time-cond: fix reading the file modification time on Windows

On Windows, stat() may adjust the unix file time by a daylight saving time
offset. Avoid this by calling GetFileTime() instead.

Fixes #2164
Closes #2204

1 files changed, 154 insertions, 0 deletions

diff --git a/src/tool_filetime.c b/src/tool_filetime.c
new file mode 100644
index 000000000..6071e44d2
--- /dev/null
+++ b/src/tool_filetime.c
@@ -0,0 +1,154 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+#include "tool_filetime.h"
+
+#ifdef HAVE_UTIME_H
+#  include <utime.h>
+#elif defined(HAVE_SYS_UTIME_H)
+#  include <sys/utime.h>
+#endif
+
+curl_off_t getfiletime(const char *filename, FILE *error_stream)
+{
+  curl_off_t result = -1;
+
+/* Windows stat() may attempt to adjust the unix GMT file time by a daylight
+   saving time offset and since it's GMT that is bad behavior. When we have
+   access to a 64-bit type we can bypass stat and get the times directly. */
+#if defined(WIN32) && (SIZEOF_CURL_OFF_T >= 8)
+  HANDLE hfile;
+
+  hfile = CreateFileA(filename, FILE_READ_ATTRIBUTES,
+                      (FILE_SHARE_READ | FILE_SHARE_WRITE |
+                       FILE_SHARE_DELETE),
+                      NULL, OPEN_EXISTING, 0, NULL);
+  if(hfile != INVALID_HANDLE_VALUE) {
+    FILETIME ft;
+    if(GetFileTime(hfile, NULL, NULL, &ft)) {
+      curl_off_t converted = (curl_off_t)ft.dwLowDateTime
+          | ((curl_off_t)ft.dwHighDateTime) << 32;
+
+      if(converted < CURL_OFF_T_C(116444736000000000)) {
+        fprintf(error_stream,
+                "Failed to get filetime: underflow\n");
+      }
+      else {
+        result = (converted - CURL_OFF_T_C(116444736000000000)) / 10000000;
+      }
+    }
+    else {
+      fprintf(error_stream,
+              "Failed to get filetime: "
+              "GetFileTime failed: GetLastError %u\n",
+              (unsigned int)GetLastError());
+    }
+    CloseHandle(hfile);
+  }
+  else if(GetLastError() != ERROR_FILE_NOT_FOUND) {
+    fprintf(error_stream,
+            "Failed to get filetime: "
+            "CreateFile failed: GetLastError %u\n",
+            (unsigned int)GetLastError());
+  }
+#else
+  struct_stat statbuf;
+  if(-1 != stat(filename, &statbuf)) {
+    result = (curl_off_t)statbuf.st_mtime;
+  }
+  else if(errno != ENOENT) {
+    fprintf(error_stream,
+            "Failed to get filetime: %s\n", strerror(errno));
+  }
+#endif
+  return result;
+}
+
+#if defined(HAVE_UTIME) || defined(HAVE_UTIMES) || \
+    (defined(WIN32) && (SIZEOF_CURL_OFF_T >= 8))
+void setfiletime(curl_off_t filetime, const char *filename,
+    FILE *error_stream)
+{
+  if(filetime >= 0) {
+/* Windows utime() may attempt to adjust the unix GMT file time by a daylight
+   saving time offset and since it's GMT that is bad behavior. When we have
+   access to a 64-bit type we can bypass utime and set the times directly. */
+#if defined(WIN32) && (SIZEOF_CURL_OFF_T >= 8)
+    HANDLE hfile;
+
+    /* 910670515199 is the maximum unix filetime that can be used as a
+       Windows FILETIME without overflow: 30827-12-31T23:59:59. */
+    if(filetime > CURL_OFF_T_C(910670515199)) {
+      fprintf(error_stream,
+              "Failed to set filetime %" CURL_FORMAT_CURL_OFF_T
+              " on outfile: overflow\n", filetime);
+      return;
+    }
+
+    hfile = CreateFileA(filename, FILE_WRITE_ATTRIBUTES,
+                        (FILE_SHARE_READ | FILE_SHARE_WRITE |
+                         FILE_SHARE_DELETE),
+                        NULL, OPEN_EXISTING, 0, NULL);
+    if(hfile != INVALID_HANDLE_VALUE) {
+      curl_off_t converted = ((curl_off_t)filetime * 10000000) +
+                             CURL_OFF_T_C(116444736000000000);
+      FILETIME ft;
+      ft.dwLowDateTime = (DWORD)(converted & 0xFFFFFFFF);
+      ft.dwHighDateTime = (DWORD)(converted >> 32);
+      if(!SetFileTime(hfile, NULL, &ft, &ft)) {
+        fprintf(error_stream,
+                "Failed to set filetime %" CURL_FORMAT_CURL_OFF_T
+                " on outfile: SetFileTime failed: GetLastError %u\n",
+                filetime, (unsigned int)GetLastError());
+      }
+      CloseHandle(hfile);
+    }
+    else {
+      fprintf(error_stream,
+              "Failed to set filetime %" CURL_FORMAT_CURL_OFF_T
+              " on outfile: CreateFile failed: GetLastError %u\n",
+              filetime, (unsigned int)GetLastError());
+    }
+
+#elif defined(HAVE_UTIMES)
+    struct timeval times[2];
+    times[0].tv_sec = times[1].tv_sec = (time_t)filetime;
+    times[0].tv_usec = times[1].tv_usec = 0;
+    if(utimes(filename, times)) {
+      fprintf(error_stream,
+              "Failed to set filetime %" CURL_FORMAT_CURL_OFF_T
+              " on outfile: %s\n", filetime, strerror(errno));
+    }
+
+#elif defined(HAVE_UTIME)
+    struct utimbuf times;
+    times.actime = (time_t)filetime;
+    times.modtime = (time_t)filetime;
+    if(utime(filename, &times)) {
+      fprintf(error_stream,
+              "Failed to set filetime %" CURL_FORMAT_CURL_OFF_T
+              " on outfile: %s\n", filetime, strerror(errno));
+    }
+#endif
+  }
+}
+#endif /* defined(HAVE_UTIME) || defined(HAVE_UTIMES) || \
+          (defined(WIN32) && (SIZEOF_CURL_OFF_T >= 8)) */