Add unit tests for ascii85 and hex decoders.

core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp

Index: core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
index 39139c40ee12a0f042a40a68c0997755dd356b59..871653eb22734f00dfd12b70f65e919f62d0eca1 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
@@ -49,35 +49,32 @@ FX_DWORD A85Decode(const uint8_t* src_buf,
                    uint8_t*& dest_buf,
                    FX_DWORD& dest_size) {
   dest_size = 0;
-  dest_buf = NULL;
-  if (src_size == 0) {
+  dest_buf = nullptr;
+  if (src_size == 0)
     return 0;
-  }
+
+  // Count legal characters and zeros.
   FX_DWORD zcount = 0;
   FX_DWORD pos = 0;
   while (pos < src_size) {
     uint8_t ch = src_buf[pos];
-    if (ch < '!' && ch != '\n' && ch != '\r' && ch != ' ' && ch != '\t') {
-      break;
-    }
     if (ch == 'z') {
       zcount++;
-    } else if (ch > 'u') {
+    } else if ((ch < '!' || ch > 'u') && !PDFCharIsLineEnding(ch) &&
+               ch != ' ' && ch != '\t') {
       break;
     }
     pos++;
   }
-  if (pos == 0) {
+  // No content to decode.
+  if (pos == 0)
     return 0;
-  }
-  if (zcount > UINT_MAX / 4) {
-    return (FX_DWORD)-1;
-  }
-  if (zcount * 4 > UINT_MAX - (pos - zcount)) {
+
+  if (zcount > (UINT_MAX - (pos - zcount)) / 4) {
     return (FX_DWORD)-1;
   }
   dest_buf = FX_Alloc(uint8_t, zcount * 4 + (pos - zcount));

[Lei Zhang, 2016/02/06 01:22:02]

I looked at this just now - isn't this just: zcount * 3 + pos? In which case,
the overflow check can be simplified to:

zcount > (UINT_MAX - pos) / 3

[Wei Li, 2016/02/06 02:18:59]

Now let's make it right :)

-  int state = 0;
+  size_t state = 0;
   uint32_t res = 0;
   pos = dest_size = 0;
   while (pos < src_size) {
@@ -90,46 +87,49 @@ FX_DWORD A85Decode(const uint8_t* src_buf,
       state = 0;
       res = 0;
       dest_size += 4;
-    } else {
-      if (ch < '!' || ch > 'u') {
-        break;
-      }
+    } else if (ch >= '!' && ch <= 'u') {
       res = res * 85 + ch - 33;
       state++;
       if (state == 5) {
-        for (int i = 0; i < 4; i++) {
+        for (size_t i = 0; i < 4; i++) {
           dest_buf[dest_size++] = (uint8_t)(res >> (3 - i) * 8);
         }
         state = 0;
         res = 0;
       }
+    } else {
+      // The end or illegal character.
+      break;
     }
   }
+  // Handle partial group.
   if (state) {
-    int i;
-    for (i = state; i < 5; i++) {
+    for (size_t i = state; i < 5; i++)
       res = res * 85 + 84;
-    }
-    for (i = 0; i < state - 1; i++) {
+    for (size_t i = 0; i < state - 1; i++)
       dest_buf[dest_size++] = (uint8_t)(res >> (3 - i) * 8);
-    }
   }
-  if (pos < src_size && src_buf[pos] == '>') {
+  if (pos < src_size && src_buf[pos] == '>')
     pos++;
-  }
   return pos;
 }
+
 FX_DWORD HexDecode(const uint8_t* src_buf,
                    FX_DWORD src_size,
                    uint8_t*& dest_buf,
                    FX_DWORD& dest_size) {
-  FX_DWORD i;
-  for (i = 0; i < src_size; i++)
-    if (src_buf[i] == '>') {
-      break;
-    }
-  dest_buf = FX_Alloc(uint8_t, i / 2 + 1);
   dest_size = 0;
+  if (src_size == 0) {
+    dest_buf = nullptr;
+    return 0;
+  }
+
+  FX_DWORD i = 0;
+  // Find the end of data.
+  while (i < src_size && src_buf[i] != '>')
+    i++;
+
+  dest_buf = FX_Alloc(uint8_t, i / 2 + 1);
   bool bFirst = true;
   for (i = 0; i < src_size; i++) {
     uint8_t ch = src_buf[i];
@@ -218,6 +218,7 @@ FX_DWORD RunLengthDecode(const uint8_t* src_buf,
   }
   return ret;
 }
+
 ICodec_ScanlineDecoder* FPDFAPI_CreateFaxDecoder(
     const uint8_t* src_buf,
     FX_DWORD src_size,
@@ -241,13 +242,14 @@ ICodec_ScanlineDecoder* FPDFAPI_CreateFaxDecoder(
       Rows = 0;
     }
     if (Columns <= 0 || Rows < 0 || Columns > USHRT_MAX || Rows > USHRT_MAX) {
-      return NULL;
+      return nullptr;
     }
   }
   return CPDF_ModuleMgr::Get()->GetFaxModule()->CreateDecoder(
       src_buf, src_size, width, height, K, EndOfLine, ByteAlign, BlackIs1,
       Columns, Rows);
 }
+
 static FX_BOOL CheckFlateDecodeParams(int Colors,
                                       int BitsPerComponent,
                                       int Columns) {
@@ -269,6 +271,7 @@ static FX_BOOL CheckFlateDecodeParams(int Colors,
   }
   return TRUE;
 }
+
 ICodec_ScanlineDecoder* FPDFAPI_CreateFlateDecoder(
     const uint8_t* src_buf,
     FX_DWORD src_size,
@@ -285,13 +288,14 @@ ICodec_ScanlineDecoder* FPDFAPI_CreateFlateDecoder(
     BitsPerComponent = pParams->GetIntegerBy("BitsPerComponent", 8);
     Columns = pParams->GetIntegerBy("Columns", 1);
     if (!CheckFlateDecodeParams(Colors, BitsPerComponent, Columns)) {
-      return NULL;
+      return nullptr;
     }
   }
   return CPDF_ModuleMgr::Get()->GetFlateModule()->CreateDecoder(
       src_buf, src_size, width, height, nComps, bpc, predictor, Colors,
       BitsPerComponent, Columns);
 }
+
 FX_DWORD FPDFAPI_FlateOrLZWDecode(FX_BOOL bLZW,
                                   const uint8_t* src_buf,
                                   FX_DWORD src_size,
@@ -316,6 +320,7 @@ FX_DWORD FPDFAPI_FlateOrLZWDecode(FX_BOOL bLZW,
       bLZW, src_buf, src_size, bEarlyChange, predictor, Colors,
       BitsPerComponent, Columns, estimated_size, dest_buf, dest_size);
 }
+
 FX_BOOL PDF_DataDecode(const uint8_t* src_buf,
                        FX_DWORD src_size,
                        const CPDF_Dictionary* pDict,
@@ -353,7 +358,7 @@ FX_BOOL PDF_DataDecode(const uint8_t* src_buf,
     int estimated_size =
         i == DecoderList.GetSize() - 1 ? last_estimated_size : 0;
     CFX_ByteString decoder = DecoderList[i];
-    // Use ToDictionary here because we can push NULL into the ParamList.
+    // Use ToDictionary here because we can push nullptr into the ParamList.
     CPDF_Dictionary* pParam = ToDictionary(ParamList[i]);
     uint8_t* new_buf = nullptr;
     FX_DWORD new_size = (FX_DWORD)-1;
@@ -417,6 +422,7 @@ FX_BOOL PDF_DataDecode(const uint8_t* src_buf,
   dest_size = last_size;
   return TRUE;
 }
+
 CFX_WideString PDF_DecodeText(const uint8_t* src_data,
                               FX_DWORD src_len,
                               CFX_CharMap* pCharMap) {
@@ -464,6 +470,7 @@ CFX_WideString PDF_DecodeText(const uint8_t* src_data,
   }
   return result;
 }
+
 CFX_ByteString PDF_EncodeText(const FX_WCHAR* pString,
                               int len,
                               CFX_CharMap* pCharMap) {
@@ -509,6 +516,7 @@ CFX_ByteString PDF_EncodeText(const FX_WCHAR* pString,
   result.ReleaseBuffer(encLen);
   return result;
 }
+
 CFX_ByteString PDF_EncodeString(const CFX_ByteString& src, FX_BOOL bHex) {
   CFX_ByteTextBuf result;
   int srclen = src.GetLength();
@@ -538,6 +546,7 @@ CFX_ByteString PDF_EncodeString(const CFX_ByteString& src, FX_BOOL bHex) {
   result.AppendChar(')');
   return result.GetByteString();
 }
+
 void FlateEncode(const uint8_t* src_buf,
                  FX_DWORD src_size,
                  uint8_t*& dest_buf,
@@ -547,6 +556,7 @@ void FlateEncode(const uint8_t* src_buf,
     pEncoders->GetFlateModule()->Encode(src_buf, src_size, dest_buf, dest_size);
   }
 }
+
 void FlateEncode(const uint8_t* src_buf,
                  FX_DWORD src_size,
                  int predictor,
@@ -562,6 +572,7 @@ void FlateEncode(const uint8_t* src_buf,
                                         dest_size);
   }
 }
+
 FX_DWORD FlateDecode(const uint8_t* src_buf,
                      FX_DWORD src_size,
                      uint8_t*& dest_buf,