tdrimg: add recover command

- recover reads old file versions from the sdcard image

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]