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523 lines
12 KiB
C
523 lines
12 KiB
C
/*-------------------------------------------------------------------------
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*
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* be-fsstubs.c
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* support for filesystem operations on large objects
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.34 1999/05/31 22:53:57 tgl Exp $
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*
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* NOTES
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* This should be moved to a more appropriate place. It is here
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* for lack of a better place.
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*
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* Builtin functions for open/close/read/write operations on large objects.
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*
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* These functions operate in a private GlobalMemoryContext, which means
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* that large object descriptors hang around until we destroy the context.
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* That happens in lo_commit(). It'd be possible to prolong the lifetime
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* of the context so that LO FDs are good across transactions (for example,
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* we could release the context only if we see that no FDs remain open).
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* But we'd need additional state in order to do the right thing at the
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* end of an aborted transaction. FDs opened during an aborted xact would
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* still need to be closed, since they might not be pointing at valid
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* relations at all. For now, we'll stick with the existing documented
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* semantics of LO FDs: they're only good within a transaction.
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*
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*-------------------------------------------------------------------------
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*/
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <string.h>
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#include <postgres.h>
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#include <lib/dllist.h>
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#include <libpq/libpq.h>
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#include <libpq/libpq-fs.h>
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#include <nodes/nodes.h>
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#include <utils/memutils.h>
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#include <lib/fstack.h>
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#include <utils/mcxt.h>
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#include <catalog/pg_shadow.h> /* for superuser() */
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#include <storage/fd.h> /* for O_ */
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#include <storage/large_object.h>
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#include <libpq/be-fsstubs.h>
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/* [PA] is Pascal André <andre@via.ecp.fr> */
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/*#define FSDB 1*/
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#define MAX_LOBJ_FDS 256
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#define BUFSIZE 1024
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#define FNAME_BUFSIZE 8192
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static LargeObjectDesc *cookies[MAX_LOBJ_FDS];
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static GlobalMemory fscxt = NULL;
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static int newLOfd(LargeObjectDesc *lobjCookie);
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static void deleteLOfd(int fd);
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/*****************************************************************************
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* File Interfaces for Large Objects
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*****************************************************************************/
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int
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lo_open(Oid lobjId, int mode)
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{
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LargeObjectDesc *lobjDesc;
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int fd;
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MemoryContext currentContext;
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#if FSDB
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elog(NOTICE, "LOopen(%u,%d)", lobjId, mode);
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#endif
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if (fscxt == NULL)
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fscxt = CreateGlobalMemory("Filesystem");
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currentContext = MemoryContextSwitchTo((MemoryContext) fscxt);
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lobjDesc = inv_open(lobjId, mode);
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if (lobjDesc == NULL)
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{ /* lookup failed */
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MemoryContextSwitchTo(currentContext);
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#if FSDB
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elog(NOTICE, "cannot open large object %u", lobjId);
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#endif
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return -1;
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}
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fd = newLOfd(lobjDesc);
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/* switch context back to orig. */
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MemoryContextSwitchTo(currentContext);
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#if FSDB
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if (fd < 0) /* newLOfd couldn't find a slot */
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elog(NOTICE, "Out of space for large object FDs");
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#endif
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return fd;
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}
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int
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lo_close(int fd)
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{
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MemoryContext currentContext;
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if (fd < 0 || fd >= MAX_LOBJ_FDS)
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{
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elog(ERROR, "lo_close: large obj descriptor (%d) out of range", fd);
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return -2;
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}
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if (cookies[fd] == NULL)
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{
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elog(ERROR, "lo_close: invalid large obj descriptor (%d)", fd);
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return -3;
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}
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#if FSDB
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elog(NOTICE, "LOclose(%d)", fd);
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#endif
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Assert(fscxt != NULL);
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currentContext = MemoryContextSwitchTo((MemoryContext) fscxt);
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inv_close(cookies[fd]);
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MemoryContextSwitchTo(currentContext);
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deleteLOfd(fd);
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return 0;
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}
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/*
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* We assume the large object supports byte oriented reads and seeks so
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* that our work is easier.
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*/
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int
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lo_read(int fd, char *buf, int len)
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{
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MemoryContext currentContext;
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int status;
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if (fd < 0 || fd >= MAX_LOBJ_FDS)
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{
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elog(ERROR, "lo_read: large obj descriptor (%d) out of range", fd);
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return -2;
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}
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if (cookies[fd] == NULL)
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{
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elog(ERROR, "lo_read: invalid large obj descriptor (%d)", fd);
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return -3;
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}
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Assert(fscxt != NULL);
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currentContext = MemoryContextSwitchTo((MemoryContext) fscxt);
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status = inv_read(cookies[fd], buf, len);
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MemoryContextSwitchTo(currentContext);
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return (status);
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}
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int
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lo_write(int fd, char *buf, int len)
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{
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MemoryContext currentContext;
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int status;
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if (fd < 0 || fd >= MAX_LOBJ_FDS)
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{
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elog(ERROR, "lo_write: large obj descriptor (%d) out of range", fd);
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return -2;
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}
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if (cookies[fd] == NULL)
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{
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elog(ERROR, "lo_write: invalid large obj descriptor (%d)", fd);
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return -3;
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}
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Assert(fscxt != NULL);
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currentContext = MemoryContextSwitchTo((MemoryContext) fscxt);
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status = inv_write(cookies[fd], buf, len);
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MemoryContextSwitchTo(currentContext);
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return (status);
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}
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int
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lo_lseek(int fd, int offset, int whence)
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{
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MemoryContext currentContext;
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int status;
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if (fd < 0 || fd >= MAX_LOBJ_FDS)
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{
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elog(ERROR, "lo_lseek: large obj descriptor (%d) out of range", fd);
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return -2;
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}
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if (cookies[fd] == NULL)
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{
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elog(ERROR, "lo_lseek: invalid large obj descriptor (%d)", fd);
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return -3;
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}
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Assert(fscxt != NULL);
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currentContext = MemoryContextSwitchTo((MemoryContext) fscxt);
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status = inv_seek(cookies[fd], offset, whence);
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MemoryContextSwitchTo(currentContext);
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return status;
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}
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Oid
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lo_creat(int mode)
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{
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LargeObjectDesc *lobjDesc;
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MemoryContext currentContext;
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Oid lobjId;
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if (fscxt == NULL)
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fscxt = CreateGlobalMemory("Filesystem");
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currentContext = MemoryContextSwitchTo((MemoryContext) fscxt);
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lobjDesc = inv_create(mode);
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if (lobjDesc == NULL)
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{
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MemoryContextSwitchTo(currentContext);
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return InvalidOid;
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}
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lobjId = RelationGetRelid(lobjDesc->heap_r);
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inv_close(lobjDesc);
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/* switch context back to original memory context */
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MemoryContextSwitchTo(currentContext);
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return lobjId;
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}
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int
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lo_tell(int fd)
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{
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if (fd < 0 || fd >= MAX_LOBJ_FDS)
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{
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elog(ERROR, "lo_tell: large object descriptor (%d) out of range", fd);
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return -2;
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}
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if (cookies[fd] == NULL)
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{
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elog(ERROR, "lo_tell: invalid large object descriptor (%d)", fd);
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return -3;
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}
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/*
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* We assume we do not need to switch contexts for inv_tell.
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* That is true for now, but is probably more than this module
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* ought to assume...
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*/
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return inv_tell(cookies[fd]);
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}
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int
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lo_unlink(Oid lobjId)
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{
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/*
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* inv_destroy does not need a context switch, indeed it doesn't
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* touch any LO-specific data structures at all. (Again, that's
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* probably more than this module ought to be assuming.)
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*
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* XXX there ought to be some code to clean up any open LOs that
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* reference the specified relation... as is, they remain "open".
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*/
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return inv_destroy(lobjId);
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}
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/*****************************************************************************
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* Read/Write using varlena
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*****************************************************************************/
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struct varlena *
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loread(int fd, int len)
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{
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struct varlena *retval;
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int totalread = 0;
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retval = (struct varlena *) palloc(VARHDRSZ + len);
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totalread = lo_read(fd, VARDATA(retval), len);
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VARSIZE(retval) = totalread + VARHDRSZ;
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return retval;
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}
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int
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lowrite(int fd, struct varlena * wbuf)
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{
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int totalwritten;
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int bytestowrite;
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bytestowrite = VARSIZE(wbuf) - VARHDRSZ;
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totalwritten = lo_write(fd, VARDATA(wbuf), bytestowrite);
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return totalwritten;
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}
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/*****************************************************************************
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* Import/Export of Large Object
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*****************************************************************************/
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/*
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* lo_import -
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* imports a file as an (inversion) large object.
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*/
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Oid
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lo_import(text *filename)
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{
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File fd;
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int nbytes,
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tmp;
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char buf[BUFSIZE];
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char fnamebuf[FNAME_BUFSIZE];
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LargeObjectDesc *lobj;
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Oid lobjOid;
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if (!superuser())
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elog(ERROR, "You must have Postgres superuser privilege to use "
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"server-side lo_import().\n\tAnyone can use the "
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"client-side lo_import() provided by libpq.");
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/*
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* open the file to be read in
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*/
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nbytes = VARSIZE(filename) - VARHDRSZ + 1;
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if (nbytes > FNAME_BUFSIZE)
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nbytes = FNAME_BUFSIZE;
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StrNCpy(fnamebuf, VARDATA(filename), nbytes);
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#ifndef __CYGWIN32__
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fd = PathNameOpenFile(fnamebuf, O_RDONLY, 0666);
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#else
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fd = PathNameOpenFile(fnamebuf, O_RDONLY | O_BINARY, 0666);
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#endif
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if (fd < 0)
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{ /* error */
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elog(ERROR, "lo_import: can't open unix file \"%s\": %m",
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fnamebuf);
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}
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/*
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* create an inversion "object"
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*/
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lobj = inv_create(INV_READ | INV_WRITE);
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if (lobj == NULL)
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{
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elog(ERROR, "lo_import: can't create inv object for \"%s\"",
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fnamebuf);
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}
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/*
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* the oid for the large object is just the oid of the relation
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* XInv??? which contains the data.
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*/
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lobjOid = RelationGetRelid(lobj->heap_r);
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/*
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* read in from the Unix file and write to the inversion file
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*/
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while ((nbytes = FileRead(fd, buf, BUFSIZE)) > 0)
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{
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tmp = inv_write(lobj, buf, nbytes);
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if (tmp < nbytes)
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elog(ERROR, "lo_import: error while reading \"%s\"",
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fnamebuf);
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}
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FileClose(fd);
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inv_close(lobj);
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return lobjOid;
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}
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/*
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* lo_export -
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* exports an (inversion) large object.
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*/
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int4
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lo_export(Oid lobjId, text *filename)
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{
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File fd;
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int nbytes,
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tmp;
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char buf[BUFSIZE];
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char fnamebuf[FNAME_BUFSIZE];
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LargeObjectDesc *lobj;
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mode_t oumask;
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if (!superuser())
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elog(ERROR, "You must have Postgres superuser privilege to use "
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"server-side lo_export().\n\tAnyone can use the "
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"client-side lo_export() provided by libpq.");
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/*
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* open the inversion "object"
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*/
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lobj = inv_open(lobjId, INV_READ);
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if (lobj == NULL)
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elog(ERROR, "lo_export: can't open inv object %u", lobjId);
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/*
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* open the file to be written to
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*
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* Note: we reduce backend's normal 077 umask to the slightly
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* friendlier 022. This code used to drop it all the way to 0,
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* but creating world-writable export files doesn't seem wise.
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*/
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nbytes = VARSIZE(filename) - VARHDRSZ + 1;
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if (nbytes > FNAME_BUFSIZE)
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nbytes = FNAME_BUFSIZE;
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StrNCpy(fnamebuf, VARDATA(filename), nbytes);
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oumask = umask((mode_t) 0022);
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#ifndef __CYGWIN32__
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fd = PathNameOpenFile(fnamebuf, O_CREAT | O_WRONLY | O_TRUNC, 0666);
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#else
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fd = PathNameOpenFile(fnamebuf, O_CREAT | O_WRONLY | O_TRUNC | O_BINARY, 0666);
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#endif
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umask(oumask);
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if (fd < 0)
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{ /* error */
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elog(ERROR, "lo_export: can't open unix file \"%s\": %m",
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fnamebuf);
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}
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/*
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* read in from the Unix file and write to the inversion file
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*/
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while ((nbytes = inv_read(lobj, buf, BUFSIZE)) > 0)
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{
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tmp = FileWrite(fd, buf, nbytes);
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if (tmp < nbytes)
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elog(ERROR, "lo_export: error while writing \"%s\"",
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fnamebuf);
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}
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inv_close(lobj);
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FileClose(fd);
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return 1;
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}
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/*
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* lo_commit -
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* prepares large objects for transaction commit [PA, 7/17/98]
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*/
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void
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lo_commit(bool isCommit)
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{
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int i;
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MemoryContext currentContext;
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if (fscxt == NULL)
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return; /* no LO operations in this xact */
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currentContext = MemoryContextSwitchTo((MemoryContext) fscxt);
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/* Clean out still-open index scans (not necessary if aborting)
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* and clear cookies array so that LO fds are no longer good.
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*/
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for (i = 0; i < MAX_LOBJ_FDS; i++)
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{
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if (cookies[i] != NULL)
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{
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if (isCommit)
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inv_cleanindex(cookies[i]);
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cookies[i] = NULL;
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}
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}
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MemoryContextSwitchTo(currentContext);
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/* Release the LO memory context to prevent permanent memory leaks. */
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GlobalMemoryDestroy(fscxt);
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fscxt = NULL;
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}
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/*****************************************************************************
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* Support routines for this file
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*****************************************************************************/
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static int
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newLOfd(LargeObjectDesc *lobjCookie)
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{
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int i;
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for (i = 0; i < MAX_LOBJ_FDS; i++)
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{
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if (cookies[i] == NULL)
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{
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cookies[i] = lobjCookie;
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return i;
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}
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}
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return -1;
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}
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static void
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deleteLOfd(int fd)
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{
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cookies[fd] = NULL;
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}
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