Problem of using malloc() without including stdlib.h (original) (raw)

Jonathan Lu luchsh at linux.vnet.ibm.com
Wed Jan 18 08:19:16 UTC 2012

Hi core-libs-dev,

I found that for some native code of OpenJDK code base, malloc() is used without including header file stdlib.h, such as following files, ./src/solaris/native/sun/java2d/opengl/GLXSurfaceData.c ./src/solaris/native/sun/java2d/x11/XRBackendNative.c ....

I assume that there's no hacking tricks involved here, right? because this may cause problem for some C compilers, which assumes 'int' as the default return type of a function if it cannot find the function's declaration during compiling. Under such a condition, actual return result of type 'void*' from malloc() will be converted to 'int', which may result in truncated pointers in 64bit platforms. If the application tries to dereference such a broken pointer, error will occur.

Indeed I found some indirect includes of stdlib.h, but there're still some I do not see a stdlib.h get included from any of the direct/indirect included headers. I think in order to fix this problem, two approaches may be considered here, a) add "#include <stdlib.h>" to every missing .c file. b) add "#include <stdlib.h>" to a commonly referenced header file, such as jni_util.h. but it would not be easy to find such a file for all and creating one is the same as approach a).

But both methods need to change many files, any other ideas about how to fix it more elegantly?

Thanks and best regards!

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