1 /*
2 * gettimeofday.c
3 * Win32 gettimeofday() replacement
4 *
5 * src/port/gettimeofday.c
6 *
7 * Copyright (c) 2003 SRA, Inc.
8 * Copyright (c) 2003 SKC, Inc.
9 *
10 * Permission to use, copy, modify, and distribute this software and
11 * its documentation for any purpose, without fee, and without a
12 * written agreement is hereby granted, provided that the above
13 * copyright notice and this paragraph and the following two
14 * paragraphs appear in all copies.
15 *
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
17 * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
18 * LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
19 * DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
20 * OF THE POSSIBILITY OF SUCH DAMAGE.
21 *
22 * THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
24 * A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
25 * IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
26 * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
27 */
28
29 #include "c.h"
30
31 #include <sys/time.h>
32
33 /* FILETIME of Jan 1 1970 00:00:00, the PostgreSQL epoch */
34 static const unsigned __int64 epoch = UINT64CONST(116444736000000000);
35
36 /*
37 * FILETIME represents the number of 100-nanosecond intervals since
38 * January 1, 1601 (UTC).
39 */
40 #define FILETIME_UNITS_PER_SEC 10000000L
41 #define FILETIME_UNITS_PER_USEC 10
42
43 /*
44 * Both GetSystemTimeAsFileTime and GetSystemTimePreciseAsFileTime share a
45 * signature, so we can just store a pointer to whichever we find. This
46 * is the pointer's type.
47 */
48 typedef VOID(WINAPI * PgGetSystemTimeFn) (LPFILETIME);
49
50 /* One-time initializer function, must match that signature. */
51 static void WINAPI init_gettimeofday(LPFILETIME lpSystemTimeAsFileTime);
52
53 /* Storage for the function we pick at runtime */
54 static PgGetSystemTimeFn pg_get_system_time = &init_gettimeofday;
55
56 /*
57 * One time initializer. Determine whether GetSystemTimePreciseAsFileTime
58 * is available and if so, plan to use it; if not, fall back to
59 * GetSystemTimeAsFileTime.
60 */
61 static void WINAPI
init_gettimeofday(LPFILETIME lpSystemTimeAsFileTime)62 init_gettimeofday(LPFILETIME lpSystemTimeAsFileTime)
63 {
64 /*
65 * Because it's guaranteed that kernel32.dll will be linked into our
66 * address space already, we don't need to LoadLibrary it and worry about
67 * closing it afterwards, so we're not using Pg's dlopen/dlsym() wrapper.
68 *
69 * We'll just look up the address of GetSystemTimePreciseAsFileTime if
70 * present.
71 *
72 * While we could look up the Windows version and skip this on Windows
73 * versions below Windows 8 / Windows Server 2012 there isn't much point,
74 * and determining the windows version is its self somewhat Windows
75 * version and development SDK specific...
76 */
77 pg_get_system_time = (PgGetSystemTimeFn) GetProcAddress(
78 GetModuleHandle(TEXT("kernel32.dll")),
79 "GetSystemTimePreciseAsFileTime");
80 if (pg_get_system_time == NULL)
81 {
82 /*
83 * The expected error from GetLastError() is ERROR_PROC_NOT_FOUND, if
84 * the function isn't present. No other error should occur.
85 *
86 * We can't report an error here because this might be running in
87 * frontend code; and even if we're in the backend, it's too early to
88 * elog(...) if we get some unexpected error. Also, it's not a
89 * serious problem, so just silently fall back to
90 * GetSystemTimeAsFileTime irrespective of why the failure occurred.
91 */
92 pg_get_system_time = &GetSystemTimeAsFileTime;
93 }
94
95 (*pg_get_system_time) (lpSystemTimeAsFileTime);
96 }
97
98 /*
99 * timezone information is stored outside the kernel so tzp isn't used anymore.
100 *
101 * Note: this function is not for Win32 high precision timing purposes. See
102 * elapsed_time().
103 */
104 int
gettimeofday(struct timeval * tp,struct timezone * tzp)105 gettimeofday(struct timeval * tp, struct timezone * tzp)
106 {
107 FILETIME file_time;
108 ULARGE_INTEGER ularge;
109
110 (*pg_get_system_time) (&file_time);
111 ularge.LowPart = file_time.dwLowDateTime;
112 ularge.HighPart = file_time.dwHighDateTime;
113
114 tp->tv_sec = (long) ((ularge.QuadPart - epoch) / FILETIME_UNITS_PER_SEC);
115 tp->tv_usec = (long) (((ularge.QuadPart - epoch) % FILETIME_UNITS_PER_SEC)
116 / FILETIME_UNITS_PER_USEC);
117
118 return 0;
119 }
120