git/archive-tar.c
René Scharfe 200589abcb archive: read short blobs in archive.c::write_archive_entry()
Centralize reading of symlink destinations and the contents of regular
files that are too small to be streamed.  This reduces code duplication
and allows future patches to add support for adding non-tracked files to
archives.  The backends are expected to stream blobs if buffer is NULL.

object_file_to_archive() is only called from archive.c and thus no
longer exported.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-19 15:56:05 -07:00

487 lines
12 KiB
C

/*
* Copyright (c) 2005, 2006 Rene Scharfe
*/
#include "cache.h"
#include "config.h"
#include "tar.h"
#include "archive.h"
#include "object-store.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);
/*
* This is the max value that a ustar size header can specify, as it is fixed
* at 11 octal digits. POSIX specifies that we switch to extended headers at
* this size.
*
* Likewise for the mtime (which happens to use a buffer of the same size).
*/
#if ULONG_MAX == 0xFFFFFFFF
#define USTAR_MAX_SIZE ULONG_MAX
#else
#define USTAR_MAX_SIZE 077777777777UL
#endif
#if TIME_MAX == 0xFFFFFFFF
#define USTAR_MAX_MTIME TIME_MAX
#else
#define USTAR_MAX_MTIME 077777777777ULL
#endif
/* 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(struct repository *r, const struct object_id *oid)
{
struct git_istream *st;
enum object_type type;
unsigned long sz;
char buf[BLOCKSIZE];
ssize_t readlen;
st = open_istream(r, oid, &type, &sz, NULL);
if (!st)
return error(_("cannot stream blob %s"), oid_to_hex(oid));
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, size_t valuelen)
{
size_t orig_len = sb->len;
size_t len, tmp;
/* "%u %s=%s\n" */
len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
for (tmp = 1; len / 10 >= tmp; tmp *= 10)
len++;
strbuf_grow(sb, len);
strbuf_addf(sb, "%"PRIuMAX" %s=", (uintmax_t)len, keyword);
strbuf_add(sb, value, valuelen);
strbuf_addch(sb, '\n');
if (len != sb->len - orig_len)
BUG("pax extended header length miscalculated as %"PRIuMAX
", should be %"PRIuMAX,
(uintmax_t)len, (uintmax_t)(sb->len - orig_len));
}
/*
* Like strbuf_append_ext_header, but for numeric values.
*/
static void strbuf_append_ext_header_uint(struct strbuf *sb,
const char *keyword,
uintmax_t value)
{
char buf[40]; /* big enough for 2^128 in decimal, plus NUL */
int len;
len = xsnprintf(buf, sizeof(buf), "%"PRIuMAX, value);
strbuf_append_ext_header(sb, keyword, buf, len);
}
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 > 1 && path[i - 1] == '/')
i--;
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)
{
xsnprintf(header->mode, sizeof(header->mode), "%07o", mode & 07777);
xsnprintf(header->size, sizeof(header->size), "%011"PRIoMAX , S_ISREG(mode) ? (uintmax_t)size : (uintmax_t)0);
xsnprintf(header->mtime, sizeof(header->mtime), "%011lo", (unsigned long) args->time);
xsnprintf(header->uid, sizeof(header->uid), "%07o", 0);
xsnprintf(header->gid, sizeof(header->gid), "%07o", 0);
strlcpy(header->uname, "root", sizeof(header->uname));
strlcpy(header->gname, "root", sizeof(header->gname));
xsnprintf(header->devmajor, sizeof(header->devmajor), "%07o", 0);
xsnprintf(header->devminor, sizeof(header->devminor), "%07o", 0);
memcpy(header->magic, "ustar", 6);
memcpy(header->version, "00", 2);
xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header));
}
static void write_extended_header(struct archiver_args *args,
const struct object_id *oid,
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;
xsnprintf(header.name, sizeof(header.name), "%s.paxheader", oid_to_hex(oid));
prepare_header(args, &header, mode, size);
write_blocked(&header, sizeof(header));
write_blocked(buffer, size);
}
static int write_tar_entry(struct archiver_args *args,
const struct object_id *oid,
const char *path, size_t pathlen,
unsigned int mode,
void *buffer, unsigned long size)
{
struct ustar_header header;
struct strbuf ext_header = STRBUF_INIT;
unsigned long size_in_header;
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, oid_to_hex(oid));
}
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 {
xsnprintf(header.name, sizeof(header.name), "%s.data",
oid_to_hex(oid));
strbuf_append_ext_header(&ext_header, "path",
path, pathlen);
}
} else
memcpy(header.name, path, pathlen);
if (S_ISLNK(mode)) {
if (size > sizeof(header.linkname)) {
xsnprintf(header.linkname, sizeof(header.linkname),
"see %s.paxheader", oid_to_hex(oid));
strbuf_append_ext_header(&ext_header, "linkpath",
buffer, size);
} else
memcpy(header.linkname, buffer, size);
}
size_in_header = size;
if (S_ISREG(mode) && size > USTAR_MAX_SIZE) {
size_in_header = 0;
strbuf_append_ext_header_uint(&ext_header, "size", size);
}
prepare_header(args, &header, mode, size_in_header);
if (ext_header.len > 0) {
write_extended_header(args, oid, ext_header.buf,
ext_header.len);
}
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(args->repo, oid);
}
return err;
}
static void write_global_extended_header(struct archiver_args *args)
{
const struct object_id *oid = args->commit_oid;
struct strbuf ext_header = STRBUF_INIT;
struct ustar_header header;
unsigned int mode;
if (oid)
strbuf_append_ext_header(&ext_header, "comment",
oid_to_hex(oid),
the_hash_algo->hexsz);
if (args->time > USTAR_MAX_MTIME) {
strbuf_append_ext_header_uint(&ext_header, "mtime",
args->time);
args->time = USTAR_MAX_MTIME;
}
if (!ext_header.len)
return;
memset(&header, 0, sizeof(header));
*header.typeflag = TYPEFLAG_GLOBAL_HEADER;
mode = 0100666;
xsnprintf(header.name, sizeof(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);
}
static struct archiver **tar_filters;
static int nr_tar_filters;
static int alloc_tar_filters;
static struct archiver *find_tar_filter(const char *name, size_t 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 *name;
const char *type;
size_t namelen;
if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
return 0;
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;
write_global_extended_header(args);
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 = CHILD_PROCESS_INIT;
const char *argv[2];
int r;
if (!ar->data)
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);
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]);
}
}