1 files changed, 250 insertions, 0 deletions
diff --git a/archive-tar.c b/archive-tar.c
new file mode 100644
index 0000000..cee06ce
--- /dev/null
+++ b/archive-tar.c
@@ -0,0 +1,250 @@
+/*
+ * Copyright (c) 2005, 2006 Rene Scharfe
+ */
+#include "cache.h"
+#include "tar.h"
+#include "archive.h"
+
+#define RECORDSIZE	(512)
+#define BLOCKSIZE	(RECORDSIZE * 20)
+
+static char block[BLOCKSIZE];
+static unsigned long offset;
+
+static int tar_umask = 002;
+
+/* writes out the whole block, but only if it is full */
+static void write_if_needed(void)
+{
+	if (offset == BLOCKSIZE) {
+		write_or_die(1, block, BLOCKSIZE);
+		offset = 0;
+	}
+}
+
+/*
+ * queues up writes, so that all our write(2) calls write exactly one
+ * full block; pads writes to RECORDSIZE
+ */
+static void write_blocked(const void *data, unsigned long size)
+{
+	const char *buf = data;
+	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) {
+		write_or_die(1, 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();
+}
+
+/*
+ * The end of tar archives is marked by 2*512 nul bytes and after that
+ * follows the rest of the block (if any).
+ */
+static void write_trailer(void)
+{
+	int tail = BLOCKSIZE - offset;
+	memset(block + offset, 0, tail);
+	write_or_die(1, block, BLOCKSIZE);
+	if (tail < 2 * RECORDSIZE) {
+		memset(block, 0, offset);
+		write_or_die(1, block, BLOCKSIZE);
+	}
+}
+
+/*
+ * 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)
+{
+	int len, tmp;
+
+	/* "%u %s=%s\n" */
+	len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
+	for (tmp = len; tmp > 9; tmp /= 10)
+		len++;
+
+	strbuf_grow(sb, len);
+	strbuf_addf(sb, "%u %s=", len, keyword);
+	strbuf_add(sb, value, valuelen);
+	strbuf_addch(sb, '\n');
+}
+
+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 size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
+{
+	size_t i = pathlen;
+	if (i > maxlen)
+		i = maxlen;
+	do {
+		i--;
+	} while (i > 0 && path[i] != '/');
+	return i;
+}
+
+static int write_tar_entry(struct archiver_args *args,
+		const unsigned char *sha1, const char *path, size_t pathlen,
+		unsigned int mode, void *buffer, unsigned long size)
+{
+	struct ustar_header header;
+	struct strbuf ext_header = STRBUF_INIT;
+	int err = 0;
+
+	memset(&header, 0, sizeof(header));
+
+	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) || S_ISGITLINK(mode)) {
+			*header.typeflag = TYPEFLAG_DIR;
+			mode = (mode | 0777) & ~tar_umask;
+		} else if (S_ISLNK(mode)) {
+			*header.typeflag = TYPEFLAG_LNK;
+			mode |= 0777;
+		} else if (S_ISREG(mode)) {
+			*header.typeflag = TYPEFLAG_REG;
+			mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
+		} else {
+			return error("unsupported file mode: 0%o (SHA1: %s)",
+					mode, sha1_to_hex(sha1));
+		}
+		if (pathlen > sizeof(header.name)) {
+			size_t plen = get_path_prefix(path, pathlen,
+					sizeof(header.prefix));
+			size_t rest = pathlen - plen - 1;
+			if (plen > 0 && rest <= sizeof(header.name)) {
+				memcpy(header.prefix, path, plen);
+				memcpy(header.name, path + plen + 1, rest);
+			} else {
+				sprintf(header.name, "%s.data",
+				        sha1_to_hex(sha1));
+				strbuf_append_ext_header(&ext_header, "path",
+						path, pathlen);
+			}
+		} else
+			memcpy(header.name, path, pathlen);
+	}
+
+	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", (unsigned long) args->time);
+
+	sprintf(header.uid, "%07o", 0);
+	sprintf(header.gid, "%07o", 0);
+	strlcpy(header.uname, "root", sizeof(header.uname));
+	strlcpy(header.gname, "root", sizeof(header.gname));
+	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) {
+		err = write_tar_entry(args, sha1, NULL, 0, 0, ext_header.buf,
+				ext_header.len);
+		if (err)
+			return err;
+	}
+	strbuf_release(&ext_header);
+	write_blocked(&header, sizeof(header));
+	if (S_ISREG(mode) && buffer && size > 0)
+		write_blocked(buffer, size);
+	return err;
+}
+
+static int write_global_extended_header(struct archiver_args *args)
+{
+	const unsigned char *sha1 = args->commit_sha1;
+	struct strbuf ext_header = STRBUF_INIT;
+	int err;
+
+	strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
+	err = write_tar_entry(args, NULL, NULL, 0, 0, ext_header.buf,
+			ext_header.len);
+	strbuf_release(&ext_header);
+	return err;
+}
+
+static int git_tar_config(const char *var, const char *value, void *cb)
+{
+	if (!strcmp(var, "tar.umask")) {
+		if (value && !strcmp(value, "user")) {
+			tar_umask = umask(0);
+			umask(tar_umask);
+		} else {
+			tar_umask = git_config_int(var, value);
+		}
+		return 0;
+	}
+	return git_default_config(var, value, cb);
+}
+
+int write_tar_archive(struct archiver_args *args)
+{
+	int err = 0;
+
+	git_config(git_tar_config, NULL);
+
+	if (args->commit_sha1)
+		err = write_global_extended_header(args);
+	if (!err)
+		err = write_archive_entries(args, write_tar_entry);
+	if (!err)
+		write_trailer();
+	return err;
+}