mirror of
https://github.com/git/git
synced 2024-10-30 04:01:21 +00:00
3c249c9506
This allows the programs to use various simplified versions of the SHA1 names, eg just say "HEAD" for the SHA1 pointed to by the .git/HEAD file etc. For example, this commit has been done with git-commit-tree $(git-write-tree) -p HEAD instead of the traditional "$(cat .git/HEAD)" syntax.
370 lines
8.9 KiB
C
370 lines
8.9 KiB
C
#include <time.h>
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#include "cache.h"
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#define RECORDSIZE (512)
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#define BLOCKSIZE (RECORDSIZE * 20)
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static const char *tar_tree_usage = "tar-tree <key> [basedir]";
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static char block[BLOCKSIZE];
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static unsigned long offset;
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static const char *basedir;
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static time_t archive_time;
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struct path_prefix {
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struct path_prefix *prev;
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const char *name;
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};
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/* tries hard to write, either succeeds or dies in the attempt */
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static void reliable_write(void *buf, unsigned long size)
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{
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while (size > 0) {
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long ret = write(1, buf, size);
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if (ret < 0) {
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if (errno == EAGAIN)
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continue;
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if (errno == EPIPE)
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exit(0);
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die("tar-tree: %s", strerror(errno));
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} else if (!ret) {
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die("tar-tree: disk full?");
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}
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size -= ret;
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buf += ret;
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}
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}
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/* writes out the whole block, but only if it is full */
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static void write_if_needed(void)
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{
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if (offset == BLOCKSIZE) {
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reliable_write(block, BLOCKSIZE);
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offset = 0;
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}
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}
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/*
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* The end of tar archives is marked by 1024 nul bytes and after that
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* follows the rest of the block (if any).
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*/
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static void write_trailer(void)
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{
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memset(block + offset, 0, RECORDSIZE);
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offset += RECORDSIZE;
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write_if_needed();
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memset(block + offset, 0, RECORDSIZE);
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offset += RECORDSIZE;
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write_if_needed();
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if (offset) {
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memset(block + offset, 0, BLOCKSIZE - offset);
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reliable_write(block, BLOCKSIZE);
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offset = 0;
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}
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}
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/*
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* queues up writes, so that all our write(2) calls write exactly one
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* full block; pads writes to RECORDSIZE
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*/
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static void write_blocked(void *buf, unsigned long size)
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{
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unsigned long tail;
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if (offset) {
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unsigned long chunk = BLOCKSIZE - offset;
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if (size < chunk)
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chunk = size;
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memcpy(block + offset, buf, chunk);
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size -= chunk;
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offset += chunk;
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buf += chunk;
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write_if_needed();
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}
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while (size >= BLOCKSIZE) {
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reliable_write(buf, BLOCKSIZE);
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size -= BLOCKSIZE;
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buf += BLOCKSIZE;
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}
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if (size) {
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memcpy(block + offset, buf, size);
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buf += size;
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offset += size;
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}
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tail = offset % RECORDSIZE;
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if (tail) {
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memset(block + offset, 0, RECORDSIZE - tail);
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offset += RECORDSIZE - tail;
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}
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write_if_needed();
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}
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static void append_string(char **p, const char *s)
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{
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unsigned int len = strlen(s);
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memcpy(*p, s, len);
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*p += len;
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}
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static void append_char(char **p, char c)
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{
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**p = c;
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*p += 1;
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}
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static void append_long(char **p, long n)
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{
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int len = sprintf(*p, "%ld", n);
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*p += len;
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}
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static void append_path_prefix(char **buffer, struct path_prefix *prefix)
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{
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if (!prefix)
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return;
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append_path_prefix(buffer, prefix->prev);
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append_string(buffer, prefix->name);
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append_char(buffer, '/');
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}
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static unsigned int path_prefix_len(struct path_prefix *prefix)
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{
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if (!prefix)
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return 0;
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return path_prefix_len(prefix->prev) + strlen(prefix->name) + 1;
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}
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static void append_path(char **p, int is_dir, const char *basepath,
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struct path_prefix *prefix, const char *path)
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{
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if (basepath) {
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append_string(p, basepath);
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append_char(p, '/');
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}
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append_path_prefix(p, prefix);
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append_string(p, path);
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if (is_dir)
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append_char(p, '/');
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}
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static unsigned int path_len(int is_dir, const char *basepath,
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struct path_prefix *prefix, const char *path)
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{
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unsigned int len = 0;
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if (basepath)
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len += strlen(basepath) + 1;
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len += path_prefix_len(prefix) + strlen(path);
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if (is_dir)
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len++;
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return len;
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}
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static void write_header(const char *, char, const char *, struct path_prefix *,
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const char *, unsigned int, unsigned long);
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/* stores a pax extended header directly in the block buffer */
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static void write_extended_header(const char *headerfilename, int is_dir,
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const char *basepath,
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struct path_prefix *prefix,
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const char *path, unsigned int namelen)
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{
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char *p;
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unsigned int size = 1 + 6 + namelen + 1;
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if (size > 9)
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size++;
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if (size > 99)
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size++;
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if (size > RECORDSIZE)
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die("tar-tree: extended header too big, wtf?");
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write_header(NULL, 'x', NULL, NULL, headerfilename, 0100600, size);
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p = block + offset;
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memset(p, 0, RECORDSIZE);
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offset += RECORDSIZE;
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append_long(&p, size);
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append_string(&p, " path=");
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append_path(&p, is_dir, basepath, prefix, path);
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append_char(&p, '\n');
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write_if_needed();
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}
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static void write_global_extended_header(const char *sha1)
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{
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char *p;
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write_header(NULL, 'g', NULL, NULL, "pax_global_header", 0, 52);
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p = block + offset;
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memset(p, 0, RECORDSIZE);
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offset += RECORDSIZE;
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append_long(&p, 52); /* 2 + 9 + 40 + 1 */
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append_string(&p, " comment=");
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append_string(&p, sha1_to_hex(sha1));
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append_char(&p, '\n');
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write_if_needed();
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}
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/* stores a ustar header directly in the block buffer */
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static void write_header(const char *sha1, char typeflag, const char *basepath,
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struct path_prefix *prefix, const char *path,
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unsigned int mode, unsigned long size)
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{
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unsigned int namelen;
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char *p, *header = NULL;
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unsigned int checksum = 0;
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int i;
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namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
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if (namelen > 500) {
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die("tar-tree: name too log of object %s\n", sha1_to_hex(sha1));
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} else if (namelen > 100) {
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char *sha1_hex = sha1_to_hex(sha1);
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char headerfilename[51];
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sprintf(headerfilename, "%s.paxheader", sha1_hex);
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/* the extended header must be written before the normal one */
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write_extended_header(headerfilename, S_ISDIR(mode), basepath,
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prefix, path, namelen);
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header = block + offset;
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memset(header, 0, RECORDSIZE);
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offset += RECORDSIZE;
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sprintf(header, "%s.data", sha1_hex);
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} else {
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header = block + offset;
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memset(header, 0, RECORDSIZE);
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offset += RECORDSIZE;
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p = header;
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append_path(&p, S_ISDIR(mode), basepath, prefix, path);
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}
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if (S_ISDIR(mode))
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mode |= 0755; /* GIT doesn't store permissions of dirs */
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sprintf(&header[100], "%07o", mode & 07777);
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/* XXX: should we provide more meaningful info here? */
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sprintf(&header[108], "%07o", 0); /* uid */
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sprintf(&header[116], "%07o", 0); /* gid */
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strncpy(&header[265], "git", 31); /* uname */
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strncpy(&header[297], "git", 31); /* gname */
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sprintf(&header[124], "%011lo", S_ISDIR(mode) ? 0 : size);
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sprintf(&header[136], "%011lo", archive_time);
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header[156] = typeflag;
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memcpy(&header[257], "ustar", 6);
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memcpy(&header[263], "00", 2);
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printf(&header[329], "%07o", 0); /* devmajor */
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printf(&header[337], "%07o", 0); /* devminor */
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memset(&header[148], ' ', 8);
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for (i = 0; i < RECORDSIZE; i++)
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checksum += header[i];
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sprintf(&header[148], "%07o", checksum & 0x1fffff);
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write_if_needed();
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}
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static void traverse_tree(void *buffer, unsigned long size,
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struct path_prefix *prefix)
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{
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struct path_prefix this_prefix;
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this_prefix.prev = prefix;
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while (size) {
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int namelen = strlen(buffer)+1;
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void *eltbuf;
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char elttype[20];
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unsigned long eltsize;
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unsigned char *sha1 = buffer + namelen;
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char *path = strchr(buffer, ' ') + 1;
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unsigned int mode;
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if (size < namelen + 20 || sscanf(buffer, "%o", &mode) != 1)
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die("corrupt 'tree' file");
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buffer = sha1 + 20;
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size -= namelen + 20;
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eltbuf = read_sha1_file(sha1, elttype, &eltsize);
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if (!eltbuf)
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die("cannot read %s", sha1_to_hex(sha1));
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write_header(sha1, S_ISDIR(mode) ? '5' : '0', basedir,
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prefix, path, mode, eltsize);
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if (!strcmp(elttype, "tree")) {
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this_prefix.name = path;
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traverse_tree(eltbuf, eltsize, &this_prefix);
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} else if (!strcmp(elttype, "blob")) {
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write_blocked(eltbuf, eltsize);
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}
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free(eltbuf);
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}
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}
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/* get commit time from committer line of commit object */
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time_t commit_time(void * buffer, unsigned long size)
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{
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time_t result = 0;
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char *p = buffer;
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while (size > 0) {
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char *endp = memchr(p, '\n', size);
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if (!endp || endp == p)
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break;
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*endp = '\0';
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if (endp - p > 10 && !memcmp(p, "committer ", 10)) {
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char *nump = strrchr(p, '>');
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if (!nump)
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break;
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nump++;
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result = strtoul(nump, &endp, 10);
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if (*endp != ' ')
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result = 0;
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break;
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}
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size -= endp - p - 1;
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p = endp + 1;
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}
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return result;
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}
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int main(int argc, char **argv)
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{
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unsigned char sha1[20];
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unsigned char commit_sha1[20];
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void *buffer;
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unsigned long size;
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switch (argc) {
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case 3:
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basedir = argv[2];
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/* FALLTHROUGH */
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case 2:
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if (get_sha1(argv[1], sha1) < 0)
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usage(tar_tree_usage);
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break;
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default:
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usage(tar_tree_usage);
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}
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sha1_file_directory = getenv(DB_ENVIRONMENT);
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if (!sha1_file_directory)
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sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
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buffer = read_object_with_reference(sha1, "commit", &size, commit_sha1);
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if (buffer) {
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write_global_extended_header(commit_sha1);
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archive_time = commit_time(buffer, size);
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free(buffer);
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}
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buffer = read_object_with_reference(sha1, "tree", &size, NULL);
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if (!buffer)
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die("not a reference to a tag, commit or tree object: %s",
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sha1_to_hex(sha1));
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if (!archive_time)
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archive_time = time(NULL);
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if (basedir)
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write_header("0", '5', NULL, NULL, basedir, 040755, 0);
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traverse_tree(buffer, size, NULL);
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free(buffer);
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write_trailer();
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return 0;
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}
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