Fixes #16 - check for required executables

readme.md

@@ -105,6 +105,7 @@ If needed you can use the folowing options to customize the behaviour of *tapeim
 |**Prefix**|Output prefix (default: `file`).|
 |**Extension**|Output file extension (default: `dd`).|
 |**Fill failed blocks**|Fill blocks that give read errors with null bytes. When this option is checked, *tapeimgr* calls *dd* with the flags `conv=noerror,sync`. The use of these flags is often recommended to ensure a forensic image with no missing/offset bytes in case of read errors (source: [*forensicswiki*](https://www.forensicswiki.org/wiki/Dd)), but when used with a block size that is larger than the actual block size it will generate padding bytes that make the extracted data unreadable. Because of this, any user-specified value of  the **Initial Block Size** setting (see above) is ignored when this option is used. **WARNING: this option may result in malformed output if the actual block size is either smaller than 512 bytes, and/or if the block size is not a multiple of 512 bytes! (I have no idea if this is even possible?).**|
+|**Swap little/big endian**|Use this option to swap the endianness of the file by adding `conv=swab` *dd* option. This is needed most commonly if the tape was created on an older [big endian OS](https://geraldonit.com/2017/09/04/big-and-little-endian-operating-systems/).|
 |**Identifier**|Unique identifier. You can either enter an existing identifier yourself, or press the *UUID* button to generate a [Universally unique identifier](https://en.wikipedia.org/wiki/Universally_unique_identifier).|
 |**Description**|A text string that describes the tape (e.g. the title that is written on its inlay card).|
 |**Notes**|Any additional info or notes you want to record with the tape.|
@@ -113,11 +114,12 @@ If needed you can use the folowing options to customize the behaviour of *tapeim
 
 It is also possible to invoke *tapeimgr* with command-line arguments. The general syntax is:
 
-    tapeimgr [-h] [--version] [--fill] [--device DEVICE]
-                [--blocksize SIZE] [--files FILES] [--prefix PREF]
-                [--extension EXT] [--identifier IDENTIFIER]
-                [--description DESCRIPTION] [--notes NOTES]
-                dirOut
+    tapeimgr [-h] [--version] [--fill] [--endianswap]
+             [--device DEVICE] [--blocksize SIZE] [--files FILES]
+             [--prefix PREF] [--extension EXT]
+             [--identifier IDENTIFIER]
+             [--description DESCRIPTION] [--notes NOTES]
+             dirOut
 
 Here `dirOut` is the output directory. So, the command-line equivalent of the first GUI example is:
 
@@ -141,6 +143,7 @@ As with the GUI interface you can customize the default behaviour by using one o
 |`--prefix PREF, -p PREF`|Output prefix (default: `file`).|
 |`--extension EXT, -e EXT`|Output file extension (default: `dd`).|
 |`--fill, -f`|Fill blocks that give read errors with null bytes. When this option is checked, *tapeimgr* calls *dd* with the flags `conv=noerror,sync`. The use of these flags is often recommended to ensure a forensic image with no missing/offset bytes in case of read errors (source: [*forensicswiki*](https://www.forensicswiki.org/wiki/Dd)), but when used with a block size that is larger than the actual block size it will generate padding bytes that make the extracted data unreadable. Because of this, any user-specified value of the `--blocksize`setting (see above) is ignored when this option is used. **WARNING: this option may result in malformed output if the actual block size is either smaller than 512 bytes, and/or if the block size is not a multiple of 512 bytes! (I have no idea if this is even possible?).**|
+|`--endianswap, -E`|Use this option to swap the endianness of the file by adding `conv=swab` *dd* option. This is needed most commonly if the tape was created on an older [big endian OS](https://geraldonit.com/2017/09/04/big-and-little-endian-operating-systems/).|
 |`--identifier IDENTIFIER, -i IDENTIFIER`|Unique identifier. You can either enter an existing identifier yourself, or enter special value `@uuid` to generate a [Universally unique identifier](https://en.wikipedia.org/wiki/Universally_unique_identifier).|
 |`--description DESCRIPTION, -c DESCRIPTION `|A text string that describes the tape (e.g. the title that is written on its inlay card).|
 |`--notes NOTES, -n NOTES`|Any additional info or notes you want to record with the tape.|

tapeimgr/cli.py

@@ -13,6 +13,7 @@
 import uuid
 from .tape import Tape
 from . import config
+from . import shared
 
 
 class tapeimgrCLI:
@@ -57,6 +58,11 @@ def parseCommandLine(self):
                                  dest='fillBlocks',
                                  default=self.tape.fillBlocks,
                                  help='fill blocks that give read errors with null bytes')
+        self.parser.add_argument('--endianswap', '-E',
+                                 action='store_true',
+                                 dest='endianSwap',
+                                 default=self.tape.endianSwap,
+                                 help='swap big/little endian')
         self.parser.add_argument('--device', '-d',
                                  action='store',
                                  type=str,
@@ -109,6 +115,7 @@ def parseCommandLine(self):
         args = self.parser.parse_args()
         self.tape.dirOut = args.dirOut
         self.tape.fillBlocks = args.fillBlocks
+        self.tape.endianSwap = args.endianSwap
         self.tape.tapeDevice = args.device
         self.tape.initBlockSize = args.size
         self.tape.files = args.files
@@ -136,6 +143,12 @@ def process(self):
         # Parse command line arguments
         self.parseCommandLine()
 
+        # Check if required command line utils are available
+        for cmd in shared.REQUIRED_CMDS:
+            if not shared.checkCmd(cmd):
+                msg = ("Command '" + cmd + "' not found. Install required packge")
+                errorExit(msg)
+
         # Validate input
         self.tape.validateInput()
 

tapeimgr/configure.py

@@ -58,6 +58,7 @@ def writeConfigFile(configRootDir, removeFlag):
     configSettings['prefix'] = 'file'
     configSettings['extension'] = 'dd'
     configSettings['fillBlocks'] = 'False'
+    configSettings['endianSwap'] = 'False'
     configSettings['timeZone'] = 'Europe/Amsterdam'
     configSettings['defaultDir'] = ''
 

tapeimgr/gui.py

@@ -23,6 +23,7 @@
 from tkfilebrowser import askopendirname
 from .tape import Tape
 from . import config
+from . import shared
 
 
 class tapeimgrGUI(tk.Frame):
@@ -73,6 +74,13 @@ def on_submit(self, event=None):
         self.tape.description = self.description_entry.get().strip()
         self.tape.notes = self.notes_entry.get(1.0, tk.END).strip()
         self.tape.fillBlocks = self.fBlocks.get()
+        self.tape.endianSwap = self.eSwap.get()
+
+        # Check if required command line utils are available
+        for cmd in shared.REQUIRED_CMDS:
+            if not shared.checkCmd(cmd):
+                msg = ("Command '" + cmd + "' not found. Install required packge")
+                errorExit(msg)
 
         # Validate input
         self.tape.validateInput()
@@ -136,6 +144,7 @@ def on_submit(self, event=None):
                 self.prefix_entry.config(state='disabled')
                 self.extension_entry.config(state='disabled')
                 self.fillblocks_entry.config(state='disabled')
+                self.endianswap_entry.config(state='disabled')
                 self.identifier_entry.config(state='disabled')
                 self.uuidButton.config(state='disabled')
                 self.description_entry.config(state='disabled')
@@ -186,124 +195,136 @@ def insertUUID(self, event=None):
     def build_gui(self):
         """Build the GUI"""
 
+        # Increment row offset after inserting a new UI element
+        rowOffset = 0
+
         self.root.title('tapeimgr v.' + config.version)
         self.root.option_add('*tearOff', 'FALSE')
-        self.grid(column=0, row=0, sticky='w')
+        self.grid(column=0, row=0+rowOffset, sticky='w')
         self.grid_columnconfigure(0, weight=0, pad=0)
         self.grid_columnconfigure(1, weight=0, pad=0)
         self.grid_columnconfigure(2, weight=0, pad=0)
         self.grid_columnconfigure(3, weight=0, pad=0)
 
         # Entry elements
-        ttk.Separator(self, orient='horizontal').grid(column=0, row=0, columnspan=4, sticky='ew')
+        ttk.Separator(self, orient='horizontal').grid(column=0, row=0+rowOffset, columnspan=4, sticky='ew')
         # Output Directory
         self.outDirButton_entry = tk.Button(self,
                                             text='Select Output Directory',
                                             underline=14,
                                             command=self.selectOutputDirectory,
                                             width=20)
-        self.outDirButton_entry.grid(column=0, row=3, sticky='w')
+        self.outDirButton_entry.grid(column=0, row=3+rowOffset, sticky='w')
         self.outDirLabel = tk.Label(self, text=self.tape.dirOut)
         self.outDirLabel.update()
-        self.outDirLabel.grid(column=1, row=3, sticky='w')
+        self.outDirLabel.grid(column=1, row=3+rowOffset, sticky='w')
 
-        ttk.Separator(self, orient='horizontal').grid(column=0, row=5, columnspan=4, sticky='ew')
+        ttk.Separator(self, orient='horizontal').grid(column=0, row=5+rowOffset, columnspan=4, sticky='ew')
 
         # Tape Device
-        tk.Label(self, text='Tape Device').grid(column=0, row=6, sticky='w')
+        tk.Label(self, text='Tape Device').grid(column=0, row=6+rowOffset, sticky='w')
         self.tapeDevice_entry = tk.Entry(self, width=20)
         self.tapeDevice_entry['background'] = 'white'
         self.tapeDevice_entry.insert(tk.END, self.tape.tapeDevice)
-        self.tapeDevice_entry.grid(column=1, row=6, sticky='w')
+        self.tapeDevice_entry.grid(column=1, row=6+rowOffset, sticky='w')
 
         # Initial Block Size
-        tk.Label(self, text='Initial Block Size').grid(column=0, row=7, sticky='w')
+        tk.Label(self, text='Initial Block Size').grid(column=0, row=7+rowOffset, sticky='w')
         self.initBlockSize_entry = tk.Entry(self, width=20)
         self.initBlockSize_entry['background'] = 'white'
         self.initBlockSize_entry.insert(tk.END, self.tape.initBlockSize)
-        self.initBlockSize_entry.grid(column=1, row=7, sticky='w')
+        self.initBlockSize_entry.grid(column=1, row=7+rowOffset, sticky='w')
         self.decreaseBSButton = tk.Button(self, text='-', command=self.decreaseBlocksize, width=1)
-        self.decreaseBSButton.grid(column=1, row=7, sticky='e')
+        self.decreaseBSButton.grid(column=1, row=7+rowOffset, sticky='e')
         self.increaseBSButton = tk.Button(self, text='+', command=self.increaseBlocksize, width=1)
-        self.increaseBSButton.grid(column=2, row=7, sticky='w')
+        self.increaseBSButton.grid(column=2, row=7+rowOffset, sticky='w')
 
         # Files
-        tk.Label(self, text='Files (comma-separated list)').grid(column=0, row=8, sticky='w')
+        tk.Label(self, text='Files (comma-separated list)').grid(column=0, row=8+rowOffset, sticky='w')
         self.files_entry = tk.Entry(self, width=20)
         self.files_entry['background'] = 'white'
         self.files_entry.insert(tk.END, self.tape.files)
-        self.files_entry.grid(column=1, row=8, sticky='w')
+        self.files_entry.grid(column=1, row=8+rowOffset, sticky='w')
 
         # Prefix
-        tk.Label(self, text='Prefix').grid(column=0, row=9, sticky='w')
+        tk.Label(self, text='Prefix').grid(column=0, row=9+rowOffset, sticky='w')
         self.prefix_entry = tk.Entry(self, width=20)
         self.prefix_entry['background'] = 'white'
         self.prefix_entry.insert(tk.END, self.tape.prefix)
-        self.prefix_entry.grid(column=1, row=9, sticky='w')
+        self.prefix_entry.grid(column=1, row=9+rowOffset, sticky='w')
 
         # Extension
-        tk.Label(self, text='Extension').grid(column=0, row=10, sticky='w')
+        tk.Label(self, text='Extension').grid(column=0, row=10+rowOffset, sticky='w')
         self.extension_entry = tk.Entry(self, width=20)
         self.extension_entry['background'] = 'white'
         self.extension_entry.insert(tk.END, self.tape.extension)
-        self.extension_entry.grid(column=1, row=10, sticky='w')
+        self.extension_entry.grid(column=1, row=10+rowOffset, sticky='w')
 
         # Fill failed blocks
-        tk.Label(self, text='Fill failed blocks').grid(column=0, row=11, sticky='w')
+        tk.Label(self, text='Fill failed blocks').grid(column=0, row=11+rowOffset, sticky='w')
         self.fBlocks = tk.BooleanVar()
         self.fBlocks.set(self.tape.fillBlocks)
         self.fillblocks_entry = tk.Checkbutton(self, variable=self.fBlocks)
-        self.fillblocks_entry.grid(column=1, row=11, sticky='w')
+        self.fillblocks_entry.grid(column=1, row=11+rowOffset, sticky='w')
+
+        # Swap Endian
+        tk.Label(self, text='Swap little/big endian').grid(column=0, row=12+rowOffset, sticky='w')
+        self.eSwap = tk.BooleanVar()
+        self.eSwap.set(self.tape.endianSwap)
+        self.endianswap_entry = tk.Checkbutton(self, variable=self.eSwap)
+        self.endianswap_entry.grid(column=1, row=12+rowOffset, sticky='w')
+
+        rowOffset =+ 1
 
-        ttk.Separator(self, orient='horizontal').grid(column=0, row=12, columnspan=4, sticky='ew')
+        ttk.Separator(self, orient='horizontal').grid(column=0, row=12+rowOffset, columnspan=4, sticky='ew')
 
         # Identifier entry field
-        tk.Label(self, text='Identifier').grid(column=0, row=13, sticky='w')
+        tk.Label(self, text='Identifier').grid(column=0, row=13+rowOffset, sticky='w')
         self.identifier_entry = tk.Entry(self, width=20)
         self.identifier_entry['background'] = 'white'
         self.identifier_entry.insert(tk.END, self.tape.identifier)
-        self.identifier_entry.grid(column=1, row=13, sticky='w')
+        self.identifier_entry.grid(column=1, row=13+rowOffset, sticky='w')
         self.uuidButton = tk.Button(self, text='UUID', underline=0,
                                     command=self.insertUUID, width=2)
-        self.uuidButton.grid(column=1, row=13, sticky='e')
+        self.uuidButton.grid(column=1, row=13+rowOffset, sticky='e')
 
         # Description entry field
-        tk.Label(self, text='Description').grid(column=0, row=14, sticky='w')
+        tk.Label(self, text='Description').grid(column=0, row=14+rowOffset, sticky='w')
         self.description_entry = tk.Entry(self, width=35)
         self.description_entry['background'] = 'white'
         self.description_entry.insert(tk.END, self.tape.description)
-        self.description_entry.grid(column=1, row=14, sticky='w', columnspan=1)
+        self.description_entry.grid(column=1, row=14+rowOffset, sticky='w', columnspan=1)
 
         # Notes entry field
-        tk.Label(self, text='Notes').grid(column=0, row=15, sticky='w')
+        tk.Label(self, text='Notes').grid(column=0, row=15+rowOffset, sticky='w')
         self.notes_entry = tk.Text(self, height=6, width=35)
         self.notes_entry['background'] = 'white'
         self.notes_entry.insert(tk.END, self.tape.notes)
-        self.notes_entry.grid(column=1, row=15, sticky='w', columnspan=1)
+        self.notes_entry.grid(column=1, row=15+rowOffset, sticky='w', columnspan=1)
 
-        ttk.Separator(self, orient='horizontal').grid(column=0, row=16, columnspan=4, sticky='ew')
+        ttk.Separator(self, orient='horizontal').grid(column=0, row=16+rowOffset, columnspan=4, sticky='ew')
 
         self.start_button = tk.Button(self,
                                       text='Start',
                                       width=10,
                                       underline=0,
                                       command=self.on_submit)
-        self.start_button.grid(column=1, row=17, sticky='w')
+        self.start_button.grid(column=1, row=17+rowOffset, sticky='w')
 
         self.quit_button = tk.Button(self,
                                      text='Exit',
                                      width=10,
                                      underline=0,
                                      command=self.on_quit)
-        self.quit_button.grid(column=1, row=17, sticky='e')
+        self.quit_button.grid(column=1, row=17+rowOffset, sticky='e')
 
-        ttk.Separator(self, orient='horizontal').grid(column=0, row=18, columnspan=4, sticky='ew')
+        ttk.Separator(self, orient='horizontal').grid(column=0, row=18+rowOffset, columnspan=4, sticky='ew')
 
         # Add ScrolledText widget to display logging info
         self.st = ScrolledText.ScrolledText(self, state='disabled', height=15)
         self.st.configure(font='TkFixedFont')
         self.st['background'] = 'white'
-        self.st.grid(column=0, row=19, sticky='ew', columnspan=4)
+        self.st.grid(column=0, row=19+rowOffset, sticky='ew', columnspan=4)
 
         # Define bindings for keyboard shortcuts: buttons
         self.root.bind_all('<Control-Key-d>', self.selectOutputDirectory)
@@ -343,6 +364,7 @@ def reset_gui(self, dirOut):
         self.prefix_entry.config(state='normal')
         self.extension_entry.config(state='normal')
         self.fillblocks_entry.config(state='normal')
+        self.endianswap_entry.config(state='normal')
         self.identifier_entry.config(state='normal')
         self.uuidButton.config(state='normal')
         self.description_entry.config(state='normal')
@@ -368,6 +390,7 @@ def reset_gui(self, dirOut):
         self.notes_entry.delete(1.0, tk.END)
         self.notes_entry.insert(tk.END, self.tape.notes)
         self.fBlocks.set(self.tape.fillBlocks)
+        self.eSwap.set(self.tape.endianSwap)
         self.start_button.config(state='normal')
         self.quit_button.config(state='normal')
 

tapeimgr/shared.py

@@ -9,6 +9,8 @@
 import subprocess as sub
 import pytz
 
+REQUIRED_CMDS = ['mt', 'dd']
+
 def launchSubProcess(args, writeLog=True):
     """Launch subprocess and return exit code, stdout and stderr"""
     try:
@@ -102,3 +104,13 @@ def generateDateTime(timeZone):
     dateTime = pst.localize(dateTime)
     dateTimeFormatted = dateTime.isoformat()
     return dateTimeFormatted
+
+def checkCmd(cmd):
+    """Check if executable is present in PATH"""
+    return sub.call(
+            "type " + cmd, 
+            shell=True, 
+            stdout=sub.PIPE, 
+            stderr=sub.PIPE
+    ) == 0
+