Fix code, test case: complain when GS fails to produce PDF/A

Modified pipeline to fix regression and return the proper error code if
we did not produce a PDF/A as expected.  The wrapper forces the output
to be PDF 1.3 which is not PDF/A compliant.

The funny thing is that in some cases JHOVE incorrectly states that a
file is PDF/A-1b compliant, well formed and valid, even when it is not
according to Acrobat XI and is missing the PDF/A metadata marker, as
far as I can tell.  JHOVE may not be as beneficial as hoped.

ocrmypdf/main.py

@@ -758,12 +758,18 @@ def merge_pages(
     filter=formatter(),
     output=options.output_file,
     extras=[_log, _pdfinfo, _pdfinfo_lock])
-def validate_pdfa(
+def copy_final(
         input_file,
         output_file,
         log,
         pdfinfo,
         pdfinfo_lock):
+    shutil.copy(input_file, output_file)
+
+
+def validate_pdfa(
+        input_file,
+        log):
 
     args_jhove = [
         'java',
@@ -798,13 +804,7 @@ def validate_pdfa(
                  re.IGNORECASE | re.MULTILINE):
         pdf_is_pdfa = True
 
-    if not pdf_is_valid:
-        log.warning('Output file: The generated PDF/A file is INVALID')
-    elif pdf_is_valid and not pdf_is_pdfa:
-        log.warning('Output file: Generated file is a VALID PDF but not PDF/A')
-    elif pdf_is_valid and pdf_is_pdfa:
-        log.info('Output file: The generated PDF/A file is VALID')
-    shutil.copy(input_file, output_file)
+    return (pdf_is_valid, pdf_is_pdfa)
 
 
 # @active_if(ocr_required and options.exact_image)
@@ -845,8 +845,25 @@ def available_cpu_count():
 def run_pipeline():
     if not options.jobs or options.jobs == 1:
         options.jobs = available_cpu_count()
+
     cmdline.run(options)
 
+    pdf_is_valid, pdf_is_pdfa = validate_pdfa(options.output_file, _log)
+
+    returncode = EXIT_OTHER_ERROR  # Assume error
+
+    if not pdf_is_valid:
+        _log.warning('Output file: The generated PDF/A file is INVALID')
+        returncode = EXIT_INVALID_OUTPUT_PDFA
+    elif pdf_is_valid and not pdf_is_pdfa:
+        _log.warning('Output file: Generated file is VALID PDF but not PDF/A')
+        returncode = EXIT_INVALID_OUTPUT_PDFA
+    elif pdf_is_valid and pdf_is_pdfa:
+        _log.info('Output file: The generated PDF/A file is VALID')
+        returncode = 0
+
+    return returncode
+
 
 if __name__ == '__main__':
-    run_pipeline()
+    sys.exit(run_pipeline())

tests/replace_ghostscript_nopdfa.py

@@ -10,7 +10,15 @@ created instead.
 It assumes that it is called from a staged system PATH where the first
 item on the PATH contains a file named 'gs' which is a symlink to this
 file.  It will strip out the first item on path to invoke the real
-'gs'.
+'gs'.  That is, it expects this when called
+
+1.   tests/output/[...test name...]/bin/gs is a symlink to this file
+2.   tests/output/bin is the first item on PATH
+3.   The real executable is on the path
+
+OCRmyPDF also calls "gs --version" and "gs --help".  gs answers both
+on stdout so, this wrapper prints to stderr.
+
 '''
 
 
@@ -21,15 +29,36 @@ def pdfa_param(arg):
         return True
     if arg.endswith('.ps'):
         return True
+    if 'ColorConversionStrategy' in arg:
+        return True
+    if 'ProcessColorModel' in arg:
+        return True
+    if 'OutputICCProfile' in arg:
+        return True
     return False
 
 
 if __name__ == '__main__':
-    args = [arg for arg in sys.argv[1:]
-            if not pdfa_param(arg)]
+    sys_args = sys.argv[1:]
 
     print("Fake Ghostscript wrapper", file=sys.stderr)
 
+    if any(pdfa_param(arg) for arg in sys_args):
+        # We were asked to produce a PDF/A
+        # Filter out PDF/A arguments
+        args = [arg for arg in sys.argv[1:]
+                if not pdfa_param(arg)]
+
+        # Tell Ghostscript to create a PDF 1.3 instead so JHOVE won't
+        # think it's a PDF/A
+        indexof_pdfwrite = next(n for n, item in enumerate(args)
+                                if 'pdfwrite' in item)
+        args.insert(indexof_pdfwrite + 1, '-dCompatibilityLevel=1.3')
+        print("Rewrote arguments", file=sys.stderr)
+    else:
+        args = sys_args
+        print("Keeping arguments", file=sys.stderr)
+
     exec_path = os.environ['PATH'].split(os.pathsep)
     env = os.environ.copy()
     env['PATH'] = os.pathsep.join(exec_path[1:])