gecko-dev/db/os.win32/os_map.c
1998-10-15 03:56:37 +00:00

271 lines
6.0 KiB
C

/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996, 1997, 1998
* Sleepycat Software. All rights reserved.
*/
#include "config.h"
#ifndef lint
static const char sccsid[] = "@(#)os_map.c 10.19 (Sleepycat) 5/3/98";
#endif /* not lint */
#include "db_int.h"
/* Return if we're Windows/95 or Windows/NT. */
#define IS_WNT ((GetVersion() & 0x80000000) == 0)
static int __os_map __P((char *, int, size_t, int, int, int, int, void **));
static int __os_unique_name __P((char *, int, char *));
/*
* __db_mapanon_ok --
* Return if this OS can support anonymous memory regions.
*
* PUBLIC: int __db_mapanon_ok __P((int));
*/
int
__db_mapanon_ok(need_names)
int need_names;
{
/*
* XXX
* Windows/95 supports anonymous regions backed by the paging file.
*
* On Windows/NT, if you call CreateFileMapping with a file descriptor,
* you get proper sharing, but without a file descriptor (i.e. request
* to use a paging file), changes are not seen by any other processes
* that open that piece of named memory.
*/
if (IS_WNT && need_names)
return (ENXIO);
return (0);
}
/*
* __db_mapinit --
* Return if shared regions need to be initialized.
*
* PUBLIC: int __db_mapinit __P((void));
*/
int
__db_mapinit()
{
/*
* XXX
* Windows/95 leaves file contents uninitialized, bless its heart.
*
* Windows/NT initializes them.
*/
return (!IS_WNT);
}
/*
* __db_mapregion --
* Attach to a shared memory region.
*
* PUBLIC: int __db_mapregion __P((char *, REGINFO *));
*/
int
__db_mapregion(path, infop)
char *path;
REGINFO *infop;
{
int ret;
/* If the user replaces the map call, call through their interface. */
if (__db_jump.j_map != NULL)
return (__db_jump.j_map(path, infop->fd, infop->size,
1, F_ISSET(infop, REGION_ANONYMOUS), 0, &infop->addr));
/* CreateFileMapping regions that aren't anonymous can grow. */
if (!F_ISSET(infop, REGION_ANONYMOUS))
F_SET(infop, REGION_CANGROW);
if ((ret = __os_map(path, infop->fd, infop->size,
1, F_ISSET(infop, REGION_ANONYMOUS),
0, F_ISSET(infop, REGION_CREATED), &infop->addr)) != 0)
return (ret);
return (0);
}
/*
* __db_unmapregion --
* Detach from the shared memory region.
*
* PUBLIC: int __db_unmapregion __P((REGINFO *));
*/
int
__db_unmapregion(infop)
REGINFO *infop;
{
if (__db_jump.j_unmap != NULL)
return (__db_jump.j_unmap(infop->addr, infop->size));
return (!UnmapViewOfFile(infop->addr) ? errno : 0);
}
/*
* __db_unlinkregion --
* Remove the shared memory region.
*
* PUBLIC: int __db_unlinkregion __P((char *, REGINFO *));
*/
int
__db_unlinkregion(name, infop)
char *name;
REGINFO *infop;
{
COMPQUIET(infop, NULL);
if (__db_jump.j_runlink != NULL)
return (__db_jump.j_runlink(name));
return (0);
}
/*
* __db_mapfile --
* Map in a shared memory file.
*
* PUBLIC: int __db_mapfile __P((char *, int, size_t, int, void **));
*/
int
__db_mapfile(path, fd, len, is_rdonly, addr)
char *path;
int fd, is_rdonly;
size_t len;
void **addr;
{
if (__db_jump.j_map != NULL)
return (__db_jump.j_map(path, fd, len, 0, 0, is_rdonly, addr));
return (__os_map(path, fd, len, 0, 0, is_rdonly, 0, addr));
}
/*
* __db_unmapfile --
* Unmap the shared memory file.
*
* PUBLIC: int __db_unmapfile __P((void *, size_t));
*/
int
__db_unmapfile(addr, len)
void *addr;
size_t len;
{
if (__db_jump.j_unmap != NULL)
return (__db_jump.j_unmap(addr, len));
return (!UnmapViewOfFile(addr) ? errno : 0);
}
/*
* __os_unique_name --
* Create a unique identifying name from a pathname (may be absolute or
* relative) and/or a file descriptor.
*
* The name returned must be unique (different files map to different
* names), and repeatable (same files, map to same names). It's not so
* easy to do by name. Should handle not only:
*
* foo.bar == ./foo.bar == c:/whatever_path/foo.bar
*
* but also understand that:
*
* foo.bar == Foo.Bar (FAT file system)
* foo.bar != Foo.Bar (NTFS)
*
* The best solution is to use the identifying number in the file
* information structure (similar to UNIX inode #).
*/
static int
__os_unique_name(orig_path, fd, result_path)
char *orig_path, *result_path;
int fd;
{
BY_HANDLE_FILE_INFORMATION fileinfo;
if (!GetFileInformationByHandle(
(HANDLE)_get_osfhandle(fd), &fileinfo))
return (errno);
(void)sprintf(result_path, "%ld.%ld.%ld",
fileinfo.dwVolumeSerialNumber,
fileinfo.nFileIndexHigh, fileinfo.nFileIndexLow);
return (0);
}
/*
* __os_map --
* The mmap(2) function for Windows.
*/
static int
__os_map(path, fd, len, is_region, is_anonymous, is_rdonly, is_create, addr)
char *path;
int fd, is_region, is_anonymous, is_rdonly, is_create;
size_t len;
void **addr;
{
HANDLE hMemory;
RLAYOUT *rlp;
int ret;
void *pMemory;
char shmem_name[MAXPATHLEN];
ret = 0;
if (is_region && is_anonymous) {
/* Get a matching name in the paging file namespace */
(void)strcpy(shmem_name, "__db_shmem.");
if ((ret = __os_unique_name(path, fd,
&shmem_name[strlen(shmem_name)])) != 0)
return (ret);
}
/*
* XXX
* DB: We have not implemented copy-on-write here.
*
* XXX
* DB: This code will fail if the library is ever compiled on a 64-bit
* machine.
*/
hMemory = CreateFileMapping(
is_region && is_anonymous ?
(HANDLE)0xFFFFFFFF : (HANDLE)_get_osfhandle(fd),
0,
is_rdonly ? PAGE_READONLY : PAGE_READWRITE,
0, len,
is_region && is_anonymous ? shmem_name : NULL);
if (hMemory == NULL)
return (errno);
pMemory = MapViewOfFile(hMemory,
(is_rdonly ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS), 0, 0, len);
CloseHandle(hMemory);
if (is_region) {
/*
* Windows/95 zeroes anonymous memory regions at last close.
* This means that the backing file can exist and reference
* the region, but the region itself is no longer initialized.
* We handle this by returning EAGAIN to the caller, who will
* attempt to remove the backing file and start all over.
*/
rlp = (RLAYOUT *)pMemory;
if (rlp->valid == 0 && !is_create) {
(void)UnmapViewOfFile(pMemory);
pMemory = NULL;
ret = EAGAIN;
}
}
*addr = pMemory;
return (ret);
}