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+This is Info file ./mmalloc.info, produced by Makeinfo version 1.68
+from the input file mmalloc.texi.
+
+START-INFO-DIR-ENTRY
+* Mmalloc: (mmalloc).		The GNU mapped-malloc package.
+END-INFO-DIR-ENTRY
+
+   This file documents the GNU mmalloc (mapped-malloc) package, written
+by fnf@cygnus.com, based on GNU malloc written by mike@ai.mit.edu.
+
+   Copyright (C) 1992 Free Software Foundation, Inc.
+
+   Permission is granted to make and distribute verbatim copies of this
+manual provided the copyright notice and this permission notice are
+preserved on all copies.
+
+   Permission is granted to copy and distribute modified versions of
+this manual under the conditions for verbatim copying, provided also
+that the entire resulting derived work is distributed under the terms
+of a permission notice identical to this one.
+
+   Permission is granted to copy and distribute translations of this
+manual into another language, under the above conditions for modified
+versions.
+
+
+File: mmalloc.info,  Node: Top,  Next: Overview,  Prev: (dir),  Up: (dir)
+
+mmalloc
+*******
+
+   This file documents the GNU memory-mapped malloc package mmalloc.
+
+* Menu:
+
+* Overview::                    Overall Description
+* Implementation::              Implementation
+
+ -- The Detailed Node Listing --
+
+Implementation
+
+* Compatibility::               Backwards Compatibility
+* Functions::                   Function Descriptions
+
+
+File: mmalloc.info,  Node: Overview,  Next: Implementation,  Prev: Top,  Up: Top
+
+Overall Description
+*******************
+
+   This is a heavily modified version of GNU `malloc'.  It uses `mmap'
+as the basic mechanism for obtaining memory from the system, rather
+than `sbrk'.  This gives it several advantages over the more
+traditional malloc:
+
+   * Several different heaps can be used, each of them growing or
+     shinking under control of `mmap', with the `mmalloc' functions
+     using a specific heap on a call by call basis.
+
+   * By using `mmap', it is easy to create heaps which are intended to
+     be persistent and exist as a filesystem object after the creating
+     process has gone away.
+
+   * Because multiple heaps can be managed, data used for a specific
+     purpose can be allocated into its own heap, making it easier to
+     allow applications to "dump" and "restore" initialized
+     malloc-managed memory regions.  For example, the "unexec" hack
+     popularized by GNU Emacs could potentially go away.
+
+
+File: mmalloc.info,  Node: Implementation,  Prev: Overview,  Up: Top
+
+Implementation
+**************
+
+   The `mmalloc' functions contain no internal static state.  All
+`mmalloc' internal data is allocated in the mapped in region, along
+with the user data that it manages.  This allows it to manage multiple
+such regions and to "pick up where it left off" when such regions are
+later dynamically mapped back in.
+
+   In some sense, malloc has been "purified" to contain no internal
+state information and generalized to use multiple memory regions rather
+than a single region managed by `sbrk'.  However the new routines now
+need an extra parameter which informs `mmalloc' which memory region it
+is dealing with (along with other information).  This parameter is
+called the "malloc descriptor".
+
+   The functions initially provided by `mmalloc' are:
+
+     void *mmalloc_attach (int fd, void *baseaddr);
+     void *mmalloc_detach (void *md);
+     int mmalloc_errno (void *md);
+     int mmalloc_setkey (void *md, int keynum, void *key);
+     void *mmalloc_getkey (void *md, int keynum);
+     
+     void *mmalloc (void *md, size_t size);
+     void *mrealloc (void *md, void *ptr, size_t size);
+     void *mvalloc (void *md, size_t size);
+     void mfree (void *md, void *ptr);
+
+* Menu:
+
+* Compatibility::               Backwards Compatibility
+* Functions::                   Function Descriptions
+
+
+File: mmalloc.info,  Node: Compatibility,  Next: Functions,  Prev: Implementation,  Up: Implementation
+
+Backwards Compatibility
+=======================
+
+   To allow a single malloc package to be used in a given application,
+provision is made for the traditional `malloc', `realloc', and `free'
+functions to be implemented as special cases of the `mmalloc'
+functions.  In particular, if any of the functions that expect malloc
+descriptors are called with a `NULL' pointer rather than a valid malloc
+descriptor, then they default to using an `sbrk' managed region.  The
+`mmalloc' package provides compatible `malloc', `realloc', and `free'
+functions using this mechanism internally.  Applications can avoid this
+extra interface layer by simply including the following defines:
+
+     #define malloc(size)		mmalloc ((void *)0, (size))
+     #define realloc(ptr,size)	mrealloc ((void *)0, (ptr), (size));
+     #define free(ptr)		mfree ((void *)0, (ptr))
+
+or replace the existing `malloc', `realloc', and `free' calls with the
+above patterns if using `#define' causes problems.
+
+
+File: mmalloc.info,  Node: Functions,  Prev: Compatibility,  Up: Implementation
+
+Function Descriptions
+=====================
+
+   These are the details on the functions that make up the `mmalloc'
+package.
+
+`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
+     object.
+
+     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
+     `mmap'.
+
+     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
+     boundary.
+
+`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
+     memory.
+
+`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).
+
+
+
+Tag Table:
+Node: Top963
+Node: Overview1397
+Node: Implementation2425
+Node: Compatibility3818
+Node: Functions4892
+
+End Tag Table