Ensure that ocrmypdf stops and reports an error if Ghostscript fails

Past behavior was to continue and let ruffus puke eventually

ocrmypdf/exceptions.py

@@ -48,7 +48,7 @@ class InputFileError(ExitCodeException):
 
 
 class SubprocessOutputError(ExitCodeException):
-    exit_code = ExitCode.other_error
+    exit_code = ExitCode.child_process_error
 
 
 class EncryptedPdfError(ExitCodeException):

ocrmypdf/exec/ghostscript.py

@@ -6,8 +6,9 @@ from subprocess import Popen, PIPE, STDOUT, check_call, CalledProcessError, \
     check_output
 from shutil import copy
 from functools import lru_cache
+import re
 from . import get_program
-from ..pdfa import SRGB_ICC_PROFILE
+from ..exceptions import SubprocessOutputError
 
 
 @lru_cache(maxsize=1)
@@ -28,6 +29,10 @@ def version():
     return version.strip()
 
 
+def _gs_error_reported(stream):
+    return re.search(r'error', stream, flags=re.IGNORECASE)
+
+
 def rasterize_pdf(input_file, output_file, xres, yres, raster_device, log,
                   pageno=1):
     with NamedTemporaryFile(delete=True) as tmp:
@@ -48,15 +53,16 @@ def rasterize_pdf(input_file, output_file, xres, yres, raster_device, log,
         p = Popen(args_gs, close_fds=True, stdout=PIPE, stderr=STDOUT,
                   universal_newlines=True)
         stdout, _ = p.communicate()
-        if 'error' in stdout:
-            log.error(stdout)  # Ghostscript puts errors in stdout
+        if _gs_error_reported(stdout):
+            log.error(stdout)
         else:
             log.debug(stdout)
 
         if p.returncode == 0:
             copy(tmp.name, output_file)
         else:
-            log.error('Ghostscript rendering failed')
+            log.error('Ghostscript rasterizing failed')
+            raise SubprocessOutputError()
 
 
 def generate_pdfa(pdf_pages, output_file, log, threads=1):
@@ -81,7 +87,7 @@ def generate_pdfa(pdf_pages, output_file, log, threads=1):
                   universal_newlines=True)
         stdout, _ = p.communicate()
 
-        if 'error' in stdout or 'ERROR' in stdout:
+        if _gs_error_reported(stdout):
             log.error(stdout)
         elif 'overprint mode not set' in stdout:
             # Unless someone is going to print PDF/A documents on a
@@ -99,4 +105,5 @@ def generate_pdfa(pdf_pages, output_file, log, threads=1):
             # PDF/A - check PDF/A status elsewhere
             copy(gs_pdf.name, output_file)
         else:
-            log.error('Ghostscript PDF/A failed')
+            log.error('Ghostscript PDF/A rendering failed')
+            raise SubprocessOutputError()

tests/spoof/gs_raster_failure.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+import sys
+import os
+
+"""Replicate Ghostscript raster failure while allowing rendering"""
+
+
+def real_ghostscript(argv):
+    gs_args = ['gs'] + argv[1:]
+    os.execvp("gs", gs_args)
+    return  # Not reachable
+
+
+def main():
+    if '--version' in sys.argv:
+        print('9.20')
+        print('SPOOFED: ' + os.path.basename(__filename__))
+        sys.exit(0)
+
+    # For any rendering calls (device == pdfwrite) call real ghostscript
+    if '-sDEVICE=pdfwrite' in sys.argv:
+        real_ghostscript(sys.argv)
+        return
+
+    # Fail
+    print("ERROR: Ghost story archive not found")
+    sys.exit(1)
+
+
+if __name__ == '__main__':
+    main()

tests/spoof/gs_render_failure.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+import sys
+import os
+
+"""Replicate Ghostscript render failure while allowing rasterizing"""
+
+
+def real_ghostscript(argv):
+    gs_args = ['gs'] + argv[1:]
+    os.execvp("gs", gs_args)
+    return  # Not reachable
+
+
+def main():
+    if '--version' in sys.argv:
+        print('9.20')
+        print('SPOOFED: ' + os.path.basename(__filename__))
+        sys.exit(0)
+
+    # For any rasterize calls (device != pdfwrite) call real ghostscript
+    if '-sDEVICE=pdfwrite' not in sys.argv:
+        real_ghostscript(sys.argv)
+        return
+
+    # Fail
+    print("ERROR: Casper is not a friendly ghost")
+    sys.exit(1)
+
+
+if __name__ == '__main__':
+    main()

tests/test_main.py

@@ -51,6 +51,16 @@ def spoof_no_tess_pdfa_warning():
     return spoof(tesseract='tesseract_noop.py', gs='gs_feature_elision.py')
 
 
+@pytest.fixture
+def spoof_no_tess_gs_render_fail():
+    return spoof(tesseract='tesseract_noop.py', gs='gs_render_failure.py')
+
+
+@pytest.fixture
+def spoof_no_tess_gs_raster_fail():
+    return spoof(tesseract='tesseract_noop.py', gs='gs_raster_failure.py')
+
+
 @pytest.fixture
 def spoof_qpdf_always_error():
     return spoof(qpdf='qpdf_dummy_return2.py')
@@ -843,4 +853,21 @@ def test_skip_big_with_no_images(spoof_tesseract_noop, resources, outpdf):
     check_ocrmypdf(resources / 'blank.pdf', outpdf,
                    '--skip-big', '5',
                    '--force-ocr',
+                   env=spoof_tesseract_noop)
+
+
+def test_gs_render_failure(spoof_no_tess_gs_render_fail, resources, outpdf):
+    p, out, err = run_ocrmypdf(
+        resources / 'blank.pdf', outpdf,
+        env=spoof_no_tess_gs_render_fail)
+    print(err)
+    assert p.returncode == ExitCode.child_process_error
+
+
+def test_gs_raster_failure(spoof_no_tess_gs_raster_fail, resources, outpdf):
+    p, out, err = run_ocrmypdf(
+        resources / 'ccitt.pdf', outpdf,
+        env=spoof_no_tess_gs_raster_fail)
+    print(err)
+    assert p.returncode == ExitCode.child_process_error
                    env=spoof_tesseract_noop)