Progressing #171

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "pdfium-render"
-version = "0.8.26"
+version = "0.8.27"
 edition = "2018"
 rust-version = "1.61"
 publish = true

README.md

@@ -69,14 +69,14 @@ Short, commented examples that demonstrate all the major Pdfium document handlin
 _Note: upcoming release 0.9.0 will remove all deprecated items. For a complete list of deprecated
 items, see <https://github.com/ajrcarey/pdfium-render/issues/36>._
 
+Release 0.8.27 fixes a bug in certain string handling operations in the WASM bindings implementation.
+
 Release 0.8.26 relaxes the minimum supported Rust version to 1.61 based on user feedback, increments the `pdfium_latest` feature to `pdfium_6721` to match new Pdfium release 6721 at <https://github.com/bblanchon/pdfium-binaries>, adds new crate features `image_025`, `image_024`, and `image_023` to allow explicitly pinning the version of `image` that should be used by `pdfium-render`, sets `image` to `image_025`, and adjusts bookmark traversal so that bookmarks are returned in a more natural order, thanks to an excellent contribution from <https://github.com/mlaiosa>.
 
 Release 0.8.25 establishes a minimum supported Rust version of 1.60 for `pdfium-render`, increments the `pdfium_latest` feature to `pdfium_6666` to match new Pdfium release 6666 at <https://github.com/bblanchon/pdfium-binaries>, adds new crate features `pdfium_use_skia`, `pdfium_use_win32`, `pdfium_enable_xfa`, and `pdfium_enable_v8` to make available certain Pdfium functions that require Pdfium to be built with specific compile-time flags, and adds bindings for all remaining `FPDF_*` functions in the Pdfium API to `PdfiumLibraryBindings`, an important milestone leading up to release 0.9.0.
 
 Release 0.8.24 fixes a bug in certain string handling operations in the WASM bindings implementation, and introduces the ability to control the version of the Pdfium API used by `pdfium-render`. By default `pdfium-render` uses the latest released version of the Pdfium API, potentially requiring you to upgrade your Pdfium library if the latest release contains breaking changes. This can be inconvenient! To explicitly use an older API version, select one of the crate's Pdfium version feature flags when taking `pdfium-render` as a dependency in your project's `Cargo.toml`. See the "Crate features" section below for more information.
 
-Release 0.8.23 updates the Pdfium bindings to the latest upstream release, adds new function `PdfPageTextChar::text_object()` for retrieving the page object containing a specific character in a text page, deprecates the `PdfFont::name()` function in favour of `PdfFont::family()` to match changes in upstream naming, adds new functions `PdfFont::is_embedded()` and `PdfFont::data()` for retrieving embedded font data, updates the `examples/fonts.rs` example to demonstrate the new functionality, and adjusts the implementation of some internal functions in response to upstream changes. Deprecated items will be removed in release 0.9.0.
-
 ## Binding to Pdfium
 
 `pdfium-render` does not include Pdfium itself. You have several options:
@@ -300,6 +300,7 @@ will be removed in release 0.9.0.
 
 ## Version history
 
+* 0.8.27: fixes a bug in string termination detection when copying `FPDF_WIDESTRING` buffers to Pdfium's WASM address space.
 * 0.8.26: relaxes version constraint on `chrono` dependency based on user feedback, relaxing the minimum supported Rust version to 1.61; increments the `pdfium_latest` feature to `pdfium_6721` to match new Pdfium release 6721 at <https://github.com/bblanchon/pdfium-binaries>; synchronises `pdfium_future` feature against current Google mainline; adds new crate features `image_025`, `image_024`, and `image_023` to allow explicitly pinning the version of `image` that should be used by `pdfium-render`, sets `image` to `image_025`; adjusts bookmark traversal so that bookmarks are returned in a more natural order, thanks to an excellent contribution from <https://github.com/mlaiosa>.
 * 0.8.25: adds bindings for all outstanding Pdfium API functions, including `FPDFAnnot_GetFormAdditionalActionJavaScript()`, `FPDFBitmap_Create()`, `FPDFAnnot_GetFormFieldAlternateName()`, `FPDFAnnot_GetFileAttachment()`, `FPDFAnnot_AddFileAttachment()`, `FPDFAvail_Create()`, `FPDFAvail_Destroy()`, `FPDFAvail_IsDocAvail()`, `FPDFAvail_GetDocument()`, `FPDFAvail_GetFirstPageNum()`, `FPDFAvail_IsPageAvail()`, `FPDFAvail_IsFormAvail()`, `FPDFAvail_IsLinearized()`, `FPDFAnnot_GetFontColor()`, `FPDFPageObj_TransformF()`, `FPDFPageObj_GetMarkedContentID()`, `FPDF_StructElement_GetActualText()`, `FPDF_StructElement_GetObjType()`, `FPDF_StructElement_GetChildMarkedContentID()`, `FPDF_StructElement_GetAttributeAtIndex()`, `FPDF_StructElement_Attr_GetName()`, `FPDF_StructElement_Attr_GetValue()`, `FPDF_StructElement_Attr_GetType()`, `FPDF_StructElement_Attr_GetBooleanValue()`, `FPDF_StructElement_Attr_GetNumberValue()`, `FPDF_StructElement_Attr_GetStringValue()`, `FPDF_StructElement_Attr_GetBlobValue()`, `FPDF_StructElement_Attr_GetChildAtIndex()`, `FPDF_StructElement_GetMarkedContentIdCount()`, `FPDF_StructElement_GetMarkedContentIdAtIndex()`, `FPDF_ARGB()`, `FPDF_GetBValue()`, `FPDF_GetGValue()`, `FPDF_GetRValue()`, `FPDF_MovePages()`, `FPDFImageObj_GetImagePixelSize()`, `FPDFPageObj_GetRotatedBounds()`, `FPDFText_LoadCidType2Font()`, `FPDFTextObj_GetRenderedBitmap()`, `FPDF_FFLDrawSkia()`, `FPDF_NewXObjectFromPage()`, `FPDF_CloseXObject()`, `FPDF_NewFormObjectFromXObject()`, `FPDF_CopyViewerPreferences()`, `FPDF_RenderPageBitmapWithColorScheme_Start()`, `FPDF_RenderPageBitmap_Start()`, `FPDF_RenderPage_Continue()`, `FPDF_RenderPage_Close()`, `FPDF_GetDefaultTTFMap()`, `FPDF_GetDefaultTTFMapCount()`, `FPDF_GetDefaultTTFMapEntry()`, `FPDF_AddInstalledFont()`, `FPDFText_IsGenerated()`, `FPDFText_IsHyphen()`, `FPDFText_HasUnicodeMapError()`, `FPDF_InitLibraryWithConfig()`, `FPDF_SetSandBoxPolicy()`, `FPDF_SetPrintMode()`, `FPDF_DocumentHasValidCrossReferenceTable()`, `FPDF_GetTrailerEnds()`, `FPDF_GetDocUserPermissions()`, `FPDF_GetPageWidth()` `FPDF_GetPageHeight()` `FPDF_GetPageSizeByIndex()` `FPDF_RenderPageSkia()`, `FPDF_CountNamedDests()`, `FPDF_GetNamedDestByName()`, `FPDF_GetNamedDest()`, `FPDF_GetXFAPacketCount()`, `FPDF_GetXFAPacketName()`, `FPDF_GetXFAPacketContent()`, `FPDF_GetRecommendedV8Flags()`, `FPDF_GetArrayBufferAllocatorSharedInstance()`, `FPDF_BStr_Init()`, `FPDF_BStr_Set()`, `FPDF_BStr_Clear()`, `FPDF_SetPrintMode()`, and `FPDF_RenderPage()`; adds `pfdium_use_skia`,`pdfium_use_win32`, `pdfium_enable_xfa`, and `pdfium_enable_v8` crate feature flags; adjusts dependency versions in `Cargo.toml` to meet a minimum supported Rust version (MSRV) of Rust 1.60; establishes upper bound on `bindgen` dependency to avoid a build failure when compiling to WASM that was introduced in `bindgen` versions 0.70.0 and later, as described at <https://github.com/ajrcarey/pdfium-render/issues/156>.
 * 0.8.24: introduces crate feature flags for selecting Pdfium API versions to use in `PdfiumLibraryBindings`; reworked `build.rs` to output bindings for multiple sets of Pdfium header files; reworks bindings implementations to differentiate between API versions that include the `FPDFFont_*` and `FPDFText_GetTextObject()` functions added in 0.8.23, and API versions that do not; reinstates `FPDFText_GetTextRenderMode()` function removed in 0.8.23 behind feature flags; adds WASM bindings utility function `copy_string_to_pdfium()` to correctly copy the string data of an `FPDF_WIDESTRING` to Pdfium's WASM memory module, instead of just the pointer location; adds `PdfiumLibraryBindings::version()` function for reporting the currently configured API version; internally reorganizes source code layout to make the code structure clearer. 

src/bindings/wasm.rs

@@ -622,27 +622,31 @@ impl PdfiumRenderWasmState {
         // two-byte pointer, not the string data itself. We must scan the source memory
         // location for two null bytes to find the correct data length.
 
+        // Many characters, such as standard ASCII characters, can be represented with
+        // a single byte. Since all characters in UTF-16 consume two bytes, ASCII characters
+        // will receive a second byte of padding in UTF-16. This second byte will be a null.
+        // When scanning the FPDF_WIDESTRING for two null bytes, we must be careful not to
+        // misinterpret a null padding byte as part of a string termination sequence.
+        // The easiest way is to iterate over the string in two-byte pairs rather than
+        // byte-by-byte. See: https://github.com/ajrcarey/pdfium-render/issues/171
+
         let mut len = 0;
-        let mut last_byte = None;
 
         log::debug!(
             "pdfium-render::PdfiumRenderWasmState::copy_string_to_pdfium(): FPDF_WIDESTRING is at heap offset {}",
             str as usize as u32,
         );
 
         loop {
-            let this_byte =
-                unsafe { Uint8Array::view_mut_raw((str as *mut u8).add(len), 1) }.get_index(0);
+            let utf16_char = unsafe { Uint8Array::view_mut_raw((str as *mut u8).add(len), 2) };
 
-            len += 1;
+            len += 2;
 
-            if this_byte == 0 && last_byte == Some(0) {
-                // We have found two sequential null bytes. This is the end of the string.
+            if utf16_char.get_index(0) == 0 && utf16_char.get_index(1) == 0 {
+                // This is the end of the string.
 
                 break;
             }
-
-            last_byte = Some(this_byte);
         }
 
         log::debug!(

src/lib.rs

@@ -62,7 +62,7 @@ mod bindgen {
     #[cfg(feature = "pdfium_5961")]
     include!("bindgen/pdfium_5961.rs");
 
-    pub type size_t = usize;
+    pub(crate) type size_t = usize;
 }
 
 mod bindings;