зеркало из https://github.com/mozilla/gecko-dev.git
bug #90394: r=dbaron, sr=asa(?). A simple fix to a big leak when |nsXPIDLC?String|s are never accessed after assignment, deallocation failed. By storing the initial pointer in the _storage_ start slot, this is avoided.
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@ -43,11 +43,16 @@
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* must be called before any other object can share the buffer,
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* and as the default implementation for |GetBufferHandle|, which is
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* the operation on which all other flat string operations are based.
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* A valid handle always contains a non-|NULL| data start and end.
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* After use as an `out' string pointer parameter, an |nsXPIDLC?String|'s
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* handle will have a non-|NULL| data start, but its data end will be
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* |NULL|. This is the signal that the length needs to be recalculated.
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* |GetSharedBufferHandle| detects this situation and repairs it.
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* A valid handle will either have all |NULL| or all non-|NULL|
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* pointers. After use as an `out' string pointer parameter, an
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* |nsXPIDLC?String|'s handle will have a non-|NULL| storage start, but
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* all other members will be |NULL|. This is the signal that the
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* length needs to be recalculated. |GetSharedBufferHandle| detects
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* this situation and repairs it.
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*
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* The one situation this _doesn't_ catch, is if no one ever tries to use
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* the string before it's destruction. In this case, because the start of
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* storage is known, storage can still be freed in the usual way.
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*
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* An |nsXPIDLC?String| is now a sharable object, just like |nsSharableC?String|.
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* This simple implementation always allocates an intermediary handle
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@ -45,7 +45,7 @@ class nsImportedStringHandle
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public:
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nsImportedStringHandle() : nsFlexBufferHandle<CharT>(0, 0, 0, 0) { }
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CharT** AddressOfDataStart() { return &(this->mDataStart); }
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CharT** AddressOfStorageStart() { return &(this->mStorageStart); }
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void RecalculateBoundaries() const;
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};
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@ -57,18 +57,17 @@ nsImportedStringHandle<CharT>::RecalculateBoundaries() const
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size_t data_length = 0;
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size_t storage_length = 0;
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CharT* data_start = NS_CONST_CAST(CharT*, this->DataStart());
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if ( data_start )
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CharT* storage_start = NS_CONST_CAST(CharT*, this->StorageStart());
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if ( storage_start )
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{
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data_length = nsCharTraits<CharT>::length(data_start);
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data_length = nsCharTraits<CharT>::length(storage_start);
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storage_length = data_length + 1;
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}
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nsImportedStringHandle<CharT>* mutable_this = NS_CONST_CAST(nsImportedStringHandle<CharT>*, this);
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mutable_this->DataEnd(data_start+data_length);
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mutable_this->StorageStart(data_start);
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mutable_this->StorageEnd(data_start+storage_length);
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mutable_this->DataStart(storage_start);
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mutable_this->DataEnd(storage_start+data_length);
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mutable_this->StorageEnd(storage_start+storage_length);
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}
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@ -103,7 +102,7 @@ nsXPIDLString::GetSharedBufferHandle() const
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{
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const nsImportedStringHandle<PRUnichar>* answer = NS_STATIC_CAST(const nsImportedStringHandle<PRUnichar>*, mBuffer.get());
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if ( answer && !answer->DataEnd() )
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if ( answer && !answer->DataEnd() && answer->StorageStart() )
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answer->RecalculateBoundaries();
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#if DEBUG_STRING_STATS
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@ -123,7 +122,7 @@ nsXPIDLString::PrepareForUseAsOutParam()
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#if DEBUG_STRING_STATS
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++sAssignCount;
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#endif
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return handle->AddressOfDataStart();
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return handle->AddressOfStorageStart();
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}
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@ -158,7 +157,7 @@ nsXPIDLCString::GetSharedBufferHandle() const
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{
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const nsImportedStringHandle<char>* answer = NS_STATIC_CAST(const nsImportedStringHandle<char>*, mBuffer.get());
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if ( answer && !answer->DataEnd() )
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if ( answer && !answer->DataEnd() && answer->StorageStart() )
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answer->RecalculateBoundaries();
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#if DEBUG_STRING_STATS
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@ -178,5 +177,5 @@ nsXPIDLCString::PrepareForUseAsOutParam()
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#if DEBUG_STRING_STATS
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++sAssignCount;
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#endif
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return handle->AddressOfDataStart();
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return handle->AddressOfStorageStart();
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}
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@ -43,11 +43,16 @@
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* must be called before any other object can share the buffer,
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* and as the default implementation for |GetBufferHandle|, which is
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* the operation on which all other flat string operations are based.
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* A valid handle always contains a non-|NULL| data start and end.
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* After use as an `out' string pointer parameter, an |nsXPIDLC?String|'s
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* handle will have a non-|NULL| data start, but its data end will be
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* |NULL|. This is the signal that the length needs to be recalculated.
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* |GetSharedBufferHandle| detects this situation and repairs it.
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* A valid handle will either have all |NULL| or all non-|NULL|
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* pointers. After use as an `out' string pointer parameter, an
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* |nsXPIDLC?String|'s handle will have a non-|NULL| storage start, but
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* all other members will be |NULL|. This is the signal that the
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* length needs to be recalculated. |GetSharedBufferHandle| detects
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* this situation and repairs it.
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*
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* The one situation this _doesn't_ catch, is if no one ever tries to use
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* the string before it's destruction. In this case, because the start of
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* storage is known, storage can still be freed in the usual way.
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*
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* An |nsXPIDLC?String| is now a sharable object, just like |nsSharableC?String|.
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* This simple implementation always allocates an intermediary handle
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@ -45,7 +45,7 @@ class nsImportedStringHandle
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public:
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nsImportedStringHandle() : nsFlexBufferHandle<CharT>(0, 0, 0, 0) { }
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CharT** AddressOfDataStart() { return &(this->mDataStart); }
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CharT** AddressOfStorageStart() { return &(this->mStorageStart); }
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void RecalculateBoundaries() const;
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};
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@ -57,18 +57,17 @@ nsImportedStringHandle<CharT>::RecalculateBoundaries() const
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size_t data_length = 0;
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size_t storage_length = 0;
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CharT* data_start = NS_CONST_CAST(CharT*, this->DataStart());
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if ( data_start )
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CharT* storage_start = NS_CONST_CAST(CharT*, this->StorageStart());
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if ( storage_start )
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{
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data_length = nsCharTraits<CharT>::length(data_start);
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data_length = nsCharTraits<CharT>::length(storage_start);
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storage_length = data_length + 1;
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}
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nsImportedStringHandle<CharT>* mutable_this = NS_CONST_CAST(nsImportedStringHandle<CharT>*, this);
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mutable_this->DataEnd(data_start+data_length);
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mutable_this->StorageStart(data_start);
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mutable_this->StorageEnd(data_start+storage_length);
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mutable_this->DataStart(storage_start);
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mutable_this->DataEnd(storage_start+data_length);
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mutable_this->StorageEnd(storage_start+storage_length);
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}
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@ -103,7 +102,7 @@ nsXPIDLString::GetSharedBufferHandle() const
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{
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const nsImportedStringHandle<PRUnichar>* answer = NS_STATIC_CAST(const nsImportedStringHandle<PRUnichar>*, mBuffer.get());
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if ( answer && !answer->DataEnd() )
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if ( answer && !answer->DataEnd() && answer->StorageStart() )
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answer->RecalculateBoundaries();
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#if DEBUG_STRING_STATS
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@ -123,7 +122,7 @@ nsXPIDLString::PrepareForUseAsOutParam()
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#if DEBUG_STRING_STATS
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++sAssignCount;
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#endif
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return handle->AddressOfDataStart();
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return handle->AddressOfStorageStart();
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}
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@ -158,7 +157,7 @@ nsXPIDLCString::GetSharedBufferHandle() const
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{
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const nsImportedStringHandle<char>* answer = NS_STATIC_CAST(const nsImportedStringHandle<char>*, mBuffer.get());
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if ( answer && !answer->DataEnd() )
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if ( answer && !answer->DataEnd() && answer->StorageStart() )
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answer->RecalculateBoundaries();
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#if DEBUG_STRING_STATS
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@ -178,5 +177,5 @@ nsXPIDLCString::PrepareForUseAsOutParam()
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#if DEBUG_STRING_STATS
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++sAssignCount;
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#endif
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return handle->AddressOfDataStart();
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return handle->AddressOfStorageStart();
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}
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