def crw_getendaddress(file, offset, debug_output):
"""
Calculate the end address of a CRW file.
This function must be implemented with exactly these parameters in order to use it for
the L{FileExtractorCore}. It determines the end of a CRW file within a binary source file.
When examing several examples of CRW files and taking some documentation of this file format
in addition it could be outworked that right at the end of a CRW file kind of a directory
is stored. Luckyly for us, some sequences in there appeared at exactly the same position within
the example files measured from the end of the file. These circumstances enable us to estimate
the end of a CRW file. Not sure, whether is works for all CRWs, but it worked for ours and
recovered more than 2000 pictures.
@param file: Source file the start sequence was found in
@type file: Reference to a file
@param offset: Position of the start sequence within the source file
@type offset: C{int}
@param debug_output: Indicates, whether to produce output to standard out.
@type debug_output: C{Boolean}
@return: -1 if the end of the file could not be determined, otherwise the offset inside the
source file for the end of the found file measured from the beginning of the source file.
@rtype: C{int}
@attention: There is no limitation implemented for the file size of the found file. Consequently,
this function will examine the source file from the start offset up to the end, which can
take quite a while.
@todo: Implement a break criterion and limit the file size.
"""
if debug_output:
print("\tEntered function in additional module manual_crw for calculating")
print("\tend address for CRW file (depending on the file size this may last several minutes)")
st = file.read(len(sequ) - 1)
while len(st) > 1:
ch = file.read(1)
st = st + ch
if ord(st[0]) == sequ[0]:
if tools.checkString(st, sequ):
pos = file.tell() - len(sequ)
file.seek(pos + 7)
st1 = file.read(5)
if tools.checkString(st1, sequ_zeros):
file.seek(pos + 12)
st2 = file.read(2)
if tools.checkString(st2, sequ1):
file.seek(pos + 22)
st2 = file.read(2)
if tools.checkString(st2, sequ2):
if debug_output:
print("\t--- Leave function - calculated end address: 0x%x" % (pos + 35))
return pos + 35
st = st[1:]
if debug_output:
print("\t--- Leave function now - no end address could be determined")
return -1
def startSearch(status_passed):
"""
Invokes the search on the file.
Central bit of the core - examines the source file byte by byte and checks against the
provided start sequences of files (provided by the signatures). Ones, a start sequence
has been found, the further actions depend on the type of signature (in fact, how the end
of the file is identified - by end sequence, file size info inside file or manual by
additional module).
The status object is constantly updated. The frequency of updating the status instance with
progress within a source file depends on the value in the settings instance (
ExecutionSettings.ExecutionSettings.output_frequency) In fact, this variable says how often
a message shall be sent to the status object in total for the current source file.
@param status_passed: Reference to the status instance for applying runtime information and
gaining settings for the running.
@type status_passed: ExecutionSettings.ExecutionStatus
return: Active Signatures; Overall Counter
rtype: C{List} of C{Signatures}; C{int}
"""
global binfile, start, skipped, size, maxlength
global status
status= status_passed
st = binfile.read(maxlength-1)
dx = size / status.settings.output_frequency # for user output only
x = dx # same here
file_pos = binfile.tell()
status.startedOneSourceFile(size)
while 1:
c = ''
if file_pos < status.file_end:
c = binfile.read(1)
file_pos = binfile.tell()
if c!='': # end of file
st += c
if file_pos-status.file_start >= x:
status.updateFineshedForCurrent(file_pos-status.file_start)
if status.settings.output_level == 0:
pass
elif status.settings.output_level == 3 and size!=0:
print "Pos: 0x%x - %d / %d KB (%d %%)" %(file_pos, (file_pos-status.file_start) / 1024 , size / 1024, (file_pos-status.file_start)*100/size)
elif status.settings.output_level == 2:
print "%d %%" %((file_pos-status.file_start)*100/size)
elif status.settings.output_level == 1:
print '#' ,
x += dx
for sig in status.settings.signatures:
if start[sig[signatures.name]] == -1:
if sig[signatures.start_seq][0] == ord(st[0]):
if checkString(st, sig[signatures.start_seq]):
start_pos = file_pos-len(st)
if status.settings.output_level == 3:
print ('Found start at 0x%x for %s' %(start_pos, sig[signatures.description]))
if sig[signatures.filesize_type] == signatures.TYPE_FILE_SIZE:
offsets = sig[signatures.filesize_address_offsets]
ofs = 0
for i in offsets:
binfile.seek(start_pos + i)
val = ord(binfile.read(1))
ofs = ofs * 256 + val
end_pos = start_pos + ofs
correction = sig[signatures.filesize_info_correction]
end_pos = end_pos + correction
writeFile(sig[signatures.name],status.counterr[sig[signatures.name]]+status.settings.counterstart_global,
sig[signatures.extension],binfile, start_pos, end_pos-1,
status.settings.dest_folder, status.settings.output_level == 3, status)
status.counter[sig[signatures.name]] += 1
status.counterr[sig[signatures.name]] += 1
status.foundFile()
binfile.seek(file_pos)
elif sig[signatures.filesize_type] == signatures.TYPE_MANUAL:
function = sig[signatures.filesizemanual_functionname]
if status.settings.output_level == 3:
print ('-- Enter signature defined function for end address determination for this file')
end_address = function(binfile, start_pos, status.settings.output_level == 3)
if (end_address < start_pos):
if status.settings.output_level == 3:
print ('-- No valid end address found - skip this file.')
continue
writeFile(sig[signatures.name],status.counterr[sig[signatures.name]]+status.settings.counterstart_global,
sig[signatures.extension],binfile, start_pos, end_address,
status.settings.dest_folder, status.settings.output_level == 3, status)
status.counter[sig[signatures.name]] += 1
status.counterr[sig[signatures.name]] += 1
status.foundFile()
binfile.seek(file_pos)
else:
start[sig[signatures.name]] = start_pos
else:
if file_pos < start[sig[signatures.name]] + len(sig[signatures.start_seq]):
continue
if sig[signatures.end_seq][0] == ord(st[0]):
if tools.checkString(st, sig[signatures.end_seq]):
end_pos = file_pos-len(st)+len(sig[signatures.end_seq])-1
if skipped[sig[signatures.name]] < sig[signatures.skip_end_seqs]:
skipped[sig[signatures.name]] +=1
if status.settings.output_level == 3:
print ('Found end at 0x%x for %s - skipped' %(end_pos, sig[signatures.description]))
continue
if status.settings.output_level == 3:
print ('Found end at 0x%x for %s' %(end_pos, sig[signatures.description]))
writeFile(sig[signatures.name],status.counterr[sig[signatures.name]]+status.settings.counterstart_global,
sig[signatures.extension],binfile, start[sig[signatures.name]], end_pos,
status.settings.dest_folder, status.settings.output_level == 3, status)
start[sig[signatures.name]] = -1
status.counter[sig[signatures.name]] += 1
status.counterr[sig[signatures.name]] += 1
status.foundFile()
skipped[sig[signatures.name]] = 0
if len(st)==1:
break
st = st[1:]
status.finishedOneSourceFile()
binfile.close()
return status.settings.signatures, status.counterr
