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251 lines (223 sloc) 6.415 kb
/*
* 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;
}
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