io interfaces: added tpax_io_seek() [for both mapped and unmapped archives].

1 files changed, 86 insertions, 0 deletions

diff --git a/src/io/tpax_io_seek.c b/src/io/tpax_io_seek.c
new file mode 100644
index 0000000..01e0683
--- /dev/null
+++ b/src/io/tpax_io_seek.c
@@ -0,0 +1,86 @@
+/**************************************************************/
+/*  tpax: a topological pax implementation                    */
+/*  Copyright (C) 2020--2024  SysDeer Technologies, LLC       */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX.         */
+/**************************************************************/
+
+#include <stdint.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include <tpax/tpax.h>
+#include <tpax/tpax_specs.h>
+#include "tpax_driver_impl.h"
+#include "tpax_errinfo_impl.h"
+
+static int tpax_io_seek_fileio(
+	struct tpax_driver_ctx *    dctx,
+	off_t                       offset,
+	int                         whence)
+{
+	int fdin;
+
+	fdin = tpax_driver_fdin(dctx);
+
+	if ((offset = lseek(fdin,offset,whence)) < 0)
+		return TPAX_SYSTEM_ERROR(dctx);
+
+	tpax_set_driver_cpos(dctx,offset);
+
+	return 0;
+}
+
+static int tpax_io_seek_mapped(
+	struct tpax_driver_ctx *    dctx,
+	off_t                       offset,
+	int                         whence)
+{
+	struct tpax_driver_ctx_impl * ictx;
+	size_t                        aoffset;
+
+	ictx = tpax_get_driver_ictx(dctx);
+
+	if (whence == SEEK_CUR) {
+		offset += tpax_get_driver_cpos(dctx);
+
+	} else if (whence == SEEK_END) {
+		offset += ictx->mapsize;
+	}
+
+	if ((offset < 0) || ((aoffset = offset) > ictx->mapsize))
+		return TPAX_CUSTOM_ERROR(
+			dctx,
+			TPAX_ERR_FLOW_ERROR);
+
+	tpax_set_driver_cpos(dctx,offset);
+
+	return 0;
+}
+
+int tpax_io_seek(struct tpax_driver_ctx * dctx, off_t offset, int whence)
+{
+	switch (whence) {
+		case SEEK_SET:
+		case SEEK_CUR:
+		case SEEK_END:
+			break;
+
+		default:
+			return TPAX_CUSTOM_ERROR(
+				dctx,
+				TPAX_ERR_FLOW_ERROR);
+	}
+
+	if (dctx->cctx->srcflags & TPAX_SOURCE_DATA_FILEIO) {
+		return tpax_io_seek_fileio(dctx,offset,whence);
+
+	} else if (dctx->cctx->srcflags & TPAX_SOURCE_DATA_MAPPED) {
+		return tpax_io_seek_mapped(dctx,offset,whence);
+
+	}
+
+	return TPAX_CUSTOM_ERROR(
+		dctx,
+		TPAX_ERR_FLOW_ERROR);
+}