Add --create-from-json and --update-from-json arguments

Also add stubs for top-level QPDF methods (createFromJSON,
updateFromJSON)

20 files changed, 186 insertions, 19 deletions

diff --git a/README-maintainer b/README-maintainer
index 88e81461..9f3c79a0 100644
--- a/README-maintainer
+++ b/README-maintainer
@@ -215,6 +215,14 @@ CODING RULES
 
 HOW TO ADD A COMMAND-LINE ARGUMENT
 
+Quick reminder:
+
+* Add an entry to the top half of job.yml for the command-line
+  argument
+* Add an entry to the bottom half of job.yml for the job JSON field
+* Add documentation for the new option to cli.rst
+* Implement the QPDFJob::Config method in QPDFJob_config.cc.
+
 QPDFJob is documented in three places:
 
 * This section provides a quick reminder for how to add a command-line
diff --git a/include/qpdf/QPDF.hh b/include/qpdf/QPDF.hh
index bbbb896e..5cba93a8 100644
--- a/include/qpdf/QPDF.hh
+++ b/include/qpdf/QPDF.hh
@@ -110,6 +110,28 @@ class QPDF
     void
     processInputSource(std::shared_ptr<InputSource>, char const* password = 0);
 
+    // Create a PDF from an input source that contains JSON as written
+    // by qpdf --json (version 2 or higher). The JSON must be a
+    // complete representation of a PDF. See "QPDF JSON Format" in the
+    // manual for details.
+    QPDF_DLL
+    void
+    createFromJSON(std::string const& json_file);
+    QPDF_DLL
+    void
+    createFromJSON(std::shared_ptr<InputSource>);
+
+    // Update a PDF from an input source that contains JSON in the
+    // same format as is written by qpdf --json (version 2 or higher).
+    // Objects in the PDF and not in the JSON are not modified. See
+    // "QPDF JSON Format" in the manual for details.
+    QPDF_DLL
+    void
+    updateFromJSON(std::string const& json_file);
+    QPDF_DLL
+    void
+    updateFromJSON(std::shared_ptr<InputSource>);
+
     // Close or otherwise release the input source. Once this has been
     // called, no other methods of qpdf can be called safely except
     // for getWarnings and anyWarnings(). After this has been called,
diff --git a/include/qpdf/QPDFJob.hh b/include/qpdf/QPDFJob.hh
index da8d3fcb..a7d86337 100644
--- a/include/qpdf/QPDFJob.hh
+++ b/include/qpdf/QPDFJob.hh
@@ -323,6 +323,8 @@ class QPDFJob
         Config* outputFile(std::string const& filename);
         QPDF_DLL
         Config* replaceInput();
+        QPDF_DLL
+        Config* createFromJson(std::string const& filename);
 
         QPDF_DLL
         std::shared_ptr<CopyAttConfig> copyAttachmentsFrom();
@@ -674,6 +676,8 @@ class QPDFJob
         bool check_requires_password;
         std::shared_ptr<char> infilename;
         std::shared_ptr<char> outfilename;
+        std::string create_from_json;
+        std::string update_from_json;
     };
     std::shared_ptr<Members> m;
 };
diff --git a/include/qpdf/auto_job_c_main.hh b/include/qpdf/auto_job_c_main.hh
index 42e30a70..cc1bf469 100644
--- a/include/qpdf/auto_job_c_main.hh
+++ b/include/qpdf/auto_job_c_main.hh
@@ -68,6 +68,7 @@ QPDF_DLL Config* rotate(std::string const& parameter);
 QPDF_DLL Config* showAttachment(std::string const& parameter);
 QPDF_DLL Config* showObject(std::string const& parameter);
 QPDF_DLL Config* jsonStreamPrefix(std::string const& parameter);
+QPDF_DLL Config* updateFromJson(std::string const& parameter);
 QPDF_DLL Config* collate(std::string const& parameter);
 QPDF_DLL Config* collate();
 QPDF_DLL Config* splitPages(std::string const& parameter);
diff --git a/job.sums b/job.sums
index 8a387e14..3814155a 100644
--- a/job.sums
+++ b/job.sums
@@ -3,15 +3,15 @@ generate_auto_job 0514289f2deb3bf7c1a6e85ef7d99ad120321ef5a6fe49d76c5274c6a658d3
 include/qpdf/auto_job_c_att.hh 4c2b171ea00531db54720bf49a43f8b34481586ae7fb6cbf225099ee42bc5bb4
 include/qpdf/auto_job_c_copy_att.hh 50609012bff14fd82f0649185940d617d05d530cdc522185c7f3920a561ccb42
 include/qpdf/auto_job_c_enc.hh 28446f3c32153a52afa239ea40503e6cc8ac2c026813526a349e0cd4ae17ddd5
-include/qpdf/auto_job_c_main.hh 50214d1583d0384e70ce7c91d6bb92c58f8cc125490a680681cfffe6455a1dce
+include/qpdf/auto_job_c_main.hh 178a0c98c80d53036910ec67165dbc3902aa8da857de8a0df52911f005918c54
 include/qpdf/auto_job_c_pages.hh b3cc0f21029f6d89efa043dcdbfa183cb59325b6506001c18911614fe8e568ec
 include/qpdf/auto_job_c_uo.hh ae21b69a1efa9333050f4833d465f6daff87e5b38e5106e49bbef5d4132e4ed1
-job.yml c046a750e0cf6889b920484ab937bcb999be55273d77b263cb227b82006fbb36
-libqpdf/qpdf/auto_job_decl.hh 74df4d7fdbdf51ecd0d58ce1e9844bb5525b9adac5a45f7c9a787ecdda2868df
-libqpdf/qpdf/auto_job_help.hh e9b37d33bfcbf165bfba21b6778df3f356b904a961bfae68f9638b85142a87e8
-libqpdf/qpdf/auto_job_init.hh 423157a51fa470fb45d6e341cc3fc8f044b5344f06f86475b37302610c7d8afd
-libqpdf/qpdf/auto_job_json_decl.hh 06caa46eaf71db8a50c046f91866baa8087745a9474319fb7c86d92634cc8297
-libqpdf/qpdf/auto_job_json_init.hh eaed8624a1a394c75a3e298e1c31015146211e240d710509eb627fc711a387a6
-libqpdf/qpdf/auto_job_schema.hh a9971c82c9821a5ec620ccc003bcb3383c054e45658b50fa559b5855e694ed1a
+job.yml a95b2446066293f409b36032a0ee411dbe570a7a94f5fd295048d009215f993f
+libqpdf/qpdf/auto_job_decl.hh 833bde9c1f8fc17b914f16498e26d9d1315361645b4ac5c50c1f830a76618ca7
+libqpdf/qpdf/auto_job_help.hh 38bf89067ca7dc244e4e697c598ba0ba8a827600a78b9195fc69f0ac1663f3a2
+libqpdf/qpdf/auto_job_init.hh f0ffab312430b232a7288b8443382ed859021e6ad6ed2c8c9a4dbbd2b33e2aa7
+libqpdf/qpdf/auto_job_json_decl.hh 81d09d4b82b2e042a64246ed1d7a187bdc83b671b45e7b8ee60ad37c0c11e9a7
+libqpdf/qpdf/auto_job_json_init.hh 2fcdae08365abe351d2dfb6a823e2b3af27a6510632de23cabef6cefa5dfb199
+libqpdf/qpdf/auto_job_schema.hh 1a80be3b8d97e9b5a55b8aa45a4b312668b1687eab6f038c4ee5f4662ab71997
 manual/_ext/qpdf.py 6add6321666031d55ed4aedf7c00e5662bba856dfcd66ccb526563bffefbb580
-manual/cli.rst f1bbf59ce4fdb5a6d29fc2470788eee321423dd946984fc2e6f3a904fe5137c1
+manual/cli.rst 4550dd1b459721d8ef9affa7c9c07f351a06379498ec1291f702f1a5994b6d84
diff --git a/job.yml b/job.yml
index c76244cf..b4fb7370 100644
--- a/job.yml
+++ b/job.yml
@@ -86,6 +86,7 @@ options:
       - underlay
       - empty
       - replace-input
+      - create-from-json
     positional: true
     bare:
       - add-attachment
@@ -163,6 +164,8 @@ options:
       show-attachment: attachment
       show-object: trailer
       json-stream-prefix: stream-file-prefix
+      create-from-json: qpdf-json file
+      update-from-json: qpdf-json file
     required_choices:
       compress-streams: yn
       decode-level: decode_level
@@ -278,6 +281,7 @@ json:
   main.password:
   password-file:
   empty:
+  create-from-json:
   # output
   _outputFile: "output filename"
   replace-input:
@@ -360,6 +364,7 @@ json:
   json-stream-prefix:
   to-json:
   # other options
+  update-from-json:
   allow-weak-crypto:
   keep-files-open:
   keep-files-open-threshold:
diff --git a/libqpdf/CMakeLists.txt b/libqpdf/CMakeLists.txt
index aa7b1fd0..1777bb08 100644
--- a/libqpdf/CMakeLists.txt
+++ b/libqpdf/CMakeLists.txt
@@ -97,6 +97,7 @@ set(libqpdf_SOURCES
   QPDF_Stream.cc
   QPDF_String.cc
   QPDF_encryption.cc
+  QPDF_json.cc
   QPDF_linearization.cc
   QPDF_optimization.cc
   QPDF_pages.cc
diff --git a/libqpdf/QPDFJob.cc b/libqpdf/QPDFJob.cc
index 55bebdcb..41e57c58 100644
--- a/libqpdf/QPDFJob.cc
+++ b/libqpdf/QPDFJob.cc
@@ -553,6 +553,13 @@ QPDFJob::run()
     if (m->check_is_encrypted || m->check_requires_password) {
         return;
     }
+
+    // If we are updating from JSON, this has to be done first before
+    // other options may cause transformations to the input.
+    if (!this->m->update_from_json.empty()) {
+        pdf.updateFromJSON(this->m->update_from_json);
+    }
+
     bool other_warnings = false;
     std::vector<std::shared_ptr<QPDF>> page_heap;
     if (!m->page_specs.empty()) {
@@ -1937,7 +1944,11 @@ QPDFJob::doProcessOnce(
     auto pdf = std::make_shared<QPDF>();
     setQPDFOptions(*pdf);
     if (empty) {
-        pdf->emptyPDF();
+        if (!this->m->create_from_json.empty()) {
+            pdf->createFromJSON(this->m->create_from_json);
+        } else {
+            pdf->emptyPDF();
+        }
     } else {
         fn(pdf.get(), password);
     }
diff --git a/libqpdf/QPDFJob_argv.cc b/libqpdf/QPDFJob_argv.cc
index a6fb5df7..3058d166 100644
--- a/libqpdf/QPDFJob_argv.cc
+++ b/libqpdf/QPDFJob_argv.cc
@@ -101,6 +101,13 @@ ArgParser::argReplaceInput()
 }
 
 void
+ArgParser::argCreateFromJson(std::string const& arg)
+{
+    c_main->createFromJson(arg);
+    this->gave_input = true;
+}
+
+void
 ArgParser::argVersion()
 {
     auto whoami = this->ap.getProgname();
diff --git a/libqpdf/QPDFJob_config.cc b/libqpdf/QPDFJob_config.cc
index f69a8137..1aa680e8 100644
--- a/libqpdf/QPDFJob_config.cc
+++ b/libqpdf/QPDFJob_config.cc
@@ -25,12 +25,14 @@ QPDFJob::Config::emptyInput()
 {
     if (o.m->infilename == 0) {
         // Various places in QPDFJob.cc know that the empty string for
-        // infile means empty. This means that passing "" as the
-        // argument to inputFile, or equivalently using "" as a
-        // positional command-line argument would be the same as
-        // --empty. This probably isn't worth blocking or coding
-        // around, but it would be better if we had a tighter way of
-        // knowing that the input file is empty.
+        // infile means empty. We set it to something other than a
+        // null pointer as an indication that some input source has
+        // been specified. The --create-from-json option also sets
+        // infilename to empty. This approach means that passing "" as
+        // the argument to inputFile in job JSON, or equivalently
+        // using "" as a positional command-line argument would be the
+        // same as --empty. This probably isn't worth blocking or
+        // coding around.
         o.m->infilename = QUtil::make_shared_cstr("");
     } else {
         usage("empty input can't be used"
@@ -294,6 +296,23 @@ QPDFJob::Config::toJson()
 }
 
 QPDFJob::Config*
+QPDFJob::Config::createFromJson(std::string const& parameter)
+{
+    // See comments in emptyInput() about setting infilename to the
+    // empty string.
+    o.m->infilename = QUtil::make_shared_cstr("");
+    o.m->create_from_json = parameter;
+    return this;
+}
+
+QPDFJob::Config*
+QPDFJob::Config::updateFromJson(std::string const& parameter)
+{
+    o.m->update_from_json = parameter;
+    return this;
+}
+
+QPDFJob::Config*
 QPDFJob::Config::testJsonSchema()
 {
     o.m->test_json_schema = true;
diff --git a/libqpdf/QPDFJob_json.cc b/libqpdf/QPDFJob_json.cc
index fcdeb666..9538153a 100644
--- a/libqpdf/QPDFJob_json.cc
+++ b/libqpdf/QPDFJob_json.cc
@@ -251,6 +251,12 @@ Handlers::setupEmpty()
 }
 
 void
+Handlers::setupCreateFromJson()
+{
+    addParameter([this](char const* p) { c_main->createFromJson(p); });
+}
+
+void
 Handlers::setupOutputFile()
 {
     addParameter([this](char const* p) { c_main->outputFile(p); });
diff --git a/libqpdf/QPDF_json.cc b/libqpdf/QPDF_json.cc
new file mode 100644
index 00000000..908615b6
--- /dev/null
+++ b/libqpdf/QPDF_json.cc
@@ -0,0 +1,27 @@
+#include <qpdf/QPDF.hh>
+
+#include <qpdf/FileInputSource.hh>
+
+void
+QPDF::createFromJSON(std::string const& json_file)
+{
+    createFromJSON(std::make_shared<FileInputSource>(json_file.c_str()));
+}
+
+void
+QPDF::createFromJSON(std::shared_ptr<InputSource>)
+{
+    // QXXXQ
+}
+
+void
+QPDF::updateFromJSON(std::string const& json_file)
+{
+    updateFromJSON(std::make_shared<FileInputSource>(json_file.c_str()));
+}
+
+void
+QPDF::updateFromJSON(std::shared_ptr<InputSource>)
+{
+    // QXXXQ
+}
diff --git a/libqpdf/qpdf/auto_job_decl.hh b/libqpdf/qpdf/auto_job_decl.hh
index 02f0ca91..8c656986 100644
--- a/libqpdf/qpdf/auto_job_decl.hh
+++ b/libqpdf/qpdf/auto_job_decl.hh
@@ -28,6 +28,7 @@ void argOverlay();
 void argPages();
 void argReplaceInput();
 void argUnderlay();
+void argCreateFromJson(std::string const&);
 void argPagesPositional(std::string const&);
 void argPagesPassword(std::string const&);
 void argEndPages();
diff --git a/libqpdf/qpdf/auto_job_help.hh b/libqpdf/qpdf/auto_job_help.hh
index d04f48a6..e17412d0 100644
--- a/libqpdf/qpdf/auto_job_help.hh
+++ b/libqpdf/qpdf/auto_job_help.hh
@@ -836,6 +836,21 @@ name as the prefix for stream data files. Whatever is given here
 will be appended with -nnn to create the name of the file that
 will contain the data for the stream stream in object nnn.
 )");
+ap.addOptionHelp("--create-from-json", "json", "create PDF from qpdf JSON", R"(--create-from-json=qpdf-json-file
+
+Create a PDF file from the prior output of qpdf --json. See the
+"QPDF JSON Format" section of the manual for information about
+how to use this option.
+)");
+ap.addOptionHelp("--update-from-json", "json", "update a PDF from qpdf JSON", R"(--update-from-json=qpdf-json-file
+
+Update a PDF file from a JSON file. Please see the "QPDF JSON
+Format" section of the manual for information about how to use
+this option.
+)");
+}
+static void add_help_8(QPDFArgParser& ap)
+{
 ap.addHelpTopic("testing", "options for testing or debugging", R"(The options below are useful when writing automated test code that
 includes files created by qpdf or when testing qpdf itself.
 )");
@@ -843,9 +858,6 @@ ap.addOptionHelp("--static-id", "testing", "use a fixed document ID", R"(Use a f
 testing only. Never use it for production files. See also
 qpdf --help=--deterministic-id.
 )");
-}
-static void add_help_8(QPDFArgParser& ap)
-{
 ap.addOptionHelp("--static-aes-iv", "testing", "use a fixed AES vector", R"(Use a static initialization vector for AES-CBC. This is intended
 for testing only so that output files can be reproducible. Never
 use it for production files. This option is not secure since it
diff --git a/libqpdf/qpdf/auto_job_init.hh b/libqpdf/qpdf/auto_job_init.hh
index f3ec1db6..9446811f 100644
--- a/libqpdf/qpdf/auto_job_init.hh
+++ b/libqpdf/qpdf/auto_job_init.hh
@@ -104,6 +104,8 @@ this->ap.addRequiredParameter("rotate", [this](std::string const& x){c_main->rot
 this->ap.addRequiredParameter("show-attachment", [this](std::string const& x){c_main->showAttachment(x);}, "attachment");
 this->ap.addRequiredParameter("show-object", [this](std::string const& x){c_main->showObject(x);}, "trailer");
 this->ap.addRequiredParameter("json-stream-prefix", [this](std::string const& x){c_main->jsonStreamPrefix(x);}, "stream-file-prefix");
+this->ap.addRequiredParameter("create-from-json", p(&ArgParser::argCreateFromJson), "qpdf-json file");
+this->ap.addRequiredParameter("update-from-json", [this](std::string const& x){c_main->updateFromJson(x);}, "qpdf-json file");
 this->ap.addOptionalParameter("collate", [this](std::string const& x){c_main->collate(x);});
 this->ap.addOptionalParameter("split-pages", [this](std::string const& x){c_main->splitPages(x);});
 this->ap.addChoices("compress-streams", [this](std::string const& x){c_main->compressStreams(x);}, true, yn_choices);
diff --git a/libqpdf/qpdf/auto_job_json_decl.hh b/libqpdf/qpdf/auto_job_json_decl.hh
index f02dc657..8160ca5a 100644
--- a/libqpdf/qpdf/auto_job_json_decl.hh
+++ b/libqpdf/qpdf/auto_job_json_decl.hh
@@ -8,6 +8,7 @@
 void setupInputFile();
 void setupPassword();
 void setupEmpty();
+void setupCreateFromJson();
 void setupOutputFile();
 void setupReplaceInput();
 void beginEncrypt(JSON);
diff --git a/libqpdf/qpdf/auto_job_json_init.hh b/libqpdf/qpdf/auto_job_json_init.hh
index cb349efc..ee124d0d 100644
--- a/libqpdf/qpdf/auto_job_json_init.hh
+++ b/libqpdf/qpdf/auto_job_json_init.hh
@@ -30,6 +30,9 @@ popHandler(); // key: passwordFile
 pushKey("empty");
 setupEmpty();
 popHandler(); // key: empty
+pushKey("createFromJson");
+setupCreateFromJson();
+popHandler(); // key: createFromJson
 pushKey("outputFile");
 setupOutputFile();
 popHandler(); // key: outputFile
@@ -262,6 +265,9 @@ popHandler(); // key: jsonStreamPrefix
 pushKey("toJson");
 addBare([this]() { c_main->toJson(); });
 popHandler(); // key: toJson
+pushKey("updateFromJson");
+addParameter([this](std::string const& p) { c_main->updateFromJson(p); });
+popHandler(); // key: updateFromJson
 pushKey("allowWeakCrypto");
 addBare([this]() { c_main->allowWeakCrypto(); });
 popHandler(); // key: allowWeakCrypto
diff --git a/libqpdf/qpdf/auto_job_schema.hh b/libqpdf/qpdf/auto_job_schema.hh
index 666b7260..0b9e29a9 100644
--- a/libqpdf/qpdf/auto_job_schema.hh
+++ b/libqpdf/qpdf/auto_job_schema.hh
@@ -3,6 +3,7 @@ static constexpr char const* JOB_SCHEMA_DATA = R"({
   "password": "password for encrypted file",
   "passwordFile": "read password from a file",
   "empty": "use empty file as input",
+  "createFromJson": "create PDF from qpdf JSON",
   "outputFile": "output filename",
   "replaceInput": "overwrite input with output",
   "qdf": "enable viewing PDF code in a text editor",
@@ -87,6 +88,7 @@ static constexpr char const* JOB_SCHEMA_DATA = R"({
   "jsonStreamData": "how to handle streams in json output",
   "jsonStreamPrefix": "prefix for json stream data files",
   "toJson": "serialize to JSON",
+  "updateFromJson": "update a PDF from qpdf JSON",
   "allowWeakCrypto": "allow insecure cryptographic algorithms",
   "keepFilesOpen": "manage keeping multiple files open",
   "keepFilesOpenThreshold": "set threshold for keepFilesOpen",
diff --git a/manual/cli.rst b/manual/cli.rst
index 92194e78..57a164cb 100644
--- a/manual/cli.rst
+++ b/manual/cli.rst
@@ -3270,6 +3270,31 @@ Related Options
    :samp:`-{nnn}` to create the name of the file that will contain the
    data for the stream stream in object :samp:`{nnn}`.
 
+.. qpdf:option:: --create-from-json=qpdf-json-file
+
+   .. help: create PDF from qpdf JSON
+
+      Create a PDF file from the prior output of qpdf --json. See the
+      "QPDF JSON Format" section of the manual for information about
+      how to use this option.
+
+   This option creates a PDF file from the previous output of ``qpdf
+   --json`` that includes stream data and information about all
+   objects. For information about converting between PDF and JSON,
+   please see :ref:`qpdf-json`.
+
+.. qpdf:option:: --update-from-json=qpdf-json-file
+
+   .. help: update a PDF from qpdf JSON
+
+      Update a PDF file from a JSON file. Please see the "QPDF JSON
+      Format" section of the manual for information about how to use
+      this option.
+
+   This option updates a PDF file from a qpdf JSON file. For a
+   information about how to use this option, please see
+   :ref:`qpdf-json`.
+
 .. _test-options:
 
 Options for Testing or Debugging
diff --git a/manual/json.rst b/manual/json.rst
index ef6bed96..a3922051 100644
--- a/manual/json.rst
+++ b/manual/json.rst
@@ -18,6 +18,13 @@ files programmatically from the command-line in languages that can't
 call or link with the qpdf library directly. Note that stream data can
 be extracted from PDF files using other qpdf command-line options.
 
+.. _qpdf-json:
+
+QPDF JSON Format
+----------------
+
+QXXXQ Write this.
+
 .. _json-guarantees:
 
 JSON Guarantees