Cleanup: split libtar header, move to sub directory

Some of the on-disk format internals are moved to a separate header
and some of the stuff from internal.h is moved to that format header.
C++ guards are added in addtion.

Everything PAX related is moved to pax_header.c, some internal
functions are marked as static.

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

2 files changed, 197 insertions, 0 deletions

diff --git a/include/tar/format.h b/include/tar/format.h
new file mode 100644
index 0000000..53a4665
--- /dev/null
+++ b/include/tar/format.h
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * format.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef TAR_FORMAT_H
+#define TAR_FORMAT_H
+
+#include "sqfs/predef.h"
+
+typedef struct {
+	char name[100];
+	char mode[8];
+	char uid[8];
+	char gid[8];
+	char size[12];
+	char mtime[12];
+	char chksum[8];
+	char typeflag;
+	char linkname[100];
+	char magic[6];
+	char version[2];
+	char uname[32];
+	char gname[32];
+	char devmajor[8];
+	char devminor[8];
+	union {
+		struct {
+			char prefix[155];
+			char padding[12];
+		} posix;
+
+		struct {
+			char atime[12];
+			char ctime[12];
+			char offset[12];
+			char deprecated[4];
+			char unused;
+			struct {
+				char offset[12];
+				char numbytes[12];
+			} sparse[4];
+			char isextended;
+			char realsize[12];
+			char padding[17];
+		} gnu;
+	} tail;
+} tar_header_t;
+
+typedef struct {
+	struct {
+		char offset[12];
+		char numbytes[12];
+	} sparse[21];
+	char isextended;
+	char padding[7];
+} gnu_sparse_t;
+
+#define TAR_TYPE_FILE '0'
+#define TAR_TYPE_LINK '1'
+#define TAR_TYPE_SLINK '2'
+#define TAR_TYPE_CHARDEV '3'
+#define TAR_TYPE_BLOCKDEV '4'
+#define TAR_TYPE_DIR '5'
+#define TAR_TYPE_FIFO '6'
+
+#define TAR_TYPE_GNU_SLINK 'K'
+#define TAR_TYPE_GNU_PATH 'L'
+#define TAR_TYPE_GNU_SPARSE 'S'
+
+#define TAR_TYPE_PAX 'x'
+#define TAR_TYPE_PAX_GLOBAL 'g'
+
+#define TAR_MAGIC "ustar"
+#define TAR_VERSION "00"
+
+#define TAR_MAGIC_OLD "ustar "
+#define TAR_VERSION_OLD " "
+
+#define TAR_RECORD_SIZE (512)
+
+/* artificially imposed implementation limits */
+#define TAR_MAX_SYMLINK_LEN (65536)
+#define TAR_MAX_PATH_LEN (65536)
+#define TAR_MAX_PAX_LEN (65536)
+#define TAR_MAX_SPARSE_ENT (65536)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int read_octal(const char *str, int digits, sqfs_u64 *out);
+
+int read_number(const char *str, int digits, sqfs_u64 *out);
+
+void update_checksum(tar_header_t *hdr);
+
+bool is_checksum_valid(const tar_header_t *hdr);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* TAR_FORMAT_H */
diff --git a/include/tar/tar.h b/include/tar/tar.h
new file mode 100644
index 0000000..128464e
--- /dev/null
+++ b/include/tar/tar.h
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * tar.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef TAR_H
+#define TAR_H
+
+#include "config.h"
+#include "compat.h"
+#include "io/istream.h"
+#include "io/ostream.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+
+typedef struct sparse_map_t {
+	struct sparse_map_t *next;
+	sqfs_u64 offset;
+	sqfs_u64 count;
+} sparse_map_t;
+
+typedef struct tar_xattr_t {
+	struct tar_xattr_t *next;
+	char *key;
+	sqfs_u8 *value;
+	size_t value_len;
+	char data[];
+} tar_xattr_t;
+
+typedef struct {
+	char *name;
+	char *link_target;
+	sparse_map_t *sparse;
+	sqfs_u64 actual_size;
+	sqfs_u64 record_size;
+	bool unknown_record;
+	bool is_hard_link;
+	tar_xattr_t *xattr;
+
+	sqfs_u16 mode;
+	sqfs_u64 uid;
+	sqfs_u64 gid;
+	sqfs_u64 devno;
+	sqfs_s64 mtime;
+} tar_header_decoded_t;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+  Returns < 0 on failure, > 0 if cannot encode, 0 on success.
+  Prints error/warning messages to stderr.
+
+  The counter is an incremental record counter used if additional
+  headers need to be generated.
+*/
+int write_tar_header(ostream_t *fp, const struct stat *sb, const char *name,
+		     const char *slink_target, const tar_xattr_t *xattr,
+		     unsigned int counter);
+
+int write_hard_link(ostream_t *fp, const struct stat *sb, const char *name,
+		    const char *target, unsigned int counter);
+
+/* calcuate and skip the zero padding */
+int skip_padding(istream_t *fp, sqfs_u64 size);
+
+/* round up to block size and skip the entire entry */
+int skip_entry(istream_t *fp, sqfs_u64 size);
+
+int read_header(istream_t *fp, tar_header_decoded_t *out);
+
+void clear_header(tar_header_decoded_t *hdr);
+
+/*
+  Write zero bytes to an output file to padd it to the tar record size.
+  Returns 0 on success. On failure, prints error message to stderr.
+*/
+int padd_file(ostream_t *fp, sqfs_u64 size);
+
+void free_sparse_list(sparse_map_t *sparse);
+
+void free_xattr_list(tar_xattr_t *list);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* TAR_H */