From c216854607c2ed2ab0df90f2e2ea5c44dfcb85ad Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Tue, 28 Dec 2021 11:58:19 -0500
Subject: Add basic framework for QPDFJob code generation

---
 generate_auto_job             | 98 +++++++++++++++++++++++++++++++++++++++++++
 job.sums                      |  3 ++
 libqpdf/build.mk              |  6 +++
 libqpdf/qpdf/auto_job_decl.hh |  5 +++
 4 files changed, 112 insertions(+)
 create mode 100755 generate_auto_job
 create mode 100644 job.sums
 create mode 100644 libqpdf/qpdf/auto_job_decl.hh

diff --git a/generate_auto_job b/generate_auto_job
new file mode 100755
index 00000000..7f92a630
--- /dev/null
+++ b/generate_auto_job
@@ -0,0 +1,98 @@
+#!/usr/bin/env python3
+import os
+import sys
+import argparse
+import hashlib
+import re
+
+whoami = os.path.basename(sys.argv[0])
+BANNER = f'''//
+// This file is automatically generated by {whoami}.
+// Edits will be automatically overwritten if the build is
+// run in maintainer mode.
+//'''
+
+
+def warn(*args, **kwargs):
+    print(*args, file=sys.stderr, **kwargs)
+
+
+class Main:
+    SOURCES = [whoami, 'job.yml']
+    SUMS = 'job.sums'
+
+    def main(self, args=sys.argv[1:], prog=whoami):
+        options = self.parse_args(args, prog)
+        self.top(options)
+
+    def parse_args(self, args, prog):
+        parser = argparse.ArgumentParser(
+            prog=prog,
+            description='Generate files for QPDFJob',
+        )
+        mxg = parser.add_mutually_exclusive_group(required=True)
+        mxg.add_argument('--check',
+                         help='update checksums if files are not up to date',
+                         action='store_true', default=False)
+        mxg.add_argument('--generate',
+                         help='generate files from sources',
+                         action='store_true', default=False)
+        return parser.parse_args(args)
+
+    def top(self, options):
+        if options.check:
+            self.check()
+        elif options.generate:
+            self.generate()
+        else:
+            exit(f'{whoami} unknown mode')
+
+    def get_hashes(self):
+        hashes = {}
+        for i in sorted(self.SOURCES):
+            m = hashlib.sha256()
+            with open(i, 'rb') as f:
+                m.update(f.read())
+            hashes[i] = m.hexdigest()
+        return hashes
+
+    def check(self):
+        hashes = self.get_hashes()
+        match = False
+        try:
+            old_hashes = {}
+            with open(self.SUMS, 'r') as f:
+                for line in f.readlines():
+                    m = re.match(r'^(\S+) (\S+)\s*$', line)
+                    if m:
+                        old_hashes[m.group(1)] = m.group(2)
+            match = old_hashes == hashes
+        except Exception:
+            pass
+        if not match:
+            exit(f'{whoami}: auto job inputs have changed')
+
+    def update_hashes(self):
+        hashes = self.get_hashes()
+        with open(self.SUMS, 'w') as f:
+            print(f'# Generated by {whoami}', file=f)
+            for k, v in hashes.items():
+                print(f'{k} {v}', file=f)
+
+    def generate(self):
+        warn(f'{whoami}: regenerating auto job files')
+
+        with open('libqpdf/qpdf/auto_job_decl.hh', 'w') as f:
+            print(BANNER, file=f)
+
+        # Update hashes last to ensure that this will be rerun in the
+        # event of a failure.
+        self.update_hashes()
+
+
+if __name__ == '__main__':
+    try:
+        os.chdir(os.path.dirname(os.path.realpath(__file__)))
+        Main().main()
+    except KeyboardInterrupt:
+        exit(130)
diff --git a/job.sums b/job.sums
new file mode 100644
index 00000000..5e32b3be
--- /dev/null
+++ b/job.sums
@@ -0,0 +1,3 @@
+# Generated by generate_auto_job
+generate_auto_job 3905985c383d33f9e8629414d1481724ea67d836749f6dff53859ca558325743
+job.yml f52d711103d50a437830c6fbcd04fb4bab49a0f82f6d26d1c791c6e8488dd090
diff --git a/libqpdf/build.mk b/libqpdf/build.mk
index 4f4020e9..4884a692 100644
--- a/libqpdf/build.mk
+++ b/libqpdf/build.mk
@@ -1,5 +1,11 @@
 TARGETS_libqpdf = libqpdf/$(OUTPUT_DIR)/$(call libname,qpdf)
 
+ifeq ($(MAINTAINER_MODE), 1)
+ifeq ($(shell if ./generate_auto_job --check; then echo 0; else echo 1; fi), 1)
+_ := $(shell ./generate_auto_job --generate)
+endif
+endif
+
 INCLUDES_libqpdf = include libqpdf
 LDFLAGS_libqpdf = -Llibqpdf/$(OUTPUT_DIR)
 LIBS_libqpdf = -lqpdf
diff --git a/libqpdf/qpdf/auto_job_decl.hh b/libqpdf/qpdf/auto_job_decl.hh
new file mode 100644
index 00000000..d6cbecfe
--- /dev/null
+++ b/libqpdf/qpdf/auto_job_decl.hh
@@ -0,0 +1,5 @@
+//
+// This file is automatically generated by generate_auto_job.
+// Edits will be automatically overwritten if the build is
+// run in maintainer mode.
+//
-- 
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