You have to do two things here:
- Create a repeating sprite
- Mask it with the shape
For the repeating sprite you will need a texture that has POT (Power Of Two) sides, e.g. 256x256. When you load your tiled texture you need to set its parameters to repeat:
CCSprite* sprite = [CCSprite spriteWithFile:@"tiled_tex.png"];
params.minFilter = GL_LINEAR;
params.magFilter = GL_LINEAR;
params.rapS = GL_REPEAT;
params.wrapT = GL_REPEAT;
Now when you set your sprites content size it will draw a repeated texture.
Masking part is a bit trickier it would be easiest to have a shader that takes as a parameter the masking texture. Since it is a bit bigger task, here is a mask shader for cocos2d someone else made: Mask Shader for Cocos2D.
I have not used this code, but from the looks of it it should work quite well.