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/*
* Copyright (c) 2005, 2006 Rene Scharfe
*/
#include "cache.h"
#include "tar.h"
#include "archive.h"
#include "streaming.h"
#include "run-command.h"

#define RECORDSIZE (512)
#define BLOCKSIZE (RECORDSIZE * 20)

static char block[BLOCKSIZE];
static unsigned long offset;

static int tar_umask = 002;

static int write_tar_filter_archive(const struct archiver *ar,
struct archiver_args *args);

/* 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 do_write_blocked(const void *data, unsigned long size)
{
const char *buf = data;

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;
}
}

static void finish_record(void)
{
unsigned long tail;
tail = offset % RECORDSIZE;
if (tail) {
memset(block + offset, 0, RECORDSIZE - tail);
offset += RECORDSIZE - tail;
}
write_if_needed();
}

static void write_blocked(const void *data, unsigned long size)
{
do_write_blocked(data, size);
finish_record();
}

/*
* 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);
}
}

/*
* queues up writes, so that all our write(2) calls write exactly one
* full block; pads writes to RECORDSIZE
*/
static int stream_blocked(const unsigned char *sha1)
{
struct git_istream *st;
enum object_type type;
unsigned long sz;
char buf[BLOCKSIZE];
ssize_t readlen;

st = open_istream(sha1, &type, &sz, NULL);
if (!st)
return error("cannot stream blob %s", sha1_to_hex(sha1));
for (;;) {
readlen = read_istream(st, buf, sizeof(buf));
if (readlen <= 0)
break;
do_write_blocked(buf, readlen);
}
close_istream(st);
if (!readlen)
finish_record();
return readlen;
}

/*
* 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)
{
const unsigned char *p = (const unsigned char *)header;
unsigned int chksum = 0;
while (p < (const unsigned char *)header->chksum)
chksum += *p++;
chksum += sizeof(header->chksum) * ' ';
p += sizeof(header->chksum);
while (p < (const unsigned 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 void prepare_header(struct archiver_args *args,
struct ustar_header *header,
unsigned int mode, unsigned long 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));
}

static int write_extended_header(struct archiver_args *args,
const unsigned char *sha1,
const void *buffer, unsigned long size)
{
struct ustar_header header;
unsigned int mode;
memset(&header, 0, sizeof(header));
*header.typeflag = TYPEFLAG_EXT_HEADER;
mode = 0100666;
sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
prepare_header(args, &header, mode, size);
write_blocked(&header, sizeof(header));
write_blocked(buffer, size);
return 0;
}

static int write_tar_entry(struct archiver_args *args,
const unsigned char *sha1,
const char *path, size_t pathlen,
unsigned int mode)
{
struct ustar_header header;
struct strbuf ext_header = STRBUF_INIT;
unsigned int old_mode = mode;
unsigned long size;
void *buffer;
int err = 0;

memset(&header, 0, sizeof(header));

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_ISREG(mode) && !args->convert &&
sha1_object_info(sha1, &size) == OBJ_BLOB &&
size > big_file_threshold)
buffer = NULL;
else if (S_ISLNK(mode) || S_ISREG(mode)) {
enum object_type type;
buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);
if (!buffer)
return error("cannot read %s", sha1_to_hex(sha1));
} else {
buffer = NULL;
size = 0;
}

if (S_ISLNK(mode)) {
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);
}

prepare_header(args, &header, mode, size);

if (ext_header.len > 0) {
err = write_extended_header(args, sha1, ext_header.buf,
ext_header.len);
if (err) {
free(buffer);
return err;
}
}
strbuf_release(&ext_header);
write_blocked(&header, sizeof(header));
if (S_ISREG(mode) && size > 0) {
if (buffer)
write_blocked(buffer, size);
else
err = stream_blocked(sha1);
}
free(buffer);
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;
struct ustar_header header;
unsigned int mode;
int err = 0;

strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
memset(&header, 0, sizeof(header));
*header.typeflag = TYPEFLAG_GLOBAL_HEADER;
mode = 0100666;
strcpy(header.name, "pax_global_header");
prepare_header(args, &header, mode, ext_header.len);
write_blocked(&header, sizeof(header));
write_blocked(ext_header.buf, ext_header.len);
strbuf_release(&ext_header);
return err;
}

static struct archiver **tar_filters;
static int nr_tar_filters;
static int alloc_tar_filters;

static struct archiver *find_tar_filter(const char *name, int len)
{
int i;
for (i = 0; i < nr_tar_filters; i++) {
struct archiver *ar = tar_filters[i];
if (!strncmp(ar->name, name, len) && !ar->name[len])
return ar;
}
return NULL;
}

static int tar_filter_config(const char *var, const char *value, void *data)
{
struct archiver *ar;
const char *dot;
const char *name;
const char *type;
int namelen;

if (prefixcmp(var, "tar."))
return 0;
dot = strrchr(var, '.');
if (dot == var + 9)
return 0;

name = var + 4;
namelen = dot - name;
type = dot + 1;

ar = find_tar_filter(name, namelen);
if (!ar) {
ar = xcalloc(1, sizeof(*ar));
ar->name = xmemdupz(name, namelen);
ar->write_archive = write_tar_filter_archive;
ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
tar_filters[nr_tar_filters++] = ar;
}

if (!strcmp(type, "command")) {
if (!value)
return config_error_nonbool(var);
free(ar->data);
ar->data = xstrdup(value);
return 0;
}
if (!strcmp(type, "remote")) {
if (git_config_bool(var, value))
ar->flags |= ARCHIVER_REMOTE;
else
ar->flags &= ~ARCHIVER_REMOTE;
return 0;
}

return 0;
}

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 tar_filter_config(var, value, cb);
}

static int write_tar_archive(const struct archiver *ar,
struct archiver_args *args)
{
int err = 0;

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;
}

static int write_tar_filter_archive(const struct archiver *ar,
struct archiver_args *args)
{
struct strbuf cmd = STRBUF_INIT;
struct child_process filter;
const char *argv[2];
int r;

if (!ar->data)
die("BUG: tar-filter archiver called with no filter defined");

strbuf_addstr(&cmd, ar->data);
if (args->compression_level >= 0)
strbuf_addf(&cmd, " -%d", args->compression_level);

memset(&filter, 0, sizeof(filter));
argv[0] = cmd.buf;
argv[1] = NULL;
filter.argv = argv;
filter.use_shell = 1;
filter.in = -1;

if (start_command(&filter) < 0)
die_errno("unable to start '%s' filter", argv[0]);
close(1);
if (dup2(filter.in, 1) < 0)
die_errno("unable to redirect descriptor");
close(filter.in);

r = write_tar_archive(ar, args);

close(1);
if (finish_command(&filter) != 0)
die("'%s' filter reported error", argv[0]);

strbuf_release(&cmd);
return r;
}

static struct archiver tar_archiver = {
"tar",
write_tar_archive,
ARCHIVER_REMOTE
};

void init_tar_archiver(void)
{
int i;
register_archiver(&tar_archiver);

tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
tar_filter_config("tar.tgz.remote", "true", NULL);
tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
tar_filter_config("tar.tar.gz.remote", "true", NULL);
git_config(git_tar_config, NULL);
for (i = 0; i < nr_tar_filters; i++) {
/* omit any filters that never had a command configured */
if (tar_filters[i]->data)
register_archiver(tar_filters[i]);
}
}
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