? -1 \
: (MDP) -> fd)
-/* Get core for the memory region specified by MDP, using SIZE as the
- amount to either add to or subtract from the existing region. Works
- like sbrk(), but using mmap().
-
- It never returns NULL. Instead, it dies verbosely on errors. */
-
+/** @brief Add memoty to this heap
+ *
+ * Get core for the memory region specified by MDP, using SIZE as the
+ * amount to either add to or subtract from the existing region. Works
+ * like sbrk(), but using mmap().
+ *
+ * It never returns NULL. Instead, it dies verbosely on errors.
+ *
+ * @param mdp The heap
+ * @param size Bytes to allocate for this heap (or <0 to free memory from this heap)
+ */
void *mmorecore(struct mdesc *mdp, ssize_t size)
{
ssize_t test = 0;
void *mapto; /* Address we actually mapped to */
char buf = 0; /* Single byte to write to extend mapped file */
-// fprintf(stderr,"increase %p by %u\n",mdp,size);
-
if (size == 0) {
/* Just return the current "break" value. */
result = mdp->breakval;
}
/* Let's call mmap. Note that it is possible that mdp->top
- is 0. In this case mmap will choose the address for us */
+ is 0. In this case mmap will choose the address for us.
+ This call might very well overwrite an already existing memory mapping
+ (leading to weird bugs).
+ */
mapto = mmap(mdp->top, mapbytes, PROT_READ | PROT_WRITE,
MAP_PRIVATE_OR_SHARED(mdp) | MAP_IS_ANONYMOUS(mdp) |
MAP_FIXED, MAP_ANON_OR_FD(mdp), foffset);
- if (mapto == (void *) -1/* That's MAP_FAILED */) {
+ if (mapto == MAP_FAILED) {
char buff[1024];
fprintf(stderr,"Internal error: mmap returned MAP_FAILED! error: %s\n",strerror(errno));
sprintf(buff,"cat /proc/%d/maps",getpid());
result = (void *) mdp->breakval;
mdp->breakval = (char *) mdp->breakval + size;
} else {
+ /* Memory is already mapped, we only need to increase the breakval: */
result = (void *) mdp->breakval;
mdp->breakval = (char *) mdp->breakval + size;
}
};
} malloc_info;
-/* Internal structure that defines the format of the malloc-descriptor.
- This gets written to the base address of the region that mmalloc is
- managing, and thus also becomes the file header for the mapped file,
- if such a file exists. */
-
+/** @brief Descriptor of a mmalloc area
+ *
+ * Internal structure that defines the format of the malloc-descriptor.
+ * This gets written to the base address of the region that mmalloc is
+ * managing, and thus also becomes the file header for the mapped file,
+ * if such a file exists.
+ * */
struct mdesc {
- /* Semaphore locking the access to the heap */
+ /** @brief Semaphore locking the access to the heap */
sem_t sem;
- /* Number of processes that attached the heap */
+ /** @brief Number of processes that attached the heap */
unsigned int refcount;
- /* Chained lists of mdescs */
+ /** @brief Chained lists of mdescs */
struct mdesc *next_mdesc;
- /* The "magic number" for an mmalloc file. */
+ /** @brief The "magic number" for an mmalloc file. */
char magic[MMALLOC_MAGIC_SIZE];
- /* The size in bytes of this structure, used as a sanity check when reusing
- a previously created mapped file. */
+ /** @brief The size in bytes of this structure
+ *
+ * Used as a sanity check when reusing a previously created mapped file.
+ * */
unsigned int headersize;
- /* The version number of the mmalloc package that created this file. */
+ /** @brief Version number of the mmalloc package that created this file. */
unsigned char version;
unsigned int options;
- /* Some flag bits to keep track of various internal things. */
+ /** @brief Some flag bits to keep track of various internal things. */
unsigned int flags;
- /* Number of info entries. */
+ /** @brief Number of info entries. */
size_t heapsize;
- /* Pointer to first block of the heap (base of the first block). */
+ /** @brief Pointer to first block of the heap (base of the first block). */
void *heapbase;
- /* Current search index for the heap table. */
- /* Search index in the info table. */
+ /** @brief Current search index for the heap table.
+ *
+ * Search index in the info table.
+ */
size_t heapindex;
- /* Limit of valid info table indices. */
+ /** @brief Limit of valid info table indices. */
size_t heaplimit;
- /* Block information table. */
- /* Table indexed by block number giving per-block information. */
+ /** @brief Block information table.
+ *
+ * Table indexed by block number giving per-block information.
+ */
malloc_info *heapinfo;
- /* List of all blocks containing free fragments of this size.
+ /* @brief List of all blocks containing free fragments of a given size.
+ *
* The array indice is the log2 of requested size.
* Actually only the sizes 8->11 seem to be used, but who cares? */
s_xbt_swag_t fraghead[BLOCKLOG];
- /* The base address of the memory region for this malloc heap. This
- is the location where the bookkeeping data for mmap and for malloc
- begins. */
-
+ /* @brief Base address of the memory region for this malloc heap
+ *
+ * This is the location where the bookkeeping data for mmap and
+ * for malloc begins.
+ */
void *base;
- /* The current location in the memory region for this malloc heap which
- represents the end of memory in use. */
-
+ /** @brief End of memory in use
+ *
+ * Some memory might be already mapped by the OS but not used
+ * by the heap.
+ * */
void *breakval;
- /* The end of the current memory region for this malloc heap. This is
- the first location past the end of mapped memory.
- Compared to breakval, this value is rounded to the next memory page.
- */
-
+ /** @brief End of the current memory region for this malloc heap.
+ *
+ * This is the first location past the end of mapped memory.
+ *
+ * Compared to breakval, this value is rounded to the next memory page.
+ */
void *top;
- /* Open file descriptor for the file to which this malloc heap is mapped.
- This will always be a valid file descriptor, since /dev/zero is used
- by default if no open file is supplied by the client. Also note that
- it may change each time the region is mapped and unmapped. */
-
+ /** @brief Open file descriptor for the file to which this malloc heap is mapped
+ *
+ * If this value is negative, MAP_ANONYMOUS memory is used.
+ *
+ * Also note that it may change each time the region is mapped and unmapped. */
int fd;
- /* Instrumentation. */
-
+ /* @brief Instrumentation */
struct mstats heapstats;
};
XBT_PUBLIC( void *)__mmalloc_remap_core(xbt_mheap_t mdp);
-/* Get core for the memory region specified by MDP, using SIZE as the
- amount to either add to or subtract from the existing region. Works
- like sbrk(), but using mmap(). */
XBT_PUBLIC( void *)mmorecore(struct mdesc *mdp, ssize_t size);
/* Thread-safety (if the sem is already created)
