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tar-util: properly deal with sparse files

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The extractor already deals with sparse files properly (because
archive_read_data_into_fd() does).

Let's also make sure the archiver also does this, and attaches the
necessary sparse file metadata to each file.
This commit is contained in:
Lennart Poettering
2025-11-04 14:12:39 +01:00
parent 63bf3ca8b0
commit a54f4520f3
3 changed files with 71 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/shared/libarchive-util.c
+4 -3
View File
@@ -37,6 +37,7 @@ DLSYM_PROTOTYPE(archive_entry_set_rdevminor) = NULL;
DLSYM_PROTOTYPE(archive_entry_set_size) = NULL;
DLSYM_PROTOTYPE(archive_entry_set_symlink) = NULL;
DLSYM_PROTOTYPE(archive_entry_set_uid) = NULL;
DLSYM_PROTOTYPE(archive_entry_sparse_add_entry) = NULL;
DLSYM_PROTOTYPE(archive_entry_symlink) = NULL;
DLSYM_PROTOTYPE(archive_entry_uid) = NULL;
#if HAVE_LIBARCHIVE_UID_IS_SET
@@ -61,7 +62,7 @@ DLSYM_PROTOTYPE(archive_write_new) = NULL;
DLSYM_PROTOTYPE(archive_write_open_FILE) = NULL;
DLSYM_PROTOTYPE(archive_write_open_fd) = NULL;
DLSYM_PROTOTYPE(archive_write_set_format_filter_by_ext) = NULL;
DLSYM_PROTOTYPE(archive_write_set_format_gnutar) = NULL;
DLSYM_PROTOTYPE(archive_write_set_format_pax) = NULL;
int dlopen_libarchive(void) {
ELF_NOTE_DLOPEN("archive",
@@ -103,6 +104,7 @@ int dlopen_libarchive(void) {
DLSYM_ARG(archive_entry_set_size),
DLSYM_ARG(archive_entry_set_symlink),
DLSYM_ARG(archive_entry_set_uid),
DLSYM_ARG(archive_entry_sparse_add_entry),
DLSYM_ARG(archive_entry_symlink),
DLSYM_ARG(archive_entry_uid),
#if HAVE_LIBARCHIVE_UID_IS_SET
@@ -127,8 +129,7 @@ int dlopen_libarchive(void) {
DLSYM_ARG(archive_write_open_FILE),
DLSYM_ARG(archive_write_open_fd),
DLSYM_ARG(archive_write_set_format_filter_by_ext),
DLSYM_ARG(archive_write_set_format_gnutar)
);
DLSYM_ARG(archive_write_set_format_pax));
}
/* libarchive uses its own file type macros. They happen to be defined the same way as the Linux ones, and
src/shared/libarchive-util.h
+2 -1
View File
@@ -33,6 +33,7 @@ extern DLSYM_PROTOTYPE(archive_entry_set_rdevminor);
extern DLSYM_PROTOTYPE(archive_entry_set_size);
extern DLSYM_PROTOTYPE(archive_entry_set_symlink);
extern DLSYM_PROTOTYPE(archive_entry_set_uid);
extern DLSYM_PROTOTYPE(archive_entry_sparse_add_entry);
extern DLSYM_PROTOTYPE(archive_entry_symlink);
extern DLSYM_PROTOTYPE(archive_entry_uid);
extern DLSYM_PROTOTYPE(archive_entry_xattr_add_entry);
@@ -54,7 +55,7 @@ extern DLSYM_PROTOTYPE(archive_write_new);
extern DLSYM_PROTOTYPE(archive_write_open_FILE);
extern DLSYM_PROTOTYPE(archive_write_open_fd);
extern DLSYM_PROTOTYPE(archive_write_set_format_filter_by_ext);
extern DLSYM_PROTOTYPE(archive_write_set_format_gnutar);
extern DLSYM_PROTOTYPE(archive_write_set_format_pax);
#if HAVE_LIBARCHIVE_UID_IS_SET
extern DLSYM_PROTOTYPE(archive_entry_gid_is_set);
src/shared/tar-util.c
+65 -7
View File
@@ -804,6 +804,57 @@ bypass:
return 0;
}
static int archive_generate_sparse(struct archive_entry *entry, int fd) {
assert(entry);
assert(fd);
off_t c = 0;
for (;;) {
/* Look for the next hole */
off_t h = lseek(fd, c, SEEK_HOLE);
if (h < 0) {
if (errno != ENXIO)
return log_error_errno(errno, "Failed to issue SEEK_HOLE: %m");
/* If errno == ENXIO, that means we've reached the final data of the file and
* that data isn't followed by anything more */
/* Figure out where the end of the file is */
off_t e = lseek(fd, 0, SEEK_END);
if (e < 0)
return log_error_errno(errno, "Failed to issue SEEK_END: %m");
/* Generate sparse entry for final block */
if (e > c && c != 0) {
log_debug("final sparse block %" PRIu64 "…%" PRIu64, (uint64_t) c, (uint64_t) e);
sym_archive_entry_sparse_add_entry(entry, c, e - c);
}
break;
}
if (h > c) {
log_debug("inner sparse block %" PRIu64 "…%" PRIu64 " (%" PRIu64 ")", (uint64_t) c, (uint64_t) h, (uint64_t) h - (uint64_t) c);
sym_archive_entry_sparse_add_entry(entry, c, h - c);
}
/* Now look for the next data after the hole */
c = lseek(fd, h, SEEK_DATA);
if (c < 0) {
if (errno != ENXIO)
return log_error_errno(errno, "Failed to issue SEEK_DATA: %m");
/* No data anymore */
break;
}
}
if (lseek(fd, 0, SEEK_SET) < 0)
return log_error_errno(errno, "Failed to reset seek offset: %m");
return 0;
}
static int archive_item(
RecurseDirEvent event,
const char *path,
@@ -912,16 +963,23 @@ static int archive_item(
sym_archive_entry_xattr_add_entry(entry, xa, buf, size);
}
_cleanup_close_ int data_fd = -EBADF;
if (S_ISREG(sx->stx_mode)) {
/* Convert the O_PATH fd into a proper fd */
data_fd = fd_reopen(inode_fd, O_RDONLY|O_CLOEXEC);
if (data_fd < 0)
return log_error_errno(data_fd, "Failed to open '%s': %m", path);
r = archive_generate_sparse(entry, data_fd);
if (r < 0)
return r;
}
if (sym_archive_write_header(d->archive, entry) != ARCHIVE_OK)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "Failed to write archive entry header: %s", sym_archive_error_string(d->archive));
if (S_ISREG(sx->stx_mode)) {
_cleanup_close_ int data_fd = -EBADF;
/* Convert the O_PATH fd in a proper fd */
data_fd = fd_reopen(inode_fd, O_RDONLY|O_CLOEXEC);
if (data_fd < 0)
return log_error_errno(data_fd, "Failed to open '%s': %m", path);
assert(data_fd >= 0);
for (;;) {
char buffer[64*1024];
@@ -965,7 +1023,7 @@ int tar_c(int tree_fd, int output_fd, const char *filename, TarFlags flags) {
if (filename)
r = sym_archive_write_set_format_filter_by_ext(a, filename);
else
r = sym_archive_write_set_format_gnutar(a);
r = sym_archive_write_set_format_pax(a);
if (r != ARCHIVE_OK)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "Failed to set libarchive output format: %s", sym_archive_error_string(a));