Backport Fix for Bug#24509 - 2048 file descriptor limit on windows needs increasing.

The patch replaces the use of the POSIX I/O interfaces in mysys on Windows with 
the Win32 API calls (CreateFile, WriteFile, etc). The Windows HANDLE for the open
 file is stored in the my_file_info struct, along with a flag for append mode 
(because the Windows API does not support opening files in append mode in all cases)
The default max open files has been increased to 16384 and can be increased further
by setting --max-open-files=<value> during the server start.

Noteworthy benefit of this patch is that it removes limits from the table_cache size - 
allowing for more simultaneus users

4 files changed, 58 insertions, 13 deletions

diff --git a/include/config-win.h b/include/config-win.h
index 6d12bb0e33f..3fd2c6c3a43 100644
--- a/include/config-win.h
+++ b/include/config-win.h
@@ -66,7 +66,6 @@
 #endif
 
 /* File and lock constants */
-#define O_SHARE		0x1000		/* Open file in sharing mode */
 #ifdef __BORLANDC__
 #define F_RDLCK		LK_NBLCK	/* read lock */
 #define F_WRLCK		LK_NBRLCK	/* write lock */
@@ -374,7 +373,7 @@ inline ulonglong double2ulonglong(double d)
 #define FN_DEVCHAR	':'
 #define FN_NETWORK_DRIVES	/* Uses \\ to indicate network drives */
 #define FN_NO_CASE_SENCE	/* Files are not case-sensitive */
-#define OS_FILE_LIMIT	2048
+#define OS_FILE_LIMIT	UINT_MAX
 
 #define DO_NOT_REMOVE_THREAD_WRAPPERS
 #define thread_safe_increment(V,L) InterlockedIncrement((long*) &(V))
diff --git a/include/my_dir.h b/include/my_dir.h
index 06509a3af19..90d708ac811 100644
--- a/include/my_dir.h
+++ b/include/my_dir.h
@@ -69,7 +69,11 @@ typedef struct my_stat
 
 #else
 
+#if(_MSC_VER)
+#define MY_STAT struct _stati64 /* 64 bit file size */
+#else
 #define MY_STAT struct stat	/* Orginal struct have what we need */
+#endif
 
 #endif /* USE_MY_STAT_STRUCT */
 
diff --git a/include/my_global.h b/include/my_global.h
index 8b71410dbf0..60c53ac937c 100644
--- a/include/my_global.h
+++ b/include/my_global.h
@@ -784,7 +784,41 @@ typedef SOCKET_SIZE_TYPE size_socket;
 #define FN_DIRSEP       "/"     /* Valid directory separators */
 #define FN_ROOTDIR	"/"
 #endif
-#define MY_NFILE	64	/* This is only used to save filenames */
+
+/* 
+  MY_FILE_MIN is  Windows speciality and is used to quickly detect
+  the mismatch of CRT and mysys file IO usage on Windows at runtime.
+  CRT file descriptors can be in the range 0-2047, whereas descriptors returned
+  by my_open() will start with 2048. If a file descriptor with value less then
+  MY_FILE_MIN is passed to mysys IO function, chances are it stemms from
+  open()/fileno() and not my_open()/my_fileno.
+
+  For Posix,  mysys functions are light wrappers around libc, and MY_FILE_MIN
+  is logically 0.
+*/
+
+#ifdef _WIN32
+#define MY_FILE_MIN  2048
+#else
+#define MY_FILE_MIN  0
+#endif
+
+/* 
+  MY_NFILE is the default size of my_file_info array.
+
+  It is larger on Windows, because it all file handles are stored in my_file_info
+  Default size is 16384 and this should be enough for most cases.If it is not 
+  enough, --max-open-files with larger value can be used.
+
+  For Posix , my_file_info array is only used to store filenames for
+  error reporting and its size is not a limitation for number of open files.
+*/ 
+#ifdef _WIN32
+#define MY_NFILE (16384 + MY_FILE_MIN)
+#else
+#define MY_NFILE 64
+#endif
+
 #ifndef OS_FILE_LIMIT
 #define OS_FILE_LIMIT	UINT_MAX
 #endif
@@ -821,9 +855,8 @@ typedef SOCKET_SIZE_TYPE size_socket;
 	/* Some things that this system doesn't have */
 
 #define NO_HASH			/* Not needed anymore */
-#ifdef __WIN__
-#define NO_DIR_LIBRARY		/* Not standar dir-library */
-#define USE_MY_STAT_STRUCT	/* For my_lib */
+#ifdef _WIN32
+#define NO_DIR_LIBRARY		/* Not standard dir-library */
 #endif
 
 /* Some defines of functions for portability */
diff --git a/include/my_sys.h b/include/my_sys.h
index d391492983d..3368236694d 100644
--- a/include/my_sys.h
+++ b/include/my_sys.h
@@ -342,11 +342,12 @@ enum file_type
 
 struct st_my_file_info
 {
-  char *		name;
-  enum file_type	type;
-#if defined(THREAD) && !defined(HAVE_PREAD)
-  pthread_mutex_t	mutex;
+  char  *name;
+#ifdef _WIN32
+  HANDLE fhandle;   /* win32 file handle */
+  int    oflag;     /* open flags, e.g O_APPEND */
 #endif
+  enum   file_type	type;
 };
 
 extern struct st_my_file_info *my_file_info;
@@ -650,12 +651,12 @@ extern void *my_memmem(const void *haystack, size_t haystacklen,
                        const void *needle, size_t needlelen);
 
 
-#ifdef __WIN__
-extern int my_access(const char *path, int amode);
-extern File my_sopen(const char *path, int oflag, int shflag, int pmode);
+#ifdef _WIN32
+extern int      my_access(const char *path, int amode);
 #else
 #define my_access access
 #endif
+
 extern int check_if_legal_filename(const char *path);
 extern int check_if_legal_tablename(const char *path);
 
@@ -666,6 +667,13 @@ extern int nt_share_delete(const char *name,myf MyFlags);
 #define my_delete_allow_opened(fname,flags)  my_delete((fname),(flags))
 #endif
 
+#ifdef _WIN32
+/* Windows-only functions (CRT equivalents)*/
+extern File     my_sopen(const char *path, int oflag, int shflag, int pmode);
+extern HANDLE   my_get_osfhandle(File fd);
+extern void     my_osmaperr(unsigned long last_error);
+#endif
+
 #ifndef TERMINATE
 extern void TERMINATE(FILE *file, uint flag);
 #endif
@@ -675,6 +683,7 @@ extern FILE *my_fopen(const char *FileName,int Flags,myf MyFlags);
 extern FILE *my_fdopen(File Filedes,const char *name, int Flags,myf MyFlags);
 extern FILE *my_freopen(const char *path, const char *mode, FILE *stream);
 extern int my_fclose(FILE *fd,myf MyFlags);
+extern File my_fileno(FILE *fd);
 extern int my_chsize(File fd,my_off_t newlength, int filler, myf MyFlags);
 extern int my_chmod(const char *name, mode_t mode, myf my_flags);
 extern int my_sync(File fd, myf my_flags);