libtar: clarify actual size vs on-disk record size

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

4 files changed, 19 insertions, 17 deletions

diff --git a/include/tar.h b/include/tar.h
index 1f8ca7e..513e5bc 100644
--- a/include/tar.h
+++ b/include/tar.h
@@ -68,7 +68,8 @@ typedef struct {
 	char *name;
 	char *link_target;
 	sparse_map_t *sparse;
-	uint64_t sparse_size;
+	uint64_t actual_size;
+	uint64_t record_size;
 	bool unknown_record;
 } tar_header_decoded_t;
 
diff --git a/lib/tar/read_header.c b/lib/tar/read_header.c
index 74666b3..21642d9 100644
--- a/lib/tar/read_header.c
+++ b/lib/tar/read_header.c
@@ -206,8 +206,7 @@ static int read_pax_header(int fd, uint64_t entsize, unsigned int *set_by_pax,
 				goto fail_errno;
 			*set_by_pax |= PAX_NAME;
 		} else if (!strncmp(line, "size=", 5)) {
-			pax_read_decimal(line + 5, &field);
-			out->sb.st_size = field;
+			pax_read_decimal(line + 5, &out->record_size);
 			*set_by_pax |= PAX_SIZE;
 		} else if (!strncmp(line, "linkpath=", 9)) {
 			free(out->link_target);
@@ -287,9 +286,8 @@ static int decode_header(const tar_header_t *hdr, unsigned int set_by_pax,
 	}
 
 	if (!(set_by_pax & PAX_SIZE)) {
-		if (read_number(hdr->size, sizeof(hdr->size), &field))
+		if (read_number(hdr->size, sizeof(hdr->size), &out->record_size))
 			return -1;
-		out->sb.st_size = field;
 	}
 
 	if (!(set_by_pax & PAX_UID)) {
@@ -617,6 +615,10 @@ int read_header(int fd, tar_header_decoded_t *out)
 			out->sparse = read_gnu_old_sparse(fd, &hdr);
 			if (out->sparse == NULL)
 				goto fail;
+			if (read_number(hdr.tail.gnu.realsize,
+					sizeof(hdr.tail.gnu.realsize),
+					&out->actual_size))
+				goto fail;
 			break;
 		}
 		break;
@@ -625,15 +627,12 @@ int read_header(int fd, tar_header_decoded_t *out)
 	if (decode_header(&hdr, set_by_pax, out, version))
 		goto fail;
 
-	if (hdr.typeflag == TAR_TYPE_GNU_SPARSE) {
-		if (read_number(hdr.tail.gnu.realsize,
-				sizeof(hdr.tail.gnu.realsize), &pax_size))
-			goto fail;
-
-		out->sparse_size = out->sb.st_size;
-		out->sb.st_size = pax_size;
+	if (out->sparse != NULL) {
+		out->sb.st_size = out->actual_size;
+	} else {
+		out->sb.st_size = out->record_size;
+		out->actual_size = out->record_size;
 	}
-
 	return 0;
 out_eof:
 	clear_header(out);
diff --git a/tar/tar2sqfs.c b/tar/tar2sqfs.c
index bce6a4d..dec717b 100644
--- a/tar/tar2sqfs.c
+++ b/tar/tar2sqfs.c
@@ -176,7 +176,7 @@ static int write_file(tar_header_decoded_t *hdr, file_info_t *fi,
 		if (ret)
 			return -1;
 
-		return skip_padding(STDIN_FILENO, hdr->sparse_size);
+		return skip_padding(STDIN_FILENO, hdr->record_size);
 	}
 
 	if (write_data_from_fd(data, fi, STDIN_FILENO))
@@ -242,7 +242,7 @@ static int process_tar_ball(fstree_t *fs, data_writer_t *data)
 				count += m->count;
 			}
 
-			if (count != hdr.sparse_size)
+			if (count != hdr.record_size)
 				skip = true;
 
 			if (skip) {
diff --git a/tests/tar_sparse_gnu.c b/tests/tar_sparse_gnu.c
index d4d65d3..4c3ee31 100644
--- a/tests/tar_sparse_gnu.c
+++ b/tests/tar_sparse_gnu.c
@@ -40,7 +40,8 @@ int main(void)
 	assert(hdr.sb.st_uid == 01750);
 	assert(hdr.sb.st_gid == 01750);
 	assert(hdr.sb.st_size == 524288);
-	assert(hdr.sparse_size == 8192);
+	assert(hdr.actual_size == 524288);
+	assert(hdr.record_size == 8192);
 	assert(strcmp(hdr.name, "input.bin") == 0);
 	assert(!hdr.unknown_record);
 
@@ -70,7 +71,8 @@ int main(void)
 	assert(hdr.sb.st_uid == 01750);
 	assert(hdr.sb.st_gid == 01750);
 	assert(hdr.sb.st_size == 2097152);
-	assert(hdr.sparse_size == 32768);
+	assert(hdr.actual_size == 2097152);
+	assert(hdr.record_size == 32768);
 	assert(strcmp(hdr.name, "input.bin") == 0);
 	assert(!hdr.unknown_record);