Builtin git-tar-tree.

Signed-off-by: Peter Eriksen <s022018@student.dtu.dk>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 351 insertions, 0 deletions

diff --git a/builtin-tar-tree.c b/builtin-tar-tree.c
new file mode 100644
index 000000000..6ada04ce3
--- /dev/null
+++ b/builtin-tar-tree.c
@@ -0,0 +1,351 @@
+/*
+ * Copyright (c) 2005, 2006 Rene Scharfe
+ */
+#include <time.h>
+#include "cache.h"
+#include "tree-walk.h"
+#include "commit.h"
+#include "strbuf.h"
+#include "tar.h"
+#include "builtin.h"
+
+#define RECORDSIZE	(512)
+#define BLOCKSIZE	(RECORDSIZE * 20)
+
+static const char tar_tree_usage[] = "git-tar-tree <key> [basedir]";
+
+static char block[BLOCKSIZE];
+static unsigned long offset;
+
+static time_t archive_time;
+
+/* tries hard to write, either succeeds or dies in the attempt */
+static void reliable_write(void *buf, unsigned long size)
+{
+	while (size > 0) {
+		long ret = xwrite(1, buf, size);
+		if (ret < 0) {
+			if (errno == EPIPE)
+				exit(0);
+			die("git-tar-tree: %s", strerror(errno));
+		} else if (!ret) {
+			die("git-tar-tree: disk full?");
+		}
+		size -= ret;
+		buf += ret;
+	}
+}
+
+/* writes out the whole block, but only if it is full */
+static void write_if_needed(void)
+{
+	if (offset == BLOCKSIZE) {
+		reliable_write(block, BLOCKSIZE);
+		offset = 0;
+	}
+}
+
+/* acquire the next record from the buffer; user must call write_if_needed() */
+static char *get_record(void)
+{
+	char *p = block + offset;
+	memset(p, 0, RECORDSIZE);
+	offset += RECORDSIZE;
+	return p;
+}
+
+/*
+ * The end of tar archives is marked by 1024 nul bytes and after that
+ * follows the rest of the block (if any).
+ */
+static void write_trailer(void)
+{
+	get_record();
+	write_if_needed();
+	get_record();
+	write_if_needed();
+	while (offset) {
+		get_record();
+		write_if_needed();
+	}
+}
+
+/*
+ * queues up writes, so that all our write(2) calls write exactly one
+ * full block; pads writes to RECORDSIZE
+ */
+static void write_blocked(void *buf, unsigned long size)
+{
+	unsigned long tail;
+
+	if (offset) {
+		unsigned long chunk = BLOCKSIZE - offset;
+		if (size < chunk)
+			chunk = size;
+		memcpy(block + offset, buf, chunk);
+		size -= chunk;
+		offset += chunk;
+		buf += chunk;
+		write_if_needed();
+	}
+	while (size >= BLOCKSIZE) {
+		reliable_write(buf, BLOCKSIZE);
+		size -= BLOCKSIZE;
+		buf += BLOCKSIZE;
+	}
+	if (size) {
+		memcpy(block + offset, buf, size);
+		offset += size;
+	}
+	tail = offset % RECORDSIZE;
+	if (tail)  {
+		memset(block + offset, 0, RECORDSIZE - tail);
+		offset += RECORDSIZE - tail;
+	}
+	write_if_needed();
+}
+
+static void strbuf_append_string(struct strbuf *sb, const char *s)
+{
+	int slen = strlen(s);
+	int total = sb->len + slen;
+	if (total > sb->alloc) {
+		sb->buf = xrealloc(sb->buf, total);
+		sb->alloc = total;
+	}
+	memcpy(sb->buf + sb->len, s, slen);
+	sb->len = total;
+}
+
+/*
+ * pax extended header records have the format "%u %s=%s\n".  %u contains
+ * the size of the whole string (including the %u), the first %s is the
+ * keyword, the second one is the value.  This function constructs such a
+ * string and appends it to a struct strbuf.
+ */
+static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
+                                     const char *value, unsigned int valuelen)
+{
+	char *p;
+	int len, total, tmp;
+
+	/* "%u %s=%s\n" */
+	len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
+	for (tmp = len; tmp > 9; tmp /= 10)
+		len++;
+
+	total = sb->len + len;
+	if (total > sb->alloc) {
+		sb->buf = xrealloc(sb->buf, total);
+		sb->alloc = total;
+	}
+
+	p = sb->buf;
+	p += sprintf(p, "%u %s=", len, keyword);
+	memcpy(p, value, valuelen);
+	p += valuelen;
+	*p = '\n';
+	sb->len = total;
+}
+
+static unsigned int ustar_header_chksum(const struct ustar_header *header)
+{
+	char *p = (char *)header;
+	unsigned int chksum = 0;
+	while (p < header->chksum)
+		chksum += *p++;
+	chksum += sizeof(header->chksum) * ' ';
+	p += sizeof(header->chksum);
+	while (p < (char *)header + sizeof(struct ustar_header))
+		chksum += *p++;
+	return chksum;
+}
+
+static int get_path_prefix(const struct strbuf *path, int maxlen)
+{
+	int i = path->len;
+	if (i > maxlen)
+		i = maxlen;
+	while (i > 0 && path->buf[i] != '/')
+		i--;
+	return i;
+}
+
+static void write_entry(const unsigned char *sha1, struct strbuf *path,
+                        unsigned int mode, void *buffer, unsigned long size)
+{
+	struct ustar_header header;
+	struct strbuf ext_header;
+
+	memset(&header, 0, sizeof(header));
+	ext_header.buf = NULL;
+	ext_header.len = ext_header.alloc = 0;
+
+	if (!sha1) {
+		*header.typeflag = TYPEFLAG_GLOBAL_HEADER;
+		mode = 0100666;
+		strcpy(header.name, "pax_global_header");
+	} else if (!path) {
+		*header.typeflag = TYPEFLAG_EXT_HEADER;
+		mode = 0100666;
+		sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
+	} else {
+		if (S_ISDIR(mode)) {
+			*header.typeflag = TYPEFLAG_DIR;
+			mode |= 0777;
+		} else if (S_ISLNK(mode)) {
+			*header.typeflag = TYPEFLAG_LNK;
+			mode |= 0777;
+		} else if (S_ISREG(mode)) {
+			*header.typeflag = TYPEFLAG_REG;
+			mode |= (mode & 0100) ? 0777 : 0666;
+		} else {
+			error("unsupported file mode: 0%o (SHA1: %s)",
+			      mode, sha1_to_hex(sha1));
+			return;
+		}
+		if (path->len > sizeof(header.name)) {
+			int plen = get_path_prefix(path, sizeof(header.prefix));
+			int rest = path->len - plen - 1;
+			if (plen > 0 && rest <= sizeof(header.name)) {
+				memcpy(header.prefix, path->buf, plen);
+				memcpy(header.name, path->buf + plen + 1, rest);
+			} else {
+				sprintf(header.name, "%s.data",
+				        sha1_to_hex(sha1));
+				strbuf_append_ext_header(&ext_header, "path",
+				                         path->buf, path->len);
+			}
+		} else
+			memcpy(header.name, path->buf, path->len);
+	}
+
+	if (S_ISLNK(mode) && buffer) {
+		if (size > sizeof(header.linkname)) {
+			sprintf(header.linkname, "see %s.paxheader",
+			        sha1_to_hex(sha1));
+			strbuf_append_ext_header(&ext_header, "linkpath",
+			                         buffer, size);
+		} else
+			memcpy(header.linkname, buffer, size);
+	}
+
+	sprintf(header.mode, "%07o", mode & 07777);
+	sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
+	sprintf(header.mtime, "%011lo", archive_time);
+
+	/* XXX: should we provide more meaningful info here? */
+	sprintf(header.uid, "%07o", 0);
+	sprintf(header.gid, "%07o", 0);
+	strncpy(header.uname, "git", 31);
+	strncpy(header.gname, "git", 31);
+	sprintf(header.devmajor, "%07o", 0);
+	sprintf(header.devminor, "%07o", 0);
+
+	memcpy(header.magic, "ustar", 6);
+	memcpy(header.version, "00", 2);
+
+	sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
+
+	if (ext_header.len > 0) {
+		write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
+		free(ext_header.buf);
+	}
+	write_blocked(&header, sizeof(header));
+	if (S_ISREG(mode) && buffer && size > 0)
+		write_blocked(buffer, size);
+}
+
+static void write_global_extended_header(const unsigned char *sha1)
+{
+	struct strbuf ext_header;
+	ext_header.buf = NULL;
+	ext_header.len = ext_header.alloc = 0;
+	strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
+	write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
+	free(ext_header.buf);
+}
+
+static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
+{
+	int pathlen = path->len;
+
+	while (tree->size) {
+		const char *name;
+		const unsigned char *sha1;
+		unsigned mode;
+		void *eltbuf;
+		char elttype[20];
+		unsigned long eltsize;
+
+		sha1 = tree_entry_extract(tree, &name, &mode);
+		update_tree_entry(tree);
+
+		eltbuf = read_sha1_file(sha1, elttype, &eltsize);
+		if (!eltbuf)
+			die("cannot read %s", sha1_to_hex(sha1));
+
+		path->len = pathlen;
+		strbuf_append_string(path, name);
+		if (S_ISDIR(mode))
+			strbuf_append_string(path, "/");
+
+		write_entry(sha1, path, mode, eltbuf, eltsize);
+
+		if (S_ISDIR(mode)) {
+			struct tree_desc subtree;
+			subtree.buf = eltbuf;
+			subtree.size = eltsize;
+			traverse_tree(&subtree, path);
+		}
+		free(eltbuf);
+	}
+}
+
+int cmd_tar_tree(int argc, const char **argv, char** envp)
+{
+	unsigned char sha1[20], tree_sha1[20];
+	struct commit *commit;
+	struct tree_desc tree;
+	struct strbuf current_path;
+
+	current_path.buf = xmalloc(PATH_MAX);
+	current_path.alloc = PATH_MAX;
+	current_path.len = current_path.eof = 0;
+
+	setup_git_directory();
+	git_config(git_default_config);
+
+	switch (argc) {
+	case 3:
+		strbuf_append_string(&current_path, argv[2]);
+		strbuf_append_string(&current_path, "/");
+		/* FALLTHROUGH */
+	case 2:
+		if (get_sha1(argv[1], sha1))
+			die("Not a valid object name %s", argv[1]);
+		break;
+	default:
+		usage(tar_tree_usage);
+	}
+
+	commit = lookup_commit_reference_gently(sha1, 1);
+	if (commit) {
+		write_global_extended_header(commit->object.sha1);
+		archive_time = commit->date;
+	} else
+		archive_time = time(NULL);
+
+	tree.buf = read_object_with_reference(sha1, tree_type, &tree.size,
+	                                      tree_sha1);
+	if (!tree.buf)
+		die("not a reference to a tag, commit or tree object: %s",
+		    sha1_to_hex(sha1));
+
+	if (current_path.len > 0)
+		write_entry(tree_sha1, &current_path, 040777, NULL, 0);
+	traverse_tree(&tree, &current_path);
+	write_trailer();
+	free(current_path.buf);
+	return 0;
+}