improve missing compressor exception handling/error messages

src/pycpio/errors/__init__.py

@@ -0,0 +1,3 @@
+from .errors import UnavailableCompression
+
+__all__ = ["UnavailableCompression"]

src/pycpio/errors/errors.py

@@ -0,0 +1,2 @@
+class UnavailableCompression(Exception):
+    pass

src/pycpio/main.py

@@ -5,6 +5,7 @@
 from zenlib.util import get_kwargs
 
 from pycpio import PyCPIO
+from pycpio.errors import UnavailableCompression
 
 
 def main():
@@ -76,7 +77,11 @@ def main():
 
     if output_file := kwargs.get("output"):
         compression = kwargs.get("compress")
-        c.write_cpio_file(Path(output_file), compression=compression)
+        try:
+            c.write_cpio_file(Path(output_file), compression=compression)
+        except UnavailableCompression as e:
+            c.logger.critical(e)
+            exit(1)
 
     if kwargs.get("list"):
         print(c.list_files())

src/pycpio/writer/writer.py

@@ -3,6 +3,7 @@
 from pathlib import Path
 
 from pycpio.header import HEADER_NEW, CPIOHeader
+from pycpio.errors import UnavailableCompression
 from zenlib.logging import loggify
 from zenlib.util import colorize
 
@@ -61,7 +62,7 @@ def compress(self, data):
             compression_module = "zstd.compress"
             compression_args = (self.compression_level,)
         elif self.compression is not False:
-            raise NotImplementedError("Compression type not supported: %s" % self.compression)
+            raise UnavailableCompression("Compression type not supported: %s" % self.compression)
         else:
             self.logger.info("No compression specified, writing uncompressed data.")
             return data
@@ -75,7 +76,7 @@ def compress(self, data):
             compressor = getattr(__import__(module), func)
             self.logger.debug("Compressing data with: %s" % compression_module)
         except ImportError as e:
-            raise ImportError("Failed to import compression module: %s" % compression_module) from e
+            raise UnavailableCompression("Failed to import compression module: %s" % compression_module) from e
 
         self.logger.info(
             "[%s] Compressing the CPIO data, original size: %.2f MiB" % (self.compression.upper(), len(data) / (2**20))