FIX: better fix of reading list of logical drives on Windows

fixes: Oldes/Rebol-issues#2031

Author: Oldes

src/core/p-dir.c

@@ -60,6 +60,15 @@
 
 	dir->data = (REBYTE*)(&file);
 
+#ifdef TO_WINDOWS
+	REBCHR *cp = file.file.path;
+	if (cp[0] == '/' && cp[1] == 0) {
+		// special case: reading drive letters -> read %/
+		// https://github.com/Oldes/Rebol-issues/issues/2031
+		SET_FLAG(dir->modes, RFM_DRIVES);
+	}
+#endif
+
 	while ((result = OS_DO_DEVICE(dir, RDC_READ)) == 0 && !GET_FLAG(dir->flags, RRF_DONE)) {
 		len = (REBCNT)LEN_STR(file.file.path);
 		if (GET_FLAG(file.modes, RFM_DIR)) len++;

src/core/s-file.c

@@ -143,13 +143,6 @@
 		out = UNI_HEAD(dst);
 #ifdef TO_WINDOWS
 		i++;
-		if (len == 1 && !full) {
-			// special case: reading drive letters -> read %/
-			// https://github.com/rebol/rebol-issues/issues/2031
-			out[0] = 0;
-			SERIES_TAIL(dst) = 0;
-			return dst;
-		}
 		if (i < len) {
 			c = GET_CHAR_UNI(uni, bp, i);
 			i++;

src/include/reb-file.h

@@ -38,6 +38,7 @@ enum {
 	RFM_RESEEK,			// file index has moved, reseek
 	RFM_NAME_MEM,		// converted name allocated in mem
 	RFM_DIR = 16,
+	RFM_DRIVES,         // used only on Windows to get logical drives letters (read %/)
 };
 
 // RFE - REBOL File Error

src/os/win32/dev-file.c

@@ -138,50 +138,18 @@ static BOOL Seek_File_64(REBREQ *file)
 
 	if (!h) {
 		file->modes = 0;		
-		if (dir->file.path[0] == 0) {
-			// Reading drives.. Rebol code: read %/
-			len = (1 + GetLogicalDriveStrings(0, NULL)) << 1;
-			h = MAKE_MEM(len);
-			GetLogicalDriveStrings(len, h);
-			dir->length = len;
-			dir->actual = 0;
-			file->modes = 0;
-			SET_FLAG(file->modes, RFM_DIR);
-		} else {
-			// Read first file entry:
-			h = FindFirstFile(dir->file.path, &info);
-			if (h == INVALID_HANDLE_VALUE) {
-				dir->error = -RFE_OPEN_FAIL;
-				return DR_ERROR;
-			}
-			cp = info.cFileName;
+		// Read first file entry:
+		h = FindFirstFile(dir->file.path, &info);
+		if (h == INVALID_HANDLE_VALUE) {
+			dir->error = -RFE_OPEN_FAIL;
+			return DR_ERROR;
 		}
+		cp = info.cFileName;
 		dir->handle = h;
 		CLR_FLAG(dir->flags, RRF_DONE);
 	}
-
-	if (dir->length > 0) {
-		// Drive names processing...
-		cp = (REBCHR*)h + dir->actual;
-		file->file.path = cp;
-		if (cp[0] == 0 || dir->length <= dir->actual) {
-			// end
-			FREE_MEM(dir->handle);
-			dir->handle = NULL;
-			SET_FLAG(dir->flags, RRF_DONE); // no more files
-			return DR_DONE;
-		}
-		while (cp[0] != 0 && dir->length > dir->actual) {
-			cp++; dir->actual++;
-		}
-		cp[-2] = 0;    // the names are as: "C:\" but we want just "C", so just terminate the string sooner
-		dir->actual++; // skip the null after current drive name
-		return DR_DONE;
-	}
-	// regular DIR processing follows...
 	// Skip over the . and .. dir cases:
 	while (cp == 0 || (cp[0] == '.' && (cp[1] == 0 || (cp[1] == '.' && cp[2] == 0)))) {
-
 		// Read next file entry, or error:
 		if (!FindNextFile(h, &info)) {
 			dir->error = GetLastError();
@@ -193,7 +161,6 @@ static BOOL Seek_File_64(REBREQ *file)
 			return DR_DONE;
 		}
 		cp = info.cFileName;
-
 	}
 
 	file->modes = 0;
@@ -204,6 +171,46 @@ static BOOL Seek_File_64(REBREQ *file)
 	return DR_DONE;
 }
 
+/***********************************************************************
+**
+*/	static int Read_Drives(REBREQ *dir, REBREQ *file)
+/*
+**		Reading list of logical drives.. Rebol code: read %/
+**
+***********************************************************************/
+{
+	HANDLE h= (HANDLE)(dir->handle);
+	REBCHR *cp = 0;
+	REBCNT len;
+	if (!h) {
+		len = (1 + GetLogicalDriveStrings(0, NULL)) << 1;
+		h = MAKE_MEM(len);
+		GetLogicalDriveStrings(len, h);
+		dir->length = len;
+		dir->actual = 0;
+		dir->handle = h;
+		file->modes = 0;
+		CLR_FLAG(dir->flags, RRF_DONE);
+	}
+	// Drive names processing...
+	cp = (REBCHR*)h + dir->actual;
+	file->file.path = cp;
+	if (cp[0] == 0 || dir->length <= dir->actual) {
+		// end
+		FREE_MEM(dir->handle);
+		dir->handle = NULL;
+		SET_FLAG(dir->flags, RRF_DONE); // no more files
+		return DR_DONE;
+	}
+	while (cp[0] != 0 && dir->length > dir->actual) {
+		cp++; dir->actual++;
+	}
+	// the names are as: "C:\" but we want "C/"
+	cp[-2] = '/';
+	cp[-1] = 0;    
+	dir->actual++; // skip the null after current drive name
+	return DR_DONE;
+}
 
 /***********************************************************************
 **
@@ -314,7 +321,10 @@ static BOOL Seek_File_64(REBREQ *file)
 ***********************************************************************/
 {
 	if (GET_FLAG(file->modes, RFM_DIR)) {
-		return Read_Directory(file, (REBREQ*)file->data);
+		if (!GET_FLAG(file->modes, RFM_DRIVES))
+			return Read_Directory(file, (REBREQ*)file->data);
+		else
+			return Read_Drives(file, (REBREQ*)file->data);
 	}
 
 	if (!file->handle) {

src/tests/units/port-test.r3

@@ -57,6 +57,16 @@ Rebol [
 			not error? try [delete-dir %units/temp-dir/]
 			not exists? %units/temp-dir/
 		]
+if system/platform = 'Windows [
+	--test-- "read %/"
+	;@@ https://github.com/Oldes/Rebol-issues/issues/2031
+		--assert all [
+			block? drives: read %/
+			not empty? drives
+			2 = length? drives/1
+			#"/" = last drives/1
+		]
+]
 
 ===end-group===