FEAT: new request-password native which reads line with hidden input and avoids command history

related to:
Oldes/Rebol-issues#476
Oldes/Rebol-issues#1388
Oldes/Rebol-issues#1400

Author: Oldes

src/boot/natives.reb

@@ -942,6 +942,10 @@ request-dir: native [
 	/keep  "Keep previous directory path"
 ]
 
+request-password: native [
+	{Asks user for input without echoing, and the entered password is not stored in the command history.}
+]
+
 ascii?: native [
 	{Returns TRUE if value or string is in ASCII character range (below 128).}
 	value [any-string! char! integer!]

src/core/n-io.c

@@ -1144,6 +1144,30 @@ static REBSER *Read_All_File(char *fname)
 }
 
 
+/***********************************************************************
+**
+*/	REBNATIVE(request_password)
+/*
+***********************************************************************/
+{
+	REBREQ  req = {0};
+	REBSER *str;
+
+	OS_REQUEST_PASSWORD(&req);
+
+	if (req.file.path == NULL) return R_NONE;
+
+#ifdef TO_WINDOWS
+	str = Decode_UTF_String(req.file.path, req.file.size, 16, 0, 0);
+#else	
+	str = Decode_UTF_String(req.file.path, req.file.size, 8, 0, 0);
+#endif
+	FREE_MEM(req.file.path);
+	SET_STRING(D_RET, str);
+	return R_RET;
+}
+
+
 /***********************************************************************
 **
 */	REBNATIVE(get_env)

src/mezz/mezz-files.reb

@@ -88,10 +88,14 @@ input: func [
 	][
 		system/ports/input: port: open [scheme: 'console]
 	]
-	if hide [ modify port 'echo false ]
-	if line: read port [ line: to string! line ]
-	if hide [ modify port 'echo true ]
-	line
+	either hide [
+		request-password
+	][
+		all [
+			line: read port
+			to string! line
+		]
+	]
 ]
 
 ask: func [

src/os/posix/host-lib.c

@@ -62,6 +62,7 @@
 #include <string.h>
 #include <errno.h>
 #include <signal.h>  //for kill
+#include <unistd.h>  //for request-password
 
 #ifndef timeval // for older systems
 #include <sys/time.h>
@@ -1370,5 +1371,38 @@ static int Try_Browser(char *browser, REBCHR *url)
 	return FALSE;
 }
 
+/***********************************************************************
+**
+*/	void OS_Request_Password(REBREQ *req)
+/*
+***********************************************************************/
+{
+	REBCNT size = 64;
+	REBCNT  pos = 0;
+	REBYTE *str = malloc(size);
+	REBYTE  c;
+
+	req->file.path = NULL;
+
+	while (read(STDIN_FILENO, &c, 1) && c != '\r') {
+		if (c ==  27) { // ESC
+			free(str);
+			return; 
+		}
+		if (c == 127) { // backspace
+			// UTF-8 aware skip back one char
+			while (pos != 0 && (str[--pos] & 0xC0) == 0x80) {}
+			continue;
+		}
+		str[pos++] = c;
+		if (pos+1 == size) {
+			size += 64;
+			str = realloc(str, size);
+		}
+	}
+	req->file.path = str;
+	req->file.size = pos;
+	str[pos++] = 0; // null terminate the tail.. just in case
+}
 
 

src/os/win32/host-lib.c

@@ -61,6 +61,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <conio.h>   // used for OS_Request_Password
 #include <windows.h>
 #include <process.h>
 #include <ShlObj.h>  // used for OS_Request_Dir
@@ -1434,3 +1435,38 @@ static INT CALLBACK BrowseCallbackProc(HWND hwnd, UINT uMsg, LPARAM lParam, LPAR
 	SHGetPathFromIDList(lpItem, fr->files);
 	return TRUE;
 }
+
+
+/***********************************************************************
+**
+*/	void OS_Request_Password(REBREQ *req)
+/*
+***********************************************************************/
+{
+	REBCNT size = 64;
+	REBCNT  pos = 0;
+	REBUNI *str = (REBUNI*)malloc(size * sizeof(REBUNI));
+	REBUNI  c;
+
+	req->file.path = NULL;
+
+	while ((c = _getwch()) != '\r') {
+		if (c ==  27) { // ESC
+			free(str);
+			return; 
+		}
+		if (c == 127) { // backspace
+			if (pos > 0) pos--;
+			continue;
+		}
+		str[pos++] = c;
+		if (pos+1 == size) {
+			size += 64;
+			str = (REBUNI*)realloc(str, size * sizeof(REBUNI));
+		}
+	}
+	req->file.path = (REBYTE*)str;
+	req->file.size = pos * sizeof(REBUNI);
+	str[pos++] = 0;
+}
+