FEAT: new to-real-file native (posix version) for resolving canonic…

…alized filenames (removing `..` and `.` path components, simplification of sequences of multiple slashes, removal of trailing slashes, and the resolution of symbolic links).

src/core/n-io.c

@@ -468,6 +468,36 @@ static REBSER *Read_All_File(char *fname)
 	return R_RET;
 }
 
+/***********************************************************************
+**
+*/	REBNATIVE(to_real_file)
+/*
+//	to-real-file: native [
+//		"Returns canonicalized absolute pathname or none if path does not exists. Resolves symbolic links."
+//		path [file! string!]
+//	]
+***********************************************************************/
+{
+	REBVAL *path = D_ARG(1);
+	REBINT  len;
+	REBSER *ser;
+	REBSER *new;
+	char   *tmp;
+
+	ser = Value_To_OS_Path(path, TRUE);
+	tmp = OS_REAL_PATH(cs_cast(VAL_BIN(path)));
+	if(!tmp) {
+		FREE_SERIES(ser);
+		return R_NONE;
+	}
+	len = strlen(tmp);
+	new = To_REBOL_Path(tmp, len, OS_WIDE, FALSE);
+	Set_Series(REB_FILE, D_RET, new);
+	FREE_SERIES(ser);
+	FREE_MEM(tmp);
+	return R_RET;
+}
+
 // Blog: http://www.rebol.net/cgi-bin/r3blog.r?view=0319
 /***********************************************************************
 **

src/os/posix/host-lib.c

@@ -663,6 +663,23 @@ int pipe2(int pipefd[2], int flags); //to avoid "implicit-function-declaration"
 }
 
 
+/***********************************************************************
+**
+*/	char* OS_Real_Path(const char *path)
+/*
+**		Returns a null-terminated string containing the canonicalized
+**		absolute pathname corresponding to path. In the returned string,
+**		symbolic links are resolved, as are . and .. pathname components.
+**		Consecutive slash (/) characters are replaced by a single slash.
+**
+**		The result should be freed after copy/conversion.
+**
+***********************************************************************/
+{
+	return realpath(path, NULL); // Be sure to call free() after usage
+}
+
+
 /***********************************************************************
 **
 */	void OS_File_Time(REBREQ *file, REBOL_DAT *dat)

src/os/win32/host-lib.c

@@ -658,6 +658,21 @@ static void *Task_Ready;
 		return GetLastError();
 }
 
+/***********************************************************************
+**
+*/	char* OS_Real_Path(const char *path)
+/*
+**		Returns a null-terminated string containing the canonicalized
+**		absolute pathname corresponding to path. In the returned string,
+**		symbolic links are resolved, as are . and .. pathname components.
+**		Consecutive slash (/) characters are replaced by a single slash.
+**
+**		The result should be freed after copy/conversion.
+**
+***********************************************************************/
+{
+	return NULL; // not yet implemented
+}
 
 /***********************************************************************
 **