fix grabbag__file_are_same() on win32 by using GetFileInformationByHandle() to compare

diff --git a/include/share/grabbag/file.h b/include/share/grabbag/file.h
index e5918ee..86260d9 100644 (file)
--- a/include/share/grabbag/file.h
+++ b/include/share/grabbag/file.h
@@ -45,8 +45,8 @@ const char *grabbag__file_get_basename(const char *srcpath);
  */
 FLAC__bool grabbag__file_change_stats(const char *filename, FLAC__bool read_only);
 
-/* returns true iff stat() succeeds for both files and they have the same device and inode */
-/*@@@ this does not work on windows so for that the function just returns !strcmp(f1,f2) */
+/* returns true iff stat() succeeds for both files and they have the same device and inode. */
+/* on windows, uses GetFileInformationByHandle() to compare */
 FLAC__bool grabbag__file_are_same(const char *f1, const char *f2);
 
 /* attempts to make writable before unlinking */

diff --git a/src/share/grabbag/file.c b/src/share/grabbag/file.c
index 9c15788..5c1c780 100644 (file)
--- a/src/share/grabbag/file.c
+++ b/src/share/grabbag/file.c
@@ -40,6 +40,11 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h> /* for strrchr() */
+#if defined _WIN32 && !defined __CYGWIN__
+// for GetFileInformationByHandle() etc
+#include <Windows.h>
+#include <Winbase.h>
+#endif
 #include "share/grabbag.h"
 
 
@@ -111,7 +116,34 @@ FLAC__bool grabbag__file_change_stats(const char *filename, FLAC__bool read_only
 FLAC__bool grabbag__file_are_same(const char *f1, const char *f2)
 {
 #if defined _MSC_VER || defined __MINGW32__
-       return f1 && f2 && 0 == strcmp(f1, f2); /*@@@@@@ need better method than strcmp */
+       /* see
+        * http://www.hydrogenaudio.org/forums/index.php?showtopic=49439&pid=444300&st=0
+        *  http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/getfileinformationbyhandle.asp
+        *  http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/by_handle_file_information_str.asp
+        *  http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/createfile.asp
+        * apparently both the files have to be open at the same time for the comparison to work
+        */
+       FLAC__bool same = false;
+       BY_HANDLE_FILE_INFORMATION info1, info2;
+       HANDLE h1, h2;
+       BOOL ok = 1;
+       h1 = CreateFile(f1, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+       h2 = CreateFile(f2, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+       if(h1 == INVALID_HANDLE_VALUE || h2 == INVALID_HANDLE_VALUE)
+               ok = 0;
+       ok &= GetFileInformationByHandle(h1, &info1);
+       ok &= GetFileInformationByHandle(h2, &info2);
+       if(ok)
+               same =
+                       info1.dwVolumeSerialNumber == info2.dwVolumeSerialNumber &&
+                       info1.nFileIndexHigh == info2.nFileIndexHigh &&
+                       info1.nFileIndexLow == info2.nFileIndexLow
+               ;
+       if(h1 != INVALID_HANDLE_VALUE)
+               CloseHandle(h1);
+       if(h2 != INVALID_HANDLE_VALUE)
+               CloseHandle(h2);
+       return same;
 #else
        struct stat s1, s2;
        return f1 && f2 && stat(f1, &s1) == 0 && stat(f2, &s2) == 0 && s1.st_ino == s2.st_ino && s1.st_dev == s2.st_dev;