Handle write-protected disks when modifying settings and shortcuts

Ensure DeskTop can run nicely when running from write protected media.
This involves updating the code that saves settings/shortcuts to do a
better job of distinguishing failure cases, and also modoifying the
ProDOS MLI call flow. Now everything follows this pattern:

1. CREATE the LOCAL/ directory (if it already exists, no-op)

2. DESTROY the settings file (if it doesn't exist, no-op); this is to
detect write protection early. Without this, OPEN/WRITE/CLOSE can fail
to flush on CLOSE and leave the system in a bad state.

3. CREATE/OPEN/WRITE/CLOSE the settings file.

... and if running from RAMCard, then temporarily swap the ProDOS
Prefix and repeat the above steps for the startup path.

At any failure point this fails then initially a prompt is shown to
confirm that the user even wants to save settings. If they continue
then any subsequent failure is either OK or Try Again/Cancel.

This applies to the Control Panels that modify settings as well as
DeskTop's shortcut modification code.

Author: inexorabletash

RELEASE-NOTES.md

@@ -68,6 +68,7 @@ Project Page: https://github.com/a2stuff/a2d
 * Make retries on "volume not found" errors more consistent.
 * Fix buttons shown in alerts for errors after actions like New Folder, Duplicate, and Make Alias.
 * Reduce disk activity needed after showing file dialog.
+* Handle write protected disk when modifying shortcuts.
 
 ### Selector
 
@@ -98,6 +99,7 @@ Project Page: https://github.com/a2stuff/a2d
 * Sci.Calc: Fix ASIN/ACOS for 1/-1.
 * New Screen Saver: Maze
 * Text Preview: Show first 64K of larger files correctly.
+* Control Panels: Handle write protected disk when modifying settings.
 
 ### Misc
 

bin/mametest

@@ -102,6 +102,14 @@ if [ ! -f "tests/images/$HARDIMG" ]; then
   make package
 fi
 
+# Generate a read-only (Zipped) copy of the A2D disk
+ROHARDIMG="$HARDIMG.zip"
+if [ ! -f "tests/images/$ROHARDIMG" -o \
+       "tests/images/$ROHARDIMG" -ot "tests/images/$HARDIMG" ] ; then
+  rm -f $ROHARDIMG
+  zip -q "tests/images/$ROHARDIMG" "tests/images/$HARDIMG"
+fi
+
 MODEL="apple2ee"
 MODELARGS="-sl2 mouse -sl7 cffa2"
 DISKARGS="-hard1 $HARDIMG"
@@ -117,14 +125,18 @@ fi
 # --------------------------------------------------
 # Disk handling
 
+# Make a fresh copy of each disk into temp directory, renamed per
+# drive e.g. "-flop1 disk.po" becomes "-flop1 /tmp/.../flop1.po"
 NEWDISKARGS=""
 while read -r arg disk; do
-  target="$DISKSDIR/${arg#?}"
+  # Maintaining extension is necessary for ZIP files
+  target="$DISKSDIR/${arg#?}.${disk##*.}"
   cp "tests/images/$disk" "$target"
   NEWDISKARGS="$NEWDISKARGS $arg $target"
 done < <(echo $DISKARGS | xargs -n 2)
 DISKARGS="$NEWDISKARGS"
 
+# Make an unformatted disk available to tests
 export UNFORMATTED_IMG="$DISKSDIR/unformatted.2mg"
 cp "tests/images/unformatted.2mg" "$UNFORMATTED_IMG"
 

src/desk_acc/date.and.time.s

@@ -1305,14 +1305,22 @@ current:
         JSR_TO_AUX aux::RunDA
         sta     result
 
+    IF bit result : VS
+        jsr     SaveSettings
+
+        ;; If we failed to save settings (e.g. write protected), don't
+        ;; bother trying to save the date as that is more error prone;
+        ;; e.g. if write protected, the CLOSE will fail leaving the IO
+        ;; buffer and file control block permanently in use.
+        bcs     ret
+    END_IF
+
     IF bit result : NS
         jsr     SaveDate
     END_IF
 
-    IF bit result : VS
-        jsr     SaveSettings
-    END_IF
 
+ret:
         rts
 
 result: .byte   0
@@ -1324,94 +1332,110 @@ result: .byte   0
 filename:
         PASCAL_STRING kFilenameLauncher
 
-filename_buffer:
+write_buffer:
+        .tag    DateTime
+        sizeof_write_buffer = * - write_buffer
+
+        ;; If running from RAMCard, we temporarily swap the ProDOS
+        ;; prefix for writing back to the startup disk.
+current_prefix:
+        .res ::kPathBufferSize
+orig_prefix:
         .res ::kPathBufferSize
 
         DEFINE_OPEN_PARAMS open_params, filename, DA_IO_BUFFER
         DEFINE_SET_MARK_PARAMS set_mark_params, kLauncherDateOffset
         DEFINE_READWRITE_PARAMS write_params, write_buffer, sizeof_write_buffer
         DEFINE_CLOSE_PARAMS close_params
 
-write_buffer:
-        .tag    DateTime
-        sizeof_write_buffer = * - write_buffer
+        DEFINE_GET_PREFIX_PARAMS current_prefix_params, current_prefix
+        DEFINE_GET_PREFIX_PARAMS orig_prefix_params, orig_prefix
+
 
 .proc SaveSettings
         ;; ProDOS GP has the updated data, copy somewhere usable.
         COPY_STRUCT DateTime, DATELO, write_buffer
 
+        ;; First time - ask if we should even try.
+        CLEAR_BIT7_FLAG retry_flag
+
         ;; Write to desktop current prefix
-        ldax    #filename
-        stax    open_params::pathname
         jsr     _DoWrite
         bcs     done            ; failed and canceled
 
         ;; Write to the original file location, if necessary
         jsr     JUMP_TABLE_GET_RAMCARD_FLAG
-        beq     done
-        ldax    #filename_buffer
-        stax    open_params::pathname
-        jsr     JUMP_TABLE_GET_ORIG_PREFIX
-        jsr     _AppendFilename
+    IF ZC
+        CALL    JUMP_TABLE_GET_ORIG_PREFIX, AX=#orig_prefix
+        JUMP_TABLE_MLI_CALL GET_PREFIX, current_prefix_params
+retry:
+        JUMP_TABLE_MLI_CALL SET_PREFIX, orig_prefix_params
+      IF CS
+        jsr     _CheckRetry
+        beq     retry
+        sec                     ; failed
+        rts
+      END_IF
         jsr     _DoWrite
+        JUMP_TABLE_MLI_CALL SET_PREFIX, current_prefix_params
+        ;; Assert: Succeeded (otherwise RAMCard was deleted out from under us)
+    END_IF
 
 done:   rts
-
-.proc _AppendFilename
-        ;; Append filename to buffer
-        inc     filename_buffer ; Add '/' separator
-        ldx     filename_buffer
-        copy8   #'/', filename_buffer,x
-
-        ldx     #0              ; Append filename
-        ldy     filename_buffer
-    DO
-        inx
-        iny
-        copy8   filename,x, filename_buffer,y
-    WHILE X <> filename
-        sty     filename_buffer
-        rts
-.endproc ; _AppendFilename
+.endproc ; SaveSettings
 
 .proc _DoWrite
-        ;; First time - ask if we should even try.
-        copy8   #kErrSaveChanges, message
-
-retry:
+retry3:
         JUMP_TABLE_MLI_CALL OPEN, open_params
-        bcs     error
+    IF CC
         lda     open_params::ref_num
         sta     set_mark_params::ref_num
         sta     write_params::ref_num
         sta     close_params::ref_num
-
         JUMP_TABLE_MLI_CALL SET_MARK, set_mark_params ; seek
-        bcs     close
+        bcs     :+
         JUMP_TABLE_MLI_CALL WRITE, write_params
-close:  php                     ; preserve result
+:       php                     ; preserve result
         JUMP_TABLE_MLI_CALL CLOSE, close_params
+        ;; BUG: If write protected, this will leave the `io_buffer` in use!
         plp
-        bcc     ret             ; succeeded
+    END_IF
+    IF CS
+        jsr     _CheckRetry
+        beq     retry3
+        bne     failed          ; always
+    END_IF
+        rts                     ; C=0
+
+failed:
+        sec
+ret:    rts                     ; C=1
+.endproc ; _DoWrite
 
-error:
-        ;; TODO: Consider doing this only on `ERR_VOL_NOT_FOUND`
-        message := *+1
-        lda     #SELF_MODIFIED_BYTE
-        jsr     JUMP_TABLE_SHOW_ALERT ; `kErrSaveChanges` or `kErrInsertSystemDisk`
+;;; Before calling: ensure `retry_flag` was cleared at some point.
+;;; Input: A = ProDOS error code
+;;; Output: Z = 1 if retry was selected
+.proc _CheckRetry
+    IF bit retry_flag : NC
+        ;; First time - prompt see if we want to try saving.
+        SET_BIT7_FLAG retry_flag
+        CALL    JUMP_TABLE_SHOW_ALERT, A=#kErrSaveChanges ; OK/Cancel
+        cmp     #kAlertResultOK
+        rts                     ; Z=1 if OK selected (i.e. retry)
+    END_IF
 
-        ;; If we do this again, prompt to insert.
-        ldx     #kErrInsertSystemDisk
-        stx     message
+        ;; Special case
+    IF A = #ERR_VOL_NOT_FOUND
+        lda     #kErrInsertSystemDisk ; Try Again/Cancel
+    END_IF
+        jsr     JUMP_TABLE_SHOW_ALERT ; arbitrary ProDOS error
+        ;; Responses are either OK or Try Again/Cancel
+        cmp     #kAlertResultTryAgain
+        rts
+.endproc
 
-        ;; Responses are either OK/Cancel or Try Again/Cancel
-        cmp     #kAlertResultCancel
-        bne     retry
+retry_flag:        .byte   0 ; bit7
 
-        sec                     ; failed
-ret:    rts
-.endproc ; _DoWrite
-.endproc ; SaveSettings
 .endproc ; save_date
 SaveDate := save_date::SaveSettings