tdrimg: add recover command

- recover reads old file versions from the sdcard image

lib/stdlib.pas

@@ -480,6 +480,9 @@ end;
    That means you cannot use pos to search inside a string
    literal. Hopefully this is not something you want to do.
    *)
+
+(* TODO: UCSD-Pascal and TP3.0 specs say, searched string
+   is a string expression so cannot be var parameter *)
 function pos(substr:string;var s:string):integer;
 var substrlen:integer;
     slen:integer;

pcomp/pcomp.pas

@@ -1,4 +1,6 @@
 (* Copyright 2021-2024 Sebastian Lederer. See the file LICENSE.md for details *)
+{$H384}
+{$S64}
 program PascalCompiler;
 {$R+}
 {$!}{$ifdef FPC}uses math,crt;{$endif}

progs/editor.pas

@@ -137,7 +137,8 @@ end;
 procedure getScreenSize;
 var c:char;
 begin
-	(* empty keyboard buffer *)
+	(* empty keyboard buffer to make sure GetTermSize
+		can read the response from the terminal *)
 	while conavail do read(con, c);
 
 	GetTermSize(screenW, screenH);
@@ -1661,11 +1662,10 @@ end;
 
 procedure gotoLine(l:integer);
 begin
-	if l < 1 then
-		l := 1
-	else
 	if l > lineCount then
 		l := lineCount;
+	if l < 1 then
+		l := 1;
 
 	topY := l - (screenH div 2);
 	if topY < 1 then
@@ -1713,7 +1713,7 @@ var error:integer;
 begin
 	success := true;
 	if isModified then
-		save;
+		writeFile(success);
 	if success then
 	begin
 		if isAsmFile(filename) then

utils/tdrimg.py

@@ -239,7 +239,7 @@ def listvolumes(img):
     return firstvolume
 
  
-def listdir(img, part, verbose=False):
+def listdir(img, part, verbose=False, deleted=False):
     print("Directory of {}:".format(part.name))
     slotno = 0
     done = False
@@ -247,6 +247,8 @@ def listdir(img, part, verbose=False):
         slot = getdirslot(img, part, slotno)
         if (slot.flags & SlotFirst):
             print(slot.name, slot.sizeBytes, slotno)
+        elif deleted and (slot.flags & SlotDeleted):
+            print(slot.name, slot.sizeBytes, slotno, slot.generation)
         else:
             if verbose:
                 print(flags2str(slot.flags))
@@ -272,6 +274,21 @@ def findfile(img, part, name):
     return None
 
 
+def finddeleted(img, part, name, gen):
+    slotno = 0
+    done = False
+    while not done:
+        slot = getdirslot(img, part, slotno)
+        if slot.flags & SlotDeleted:
+            if slot.name == name and slot.generation == gen:
+                return slotno
+        slotno += 1
+        if (slot.flags & SlotEndScan) or (slotno >= part.dirSize):
+            done = True
+
+    return None
+
+
 def readfile(img, part, slotno):
     pos = part.startBlock * 512 + slotno * part.extentSize
     dirslot = getdirslot(img, part, slotno)
@@ -317,6 +334,24 @@ def readfromimg(img, pathname,outfilepath):
         f.write(data)
 
 
+def recoverfromimg(img, pathname, gen, outfilepath):
+    vol, filename = parsepath(img, pathname)
+    if vol is None:
+        return
+
+    listdir(img, vol, deleted=True)
+
+    slotno = finddeleted(img, vol, filename, gen)
+    if slotno is None:
+        print("File", filename,"not found with generation no", gen)
+        return
+
+    data = readfile(img, vol, slotno)
+
+    with open(outfilepath, "wb") as f:
+        f.write(data)
+
+
 def writetoimg(img, pathname, infilepath):
     vol, filename = parsepath(img, pathname)
     if vol is None:
@@ -555,6 +590,9 @@ if __name__ == "__main__":
         if sys.argv[1] == "get":
             f = open(sys.argv[2], "rb")
             readfromimg(f, sys.argv[3], sys.argv[4])
+        elif sys.argv[1] == "recover":
+            f = open(sys.argv[2], "rb")
+            recoverfromimg(f, sys.argv[3], int(sys.argv[4]), sys.argv[5])
         elif sys.argv[1] == "put":
             imgfile = open(sys.argv[2], "r+b")
             infilepath = sys.argv[3]