commit cd3d3798cee48375d4f9d57b4e0a37b5bf04d3dd
author Lei Zhang <thestig@chromium.org> Wed Sep 28 17:22:04 2022 +0000
committer Pdfium LUCI CQ <pdfium-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Sep 28 17:22:04 2022 +0000
tree 6c5ad12c2b68e096a41e5fb5b473f079bac19ca7
parent bb040742ce9af87ac841f31b0a9a4f465d24401e

Rework CPDFSDK_FormFillEnvironment::JS_appResponse() callers.

Since JS_appResponse() returns how much of the buffer is actually used,
and the function that handles the returned buffer also takes a size,
there is no need to pad the buffer with NULL characters. Remove the code
that assumes this is the case.

Change-Id: Ia83105679a82bf14c388c6e638438b5d86b3503a
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/98571
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

fxjs/cjs_app.cpp

diff --git a/fxjs/cjs_app.cpp b/fxjs/cjs_app.cpp
index b417106..e7c23e7 100644
--- a/fxjs/cjs_app.cpp
+++ b/fxjs/cjs_app.cpp
@@ -8,6 +8,7 @@
 
 #include <stdint.h>
 
+#include <algorithm>
 #include <utility>
 
 #include "core/fxcrt/fixed_zeroed_data_vector.h"
@@ -549,20 +550,20 @@
   if (IsExpandedParamKnown(newParams[4]))
     swLabel = pRuntime->ToWideString(newParams[4]);
 
-  constexpr int kMaxBytes = 2048;
-  constexpr int kMaxWideChars = kMaxBytes / 2;
-  // Add 1 char for a NUL terminator.
-  FixedZeroedDataVector<uint16_t> buffer(kMaxWideChars + 1);
+  constexpr int kMaxWideChars = 1024;
+  constexpr int kMaxBytes = kMaxWideChars * sizeof(uint16_t);
+  FixedZeroedDataVector<uint16_t> buffer(kMaxWideChars);
+  pdfium::span<uint16_t> buffer_span = buffer.writable_span();
   int byte_length = pRuntime->GetFormFillEnv()->JS_appResponse(
       swQuestion, swTitle, swDefault, swLabel, bPassword,
-      pdfium::as_writable_bytes(buffer.writable_span().first(kMaxWideChars)));
-
+      pdfium::as_writable_bytes(buffer_span));
   if (byte_length < 0 || byte_length > kMaxBytes)
     return CJS_Result::Failure(JSMessage::kParamTooLongError);
 
+  buffer_span = buffer_span.first(
+      std::min<size_t>(kMaxWideChars, byte_length / sizeof(uint16_t)));
   return CJS_Result::Success(pRuntime->NewString(
-      WideString::FromUTF16LE(buffer.span().data(),
-                              byte_length / sizeof(uint16_t))
+      WideString::FromUTF16LE(buffer_span.data(), buffer_span.size())
           .AsStringView()));
 }