1 files changed, 309 insertions, 0 deletions
diff --git a/db/os_windows/os_map.c b/db/os_windows/os_map.c
new file mode 100644
index 000000000..e254ea429
--- /dev/null
+++ b/db/os_windows/os_map.c
@@ -0,0 +1,309 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 1996-2006
+ *	Oracle Corporation.  All rights reserved.
+ *
+ * $Id: os_map.c,v 12.8 2006/08/24 14:46:21 bostic Exp $
+ */
+
+#include "db_config.h"
+
+#include "db_int.h"
+
+static int __os_map
+  __P((DB_ENV *, char *, REGINFO *, DB_FH *, size_t, int, int, int, void **));
+static int __os_unique_name __P((_TCHAR *, HANDLE, _TCHAR *, size_t));
+
+/*
+ * __os_r_sysattach --
+ *	Create/join a shared memory region.
+ */
+int
+__os_r_sysattach(dbenv, infop, rp)
+	DB_ENV *dbenv;
+	REGINFO *infop;
+	REGION *rp;
+{
+	DB_FH *fhp;
+	int is_system, ret;
+
+	/*
+	 * Try to open/create the file.  We DO NOT need to ensure that multiple
+	 * threads/processes attempting to simultaneously create the region are
+	 * properly ordered, our caller has already taken care of that.
+	 */
+	if ((ret = __os_open(dbenv, infop->name,
+	    F_ISSET(infop, REGION_CREATE_OK) ? DB_OSO_CREATE: 0,
+	    dbenv->db_mode, &fhp)) != 0) {
+		__db_err(dbenv, ret, "%s", infop->name);
+		return (ret);
+	}
+
+	/*
+	 * On Windows/9X, files that are opened by multiple processes do not
+	 * share data correctly.  For this reason, the DB_SYSTEM_MEM flag is
+	 * implied for any application that does not specify the DB_PRIVATE
+	 * flag.
+	 */
+	is_system = F_ISSET(dbenv, DB_ENV_SYSTEM_MEM) ||
+	    (!F_ISSET(dbenv, DB_ENV_PRIVATE) && __os_is_winnt() == 0);
+
+	/*
+	 * Map the file in.  If we're creating an in-system-memory region,
+	 * specify a segment ID (which is never used again) so that the
+	 * calling code writes out the REGENV_REF structure to the primary
+	 * environment file.
+	 */
+	ret = __os_map(dbenv, infop->name, infop, fhp, rp->size,
+	   1, is_system, 0, &infop->addr);
+	if (ret == 0 && is_system == 1)
+		rp->segid = 1;
+
+	(void)__os_closehandle(dbenv, fhp);
+
+	return (ret);
+}
+
+/*
+ * __os_r_sysdetach --
+ *	Detach from a shared memory region.
+ */
+int
+__os_r_sysdetach(dbenv, infop, destroy)
+	DB_ENV *dbenv;
+	REGINFO *infop;
+	int destroy;
+{
+	int ret, t_ret;
+
+	if (infop->wnt_handle != NULL) {
+		(void)CloseHandle(infop->wnt_handle);
+		infop->wnt_handle = NULL;
+	}
+
+	ret = !UnmapViewOfFile(infop->addr) ? __os_get_syserr() : 0;
+	if (ret != 0) {
+		__db_syserr(dbenv, ret, "UnmapViewOfFile");
+		ret = __os_posix_err(ret);
+	}
+
+	if (!F_ISSET(dbenv, DB_ENV_SYSTEM_MEM) && destroy) {
+		if (F_ISSET(dbenv, DB_ENV_OVERWRITE))
+			(void)__db_file_multi_write(dbenv, infop->name);
+		if ((t_ret = __os_unlink(dbenv, infop->name)) != 0 && ret == 0)
+			ret = t_ret;
+	}
+
+	return (ret);
+}
+
+/*
+ * __os_mapfile --
+ *	Map in a shared memory file.
+ */
+int
+__os_mapfile(dbenv, path, fhp, len, is_rdonly, addr)
+	DB_ENV *dbenv;
+	char *path;
+	DB_FH *fhp;
+	int is_rdonly;
+	size_t len;
+	void **addr;
+{
+	return (__os_map(dbenv, path, NULL, fhp, len, 0, 0, is_rdonly, addr));
+}
+
+/*
+ * __os_unmapfile --
+ *	Unmap the shared memory file.
+ */
+int
+__os_unmapfile(dbenv, addr, len)
+	DB_ENV *dbenv;
+	void *addr;
+	size_t len;
+{
+	return (!UnmapViewOfFile(addr) ? __os_posix_err(__os_get_syserr()) : 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 file index, found in the file
+ *	information structure (similar to UNIX inode #).
+ *
+ *	When a file is deleted, its file index may be reused,
+ *	but if the unique name has not gone from its namespace,
+ *	we may get a conflict.  So to ensure some tie in to the
+ *	original pathname, we also use the creation time and the
+ *	file basename.  This is not a perfect system, but it
+ *	should work for all but anamolous test cases.
+ *
+ */
+static int
+__os_unique_name(orig_path, hfile, result_path, result_path_len)
+	_TCHAR *orig_path, *result_path;
+	HANDLE hfile;
+	size_t result_path_len;
+{
+	BY_HANDLE_FILE_INFORMATION fileinfo;
+	_TCHAR *basename, *p;
+
+	/*
+	 * In Windows, pathname components are delimited by '/' or '\', and
+	 * if neither is present, we need to strip off leading drive letter
+	 * (e.g. c:foo.txt).
+	 */
+	basename = _tcsrchr(orig_path, '/');
+	p = _tcsrchr(orig_path, '\\');
+	if (basename == NULL || (p != NULL && p > basename))
+		basename = p;
+	if (basename == NULL)
+		basename = _tcsrchr(orig_path, ':');
+
+	if (basename == NULL)
+		basename = orig_path;
+	else
+		basename++;
+
+	if (!GetFileInformationByHandle(hfile, &fileinfo))
+		return (__os_posix_err(__os_get_syserr()));
+
+	(void)_sntprintf(result_path, result_path_len,
+	    _T("__db_shmem.%8.8lx.%8.8lx.%8.8lx.%8.8lx.%8.8lx.%s"),
+	    fileinfo.dwVolumeSerialNumber,
+	    fileinfo.nFileIndexHigh,
+	    fileinfo.nFileIndexLow,
+	    fileinfo.ftCreationTime.dwHighDateTime,
+	    fileinfo.ftCreationTime.dwHighDateTime,
+	    basename);
+
+	return (0);
+}
+
+/*
+ * __os_map --
+ *	The mmap(2) function for Windows.
+ */
+static int
+__os_map(dbenv, path, infop, fhp, len, is_region, is_system, is_rdonly, addr)
+	DB_ENV *dbenv;
+	REGINFO *infop;
+	char *path;
+	DB_FH *fhp;
+	int is_region, is_system, is_rdonly;
+	size_t len;
+	void **addr;
+{
+	HANDLE hMemory;
+	int ret, use_pagefile;
+	_TCHAR *tpath, shmem_name[DB_MAXPATHLEN];
+	void *pMemory;
+
+	ret = 0;
+	if (infop != NULL)
+		infop->wnt_handle = NULL;
+
+	use_pagefile = is_region && is_system;
+
+	/*
+	 * If creating a region in system space, get a matching name in the
+	 * paging file namespace.
+	 */
+	if (use_pagefile) {
+		TO_TSTRING(dbenv, path, tpath, ret);
+		if (ret != 0)
+			return (ret);
+		ret = __os_unique_name(tpath, fhp->handle,
+		    shmem_name, sizeof(shmem_name));
+		FREE_STRING(dbenv, tpath);
+		if (ret != 0)
+			return (ret);
+	}
+
+	/*
+	 * XXX
+	 * DB: We have not implemented copy-on-write here.
+	 *
+	 * If this is an region in system memory, we try to open it using the
+	 * OpenFileMapping() first, and only call CreateFileMapping() if we're
+	 * really creating the section.  There are two reasons:
+	 *
+	 * 1) We only create the mapping if we have newly created the region.
+	 *    This avoids a long-running problem caused by Windows reference
+	 *    counting, where regions that are closed by all processes are
+	 *    deleted.  It turns out that just checking for a zeroed region
+	 *    is not good enough. See [#4882] and [#7127] for the details.
+	 *
+	 * 2) CreateFileMapping seems to mess up making the commit charge to
+	 *    the process. It thinks, incorrectly, that when we want to join a
+	 *    previously existing section, that it should make a commit charge
+	 *    for the whole section.  In fact, there is no new committed memory
+	 *    whatever.  The call can fail if there is insufficient memory free
+	 *    to handle the erroneous commit charge.  So, we find that the
+	 *    bogus commit is not made if we call OpenFileMapping.
+	 */
+	hMemory = NULL;
+	if (use_pagefile) {
+		hMemory = OpenFileMapping(
+		    is_rdonly ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS,
+		    0, shmem_name);
+
+		if (hMemory == NULL && F_ISSET(infop, REGION_CREATE_OK))
+			hMemory = CreateFileMapping((HANDLE)-1, 0,
+			    is_rdonly ? PAGE_READONLY : PAGE_READWRITE,
+			    0, (DWORD)len, shmem_name);
+	} else
+		hMemory = CreateFileMapping(fhp->handle, 0,
+		    is_rdonly ? PAGE_READONLY : PAGE_READWRITE,
+		    0, (DWORD)len, NULL);
+
+	if (hMemory == NULL) {
+		ret = __os_get_syserr();
+		__db_syserr(dbenv, ret, "OpenFileMapping");
+		return (__db_panic(dbenv, __os_posix_err(ret)));
+	}
+
+	pMemory = MapViewOfFile(hMemory,
+	    (is_rdonly ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS), 0, 0, len);
+	if (pMemory == NULL) {
+		ret = __os_get_syserr();
+		__db_syserr(dbenv, ret, "MapViewOfFile");
+		return (__db_panic(dbenv, __os_posix_err(ret)));
+	}
+
+	/*
+	 * XXX
+	 * It turns out that the kernel object underlying the named section
+	 * is reference counted, but that the call to MapViewOfFile() above
+	 * does NOT increment the reference count! So, if we close the handle
+	 * here, the kernel deletes the object from the kernel namespace.
+	 * When a second process comes along to join the region, the kernel
+	 * happily creates a new object with the same name, but completely
+	 * different identity. The two processes then have distinct isolated
+	 * mapped sections, not at all what was wanted. Not closing the handle
+	 * here fixes this problem.  We carry the handle around in the region
+	 * structure so we can close it when unmap is called.
+	 */
+	if (use_pagefile && infop != NULL)
+		infop->wnt_handle = hMemory;
+	else
+		CloseHandle(hMemory);
+
+	*addr = pMemory;
+	return (ret);
+}