uclibc-ng/libc/stdlib/malloc-simple/alloc.c

/* alloc.c
 *
 * Written by Erik Andersen <andersee@debian.org>
 * LGPLv2
 *
 * Parts of the memalign code were stolen from malloc-930716.
 */

#define _GNU_SOURCE
#include <features.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/mman.h>


#ifdef L_malloc
void *malloc(size_t size)
{
    void *result;

    if (unlikely(size == 0)) {
#if defined(__MALLOC_GLIBC_COMPAT__)
	size++;
#else
	/* Some programs will call malloc (0).  Lets be strict and return NULL */
	return 0;
#endif
    }

#ifdef __ARCH_HAS_MMU__
    result = mmap((void *) 0, size + sizeof(size_t), PROT_READ | PROT_WRITE,
	    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    if (result == MAP_FAILED)
	return 0;
    * (size_t *) result = size;
    return(result + sizeof(size_t));
#else
    result = mmap((void *) 0, size, PROT_READ | PROT_WRITE,
	    MAP_SHARED | MAP_ANONYMOUS, -1, 0);
    if (result == MAP_FAILED)
	return 0;
    return(result);
#endif
}
#endif

#ifdef L_calloc
void * calloc(size_t nmemb, size_t lsize)
{
	void *result;
	size_t size=lsize * nmemb;

	/* guard vs integer overflow, but allow nmemb
	 * to fall through and call malloc(0) */
	if (nmemb && lsize != (size / nmemb)) {
		__set_errno(ENOMEM);
		return NULL;
	}
	result=malloc(size);
#if 0
	/* Standard unix mmap using /dev/zero clears memory so calloc
	 * doesn't need to actually zero anything....
	 */
	if (result != NULL) {
		memset(result, 0, size);
	}
#endif
	return result;
}
#endif

#ifdef L_realloc
void *realloc(void *ptr, size_t size)
{
    void *newptr = NULL;

    if (!ptr)
	return malloc(size);
    if (!size) {
	free(ptr);
	return malloc(0);
    }

    newptr = malloc(size);
    if (newptr) {
	memcpy(newptr, ptr,
#ifdef __ARCH_HAS_MMU__
		*((size_t *) (ptr - sizeof(size_t)))
#else
		size
#endif
	      );
	free(ptr);
    }
    return newptr;
}
#endif

#ifdef L_free
extern int weak_function __libc_free_aligned(void *ptr);
void free(void *ptr)
{
    if (ptr == NULL)
	return;
    if (unlikely(__libc_free_aligned!=NULL)) {
	if (__libc_free_aligned(ptr)) {
	    return;
	}
    }
#ifdef __ARCH_HAS_MMU__
    ptr -= sizeof(size_t);
    munmap(ptr, * (size_t *) ptr + sizeof(size_t));
#else
    munmap(ptr, 0);
#endif
}
#endif

#ifdef L_memalign
#ifdef __UCLIBC_HAS_THREADS__
#include <pthread.h>
pthread_mutex_t __malloc_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
# define LOCK	__pthread_mutex_lock(&__malloc_lock)
# define UNLOCK	__pthread_mutex_unlock(&__malloc_lock);
#else
# define LOCK
# define UNLOCK
#endif

/* List of blocks allocated with memalign or valloc */
struct alignlist
{
    struct alignlist *next;
    __ptr_t aligned;	/* The address that memaligned returned.  */
    __ptr_t exact;	/* The address that malloc returned.  */
};
struct alignlist *_aligned_blocks;

/* Return memory to the heap. */
int __libc_free_aligned(void *ptr)
{
    struct alignlist *l;

    if (ptr == NULL)
	return 0;

    LOCK;
    for (l = _aligned_blocks; l != NULL; l = l->next) {
	if (l->aligned == ptr) {
	    /* Mark the block as free */
	    l->aligned = NULL;
	    ptr = l->exact;
#ifdef __ARCH_HAS_MMU__
	    ptr -= sizeof(size_t);
	    munmap(ptr, * (size_t *) ptr + sizeof(size_t));
#else
	    munmap(ptr, 0);
#endif
	    return 1;
	}
    }
    UNLOCK;
    return 0;
}
void * memalign (size_t alignment, size_t size)
{
    void * result;
    unsigned long int adj;

    result = malloc (size + alignment - 1);
    if (result == NULL)
	return NULL;
    adj = (unsigned long int) ((unsigned long int) ((char *) result -
		(char *) NULL)) % alignment;
    if (adj != 0)
    {
	struct alignlist *l;
	LOCK;
	for (l = _aligned_blocks; l != NULL; l = l->next)
	    if (l->aligned == NULL)
		/* This slot is free.  Use it.  */
		break;
	if (l == NULL)
	{
	    l = (struct alignlist *) malloc (sizeof (struct alignlist));
	    if (l == NULL) {
		free(result);
		UNLOCK;
		return NULL;
	    }
	    l->next = _aligned_blocks;
	    _aligned_blocks = l;
	}
	l->exact = result;
	result = l->aligned = (char *) result + alignment - adj;
	UNLOCK;
    }

    return result;
}
#endif