Add C API to QPDFLogger

4 files changed, 175 insertions, 8 deletions

diff --git a/libqpdf/CMakeLists.txt b/libqpdf/CMakeLists.txt
index a6b036a7..3c14115b 100644
--- a/libqpdf/CMakeLists.txt
+++ b/libqpdf/CMakeLists.txt
@@ -110,7 +110,8 @@ set(libqpdf_SOURCES
   SF_FlateLzwDecode.cc
   SparseOHArray.cc
   qpdf-c.cc
-  qpdfjob-c.cc)
+  qpdfjob-c.cc
+  qpdflogger-c.cc)
 
 include(FindPkgConfig)
 include(CheckTypeSize)
diff --git a/libqpdf/QPDFJob.cc b/libqpdf/QPDFJob.cc
index b25257a1..606a612a 100644
--- a/libqpdf/QPDFJob.cc
+++ b/libqpdf/QPDFJob.cc
@@ -710,7 +710,7 @@ QPDFJob::checkConfiguration()
         save_to_stdout = true;
     }
     if (save_to_stdout) {
-        this->m->log->saveToStandardOutput();
+        this->m->log->saveToStandardOutput(true);
     }
     if ((!m->split_pages) &&
         QUtil::same_file(m->infilename.get(), m->outfilename.get())) {
@@ -925,7 +925,7 @@ QPDFJob::doShowObj(QPDF& pdf)
             } else {
                 // If anything has been written to standard output,
                 // this will fail.
-                this->m->log->saveToStandardOutput();
+                this->m->log->saveToStandardOutput(true);
                 obj.pipeStreamData(
                     this->m->log->getSave().get(),
                     (filter && m->normalize) ? qpdf_ef_normalize : 0,
@@ -1031,7 +1031,7 @@ QPDFJob::doShowAttachment(QPDF& pdf)
     auto efs = fs->getEmbeddedFileStream();
     // saveToStandardOutput has already been called, but it's harmless
     // to call it again, so do as defensive coding.
-    this->m->log->saveToStandardOutput();
+    this->m->log->saveToStandardOutput(true);
     efs.pipeStreamData(this->m->log->getSave().get(), 0, qpdf_dl_all);
 }
 
@@ -3289,7 +3289,7 @@ QPDFJob::writeOutfile(QPDF& pdf)
         } else {
             // saveToStandardOutput has already been called, but
             // calling it again is defensive and harmless.
-            this->m->log->saveToStandardOutput();
+            this->m->log->saveToStandardOutput(true);
             w.setOutputPipeline(this->m->log->getSave().get());
         }
         setWriterOptions(pdf, w);
diff --git a/libqpdf/QPDFLogger.cc b/libqpdf/QPDFLogger.cc
index 3b25c050..78cb2a32 100644
--- a/libqpdf/QPDFLogger.cc
+++ b/libqpdf/QPDFLogger.cc
@@ -181,8 +181,11 @@ QPDFLogger::setError(std::shared_ptr<Pipeline> p)
 }
 
 void
-QPDFLogger::setSave(std::shared_ptr<Pipeline> p)
+QPDFLogger::setSave(std::shared_ptr<Pipeline> p, bool only_if_not_set)
 {
+    if (only_if_not_set && (this->m->p_save != nullptr)) {
+        return;
+    }
     if (this->m->p_save == p) {
         return;
     }
@@ -202,9 +205,9 @@ QPDFLogger::setSave(std::shared_ptr<Pipeline> p)
 }
 
 void
-QPDFLogger::saveToStandardOutput()
+QPDFLogger::saveToStandardOutput(bool only_if_not_set)
 {
-    setSave(standardOutput());
+    setSave(standardOutput(), only_if_not_set);
 }
 
 void
diff --git a/libqpdf/qpdflogger-c.cc b/libqpdf/qpdflogger-c.cc
new file mode 100644
index 00000000..46fd9fba
--- /dev/null
+++ b/libqpdf/qpdflogger-c.cc
@@ -0,0 +1,163 @@
+#include <qpdf/qpdflogger-c.h>
+
+#include <qpdf/Pipeline.hh>
+#include <qpdf/QIntC.hh>
+#include <qpdf/QPDFLogger.hh>
+#include <functional>
+#include <memory>
+
+struct _qpdflogger_handle
+{
+    _qpdflogger_handle(std::shared_ptr<QPDFLogger> l);
+    ~_qpdflogger_handle() = default;
+
+    std::shared_ptr<QPDFLogger> l;
+};
+
+namespace
+{
+    class FunctionPipeline: public Pipeline
+    {
+      public:
+        FunctionPipeline(char const* identifier, qpdf_log_fn_t fn, void* udata);
+        virtual ~FunctionPipeline() = default;
+
+        virtual void write(unsigned char const* buf, size_t len) override;
+        virtual void finish() override;
+
+      private:
+        qpdf_log_fn_t fn;
+        void* udata;
+    };
+}; // namespace
+
+FunctionPipeline::FunctionPipeline(
+    char const* identifier, qpdf_log_fn_t fn, void* udata) :
+    Pipeline(identifier, nullptr),
+    fn(fn),
+    udata(udata)
+{
+}
+
+void
+FunctionPipeline::write(unsigned char const* buf, size_t len)
+{
+    fn(reinterpret_cast<char const*>(buf), QIntC::to_ulong(len), udata);
+}
+
+void
+FunctionPipeline::finish()
+{
+    // Nothing needed
+}
+
+_qpdflogger_handle::_qpdflogger_handle(std::shared_ptr<QPDFLogger> l) :
+    l(l)
+{
+}
+
+qpdflogger_handle
+qpdflogger_default_logger()
+{
+    return new _qpdflogger_handle(QPDFLogger::defaultLogger());
+}
+
+void
+qpdflogger_cleanup(qpdflogger_handle* l)
+{
+    delete *l;
+    *l = nullptr;
+}
+
+static void
+set_log_dest(
+    QPDFLogger* l,
+    std::function<void(std::shared_ptr<Pipeline>)> method,
+    qpdf_log_dest_e dest,
+    char const* identifier,
+    qpdf_log_fn_t fn,
+    void* udata)
+{
+    switch (dest) {
+    case qpdf_log_dest_default:
+        method(nullptr);
+        break;
+    case qpdf_log_dest_stdout:
+        method(l->standardOutput());
+        break;
+    case qpdf_log_dest_stderr:
+        method(l->standardError());
+        break;
+    case qpdf_log_dest_discard:
+        method(l->discard());
+        break;
+    case qpdf_log_dest_custom:
+        method(std::make_shared<FunctionPipeline>(identifier, fn, udata));
+        break;
+    }
+}
+
+static void
+set_log_dest(
+    QPDFLogger* l,
+    void (QPDFLogger::*method)(std::shared_ptr<Pipeline>),
+    qpdf_log_dest_e dest,
+    char const* identifier,
+    qpdf_log_fn_t fn,
+    void* udata)
+{
+    set_log_dest(
+        l,
+        std::bind(std::mem_fn(method), l, std::placeholders::_1),
+        dest,
+        identifier,
+        fn,
+        udata);
+}
+
+void
+qpdflogger_set_info(
+    qpdflogger_handle l, qpdf_log_dest_e dest, qpdf_log_fn_t fn, void* udata)
+{
+    set_log_dest(
+        l->l.get(), &QPDFLogger::setInfo, dest, "info logger", fn, udata);
+}
+
+void
+qpdflogger_set_warn(
+    qpdflogger_handle l, qpdf_log_dest_e dest, qpdf_log_fn_t fn, void* udata)
+{
+    set_log_dest(
+        l->l.get(), &QPDFLogger::setWarn, dest, "warn logger", fn, udata);
+}
+
+void
+qpdflogger_set_error(
+    qpdflogger_handle l, qpdf_log_dest_e dest, qpdf_log_fn_t fn, void* udata)
+{
+    set_log_dest(
+        l->l.get(), &QPDFLogger::setError, dest, "error logger", fn, udata);
+}
+
+void
+qpdflogger_set_save(
+    qpdflogger_handle l,
+    qpdf_log_dest_e dest,
+    qpdf_log_fn_t fn,
+    void* udata,
+    int only_if_not_set)
+{
+    auto method = std::bind(
+        std::mem_fn(&QPDFLogger::setSave),
+        l->l.get(),
+        std::placeholders::_1,
+        only_if_not_set);
+    set_log_dest(l->l.get(), method, dest, "save logger", fn, udata);
+}
+
+void
+qpdflogger_save_to_standard_output(qpdflogger_handle l, int only_if_not_set)
+{
+    qpdflogger_set_save(
+        l, qpdf_log_dest_stdout, nullptr, nullptr, only_if_not_set);
+}