Implement FPDF_VIEWERREF_GetName() API.chromium/2910

This is a generic API function to retrieve any viewer preference of type
name.

BUG=pdfium:414

Review-Url: https://codereview.chromium.org/2475923003

3 files changed, 67 insertions, 1 deletions

diff --git a/fpdfsdk/fpdfview.cpp b/fpdfsdk/fpdfview.cpp
index cde15dff9b..9142dc78c9 100644
--- a/fpdfsdk/fpdfview.cpp
+++ b/fpdfsdk/fpdfview.cpp
@@ -942,6 +942,25 @@ FPDF_VIEWERREF_GetDuplex(FPDF_DOCUMENT document) {
   return DuplexUndefined;
 }
 
+DLLEXPORT unsigned long STDCALL FPDF_VIEWERREF_GetName(FPDF_DOCUMENT document,
+                                                       FPDF_BYTESTRING key,
+                                                       char* buffer,
+                                                       unsigned long length) {
+  CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(document);
+  if (!pDoc)
+    return 0;
+
+  CPDF_ViewerPreferences viewRef(pDoc);
+  CFX_ByteString bsVal;
+  if (!viewRef.GenericName(key, &bsVal))
+    return 0;
+
+  unsigned long dwStringLen = bsVal.GetLength() + 1;
+  if (buffer && length >= dwStringLen)
+    memcpy(buffer, bsVal.c_str(), dwStringLen);
+  return dwStringLen;
+}
+
 DLLEXPORT FPDF_DWORD STDCALL FPDF_CountNamedDests(FPDF_DOCUMENT document) {
   CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(document);
   if (!pDoc)
diff --git a/fpdfsdk/fpdfview_c_api_test.c b/fpdfsdk/fpdfview_c_api_test.c
index 2f0cb49fc2..4847180e46 100644
--- a/fpdfsdk/fpdfview_c_api_test.c
+++ b/fpdfsdk/fpdfview_c_api_test.c
@@ -228,6 +228,7 @@ int CheckPDFiumCApi() {
     CHK(FPDF_VIEWERREF_GetNumCopies);
     CHK(FPDF_VIEWERREF_GetPrintPageRange);
     CHK(FPDF_VIEWERREF_GetDuplex);
+    CHK(FPDF_VIEWERREF_GetName);
     CHK(FPDF_CountNamedDests);
     CHK(FPDF_GetNamedDestByName);
     CHK(FPDF_GetNamedDest);
diff --git a/fpdfsdk/fpdfview_embeddertest.cpp b/fpdfsdk/fpdfview_embeddertest.cpp
index 820d496bdc..e712edb89a 100644
--- a/fpdfsdk/fpdfview_embeddertest.cpp
+++ b/fpdfsdk/fpdfview_embeddertest.cpp
@@ -56,6 +56,10 @@ TEST_F(FPDFViewEmbeddertest, EmptyDocument) {
   EXPECT_EQ(1, FPDF_VIEWERREF_GetNumCopies(document()));
   EXPECT_EQ(DuplexUndefined, FPDF_VIEWERREF_GetDuplex(document()));
 
+  char buf[100];
+  EXPECT_EQ(0U, FPDF_VIEWERREF_GetName(document(), "foo", nullptr, 0));
+  EXPECT_EQ(0U, FPDF_VIEWERREF_GetName(document(), "foo", buf, sizeof(buf)));
+
   EXPECT_EQ(0u, FPDF_CountNamedDests(document()));
 }
 
@@ -69,11 +73,53 @@ TEST_F(FPDFViewEmbeddertest, Page) {
   EXPECT_EQ(nullptr, LoadPage(1));
 }
 
-TEST_F(FPDFViewEmbeddertest, ViewerRef) {
+TEST_F(FPDFViewEmbeddertest, ViewerRefDummy) {
   EXPECT_TRUE(OpenDocument("about_blank.pdf"));
   EXPECT_TRUE(FPDF_VIEWERREF_GetPrintScaling(document()));
   EXPECT_EQ(1, FPDF_VIEWERREF_GetNumCopies(document()));
   EXPECT_EQ(DuplexUndefined, FPDF_VIEWERREF_GetDuplex(document()));
+
+  char buf[100];
+  EXPECT_EQ(0U, FPDF_VIEWERREF_GetName(document(), "foo", nullptr, 0));
+  EXPECT_EQ(0U, FPDF_VIEWERREF_GetName(document(), "foo", buf, sizeof(buf)));
+}
+
+TEST_F(FPDFViewEmbeddertest, ViewerRef) {
+  EXPECT_TRUE(OpenDocument("viewer_ref.pdf"));
+  EXPECT_TRUE(FPDF_VIEWERREF_GetPrintScaling(document()));
+  EXPECT_EQ(5, FPDF_VIEWERREF_GetNumCopies(document()));
+  EXPECT_EQ(DuplexUndefined, FPDF_VIEWERREF_GetDuplex(document()));
+
+  // Test some corner cases.
+  char buf[100];
+  EXPECT_EQ(0U, FPDF_VIEWERREF_GetName(document(), "", buf, sizeof(buf)));
+  EXPECT_EQ(0U, FPDF_VIEWERREF_GetName(document(), "foo", nullptr, 0));
+  EXPECT_EQ(0U, FPDF_VIEWERREF_GetName(document(), "foo", buf, sizeof(buf)));
+
+  // Make sure |buf| does not get written into when it appears to be too small.
+  strcpy(buf, "ABCD");
+  EXPECT_EQ(4U, FPDF_VIEWERREF_GetName(document(), "Foo", buf, 1));
+  EXPECT_STREQ("ABCD", buf);
+
+  // Note "Foo" is a different key from "foo".
+  EXPECT_EQ(4U,
+            FPDF_VIEWERREF_GetName(document(), "Foo", nullptr, sizeof(buf)));
+  ASSERT_EQ(4U, FPDF_VIEWERREF_GetName(document(), "Foo", buf, sizeof(buf)));
+  EXPECT_STREQ("foo", buf);
+
+  // Try to retrieve a boolean and an integer.
+  EXPECT_EQ(
+      0U, FPDF_VIEWERREF_GetName(document(), "HideToolbar", buf, sizeof(buf)));
+  EXPECT_EQ(0U,
+            FPDF_VIEWERREF_GetName(document(), "NumCopies", buf, sizeof(buf)));
+
+  // Try more valid cases.
+  ASSERT_EQ(4U,
+            FPDF_VIEWERREF_GetName(document(), "Direction", buf, sizeof(buf)));
+  EXPECT_STREQ("R2L", buf);
+  ASSERT_EQ(8U,
+            FPDF_VIEWERREF_GetName(document(), "ViewArea", buf, sizeof(buf)));
+  EXPECT_STREQ("CropBox", buf);
 }
 
 TEST_F(FPDFViewEmbeddertest, NamedDests) {