1 files changed, 80 insertions, 0 deletions
diff --git a/src/host/path_getrelative.c b/src/host/path_getrelative.c
new file mode 100644
index 0000000..dc6629b
--- /dev/null
+++ b/src/host/path_getrelative.c
@@ -0,0 +1,80 @@
+/**
+ * \file   path_getrelative.c
+ * \brief  Returns a path relative to another.
+ * \author Copyright (c) 2002-2013 Jason Perkins and the Premake project
+ */
+
+#include "premake.h"
+#include <string.h>
+
+
+int path_getrelative(lua_State* L)
+{
+	int i, last, count;
+	char src[0x4000];
+	char dst[0x4000];
+
+	const char* p1 = luaL_checkstring(L, 1);
+	const char* p2 = luaL_checkstring(L, 2);
+
+	/* normalize the paths */
+	do_getabsolute(src, p1, NULL);
+	do_getabsolute(dst, p2, NULL);
+
+	/* same directory? */
+	if (strcmp(src, dst) == 0) {
+		lua_pushstring(L, ".");
+		return 1;
+	}
+
+	/* dollar macro? Can't tell what the real path might be, so treat
+	 * as absolute. This enables paths like $(SDK_ROOT)/include to
+	 * work as expected. */
+	if (dst[0] == '$') {
+		lua_pushstring(L, dst);
+		return 1;
+	}
+
+	/* find the common leading directories */
+	strcat(src, "/");
+	strcat(dst, "/");
+
+	last = -1;
+	i = 0;
+	while (src[i] && dst[i] && src[i] == dst[i]) {
+		if (src[i] == '/') {
+			last = i;
+		}
+		++i;
+	}
+
+	/* if I end up with just the root of the filesystem, either a single
+	 * slash (/) or a drive letter (c:) then return the absolute path. */
+	if (last <= 0 || (last == 2 && src[1] == ':')) {
+		dst[strlen(dst) - 1] = '\0';
+		lua_pushstring(L, dst);
+		return 1;
+	}
+
+	/* count remaining levels in src */
+	count = 0;
+	for (i = last + 1; src[i] != '\0'; ++i) {
+		if (src[i] == '/') {
+			++count;
+		}
+	}
+
+	/* start my result by backing out that many levels */
+	src[0] = '\0';
+	for (i = 0; i < count; ++i) {
+		strcat(src, "../");
+	}
+
+	/* append what's left */
+	strcat(src, dst + last + 1);
+
+	/* remove trailing slash and done */
+	src[strlen(src) - 1] = '\0';
+	lua_pushstring(L, src);
+	return 1;
+}