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/* SPDX-License-Identifier: GPL-3.0-or-later */
#include "internal.h"
static unsigned long pax_hdr_counter = 0;
static char buffer[4096];
static int name_to_tar_header(tar_header_t *hdr, const char *path)
{
size_t len = strlen(path);
const char *ptr;
if ((len + 1) <= sizeof(hdr->name)) {
memcpy(hdr->name, path, len);
return 0;
}
for (ptr = path; ; ++ptr) {
ptr = strchr(ptr, '/');
if (ptr == NULL)
return -1;
len = ptr - path;
if (len >= sizeof(hdr->tail.posix.prefix))
continue;
if (strlen(ptr + 1) >= sizeof(hdr->name))
continue;
break;
}
memcpy(hdr->tail.posix.prefix, path, ptr - path);
memcpy(hdr->name, ptr + 1, strlen(ptr + 1));
return 0;
}
static void init_header(tar_header_t *hdr, const struct stat *sb,
const char *name, const char *slink_target)
{
memset(hdr, 0, sizeof(*hdr));
name_to_tar_header(hdr, name);
memcpy(hdr->magic, TAR_MAGIC, sizeof(hdr->magic));
memcpy(hdr->version, TAR_VERSION, sizeof(hdr->version));
write_octal(hdr->mode, sb->st_mode & ~S_IFMT, 6);
write_octal(hdr->uid, sb->st_uid, 6);
write_octal(hdr->gid, sb->st_gid, 6);
write_octal(hdr->mtime, sb->st_mtime, 11);
write_octal(hdr->size, 0, 11);
write_octal(hdr->devmajor, 0, 6);
write_octal(hdr->devminor, 0, 6);
switch (sb->st_mode & S_IFMT) {
case S_IFREG:
write_octal(hdr->size, sb->st_size & 077777777777L, 11);
break;
case S_IFLNK:
if (sb->st_size < (off_t)sizeof(hdr->linkname))
strcpy(hdr->linkname, slink_target);
break;
case S_IFCHR:
case S_IFBLK:
write_octal(hdr->devmajor, major(sb->st_rdev), 6);
write_octal(hdr->devminor, minor(sb->st_rdev), 6);
break;
}
sprintf(hdr->uname, "%u", sb->st_uid);
sprintf(hdr->gname, "%u", sb->st_gid);
}
static bool need_pax_header(const struct stat *sb, const char *name)
{
tar_header_t tmp;
if (sb->st_uid > 0777777 || sb->st_gid > 0777777)
return true;
if (S_ISREG(sb->st_mode) && sb->st_size > 077777777777L)
return true;
if (S_ISLNK(sb->st_mode) && sb->st_size >= (off_t)sizeof(tmp.linkname))
return true;
if (name_to_tar_header(&tmp, name))
return true;
return false;
}
static char *write_pax_entry(char *dst, const char *key, const char *value)
{
size_t i, len, prefix = 0, oldprefix;
do {
len = prefix + 1 + strlen(key) + 1 + strlen(value) + 1;
oldprefix = prefix;
prefix = 1;
for (i = len; i >= 10; i /= 10)
++prefix;
} while (oldprefix != prefix);
sprintf(dst, "%zu %s=%s\n", len, key, value);
return dst + len;
}
static int write_pax_header(int fd, const struct stat *sb, const char *name,
const char *slink_target)
{
char temp[64], *ptr;
struct stat fakesb;
tar_header_t hdr;
ssize_t ret;
size_t len;
memset(buffer, 0, sizeof(buffer));
memset(&fakesb, 0, sizeof(fakesb));
fakesb.st_mode = S_IFREG | 0644;
sprintf(temp, "pax%lu", pax_hdr_counter);
init_header(&hdr, &fakesb, temp, NULL);
hdr.typeflag = TAR_TYPE_PAX;
sprintf(temp, "%u", sb->st_uid);
ptr = buffer;
ptr = write_pax_entry(ptr, "uid", temp);
ptr = write_pax_entry(ptr, "uname", temp);
sprintf(temp, "%lu", sb->st_mtime);
ptr = write_pax_entry(ptr, "mtime", temp);
sprintf(temp, "%u", sb->st_gid);
ptr = write_pax_entry(ptr, "gid", temp);
ptr = write_pax_entry(ptr, "gname", temp);
ptr = write_pax_entry(ptr, "path", name);
if (S_ISLNK(sb->st_mode)) {
write_pax_entry(ptr, "linkpath", slink_target);
} else if (S_ISREG(sb->st_mode)) {
sprintf(temp, "%lu", sb->st_size);
write_pax_entry(ptr, "size", temp);
}
len = strlen(buffer);
write_octal(hdr.size, len, 11);
update_checksum(&hdr);
ret = write_retry(fd, &hdr, sizeof(hdr));
if (ret < 0)
goto fail_wr;
if ((size_t)ret < sizeof(hdr))
goto fail_trunc;
ret = write_retry(fd, buffer, len);
if (ret < 0)
goto fail_wr;
if ((size_t)ret < len)
goto fail_trunc;
return padd_file(fd, len, 512);
fail_wr:
perror("writing pax header");
return -1;
fail_trunc:
fputs("writing pax header: truncated write\n", stderr);
return -1;
}
int write_tar_header(int fd, const struct stat *sb, const char *name,
const char *slink_target)
{
const char *reason;
tar_header_t hdr;
ssize_t ret;
if (need_pax_header(sb, name)) {
if (write_pax_header(fd, sb, name, slink_target))
return -1;
sprintf(buffer, "pax%lu_data", pax_hdr_counter++);
name = buffer;
}
init_header(&hdr, sb, name, slink_target);
switch (sb->st_mode & S_IFMT) {
case S_IFCHR: hdr.typeflag = TAR_TYPE_CHARDEV; break;
case S_IFBLK: hdr.typeflag = TAR_TYPE_BLOCKDEV; break;
case S_IFLNK: hdr.typeflag = TAR_TYPE_SLINK; break;
case S_IFREG: hdr.typeflag = TAR_TYPE_FILE; break;
case S_IFDIR: hdr.typeflag = TAR_TYPE_DIR; break;
case S_IFIFO: hdr.typeflag = TAR_TYPE_FIFO; break;
case S_IFSOCK:
reason = "cannot pack socket";
goto out_skip;
default:
reason = "unknown type";
goto out_skip;
}
update_checksum(&hdr);
ret = write_retry(fd, &hdr, sizeof(hdr));
if (ret < 0) {
perror("writing header record");
} else if ((size_t)ret < sizeof(hdr)) {
fputs("writing header record: truncated write\n", stderr);
ret = -1;
} else {
ret = 0;
}
return ret;
out_skip:
fprintf(stderr, "WARNING: skipping '%s' (%s)\n", name, reason);
return 1;
}
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