Function kmalloc

src/kernel/arch/x86/alloc.cc:43–110

allocate memory block */

	/* allocate memory block */
	void *kmalloc(unsigned long size)
	{
		if (size==0)
			return 0;
			
		unsigned long realsize;	/* taille totale de l'enregistrement */
		struct kmalloc_header *chunk, *other;

		if ((realsize =
		     sizeof(struct kmalloc_header) + size) < KMALLOC_MINSIZE)
			realsize = KMALLOC_MINSIZE;

		/* 
		 * On recherche un bloc libre de 'size' octets en parcourant le HEAP
		 * kernel a partir du debut
		 */
		chunk = (struct kmalloc_header *) KERN_HEAP;
		while (chunk->used || chunk->size < realsize) {
			if (chunk->size == 0) {
				io.print
				    ("\nPANIC: kmalloc(): corrupted chunk on %x with null size (heap %x) !\nSystem halted\n",
				     chunk, kern_heap);
					 //error
					 asm("hlt");
					 return 0;
			}

			chunk =
			    (struct kmalloc_header *) ((char *) chunk +
						       chunk->size);

			if (chunk == (struct kmalloc_header *) kern_heap) {
				if ((int)(ksbrk((realsize / PAGESIZE) + 1)) < 0) {
					io.print
					    ("\nPANIC: kmalloc(): no memory left for kernel !\nSystem halted\n");
					 asm("hlt");
					return 0;
				}
			} else if (chunk > (struct kmalloc_header *) kern_heap) {
				io.print
				    ("\nPANIC: kmalloc(): chunk on %x while heap limit is on %x !\nSystem halted\n",
				     chunk, kern_heap);
				 asm("hlt");
				return 0;
			}
		}

		/* 
		 * Found free block with size >= 'size'
		 * We limit size block
		 */
		if (chunk->size - realsize < KMALLOC_MINSIZE)
			chunk->used = 1;
		else {
			other =
			    (struct kmalloc_header *) ((char *) chunk + realsize);
			other->size = chunk->size - realsize;
			other->used = 0;