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[PATCH] GIT: Create tar archives of tree on the fly

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Write commit ID to global extended pax header at the beginning of the tar
file, if possible.  get-tar-commit-id.c is an example program to get the
ID back out of such a tar archive.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Rene Scharfe 2005-04-29 19:51:04 -07:00 committed by Linus Torvalds
parent 0fc65a4572
commit 87fec8fc9e
2 changed files with 54 additions and 16 deletions
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27
get-tar-commit-id.c Normal file
View File

@ -0,0 +1,27 @@
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#define HEADERSIZE 1024
int main(int argc, char **argv)
{
char buffer[HEADERSIZE];
ssize_t n;
n = read(0, buffer, HEADERSIZE);
if (n < HEADERSIZE) {
fprintf(stderr, "read error\n");
return 3;
}
if (buffer[156] != 'g')
return 1;
if (memcmp(&buffer[512], "52 comment=", 11))
return 1;
n = write(1, &buffer[523], 41);
if (n < 41) {
fprintf(stderr, "write error\n");
return 2;
}
return 0;
}

43
tar-tree.c
View File

@ -160,7 +160,7 @@ static unsigned int path_len(int is_dir, const char *basepath,
return len;
}
static void write_header(const char *, const char *, struct path_prefix *,
static void write_header(const char *, char, const char *, struct path_prefix *,
const char *, unsigned int, unsigned long);
/* stores a pax extended header directly in the block buffer */
@ -169,7 +169,7 @@ static void write_extended_header(const char *headerfilename, int is_dir,
struct path_prefix *prefix,
const char *path, unsigned int namelen)
{
char *records, *p;
char *p;
unsigned int size = 1 + 6 + namelen + 1;
if (size > 9)
size++;
@ -177,12 +177,10 @@ static void write_extended_header(const char *headerfilename, int is_dir,
size++;
if (size > RECORDSIZE)
die("tar-tree: extended header too big, wtf?");
write_header(NULL, NULL, NULL, headerfilename, 0100600, size);
records = block + offset;
memset(records, 0, RECORDSIZE);
write_header(NULL, 'x', NULL, NULL, headerfilename, 0100600, size);
p = block + offset;
memset(p, 0, RECORDSIZE);
offset += RECORDSIZE;
p = records;
append_long(&p, size);
append_string(&p, " path=");
append_path(&p, is_dir, basepath, prefix, path);
@ -190,8 +188,22 @@ static void write_extended_header(const char *headerfilename, int is_dir,
write_if_needed();
}
static void write_global_extended_header(const char *sha1)
{
char *p;
write_header(NULL, 'g', NULL, NULL, "pax_global_header", 0, 52);
p = block + offset;
memset(p, 0, RECORDSIZE);
offset += RECORDSIZE;
append_long(&p, 52); /* 2 + 9 + 40 + 1 */
append_string(&p, " comment=");
append_string(&p, sha1_to_hex(sha1));
append_char(&p, '\n');
write_if_needed();
}
/* stores a ustar header directly in the block buffer */
static void write_header(const char *sha1, const char *basepath,
static void write_header(const char *sha1, char typeflag, const char *basepath,
struct path_prefix *prefix, const char *path,
unsigned int mode, unsigned long size)
{
@ -236,11 +248,7 @@ static void write_header(const char *sha1, const char *basepath,
sprintf(&header[124], "%011lo", S_ISDIR(mode) ? 0 : size);
sprintf(&header[136], "%011lo", archive_time);
/* typeflag */
if (!sha1)
header[156] = 'x'; /* extended header */
else
header[156] = S_ISDIR(mode) ? '5' : '0';
header[156] = typeflag;
memcpy(&header[257], "ustar", 6);
memcpy(&header[263], "00", 2);
@ -279,7 +287,8 @@ static void traverse_tree(void *buffer, unsigned long size,
eltbuf = read_sha1_file(sha1, elttype, &eltsize);
if (!eltbuf)
die("cannot read %s", sha1_to_hex(sha1));
write_header(sha1, basedir, prefix, path, mode, eltsize);
write_header(sha1, S_ISDIR(mode) ? '5' : '0', basedir,
prefix, path, mode, eltsize);
if (!strcmp(elttype, "tree")) {
this_prefix.name = path;
traverse_tree(eltbuf, eltsize, &this_prefix);
@ -320,6 +329,7 @@ time_t commit_time(void * buffer, unsigned long size)
int main(int argc, char **argv)
{
unsigned char sha1[20];
unsigned char commit_sha1[20];
void *buffer;
unsigned long size;
@ -339,8 +349,9 @@ int main(int argc, char **argv)
if (!sha1_file_directory)
sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
buffer = read_object_with_reference(sha1, "commit", &size, NULL);
buffer = read_object_with_reference(sha1, "commit", &size, commit_sha1);
if (buffer) {
write_global_extended_header(commit_sha1);
archive_time = commit_time(buffer, size);
free(buffer);
}
@ -351,7 +362,7 @@ int main(int argc, char **argv)
if (!archive_time)
archive_time = time(NULL);
if (basedir)
write_header("0", NULL, NULL, basedir, 040755, 0);
write_header("0", '5', NULL, NULL, basedir, 040755, 0);
traverse_tree(buffer, size, NULL);
free(buffer);
write_trailer();