-/* Heap management routines for GNU Emacs on the Microsoft Windows API.
- Copyright (C) 1994, 2001-2014 Free Software Foundation, Inc.
-
-This file is part of GNU Emacs.
-
-GNU Emacs is free software: you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation, either version 3 of the License, or
-(at your option) any later version.
-
-GNU Emacs is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License
-along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
-
-/*
- Geoff Voelker (voelker@cs.washington.edu) 7-29-94
-*/
-
-#include <config.h>
-#include <stdio.h>
-
-#include "w32common.h"
-#include "w32heap.h"
-#include "lisp.h" /* for VALMASK */
-
-#define RVA_TO_PTR(rva) ((unsigned char *)((DWORD_PTR)(rva) + (DWORD_PTR)GetModuleHandle (NULL)))
-
-/* Emulate getpagesize. */
-int
-getpagesize (void)
-{
- return sysinfo_cache.dwPageSize;
-}
-
-/* Info for managing our preload heap, which is essentially a fixed size
- data area in the executable. */
-PIMAGE_SECTION_HEADER preload_heap_section;
-
-/* Info for keeping track of our heap. */
-unsigned char *data_region_base = NULL;
-unsigned char *data_region_end = NULL;
-unsigned char *real_data_region_end = NULL;
-size_t reserved_heap_size = 0;
-
-/* The start of the data segment. */
-unsigned char *
-get_data_start (void)
-{
- return data_region_base;
-}
-
-/* The end of the data segment. */
-unsigned char *
-get_data_end (void)
-{
- return data_region_end;
-}
-
-#if !USE_LSB_TAG
-static char *
-allocate_heap (void)
-{
- /* Try to get as much as possible of the address range from the end of
- the preload heap section up to the usable address limit. Since GNU
- malloc can handle gaps in the memory it gets from sbrk, we can
- simply set the sbrk pointer to the base of the new heap region. */
- DWORD_PTR base =
- ROUND_UP ((RVA_TO_PTR (preload_heap_section->VirtualAddress)
- + preload_heap_section->Misc.VirtualSize),
- get_allocation_unit ());
- DWORD_PTR end = ((unsigned __int64)1) << VALBITS; /* 256MB */
- void *ptr = NULL;
-
- while (!ptr && (base < end))
- {
-#ifdef _WIN64
- reserved_heap_size = min(end - base, 0x4000000000ull); /* Limit to 256Gb */
-#else
- reserved_heap_size = end - base;
-#endif
- ptr = VirtualAlloc ((void *) base,
- get_reserved_heap_size (),
- MEM_RESERVE,
- PAGE_NOACCESS);
- base += 0x00100000; /* 1MB increment */
- }
-
- return ptr;
-}
-#else /* USE_LSB_TAG */
-static char *
-allocate_heap (void)
-{
-#ifdef _WIN64
- size_t size = 0x4000000000ull; /* start by asking for 32GB */
-#else
- /* We used to start with 2GB here, but on Windows 7 that would leave
- too little room in the address space for threads started by
- Windows on our behalf, e.g. when we pop up the file selection
- dialog. */
- size_t size = 0x68000000; /* start by asking for 1.7GB */
-#endif
- void *ptr = NULL;
-
- while (!ptr && size > 0x00100000)
- {
- reserved_heap_size = size;
- ptr = VirtualAlloc (NULL,
- get_reserved_heap_size (),
- MEM_RESERVE,
- PAGE_NOACCESS);
- size -= 0x00800000; /* if failed, decrease request by 8MB */
- }
-
- return ptr;
-}
-#endif /* USE_LSB_TAG */
-
-
-/* Emulate Unix sbrk. Note that ralloc.c expects the return value to
- be the address of the _start_ (not end) of the new block in case of
- success, and zero (not -1) in case of failure. */
-void *
-sbrk (ptrdiff_t increment)
-{
- void *result;
- ptrdiff_t size = increment;
-
- result = data_region_end;
-
- /* If size is negative, shrink the heap by decommitting pages. */
- if (size < 0)
- {
- ptrdiff_t new_size;
- unsigned char *new_data_region_end;
-
- size = -size;
-
- /* Sanity checks. */
- if ((data_region_end - size) < data_region_base)
- return NULL;
-
- /* We can only decommit full pages, so allow for
- partial deallocation [cga]. */
- new_data_region_end = (data_region_end - size);
- new_data_region_end = (unsigned char *)
- ((DWORD_PTR) (new_data_region_end + syspage_mask) & ~syspage_mask);
- new_size = real_data_region_end - new_data_region_end;
- real_data_region_end = new_data_region_end;
- if (new_size > 0)
- {
- /* Decommit size bytes from the end of the heap. */
- if (using_dynamic_heap
- && !VirtualFree (real_data_region_end, new_size, MEM_DECOMMIT))
- return NULL;
- }
-
- data_region_end -= size;
- }
- /* If size is positive, grow the heap by committing reserved pages. */
- else if (size > 0)
- {
- /* Sanity checks. */
- if ((data_region_end + size) >
- (data_region_base + get_reserved_heap_size ()))
- return NULL;
-
- /* Commit more of our heap. */
- if (using_dynamic_heap
- && VirtualAlloc (data_region_end, size, MEM_COMMIT,
- PAGE_READWRITE) == NULL)
- return NULL;
- data_region_end += size;
-
- /* We really only commit full pages, so record where
- the real end of committed memory is [cga]. */
- real_data_region_end = (unsigned char *)
- ((DWORD_PTR) (data_region_end + syspage_mask) & ~syspage_mask);
- }
-
- return result;
-}
-
-/* Initialize the internal heap variables used by sbrk. When running in
- preload phase (ie. in the undumped executable), we rely entirely on a
- fixed size heap section included in the .exe itself; this is
- preserved during dumping, and truncated to the size actually used.
-
- When running in the dumped executable, we reserve as much as possible
- of the address range that is addressable by Lisp object pointers, to
- supplement what is left of the preload heap. Although we cannot rely
- on the dynamically allocated arena being contiguous with the static
- heap area, it is not a problem because sbrk can pretend that the gap
- was allocated by something else; GNU malloc detects when there is a
- jump in the sbrk values, and starts a new heap block. */
-void
-init_heap (void)
-{
- PIMAGE_DOS_HEADER dos_header;
- PIMAGE_NT_HEADERS nt_header;
-
- dos_header = (PIMAGE_DOS_HEADER) RVA_TO_PTR (0);
- nt_header = (PIMAGE_NT_HEADERS) (((DWORD_PTR) dos_header) +
- dos_header->e_lfanew);
- preload_heap_section = find_section ("EMHEAP", nt_header);
-
- if (using_dynamic_heap)
- {
- data_region_base = allocate_heap ();
- if (!data_region_base)
- {
- printf ("Error: Could not reserve dynamic heap area.\n");
- exit (1);
- }
-
-#if !USE_LSB_TAG
- /* Ensure that the addresses don't use the upper tag bits since
- the Lisp type goes there. */
- if (((DWORD_PTR) data_region_base & ~VALMASK) != 0)
- {
- printf ("Error: The heap was allocated in upper memory.\n");
- exit (1);
- }
-#endif
- data_region_end = data_region_base;
- real_data_region_end = data_region_end;
- }
- else
- {
- data_region_base = RVA_TO_PTR (preload_heap_section->VirtualAddress);
- data_region_end = data_region_base;
- real_data_region_end = data_region_end;
- reserved_heap_size = preload_heap_section->Misc.VirtualSize;
- }
-
- /* Update system version information to match current system. */
- cache_system_info ();
-}
-
-/* Round the heap up to the given alignment. */
-void
-round_heap (size_t align)
-{
- DWORD_PTR needs_to_be;
- DWORD_PTR need_to_alloc;
-
- needs_to_be = (DWORD_PTR) ROUND_UP (get_heap_end (), align);
- need_to_alloc = needs_to_be - (DWORD_PTR) get_heap_end ();
-
- if (need_to_alloc)
- sbrk (need_to_alloc);
-}
+/* Heap management routines for GNU Emacs on the Microsoft Windows
+ API. Copyright (C) 1994, 2001-2014 Free Software Foundation, Inc.
+
+ This file is part of GNU Emacs.
+
+ GNU Emacs is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ GNU Emacs is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
+
+/*
+ Geoff Voelker (voelker@cs.washington.edu) 7-29-94
+*/
+
+/*
+ Heavily modified by Fabrice Popineau (fabrice.popineau@gmail.com) 28-02-2014
+*/
+
+/*
+ Memory allocation scheme for w32/w64:
+
+ - Buffers are mmap'ed using a very simple emulation of mmap/munmap
+ - During the temacs phase:
+ * we use a private heap declared to be stored into the `dumped_data'
+ * unfortunately, this heap cannot be made growable, so the size of
+ blocks it can allocate is limited to (0x80000 - pagesize)
+ * the blocks that are larger than this are allocated from the end
+ of the `dumped_data' array; there are not so many of them.
+ We use a very simple first-fit scheme to reuse those blocks.
+ * we check that the private heap does not cross the area used
+ by the bigger chunks.
+ - During the emacs phase:
+ * we create a private heap for new memory blocks
+ * we make sure that we never free a block that has been dumped.
+ Freeing a dumped block could work in principle, but may prove
+ unreliable if we distribute binaries of emacs.exe: MS does not
+ guarantee that the heap data structures are the same across all
+ versions of their OS, even though the API is available since XP. */
+
+#include <config.h>
+#include <stdio.h>
+
+#include <sys/mman.h>
+#include "w32common.h"
+#include "w32heap.h"
+#include "lisp.h" /* for VALMASK */
+
+/* We chose to leave those declarations here. They are used only in
+ this file. The RtlCreateHeap is available since XP. It is located
+ in ntdll.dll and is available with the DDK. People often
+ complained that HeapCreate doesn't offer the ability to create a
+ heap at a given place, which we need here, and which RtlCreateHeap
+ provides. We reproduce here the definitions available with the
+ DDK. */
+
+typedef PVOID (WINAPI * RtlCreateHeap_Proc) (
+ /* _In_ */ ULONG Flags,
+ /* _In_opt_ */ PVOID HeapBase,
+ /* _In_opt_ */ SIZE_T ReserveSize,
+ /* _In_opt_ */ SIZE_T CommitSize,
+ /* _In_opt_ */ PVOID Lock,
+ /* _In_opt_ */ PVOID Parameters
+ );
+
+typedef LONG NTSTATUS;
+
+typedef NTSTATUS
+(NTAPI * PRTL_HEAP_COMMIT_ROUTINE)(
+ IN PVOID Base,
+ IN OUT PVOID *CommitAddress,
+ IN OUT PSIZE_T CommitSize
+ );
+
+typedef struct _RTL_HEAP_PARAMETERS {
+ ULONG Length;
+ SIZE_T SegmentReserve;
+ SIZE_T SegmentCommit;
+ SIZE_T DeCommitFreeBlockThreshold;
+ SIZE_T DeCommitTotalFreeThreshold;
+ SIZE_T MaximumAllocationSize;
+ SIZE_T VirtualMemoryThreshold;
+ SIZE_T InitialCommit;
+ SIZE_T InitialReserve;
+ PRTL_HEAP_COMMIT_ROUTINE CommitRoutine;
+ SIZE_T Reserved[ 2 ];
+} RTL_HEAP_PARAMETERS, *PRTL_HEAP_PARAMETERS;
+
+/* We reserve space for dumping emacs lisp byte-code inside a static
+ array. By storing it in an array, the generic mechanism in
+ unexecw32.c will be able to dump it without the need to add a
+ special segment to the executable. In order to be able to do this
+ without losing too much space, we need to create a Windows heap at
+ the specific address of the static array. The RtlCreateHeap
+ available inside the NT kernel since XP will do this. It allows to
+ create a non-growable heap at a specific address. So before
+ dumping, we create a non-growable heap at the address of the
+ dumped_data[] array. After dumping, we reuse memory allocated
+ there without being able to free it (but most of it is not meant to
+ be freed anyway), and we use a new private heap for all new
+ allocations. */
+
+unsigned char dumped_data[DUMPED_HEAP_SIZE];
+
+/* Info for managing our preload heap, which is essentially a fixed size
+ data area in the executable. */
+/* Info for keeping track of our heap. */
+unsigned char *data_region_base = NULL;
+unsigned char *data_region_end = NULL;
+static DWORD_PTR committed = 0;
+
+/* The maximum block size that can be handled by a non-growable w32
+ heap is limited by the MaxBlockSize value below.
+
+ This point deserves and explanation.
+
+ The W32 heap allocator can be used for a growable
+ heap or a non-growable one.
+
+ A growable heap is not compatible with a fixed base address for the
+ heap. Only a non-growable one is. One drawback of non-growable
+ heaps is that they can hold only objects smaller than a certain
+ size (the one defined below). Most of the largest blocks are GC'ed
+ before dumping. In any case and to be safe, we implement a simple
+ first-fit allocation algorithm starting at the end of the
+ dumped_data[] array like depicted below:
+
+ ----------------------------------------------
+ | | | |
+ | Private heap |-> <-| Big chunks |
+ | | | |
+ ----------------------------------------------
+ ^ ^ ^
+ dumped_data dumped_data bc_limit
+ + committed
+
+*/
+#define HEAP_ENTRY_SHIFT 3
+#define PAGE_SIZE 0x1000
+#define MaxBlockSize (0x80000 - PAGE_SIZE)
+
+#define MAX_BLOCKS 0x40
+
+static struct
+{
+ unsigned char *address;
+ size_t size;
+ DWORD occupied;
+} blocks[MAX_BLOCKS];
+
+static DWORD blocks_number = 0;
+static unsigned char *bc_limit;
+
+/* Handle for the private heap:
+ - inside the dumped_data[] array before dump,
+ - outside of it after dump.
+*/
+HANDLE heap = NULL;
+
+/* We redirect the standard allocation functions. */
+malloc_fn the_malloc_fn;
+realloc_fn the_realloc_fn;
+free_fn the_free_fn;
+
+/* It doesn't seem to be useful to allocate from a file mapping.
+ It would be if the memory was shared.
+ http://stackoverflow.com/questions/307060/what-is-the-purpose-of-allocating-pages-in-the-pagefile-with-createfilemapping */
+
+/* This is the function to commit memory when the heap allocator
+ claims for new memory. Before dumping, we allocate space
+ from the fixed size dumped_data[] array.
+*/
+NTSTATUS NTAPI
+dumped_data_commit (PVOID Base, PVOID *CommitAddress, PSIZE_T CommitSize)
+{
+ /* This is used before dumping.
+
+ The private heap is stored at dumped_data[] address.
+ We commit contiguous areas of the dumped_data array
+ as requests arrive. */
+ *CommitAddress = data_region_base + committed;
+ committed += *CommitSize;
+ if (((unsigned char *)(*CommitAddress)) + *CommitSize >= bc_limit)
+ {
+ /* Check that the private heap area does not overlap the big
+ chunks area. */
+ fprintf(stderr,
+ "dumped_data_commit: memory exhausted.\nEnlarge dumped_data[]!\n");
+ exit (-1);
+ }
+ return 0;
+}
+
+/* Heap creation. */
+
+/* Under MinGW32, we want to turn on Low Fragmentation Heap for XP.
+ MinGW32 lacks those definitions. */
+#ifndef _W64
+typedef enum _HEAP_INFORMATION_CLASS {
+ HeapCompatibilityInformation
+} HEAP_INFORMATION_CLASS;
+
+typedef WINBASEAPI BOOL (WINAPI * HeapSetInformation_Proc)(HANDLE,HEAP_INFORMATION_CLASS,PVOID,SIZE_T);
+#endif
+
+void
+init_heap (void)
+{
+ if (using_dynamic_heap)
+ {
+ unsigned long enable_lfh = 2;
+
+ /* After dumping, use a new private heap. We explicitly enable
+ the low fragmentation heap here, for the sake of pre Vista
+ versions. Note: this will harnlessly fail on Vista and
+ later, whyere the low fragmentation heap is enabled by
+ default. It will also fail on pre-Vista versions when Emacs
+ is run under a debugger; set _NO_DEBUG_HEAP=1 in the
+ environment before starting GDB to get low fragmentation heap
+ on XP and older systems, for the price of losing "certain
+ heap debug options"; for the details see
+ http://msdn.microsoft.com/en-us/library/windows/desktop/aa366705%28v=vs.85%29.aspx. */
+ data_region_end = data_region_base;
+
+ /* Create the private heap. */
+ heap = HeapCreate(0, 0, 0);
+
+#ifndef _W64
+ /* Set the low-fragmentation heap for OS before XP and Windows
+ Server 2003. */
+ HMODULE hm_kernel32dll = LoadLibrary("kernel32.dll");
+ HeapSetInformation_Proc s_pfn_Heap_Set_Information = (HeapSetInformation_Proc) GetProcAddress(hm_kernel32dll, "HeapSetInformation");
+ if (s_pfn_Heap_Set_Information != NULL)
+ if (s_pfn_Heap_Set_Information ((PVOID) heap,
+ HeapCompatibilityInformation,
+ &enable_lfh, sizeof(enable_lfh)) == 0)
+ DebPrint (("Enabling Low Fragmentation Heap failed\n"));
+#endif
+
+ the_malloc_fn = malloc_after_dump;
+ the_realloc_fn = realloc_after_dump;
+ the_free_fn = free_after_dump;
+ }
+ else
+ {
+ /* Find the RtlCreateHeap function. Headers for this function
+ are provided with the w32 ddk, but the function is available
+ in ntdll.dll since XP. */
+ HMODULE hm_ntdll = LoadLibrary ("ntdll.dll");
+ RtlCreateHeap_Proc s_pfn_Rtl_Create_Heap
+ = (RtlCreateHeap_Proc) GetProcAddress (hm_ntdll, "RtlCreateHeap");
+ /* Specific parameters for the private heap. */
+ RTL_HEAP_PARAMETERS params;
+ ZeroMemory(¶ms, sizeof(params));
+ params.Length = sizeof(RTL_HEAP_PARAMETERS);
+
+ data_region_base = (unsigned char *)ROUND_UP (dumped_data, 0x1000);
+ data_region_end = bc_limit = dumped_data + DUMPED_HEAP_SIZE;
+
+ params.InitialCommit = committed = 0x1000;
+ params.InitialReserve = sizeof(dumped_data);
+ /* Use our own routine to commit memory from the dumped_data
+ array. */
+ params.CommitRoutine = &dumped_data_commit;
+
+ /* Create the private heap. */
+ heap = s_pfn_Rtl_Create_Heap (0, data_region_base, 0, 0, NULL, ¶ms);
+ the_malloc_fn = malloc_before_dump;
+ the_realloc_fn = realloc_before_dump;
+ the_free_fn = free_before_dump;
+ }
+
+ /* Update system version information to match current system. */
+ cache_system_info ();
+}
+
+#undef malloc
+#undef realloc
+#undef calloc
+#undef free
+
+/* FREEABLE_P checks if the block can be safely freed. */
+#define FREEABLE_P(addr) \
+ ((unsigned char *)(addr) < dumped_data \
+ || (unsigned char *)(addr) >= dumped_data + DUMPED_HEAP_SIZE)
+
+void *
+malloc_after_dump (size_t size)
+{
+ /* Use the new private heap. */
+ void *p = HeapAlloc (heap, 0, size);
+
+ /* After dump, keep track of the last allocated byte for sbrk(0). */
+ data_region_end = p + size - 1;
+ return p;
+}
+
+void *
+malloc_before_dump (size_t size)
+{
+ void *p;
+
+ /* Before dumping. The private heap can handle only requests for
+ less than MaxBlockSize. */
+ if (size < MaxBlockSize)
+ {
+ /* Use the private heap if possible. */
+ p = HeapAlloc (heap, 0, size);
+ }
+ else
+ {
+ /* Find the first big chunk that can hold the requested size. */
+ int i = 0;
+
+ for (i = 0; i < blocks_number; i++)
+ {
+ if (blocks[i].occupied == 0 && blocks[i].size >= size)
+ break;
+ }
+ if (i < blocks_number)
+ {
+ /* If found, use it. */
+ p = blocks[i].address;
+ blocks[i].occupied = TRUE;
+ }
+ else
+ {
+ /* Allocate a new big chunk from the end of the dumped_data
+ array. */
+ if (blocks_number >= MAX_BLOCKS)
+ {
+ fprintf(stderr,
+ "malloc_before_dump: no more big chunks available.\nEnlarge MAX_BLOCKS!\n");
+ exit (-1);
+ }
+ bc_limit -= size;
+ bc_limit = (unsigned char *)ROUND_DOWN (bc_limit, 0x10);
+ p = bc_limit;
+ blocks[blocks_number].address = p;
+ blocks[blocks_number].size = size;
+ blocks[blocks_number].occupied = TRUE;
+ blocks_number++;
+ if (bc_limit < dumped_data + committed)
+ {
+ /* Check that areas do not overlap. */
+ fprintf(stderr,
+ "malloc_before_dump: memory exhausted.\nEnlarge dumped_data[]!\n");
+ exit (-1);
+ }
+ }
+ }
+ return p;
+}
+
+/* Re-allocate the previously allocated block in ptr, making the new
+ block SIZE bytes long. */
+void *
+realloc_after_dump (void *ptr, size_t size)
+{
+ void *p;
+
+ /* After dumping. */
+ if (FREEABLE_P (ptr))
+ {
+ /* Reallocate the block since it lies in the new heap. */
+ p = HeapReAlloc (heap, 0, ptr, size);
+ }
+ else
+ {
+ /* If the block lies in the dumped data, do not free it. Only
+ allocate a new one. */
+ p = HeapAlloc (heap, 0, size);
+ CopyMemory (p, ptr, size);
+ }
+ /* After dump, keep track of the last allocated byte for sbrk(0). */
+ data_region_end = p + size - 1;
+ return p;
+}
+
+void *
+realloc_before_dump (void *ptr, size_t size)
+{
+ void *p;
+
+ /* Before dumping. */
+ if (dumped_data < (unsigned char *)ptr
+ && (unsigned char *)ptr < bc_limit && size <= MaxBlockSize)
+ p = HeapReAlloc (heap, 0, ptr, size);
+ else
+ {
+ /* In this case, either the new block is too large for the heap,
+ or the old block was already too large. In both cases,
+ malloc_before_dump() and free_before_dump() will take care of
+ reallocation. */
+ p = malloc_before_dump (size);
+ CopyMemory (p, ptr, size);
+ free_before_dump (ptr);
+ }
+ return p;
+}
+
+/* Free a block allocated by `malloc', `realloc' or `calloc'. */
+void
+free_after_dump (void *ptr)
+{
+ /* After dumping. */
+ if (FREEABLE_P (ptr))
+ {
+ /* Free the block if it is in the new private heap. */
+ HeapFree (heap, 0, ptr);
+ }
+}
+
+void
+free_before_dump (void *ptr)
+{
+ /* Before dumping. */
+ if (dumped_data < (unsigned char *)ptr
+ && (unsigned char *)ptr < bc_limit)
+ {
+ /* Free the block if it is allocated in the private heap. */
+ HeapFree (heap, 0, ptr);
+ }
+ else
+ {
+ /* Look for the big chunk. */
+ int i;
+
+ for(i = 0; i < blocks_number; i++)
+ {
+ if (blocks[i].address == ptr)
+ {
+ /* Reset block occupation if found. */
+ blocks[i].occupied = 0;
+ break;
+ }
+ /* What if the block is not found? We should trigger an
+ error here. */
+ eassert (i < blocks_number);
+ }
+ }
+}
+
+/* Emulate getpagesize. */
+int
+getpagesize (void)
+{
+ return sysinfo_cache.dwPageSize;
+}
+
+void *
+sbrk (ptrdiff_t increment)
+{
+ /* The data_region_end address is the one of the last byte
+ allocated. The sbrk() function is not emulated at all, except
+ for a 0 value of its parameter. This is needed by the emacs lisp
+ function `memory-limit'. */
+ return data_region_end;
+}
+
+#define MAX_BUFFER_SIZE (512 * 1024 * 1024)
+
+/* MMAP allocation for buffers. */
+void *
+mmap_alloc (void **var, size_t nbytes)
+{
+ void *p = NULL;
+
+ /* We implement amortized allocation. We start by reserving twice
+ the size requested and commit only the size requested. Then
+ realloc could proceed and use the reserved pages, reallocating
+ only if needed. Buffer shrink would happen only so that we stay
+ in the 2x range. This is a big win when visiting compressed
+ files, where the final size of the buffer is not known in
+ advance, and the buffer is enlarged several times as the data is
+ decompressed on the fly. */
+ if (nbytes < MAX_BUFFER_SIZE)
+ p = VirtualAlloc (NULL, (nbytes * 2), MEM_RESERVE, PAGE_READWRITE);
+
+ /* If it fails, or if the request is above 512MB, try with the
+ requested size. */
+ if (p == NULL)
+ p = VirtualAlloc (NULL, nbytes, MEM_RESERVE, PAGE_READWRITE);
+
+ if (p != NULL)
+ {
+ /* Now, commit pages for NBYTES. */
+ *var = VirtualAlloc (p, nbytes, MEM_COMMIT, PAGE_READWRITE);
+ }
+
+ if (!p && GetLastError () != ERROR_NOT_ENOUGH_MEMORY)
+ DebPrint (("mmap_alloc: error %ld\n", GetLastError()));
+
+ return *var = p;
+}
+
+void
+mmap_free (void **var)
+{
+ if (*var)
+ {
+ if (VirtualFree (*var, 0, MEM_RELEASE) == 0)
+ DebPrint (("mmap_free: error %ld\n", GetLastError()));
+ *var = NULL;
+ }
+}
+
+void *
+mmap_realloc (void **var, size_t nbytes)
+{
+ MEMORY_BASIC_INFORMATION memInfo, m2;
+
+ if (*var == NULL)
+ return mmap_alloc (var, nbytes);
+
+ /* This case happens in init_buffer(). */
+ if (nbytes == 0)
+ {
+ mmap_free (var);
+ return mmap_alloc (var, nbytes);
+ }
+
+ if (VirtualQuery (*var, &memInfo, sizeof (memInfo)) == 0)
+ DebPrint (("mmap_realloc: VirtualQuery error = %ld\n", GetLastError()));
+
+ /* We need to enlarge the block. */
+ if (memInfo.RegionSize < nbytes)
+ {
+ if (VirtualQuery (*var + memInfo.RegionSize, &m2, sizeof(m2)) == 0)
+ DebPrint (("mmap_realloc: VirtualQuery error = %ld\n", GetLastError()));
+ /* If there is enough room in the current reserved area, then
+ commit more pages as needed. */
+ if (m2.State == MEM_RESERVE
+ && nbytes <= memInfo.RegionSize + m2.RegionSize)
+ {
+ void *p;
+
+ p = VirtualAlloc (*var + memInfo.RegionSize,
+ nbytes - memInfo.RegionSize,
+ MEM_COMMIT, PAGE_READWRITE);
+ if (!p /* && GetLastError() != ERROR_NOT_ENOUGH_MEMORY */)
+ DebPrint (("realloc enlarge: VirtualAlloc error %ld\n",
+ GetLastError()));
+ return *var;
+ }
+ else
+ {
+ /* Else we must actually enlarge the block by allocating a
+ new one and copying previous contents from the old to the
+ new one. */
+ void *old_ptr = *var;
+
+ if (mmap_alloc (var, nbytes))
+ {
+ CopyMemory (*var, old_ptr, memInfo.RegionSize);
+ mmap_free (&old_ptr);
+ return *var;
+ }
+ else
+ {
+ /* We failed to enlarge the buffer. */
+ *var = old_ptr;
+ return NULL;
+ }
+ }
+ }
+
+ /* If we are shrinking by more than one page... */
+ if (memInfo.RegionSize > nbytes + getpagesize())
+ {
+ /* If we are shrinking a lot... */
+ if ((memInfo.RegionSize / 2) > nbytes)
+ {
+ /* Let's give some memory back to the system and release
+ some pages. */
+ void *old_ptr = *var;
+
+ if (mmap_alloc (var, nbytes))
+ {
+ CopyMemory (*var, old_ptr, nbytes);
+ mmap_free (&old_ptr);
+ return *var;
+ }
+ else
+ {
+ /* In case we fail to shrink, try to go on with the old block.
+ But that means there is a lot of memory pressure.
+ We could also decommit pages. */
+ *var = old_ptr;
+ return *var;
+ }
+ }
+
+ /* We still can decommit pages. */
+ if (VirtualFree (*var + nbytes + get_page_size(),
+ memInfo.RegionSize - nbytes - get_page_size(),
+ MEM_DECOMMIT) == 0)
+ DebPrint (("mmap_realloc: VirtualFree error %ld\n", GetLastError()));
+ return *var;
+ }
+
+ /* Not enlarging, not shrinking by more than one page. */
+ return *var;
+}
HCoop / bpt / emacs.git / commitdiff