tree.data) {
-		r->last_tree.data = xmalloc(t->last_tree.len);
-		r->last_tree.len = t->last_tree.len;
-		r->last_tree.depth = t->last_tree.depth;
-		memcpy(r->last_tree.data, t->last_tree.data, t->last_tree.len);
-		memcpy(r->last_tree.sha1, t->last_tree.sha1, sizeof(t->last_tree.sha1));
-	}
-
-	r->entry_count = t->entry_count;
-	r->entries = xmalloc(t->entry_count * sizeof(struct tree_entry*));
-	for (i = 0; i < t->entry_count; i++) {
-		struct tree_entry *a = t->entries[i];
-		struct tree_entry *b;
-
-		b = xmalloc(sizeof(struct tree_entry) + strlen(a->name) + 1);
-		b->tree = a->tree ? deep_copy_tree(a->tree) : 0;
-		b->mode = a->mode;
-		memcpy(b->sha1, a->sha1, sizeof(a->sha1));
-		strcpy(b->name, a->name);
-		r->entries[i] = b;
-	}
-
-	return r;
+	load_tree(&b->branch_tree);
+	b->active_next_branch = active_branches;
+	active_branches = b;
+	cur_active_branches++;
 }
 
-static void store_tree (struct tree_entry *e)
+static void file_change_m(struct branch *b)
 {
-	struct tree *t = e->tree;
-	unsigned long maxlen, i;
-	char *buf, *c;
+	const char *path = read_path();
+	char hexsha1[41];
+	unsigned char sha1[20];
 
-	if (memcmp(null_sha1, e->sha1, sizeof(e->sha1)))
-		return;
+	yread(0, hexsha1, 40);
+	hexsha1[40] = 0;
 
-	maxlen = t->entry_count * 32;
-	for (i = 0; i < t->entry_count; i++)
-		maxlen += strlen(t->entries[i]->name);
+	if (get_sha1_hex(hexsha1, sha1))
+		die("Invalid sha1 %s for %s", hexsha1, path);
 
-	buf = c = xmalloc(maxlen);
-	for (i = 0; i < t->entry_count; i++) {
-		struct tree_entry *e = t->entries[i];
-		c += sprintf(c, "%o %s", e->mode, e->name) + 1;
-		if (e->tree)
-			store_tree(e);
-		memcpy(c, e->sha1, sizeof(e->sha1));
-		c += sizeof(e->sha1);
-	}
+	tree_content_set(&b->branch_tree, path, sha1, 0100644);
+}
 
-	if (!store_object(OBJ_TREE, buf, c - buf, &t->last_tree, e->sha1))
-		free(buf);
+static void file_change_d(struct branch *b)
+{
+	tree_content_remove(&b->branch_tree, read_path());
 }
 
-static void new_branch()
+static void cmd_new_commit()
 {
-	struct branch *nb = xcalloc(1, sizeof(struct branch));
-	const char *source_name;
+	static const unsigned int max_hdr_len = 94;
+	const char *name = read_path();
+	struct branch *b = lookup_branch(name);
+	unsigned int acmsglen;
+	char *body, *c;
+
+	if (!b)
+		die("Branch not declared: %s", name);
+	if (!b->branch_tree.tree) {
+		unload_one_branch();
+		load_branch(b);
+	}
 
-	nb->name = strdup(read_required_string());
-	source_name = read_string();
-	if (source_name) {
-		struct branch *sb = lookup_branch(source_name);
-		nb->tree.tree = deep_copy_tree(sb->tree.tree);
-		memcpy(nb->tree.sha1, sb->tree.sha1, sizeof(sb->tree.sha1));
-		memcpy(nb->sha1, sb->sha1, sizeof(sb->sha1));
-	} else {
-		nb->tree.tree = xcalloc(1, sizeof(struct tree));
-		nb->tree.tree->entries = xmalloc(8*sizeof(struct tree_entry*));
+	/* author_committer_msg */
+	yread(0, &acmsglen, 4);
+	body = xmalloc(acmsglen + max_hdr_len);
+	c = body + max_hdr_len;
+	yread(0, c, acmsglen);
+
+	/* file_change* */
+	for (;;) {
+		unsigned char cmd;
+		yread(0, &cmd, 1);
+		if (cmd == '0')
+			break;
+		else if (cmd == 'M')
+			file_change_m(b);
+		else if (cmd == 'D')
+			file_change_d(b);
+		else
+			die("Unsupported file_change: %c", cmd);
 	}
-	nb->next_branch = branches;
-	branches = nb;
-	branch_count++;
-}
 
-static void set_branch()
-{
-	current_branch = lookup_branch(read_required_string());
+	if (memcmp(b->sha1, null_sha1, 20)) {
+		sprintf(c - 48, "parent %s", sha1_to_hex(b->sha1));
+		*(c - 1) = '\n';
+		c -= 48;
+	}
+	store_tree(&b->branch_tree);
+	sprintf(c - 46, "tree %s", sha1_to_hex(b->branch_tree.sha1));
+	*(c - 1) = '\n';
+	c -= 46;
+
+	store_object(OBJ_COMMIT,
+		c, (body + max_hdr_len + acmsglen) - c,
+		NULL, b->sha1);
+	free(body);
+	b->last_commit = object_count_by_type[OBJ_COMMIT];
 }
 
-static void commit()
+static void cmd_new_branch()
 {
-	store_tree(&current_branch->tree);
+	struct branch *b = new_branch(read_path());
+	const char *base = read_path();
+	struct branch *s = lookup_branch(base);
+
+	if (!strcmp(b->name, base))
+		die("Can't create a branch from itself: %s", base);
+	else if (s) {
+		memcpy(b->sha1, s->sha1, 20);
+		memcpy(b->branch_tree.sha1, s->branch_tree.sha1, 20);
+	}
+	else if (!get_sha1(base, b->sha1)) {
+		if (!memcmp(b->sha1, null_sha1, 20))
+			memcpy(b->branch_tree.sha1, null_sha1, 20);
+		else {
+			unsigned long size;
+			char *buf;
+
+			buf = read_object_with_reference(b->sha1,
+				type_names[OBJ_COMMIT], &size, b->sha1);
+			if (!buf || size < 46)
+				die("Not a valid commit: %s", base);
+			if (memcmp("tree ", buf, 5)
+				|| get_sha1_hex(buf + 5, b->branch_tree.sha1))
+				die("The commit %s is corrupt", sha1_to_hex(b->sha1));
+			free(buf);
+		}
+	} else
+		die("Not a SHA1 or branch: %s", base);
 }
 
 int main(int argc, const char **argv)
@@ -515,6 +1057,9 @@ int main(int argc, const char **argv)
 	char *idx_name;
 	struct stat sb;
 
+	setup_ident();
+	git_config(git_default_config);
+
 	pack_name = xmalloc(strlen(base_name) + 6);
 	sprintf(pack_name, "%s.pack", base_name);
 	idx_name = xmalloc(strlen(base_name) + 5);
@@ -525,17 +1070,21 @@ int main(int argc, const char **argv)
 		die("Can't create %s: %s", pack_name, strerror(errno));
 
 	alloc_objects(est_obj_cnt);
+
+	atom_table = xcalloc(atom_table_sz, sizeof(struct atom_str*));
+	branch_table = xcalloc(branch_table_sz, sizeof(struct branch*));
+	avail_tree_table = xcalloc(avail_tree_table_sz, sizeof(struct avail_tree_content*));
+
 	init_pack_header();
 	for (;;) {
 		unsigned long cmd;
-		if (yread(0, &cmd, 4) != 4)
+		if (optional_read(0, &cmd, 4))
 			break;
 
-		switch (cmd) {
-		case 'blob': new_blob();   break;
-		case 'newb': new_branch(); break;
-		case 'setb': set_branch(); break;
-		case 'comt': commit();     break;
+		switch (ntohl(cmd)) {
+		case 'blob': cmd_new_blob();   break;
+		case 'comt': cmd_new_commit(); break;
+		case 'brch': cmd_new_branch(); break;
 		default:
 			die("Invalid command %lu", cmd);
 		}
@@ -543,6 +1092,7 @@ int main(int argc, const char **argv)
 	fixup_header_footer();
 	close(pack_fd);
 	write_index(idx_name);
+	dump_branches();
 
 	fprintf(stderr, "%s statistics:\n", argv[0]);
 	fprintf(stderr, "---------------------------------------------------\n");
@@ -553,6 +1103,8 @@ int main(int argc, const char **argv)
 	fprintf(stderr, "      commits:   %10lu (%10lu duplicates)\n", object_count_by_type[OBJ_COMMIT], duplicate_count_by_type[OBJ_COMMIT]);
 	fprintf(stderr, "      tags   :   %10lu (%10lu duplicates)\n", object_count_by_type[OBJ_TAG], duplicate_count_by_type[OBJ_TAG]);
 	fprintf(stderr, "Total branches:  %10lu\n", branch_count);
+	fprintf(stderr, "Total atoms:     %10u\n", atom_cnt);
+	fprintf(stderr, "Memory pools:    %10lu MiB\n", total_allocd/(1024*1024));
 	fprintf(stderr, "---------------------------------------------------\n");
 
 	stat(pack_name, &sb);
-- 
2.26.2