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Function Descriptions

   These are the details on the functions that make up the `mmalloc'

`void *mmalloc_attach (int FD, void *BASEADDR);'
     Initialize access to a `mmalloc' managed region.

     If FD is a valid file descriptor for an open file, then data for
     the `mmalloc' managed region is mapped to that file.   Otherwise
     `/dev/zero' is used and the data will not exist in any filesystem

     If the open file corresponding to FD is from a previous use of
     `mmalloc' and passes some basic sanity checks to ensure that it is
     compatible with the current `mmalloc' package, then its data is
     mapped in and is immediately accessible at the same addresses in
     the current process as the process that created the file.

     If BASEADDR is not `NULL', the mapping is established starting at
     the specified address in the process address space.  If BASEADDR
     is `NULL', the `mmalloc' package chooses a suitable address at
     which to start the mapped region, which will be the value of the
     previous mapping if opening an existing file which was previously
     built by `mmalloc', or for new files will be a value chosen by

     Specifying BASEADDR provides more control over where the regions
     start and how big they can be before bumping into existing mapped
     regions or future mapped regions.

     On success, returns a malloc descriptor which is used in subsequent
     calls to other `mmalloc' package functions.  It is explicitly
     `void *' (`char *' for systems that don't fully support `void') so
     that users of the package don't have to worry about the actual
     implementation details.

     On failure returns `NULL'.

`void *mmalloc_detach (void *MD);'
     Terminate access to a `mmalloc' managed region identified by the
     descriptor MD, by closing the base file and unmapping all memory
     pages associated with the region.

     Returns `NULL' on success.

     Returns the malloc descriptor on failure, which can subsequently
     be used for further action (such as obtaining more information
     about the nature of the failure).

`void *mmalloc (void *MD, size_t SIZE);'
     Given an `mmalloc' descriptor MD, allocate additional memory of
     SIZE bytes in the associated mapped region.

`*mrealloc (void *MD, void *PTR, size_t SIZE);'
     Given an `mmalloc' descriptor MD and a pointer to memory
     previously allocated by `mmalloc' in PTR, reallocate the memory to
     be SIZE bytes long, possibly moving the existing contents of
     memory if necessary.

`void *mvalloc (void *MD, size_t SIZE);'
     Like `mmalloc' but the resulting memory is aligned on a page

`void mfree (void *MD, void *PTR);'
     Given an `mmalloc' descriptor MD and a pointer to memory previously
     allocated by `mmalloc' in PTR, free the previously allocated

`int mmalloc_errno (void *MD);'
     Given a `mmalloc' descriptor, if the last `mmalloc' operation
     failed for some reason due to a system call failure, then returns
     the associated `errno'.  Returns 0 otherwise.  (This function is
     not yet implemented).

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