Add 'temporary file' facility to fd.c, and arrange for temp

files to be closed automatically at transaction abort or commit, should
they still be open.  Also close any still-open stdio files allocated with
AllocateFile at abort/commit.  This should eliminate problems with leakage
of file descriptors after an error.  Also, put in some primitive buffered-IO
support so that psort.c can use virtual files without severe performance
penalties.

src/backend/access/transam/xact.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.33 1999/03/28 20:31:59 vadim Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.34 1999/05/09 00:52:08 tgl Exp $
  *
  * NOTES
  *		Transaction aborts can now occur two ways:
@@ -148,6 +148,7 @@
 #include <utils/inval.h>
 #include <utils/portal.h>
 #include <access/transam.h>
+#include <storage/fd.h>
 #include <storage/proc.h>
 #include <utils/mcxt.h>
 #include <catalog/heap.h>
@@ -920,6 +921,7 @@ CommitTransaction()
 	AtCommit_Cache();
 	AtCommit_Locks();
 	AtCommit_Memory();
+	AtEOXact_Files();
 
 	/* ----------------
 	 *	done with commit processing, set current transaction
@@ -990,6 +992,7 @@ AbortTransaction()
 	AtAbort_Cache();
 	AtAbort_Locks();
 	AtAbort_Memory();
+	AtEOXact_Files();
 
 	/* ----------------
 	 *	done with abort processing, set current transaction

src/include/storage/fd.h

@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: fd.h,v 1.12 1999/02/13 23:22:05 momjian Exp $
+ * $Id: fd.h,v 1.13 1999/05/09 00:52:06 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -17,19 +17,23 @@
  *	{File Name Open, Allocate, Free} File
  *
  * These are NOT JUST RENAMINGS OF THE UNIX ROUTINES.
- * use them for all file activity...
+ * Use them for all file activity...
  *
- *	fd = FilePathOpenFile("foo", O_RDONLY);
  *	File fd;
- *
+ *	fd = FilePathOpenFile("foo", O_RDONLY);
- * use AllocateFile if you need a file descriptor in some other context.
- * it will make sure that there is a file descriptor free
- *
- * use FreeFile to let the virtual file descriptor package know that
- * there is now a free fd (when you are done with it)
  *
  *	AllocateFile();
  *	FreeFile();
+ *
+ * Use AllocateFile, not fopen, if you need a stdio file (FILE*); then
+ * use FreeFile, not fclose, to close it.  AVOID using stdio for files
+ * that you intend to hold open for any length of time, since there is
+ * no way for them to share kernel file descriptors with other files.
+ *
+ * The BufFile routines provide a partial replacement for stdio.  Currently
+ * they only support buffered access to a virtual file, without any of
+ * stdio's formatting features.  That's enough for immediate needs, but
+ * the set of facilities could be expanded if necessary.
  */
 #ifndef FD_H
 #define FD_H
@@ -44,7 +48,11 @@ typedef char *FileName;
 
 typedef int File;
 
-/* originally in libpq-fs.h */
+/* BufFile is an opaque type whose details are not known outside fd.c. */
+
+typedef struct BufFile BufFile;
+
+/* why is this here? fd.c doesn't want it ... */
 struct pgstat
 {								/* just the fields we need from stat
 								 * structure */
@@ -62,8 +70,11 @@ struct pgstat
 /*
  * prototypes for functions in fd.c
  */
+
+/* Operations on virtual Files --- equivalent to Unix kernel file ops */
 extern File FileNameOpenFile(FileName fileName, int fileFlags, int fileMode);
 extern File PathNameOpenFile(FileName fileName, int fileFlags, int fileMode);
+extern File OpenTemporaryFile(void);
 extern void FileClose(File file);
 extern void FileUnlink(File file);
 extern int	FileRead(File file, char *buffer, int amount);
@@ -71,10 +82,25 @@ extern int	FileWrite(File file, char *buffer, int amount);
 extern long FileSeek(File file, long offset, int whence);
 extern int	FileTruncate(File file, int offset);
 extern int	FileSync(File file);
-extern int	FileNameUnlink(char *filename);
+
+/* Operations that allow use of regular stdio --- USE WITH CAUTION */
 extern FILE *AllocateFile(char *name, char *mode);
 extern void FreeFile(FILE *);
+
+/* Operations on BufFiles --- a very incomplete emulation of stdio
+ * atop virtual Files...
+ */
+extern BufFile *BufFileCreate(File file);
+extern void BufFileClose(BufFile *file);
+extern size_t BufFileRead(BufFile *file, void *ptr, size_t size);
+extern size_t BufFileWrite(BufFile *file, void *ptr, size_t size);
+extern int BufFileFlush(BufFile *file);
+extern long BufFileSeek(BufFile *file, long offset, int whence);
+
+/* Miscellaneous support routines */
+extern int	FileNameUnlink(char *filename);
 extern void closeAllVfds(void);
+extern void AtEOXact_Files(void);
 extern int	pg_fsync(int fd);
 
 #endif	 /* FD_H */