Bug 393286: Make nsCSSScanner::Read regularize newlines. r+sr=bzbarsky, a=dbaron

layout/style/nsCSSScanner.cpp

@@ -288,7 +288,6 @@ void nsCSSScanner::Init(nsIUnicharInputStream* aInput,
   // Reset variables that we use to keep track of our progress through the input
   mOffset = 0;
   mPushbackCount = 0;
-  mLastRead = 0;
 
 #ifdef CSS_REPORT_PARSE_ERRORS
   mColNumber = 0;
@@ -466,6 +465,24 @@ void nsCSSScanner::Close()
 #define TAB_STOP_WIDTH 8
 #endif
 
+PRBool nsCSSScanner::EnsureData(nsresult& aErrorCode)
+{
+  if (mOffset < mCount)
+    return PR_TRUE;
+
+  if (mInputStream) {
+    mOffset = 0;
+    aErrorCode = mInputStream->Read(mBuffer, CSS_BUFFER_SIZE, &mCount);
+    if (NS_FAILED(aErrorCode) || mCount == 0) {
+      mCount = 0;
+      return PR_FALSE;
+    }
+    return PR_TRUE;
+  }
+
+  return PR_FALSE;
+}
+
 // Returns -1 on error or eof
 PRInt32 nsCSSScanner::Read(nsresult& aErrorCode)
 {
@@ -473,20 +490,21 @@ PRInt32 nsCSSScanner::Read(nsresult& aErrorCode)
   if (0 < mPushbackCount) {
     rv = PRInt32(mPushback[--mPushbackCount]);
   } else {
-    if (mOffset == mCount) {
-      mOffset = 0;
-      if (!mInputStream) {
-        mCount = 0;
-        return -1;
-      }
-      aErrorCode = mInputStream->Read(mBuffer, CSS_BUFFER_SIZE, &mCount);
-      if (NS_FAILED(aErrorCode) || mCount == 0) {
-        mCount = 0;
-        return -1;
-      }
+    if (mOffset == mCount && !EnsureData(aErrorCode)) {
+      return -1;
     }
     rv = PRInt32(mReadPointer[mOffset++]);
-    if (((rv == '\n') && (mLastRead != '\r')) || (rv == '\r')) {
+    // There are four types of newlines in CSS: "\r", "\n", "\r\n", and "\f".
+    // To simplify dealing with newlines, they are all normalized to "\n" here
+    if (rv == '\r') {
+      if (EnsureData(aErrorCode) && mReadPointer[mOffset] == '\n') {
+        mOffset++;
+      }
+      rv = '\n';
+    } else if (rv == '\f') {
+      rv = '\n';
+    }
+    if (rv == '\n') {
       // 0 is a magical line number meaning that we don't know (i.e., script)
       if (mLineNumber != 0)
         ++mLineNumber;
@@ -503,7 +521,6 @@ PRInt32 nsCSSScanner::Read(nsresult& aErrorCode)
     }
 #endif
   }
-  mLastRead = rv;
 //printf("Read => %x\n", rv);
   return rv;
 }
@@ -511,9 +528,7 @@ PRInt32 nsCSSScanner::Read(nsresult& aErrorCode)
 PRInt32 nsCSSScanner::Peek(nsresult& aErrorCode)
 {
   if (0 == mPushbackCount) {
-    PRInt32 savedLastRead = mLastRead;
     PRInt32 ch = Read(aErrorCode);
-    mLastRead = savedLastRead;
     if (ch < 0) {
       return -1;
     }
@@ -562,7 +577,7 @@ PRBool nsCSSScanner::EatWhiteSpace(nsresult& aErrorCode)
     if (ch < 0) {
       break;
     }
-    if ((ch == ' ') || (ch == '\n') || (ch == '\r') || (ch == '\t')) {
+    if ((ch == ' ') || (ch == '\n') || (ch == '\t')) {
       eaten = PR_TRUE;
       continue;
     }
@@ -579,13 +594,7 @@ PRBool nsCSSScanner::EatNewline(nsresult& aErrorCode)
     return PR_FALSE;
   }
   PRBool eaten = PR_FALSE;
-  if (ch == '\r') {
-    eaten = PR_TRUE;
-    ch = Peek(aErrorCode);
-    if (ch == '\n') {
-      (void) Read(aErrorCode);
-    }
-  } else if (ch == '\n') {
+  if (ch == '\n') {
     eaten = PR_TRUE;
   } else {
     Pushback(ch);
@@ -862,10 +871,6 @@ nsCSSScanner::ParseAndAppendEscape(nsresult& aErrorCode, nsString& aOutput)
       } else {
         NS_ASSERTION((lexTable[ch] & IS_WHITESPACE) != 0, "bad control flow");
         // single space ends escape
-        if (ch == '\r' && Peek(aErrorCode) == '\n') {
-          // if CR/LF, eat LF too
-          Read(aErrorCode);
-        }
         break;
       }
     }
@@ -874,13 +879,6 @@ nsCSSScanner::ParseAndAppendEscape(nsresult& aErrorCode, nsString& aOutput)
       if ((0 <= ch) && (ch <= 255) && 
           ((lexTable[ch] & IS_WHITESPACE) != 0)) {
         ch = Read(aErrorCode);
-        // special case: if trailing whitespace is CR/LF, eat both chars (not part of spec, but should be)
-        if (ch == '\r') {
-          ch = Peek(aErrorCode);
-          if (ch == '\n') {
-            ch = Read(aErrorCode);
-          }
-        }
       }
     }
     NS_ASSERTION(rv >= 0, "How did rv become negative?");

layout/style/nsCSSScanner.h

@@ -198,6 +198,7 @@ class nsCSSScanner {
   }
   
 protected:
+  PRBool EnsureData(nsresult& aErrorCode);
   PRInt32 Read(nsresult& aErrorCode);
   PRInt32 Peek(nsresult& aErrorCode);
   void Pushback(PRUnichar aChar);
@@ -230,7 +231,6 @@ protected:
   PRUnichar* mPushback;
   PRInt32 mPushbackCount;
   PRInt32 mPushbackSize;
-  PRInt32 mLastRead;
   PRUnichar mLocalPushback[4];
 
   PRUint32 mLineNumber;