Leave space for null characters when getting text

The conversion from WideString to ByeString adds in null characters at
the end, so we need to account for these when selecting the range of
text to initially extract.

BUG=chromium:761770,chromium:761626

Change-Id: Ib8f863e997ebccaaf882e0beb29733f27a18826d
Reviewed-on: https://pdfium-review.googlesource.com/13110
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

1 files changed, 13 insertions, 4 deletions

diff --git a/fpdfsdk/fpdftext_embeddertest.cpp b/fpdfsdk/fpdftext_embeddertest.cpp
index a83ffe7c29..7e8e033ae0 100644
--- a/fpdfsdk/fpdftext_embeddertest.cpp
+++ b/fpdfsdk/fpdftext_embeddertest.cpp
@@ -16,13 +16,12 @@ namespace {
 bool check_unsigned_shorts(const char* expected,
                            const unsigned short* actual,
                            size_t length) {
-  if (length > strlen(expected) + 1) {
+  if (length > strlen(expected) + 1)
     return false;
-  }
+
   for (size_t i = 0; i < length; ++i) {
-    if (actual[i] != static_cast<unsigned short>(expected[i])) {
+    if (actual[i] != static_cast<unsigned short>(expected[i]))
       return false;
-    }
   }
   return true;
 }
@@ -64,6 +63,16 @@ TEST_F(FPDFTextEmbeddertest, Text) {
         << " at " << i;
   }
 
+  // Extracting using a buffer that will be completely filled. Small buffer is
+  // 12 elements long, since it will need 2 locations per displayed character in
+  // the expected string, plus 2 more for the terminating character.
+  static const char small_expected[] = "Hello";
+  unsigned short small_buffer[12];
+  memset(fixed_buffer, 0xbd, sizeof(fixed_buffer));
+  EXPECT_EQ(6, FPDFText_GetText(textpage, 0, 6, small_buffer));
+  EXPECT_TRUE(check_unsigned_shorts(small_expected, small_buffer,
+                                    sizeof(small_expected)));
+
   EXPECT_EQ(12.0, FPDFText_GetFontSize(textpage, 0));
   EXPECT_EQ(16.0, FPDFText_GetFontSize(textpage, 15));