From 8fb8f962f58680a040390d42ab412e27f5e93a3d Mon Sep 17 00:00:00 2001
From: midipix <writeonce@midipix.org>
Date: May 23 2020 05:59:02 +0000
Subject: helper interfaces: tpax_path_copy(): initial implementation.


---

diff --git a/include/tpax/tpax.h b/include/tpax/tpax.h
index 059dbac..5281ea1 100644
--- a/include/tpax/tpax.h
+++ b/include/tpax/tpax.h
@@ -147,6 +147,7 @@ tpax_api int  tpax_set_driver_fdctx     (struct tpax_driver_ctx *, const struct 
 /* core api */
 
 /* helper api */
+tpax_api int  tpax_path_copy            (char *, const char *, size_t, uint32_t, size_t *);
 
 /* utility api */
 tpax_api int  tpax_main                 (char **, char **,
diff --git a/project/common.mk b/project/common.mk
index 54f7d11..ca6bc81 100644
--- a/project/common.mk
+++ b/project/common.mk
@@ -2,6 +2,7 @@ API_SRCS = \
 	src/driver/tpax_amain.c \
 	src/driver/tpax_driver_ctx.c \
 	src/driver/tpax_unit_ctx.c \
+	src/helper/tpax_path_copy.c \
 	src/logic/tpax_init_ustar_header.c \
 	src/output/tpax_output_error.c \
 	src/skin/tpax_skin_default.c \
diff --git a/project/tree.mk b/project/tree.mk
index ab26f1e..548db6f 100644
--- a/project/tree.mk
+++ b/project/tree.mk
@@ -1,5 +1,6 @@
 TREE_DIRS     = bin lib src \
 		src/driver \
+		src/helper \
 		src/internal \
 		src/logic \
 		src/output \
diff --git a/src/helper/tpax_path_copy.c b/src/helper/tpax_path_copy.c
new file mode 100644
index 0000000..0df6c17
--- /dev/null
+++ b/src/helper/tpax_path_copy.c
@@ -0,0 +1,86 @@
+/******************************************************/
+/*  tpax: a topological pax implementation            */
+/*  Copyright (C) 2020  Z. Gilboa                     */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
+/******************************************************/
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/stat.h>
+
+#include <tpax/tpax.h>
+#include "tpax_driver_impl.h"
+
+int tpax_path_copy(
+	char *          dstpath,
+	const char *    srcpath,
+	size_t          bufsize,
+	uint32_t        flags,
+	size_t *        nwritten)
+{
+	const char *    src;
+	char *          dst;
+	char *          cap;
+
+	if (!bufsize) {
+		errno = ENOBUFS;
+		return -1;
+	}
+
+	src = srcpath;
+	dst = dstpath;
+	cap = &dst[bufsize];
+
+	if ((src[0] == '/') && (src[1] == '/') && (src[2] != '/')) {
+		*dst++ = *src++;
+		*dst++ = *src++;
+	}
+
+	if (flags & TPAX_DRIVER_PURE_PATH_OUTPUT)
+		if ((src[0] == '.') && (src[1] == '/'))
+			for (++src; *src=='/'; src++)
+				(void)0;
+
+	for (; *src; ) {
+		if ((src[0] == '.') && (src[1] == '.')) {
+			if ((src[2] == '/') || (src[2] == '\0')) {
+				if (flags & TPAX_DRIVER_STRICT_PATH_INPUT) {
+					errno = EINVAL;
+					return -1;
+				}
+			}
+		}
+
+		if (flags & TPAX_DRIVER_PURE_PATH_OUTPUT) {
+			if ((src[0] == '.') && (src[1] == '/') && (src[-1] == '/')) {
+				for (++src; *src=='/'; src++)
+					(void)0;
+
+			} else if ((src[0] == '/')) {
+				for (src++; *src=='/'; src++)
+					(void)0;
+
+				*dst++ = '/';
+
+			} else {
+				*dst++ = *src++;
+			}
+		} else {
+			*dst++ = *src++;
+		}
+
+		if (dst == cap) {
+			errno = ENOBUFS;
+			return -1;
+		}
+	}
+
+	if (nwritten)
+		*nwritten = dst - dstpath;
+
+	*dst = '\0';
+
+	return 0;
+}