1 files changed, 129 insertions, 0 deletions
diff --git a/db-4.8.30/os_windows/os_fid.c b/db-4.8.30/os_windows/os_fid.c
new file mode 100644
index 0000000..3283ea5
--- /dev/null
+++ b/db-4.8.30/os_windows/os_fid.c
@@ -0,0 +1,129 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 1996-2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#include "db_config.h"
+
+#include "db_int.h"
+
+/*
+ * __os_fileid --
+ *	Return a unique identifier for a file.
+ */
+int
+__os_fileid(env, fname, unique_okay, fidp)
+	ENV *env;
+	const char *fname;
+	int unique_okay;
+	u_int8_t *fidp;
+{
+	pid_t pid;
+	size_t i;
+	u_int32_t tmp;
+	u_int8_t *p;
+	int ret;
+
+	/*
+	 * The documentation for GetFileInformationByHandle() states that the
+	 * inode-type numbers are not constant between processes.  Actually,
+	 * they are, they're the NTFS MFT indexes.  So, this works on NTFS,
+	 * but perhaps not on other platforms, and perhaps not over a network.
+	 * Can't think of a better solution right now.
+	 */
+	DB_FH *fhp;
+	BY_HANDLE_FILE_INFORMATION fi;
+	BOOL retval = FALSE;
+
+	DB_ASSERT(env, fname != NULL);
+
+	/* Clear the buffer. */
+	memset(fidp, 0, DB_FILE_ID_LEN);
+
+	/*
+	 * First we open the file, because we're not given a handle to it.
+	 * If we can't open it, we're in trouble.
+	 */
+	if ((ret = __os_open(env, fname, 0,
+	    DB_OSO_RDONLY, DB_MODE_400, &fhp)) != 0)
+		return (ret);
+
+	/* File open, get its info */
+	if ((retval = GetFileInformationByHandle(fhp->handle, &fi)) == FALSE)
+		ret = __os_get_syserr();
+	(void)__os_closehandle(env, fhp);
+
+	if (retval == FALSE)
+		return (__os_posix_err(ret));
+
+	/*
+	 * We want the three 32-bit words which tell us the volume ID and
+	 * the file ID.  We make a crude attempt to copy the bytes over to
+	 * the callers buffer.
+	 *
+	 * We don't worry about byte sexing or the actual variable sizes.
+	 *
+	 * When this routine is called from the DB access methods, it's only
+	 * called once -- whatever ID is generated when a database is created
+	 * is stored in the database file's metadata, and that is what is
+	 * saved in the mpool region's information to uniquely identify the
+	 * file.
+	 *
+	 * When called from the mpool layer this routine will be called each
+	 * time a new thread of control wants to share the file, which makes
+	 * things tougher.  As far as byte sexing goes, since the mpool region
+	 * lives on a single host, there's no issue of that -- the entire
+	 * region is byte sex dependent.  As far as variable sizes go, we make
+	 * the simplifying assumption that 32-bit and 64-bit processes will
+	 * get the same 32-bit values if we truncate any returned 64-bit value
+	 * to a 32-bit value.
+	 */
+	tmp = (u_int32_t)fi.nFileIndexLow;
+	for (p = (u_int8_t *)&tmp, i = sizeof(u_int32_t); i > 0; --i)
+		*fidp++ = *p++;
+	tmp = (u_int32_t)fi.nFileIndexHigh;
+	for (p = (u_int8_t *)&tmp, i = sizeof(u_int32_t); i > 0; --i)
+		*fidp++ = *p++;
+
+	if (unique_okay) {
+		/* Add in 32-bits of (hopefully) unique number. */
+		__os_unique_id(env, &tmp);
+		for (p = (u_int8_t *)&tmp, i = sizeof(u_int32_t); i > 0; --i)
+			*fidp++ = *p++;
+
+		/*
+		 * Initialize/increment the serial number we use to help
+		 * avoid fileid collisions.  Note we don't bother with
+		 * locking; it's unpleasant to do from down in here, and
+		 * if we race on this no real harm will be done, since the
+		 * finished fileid has so many other components.
+		 *
+		 * We use the bottom 32-bits of the process ID, hoping they
+		 * are more random than the top 32-bits (should we be on a
+		 * machine with 64-bit process IDs).
+		 *
+		 * We increment by 100000 on each call as a simple way of
+		 * randomizing; simply incrementing seems potentially less
+		 * useful if pids are also simply incremented, since this
+		 * is process-local and we may be one of a set of processes
+		 * starting up.  100000 pushes us out of pid space on most
+		 * 32-bit platforms, and has few interesting properties in
+		 * base 2.
+		 */
+		if (DB_GLOBAL(fid_serial) == 0) {
+			__os_id(env->dbenv, &pid, NULL);
+			DB_GLOBAL(fid_serial) = (u_int32_t)pid;
+		} else
+			DB_GLOBAL(fid_serial) += 100000;
+
+	} else {
+		tmp = (u_int32_t)fi.dwVolumeSerialNumber;
+		for (p = (u_int8_t *)&tmp, i = sizeof(u_int32_t); i > 0; --i)
+			*fidp++ = *p++;
+	}
+
+	return (0);
+}