On Fri, Apr 29, 2005 at 03:26:14PM -0700, Linus Torvalds wrote: > > > Having just done the git-0.7.tar.gz file with git-tar-tree, I started > wondering if there is some nice way to encode the commit version that got > tarred up into the tar archive itself. ... and here is the patch that changes git-tar-tree to add the commit ID as a comment in a global pax header to the tar file. Archivers ignore this field. A little sample program is included to read the ID from a previously prepared archive. Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> 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. --- commit 716d21c45ba1c329fb88febf4704a4ab629a3933 tree 72f4d42eac2cd9099a663c16cb8201f90a8ff9c9 parent 0fc65a4572625405ff6dd9d8c16d835f2b1ebd49 author Rene Scharfe <rene.scharfe@lsrfire.ath.cx> 1114812895 +0200 committer Rene Scharfe <rene.scharfe@lsrfire.ath.cx> 1114812895 +0200 Index: get-tar-commit-id.c =================================================================== --- /dev/null (tree:c1546808797f6a3c4e6ae82069cee3dc316fbf24) +++ 72f4d42eac2cd9099a663c16cb8201f90a8ff9c9/get-tar-commit-id.c (mode:100644 sha1:a1a17e53d29136df431d2a128292d7aefefaea41) @@ -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; +} Index: tar-tree.c =================================================================== --- c1546808797f6a3c4e6ae82069cee3dc316fbf24/tar-tree.c (mode:100644 sha1:5cc7cfef6db1269d81589b82255537fb64ba02fa) +++ 72f4d42eac2cd9099a663c16cb8201f90a8ff9c9/tar-tree.c (mode:100644 sha1:ea7ea91add54532c38dde9e343efe34d56805341) @@ -160,7 +160,7 @@ 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 @@ 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 @@ 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 @@ 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 @@ 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 @@ 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 @@ int main(int argc, char **argv) { unsigned char sha1[20]; + unsigned char commit_sha1[20]; void *buffer; unsigned long size; @@ -339,8 +349,9 @@ 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 @@ 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(); - To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.htmlReceived on Sat Apr 30 11:23:21 2005
This archive was generated by hypermail 2.1.8 : 2005-04-30 11:23:21 EST