The attached patch implements a symlink for win32 using junctions, and

uses that for win32 tablespaces.

Andreas Pflug

src/include/port.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/port.h,v 1.47 2004/08/01 06:56:39 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/port.h,v 1.48 2004/08/07 21:48:09 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -80,7 +80,7 @@ extern void set_pglocale_pgservice(const char *argv0, const char *app);
 extern int find_my_exec(const char *argv0, char *retpath);
 extern int find_other_exec(const char *argv0, const char *target,
 						   const char *versionstr, char *retpath);
-#if defined(__CYGWIN__) || defined(WIN32)
+#if defined(WIN32) || defined(__CYGWIN__)
 #define EXE ".exe"
 #define DEVNULL "nul"
 #else
@@ -140,14 +140,17 @@ extern int pgkill(int pid, int sig);
 
 extern int pclose_check(FILE *stream);
 
-#if defined(__MINGW32__) || defined(__CYGWIN__)
+#if defined(WIN32) || defined(__CYGWIN__)
 /*
- * Win32 doesn't have reliable rename/unlink during concurrent access
+ *	Win32 doesn't have reliable rename/unlink during concurrent access,
+ *	and we need special code to do symlinks.
  */
 extern int	pgrename(const char *from, const char *to);
 extern int	pgunlink(const char *path);
+extern int	pgsymlink(const char *oldpath, const char *newpath);
 #define rename(from, to)		pgrename(from, to)
 #define unlink(path)			pgunlink(path)
+#define symlink(oldpath, newpath)	pgsymlink(oldpath, newpath)
 #endif
 
 extern bool rmtree(char *path, bool rmtopdir);

src/port/dirmod.c

@@ -10,7 +10,7 @@
  *	Win32 (NT, Win2k, XP).	replace() doesn't work on Win95/98/Me.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/port/dirmod.c,v 1.13 2004/08/01 06:19:26 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/port/dirmod.c,v 1.14 2004/08/07 21:48:09 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -33,10 +33,14 @@
 
 
 #include "miscadmin.h"
+#include <winioctl.h>
 
 #undef rename
 #undef unlink
 
+/*
+ *	pgrename
+ */
 int
 pgrename(const char *from, const char *to)
 {
@@ -79,6 +83,9 @@ pgrename(const char *from, const char *to)
 }
 
 
+/*
+ *	pgunlink
+ */
 int
 pgunlink(const char *path)
 {
@@ -110,12 +117,119 @@ pgunlink(const char *path)
 	return 0;
 }
 
+
+/*
+ *	pgsymlink support:
+ *
+ *	This struct is a replacement for REPARSE_DATA_BUFFER which is defined in VC6 winnt.h
+ *	but omitted in later SDK functions.
+ *	We only need the SymbolicLinkReparseBuffer part of the original struct's union.
+ */
+typedef struct
+{
+    DWORD  ReparseTag;
+    WORD   ReparseDataLength;
+    WORD   Reserved;
+    /* SymbolicLinkReparseBuffer */
+        WORD   SubstituteNameOffset;
+        WORD   SubstituteNameLength;
+        WORD   PrintNameOffset;
+        WORD   PrintNameLength;
+        WCHAR PathBuffer[1];
+}
+REPARSE_JUNCTION_DATA_BUFFER;
+
+#define REPARSE_JUNCTION_DATA_BUFFER_HEADER_SIZE   \
+		FIELD_OFFSET(REPARSE_JUNCTION_DATA_BUFFER, SubstituteNameOffset)
+
+
+/*
+ *	pgsymlink - uses Win32 junction points
+ *
+ *	For reference:	http://www.codeproject.com/w2k/junctionpoints.asp
+ */
+int
+pgsymlink(const char *oldpath, const char *newpath)
+{
+	HANDLE dirhandle;
+	DWORD len;
+	char *p = nativeTarget;
+	char buffer[MAX_PATH*sizeof(WCHAR) + sizeof(REPARSE_JUNCTION_DATA_BUFFER)];
+	char nativeTarget[MAX_PATH];
+	REPARSE_JUNCTION_DATA_BUFFER *reparseBuf = (REPARSE_JUNCTION_DATA_BUFFER*)buffer;
+    
+	CreateDirectory(newpath, 0);
+	dirhandle = CreateFile(newpath, GENERIC_READ | GENERIC_WRITE, 
+			0, 0, OPEN_EXISTING, 
+			FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS, 0);
+    
+	if (dirhandle == INVALID_HANDLE_VALUE)
+		return -1;
+    
+	/* make sure we have an unparsed native win32 path */
+	if (memcmp("\\??\\", oldpath, 4))
+		sprintf(nativeTarget, "\\??\\%s", oldpath);
+	else
+		strcpy(nativeTarget, oldpath);
+    
+	while ((p = strchr(p, '/')) != 0)
+		*p++ = '\\';
+
+	len = strlen(nativeTarget) * sizeof(WCHAR);
+	reparseBuf->ReparseTag = IO_REPARSE_TAG_MOUNT_POINT;
+	reparseBuf->ReparseDataLength = len + 12;
+	reparseBuf->Reserved = 0;
+	reparseBuf->SubstituteNameOffset = 0;
+	reparseBuf->SubstituteNameLength = len;
+	reparseBuf->PrintNameOffset = len+sizeof(WCHAR);
+	reparseBuf->PrintNameLength = 0;
+	MultiByteToWideChar(CP_ACP, 0, nativeTarget, -1,
+						reparseBuf->PathBuffer, MAX_PATH);
+    
+	/*
+	 * FSCTL_SET_REPARSE_POINT is coded differently depending on SDK version;
+	 * we use our own definition
+	 */
+	if (!DeviceIoControl(dirhandle, 
+		CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 41, METHOD_BUFFERED, FILE_ANY_ACCESS),
+		reparseBuf, 
+		reparseBuf->ReparseDataLength + REPARSE_JUNCTION_DATA_BUFFER_HEADER_SIZE,
+		0, 0, &len, 0))
+	{
+		LPSTR msg;
+
+		errno=0;
+		FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
+					  NULL, GetLastError(), 
+					  MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+					  (LPSTR)&msg, 0, NULL );
+		ereport(ERROR, (errcode_for_file_access(),
+			errmsg("Error setting junction for %s: %s", nativeTarget, msg)));
+	    
+		LocalFree(msg);
+	    
+		CloseHandle(dirhandle);
+		RemoveDirectory(newpath);
+		return -1;
+	}
+
+	CloseHandle(dirhandle);
+
+	return 0;
+}
+
 #endif
 
+
+/* ----------------
+ *	rmtree routines
+ * ----------------
+ */
+
+
+/* We undefined these above, so we redefine them */
 #if defined(WIN32) || defined(__CYGWIN__)
-#define rmt_unlink(path) pgunlink(path)
-#else
-#define rmt_unlink(path) unlink(path)
+#define unlink(path)	pgunlink(path)
 #endif
 
 #ifdef FRONTEND
@@ -175,16 +289,15 @@ rmt_cleanup(char ** filenames)
 	xfree(filenames);
 }
 
-
-
 /*
- * delete a directory tree recursively
- * assumes path points to a valid directory
- * deletes everything under path
- * if rmtopdir is true deletes the directory too
+ *	rmtree
+ *
+ *	Delete a directory tree recursively.
+ *	Assumes path points to a valid directory.
+ *	Deletes everything under path.
+ *	If rmtopdir is true deletes the directory too.
  *
  */
-
 bool
 rmtree(char *path, bool rmtopdir)
 {
@@ -249,7 +362,7 @@ rmtree(char *path, bool rmtopdir)
 		}
 		else
 		{
-			if (rmt_unlink(filepath) != 0)
+			if (unlink(filepath) != 0)
 			{
 				rmt_cleanup(filenames);
 				return false;