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postgresql/src/interfaces/libpq/fe-lobj.c

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/*-------------------------------------------------------------------------
*
* fe-lobj.c
* Front-end large object interface
*
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/interfaces/libpq/fe-lobj.c
*
*-------------------------------------------------------------------------
*/
#ifdef WIN32
/*
* As unlink/rename are #define'd in port.h (via postgres_fe.h), io.h
* must be included first on MS C. Might as well do it for all WIN32's
* here.
*/
#include <io.h>
#endif
#include "postgres_fe.h"
#ifdef WIN32
#include "win32.h"
#else
#include <unistd.h>
#endif
#include <fcntl.h>
#include <sys/stat.h>
#include "libpq-fe.h"
#include "libpq-int.h"
#include "libpq/libpq-fs.h" /* must come after sys/stat.h */
#define LO_BUFSIZE 8192
static int lo_initialize(PGconn *conn);
static Oid
lo_import_internal(PGconn *conn, const char *filename, const Oid oid);
/*
* lo_open
* opens an existing large object
*
* returns the file descriptor for use in later lo_* calls
* return -1 upon failure.
*/
int
lo_open(PGconn *conn, Oid lobjId, int mode)
{
int fd;
int result_len;
PQArgBlock argv[2];
PGresult *res;
if (conn->lobjfuncs == NULL)
{
if (lo_initialize(conn) < 0)
return -1;
}
argv[0].isint = 1;
argv[0].len = 4;
argv[0].u.integer = lobjId;
argv[1].isint = 1;
argv[1].len = 4;
argv[1].u.integer = mode;
res = PQfn(conn, conn->lobjfuncs->fn_lo_open, &fd, &result_len, 1, argv, 2);
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return fd;
}
else
{
PQclear(res);
return -1;
}
}
/*
* lo_close
* closes an existing large object
*
* returns 0 upon success
* returns -1 upon failure.
*/
int
lo_close(PGconn *conn, int fd)
{
PQArgBlock argv[1];
PGresult *res;
int retval;
int result_len;
if (conn->lobjfuncs == NULL)
{
if (lo_initialize(conn) < 0)
return -1;
}
argv[0].isint = 1;
argv[0].len = 4;
argv[0].u.integer = fd;
res = PQfn(conn, conn->lobjfuncs->fn_lo_close,
&retval, &result_len, 1, argv, 1);
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return retval;
}
else
{
PQclear(res);
return -1;
}
}
/*
* lo_truncate
* truncates an existing large object to the given size
*
* returns 0 upon success
* returns -1 upon failure
*/
int
lo_truncate(PGconn *conn, int fd, size_t len)
{
PQArgBlock argv[2];
PGresult *res;
int retval;
int result_len;
if (conn->lobjfuncs == NULL)
{
if (lo_initialize(conn) < 0)
return -1;
}
/* Must check this on-the-fly because it's not there pre-8.3 */
if (conn->lobjfuncs->fn_lo_truncate == 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("cannot determine OID of function lo_truncate\n"));
return -1;
}
argv[0].isint = 1;
argv[0].len = 4;
argv[0].u.integer = fd;
argv[1].isint = 1;
argv[1].len = 4;
argv[1].u.integer = len;
res = PQfn(conn, conn->lobjfuncs->fn_lo_truncate,
&retval, &result_len, 1, argv, 2);
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return retval;
}
else
{
PQclear(res);
return -1;
}
}
/*
* lo_read
* read len bytes of the large object into buf
*
* returns the number of bytes read, or -1 on failure.
* the CALLER must have allocated enough space to hold the result returned
*/
int
lo_read(PGconn *conn, int fd, char *buf, size_t len)
{
PQArgBlock argv[2];
PGresult *res;
int result_len;
if (conn->lobjfuncs == NULL)
{
if (lo_initialize(conn) < 0)
return -1;
}
argv[0].isint = 1;
argv[0].len = 4;
argv[0].u.integer = fd;
argv[1].isint = 1;
argv[1].len = 4;
argv[1].u.integer = len;
res = PQfn(conn, conn->lobjfuncs->fn_lo_read,
(int *) buf, &result_len, 0, argv, 2);
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return result_len;
}
else
{
PQclear(res);
return -1;
}
}
/*
* lo_write
* write len bytes of buf into the large object fd
*
* returns the number of bytes written, or -1 on failure.
*/
int
lo_write(PGconn *conn, int fd, const char *buf, size_t len)
{
PQArgBlock argv[2];
PGresult *res;
int result_len;
int retval;
if (conn->lobjfuncs == NULL)
{
if (lo_initialize(conn) < 0)
return -1;
}
if (len <= 0)
return 0;
argv[0].isint = 1;
argv[0].len = 4;
argv[0].u.integer = fd;
argv[1].isint = 0;
argv[1].len = len;
argv[1].u.ptr = (int *) buf;
res = PQfn(conn, conn->lobjfuncs->fn_lo_write,
&retval, &result_len, 1, argv, 2);
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return retval;
}
else
{
PQclear(res);
return -1;
}
}
/*
* lo_lseek
* change the current read or write location on a large object
* currently, only L_SET is a legal value for whence
*
*/
int
lo_lseek(PGconn *conn, int fd, int offset, int whence)
{
PQArgBlock argv[3];
PGresult *res;
int retval;
int result_len;
if (conn->lobjfuncs == NULL)
{
if (lo_initialize(conn) < 0)
return -1;
}
argv[0].isint = 1;
argv[0].len = 4;
argv[0].u.integer = fd;
argv[1].isint = 1;
argv[1].len = 4;
argv[1].u.integer = offset;
argv[2].isint = 1;
argv[2].len = 4;
argv[2].u.integer = whence;
res = PQfn(conn, conn->lobjfuncs->fn_lo_lseek,
&retval, &result_len, 1, argv, 3);
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return retval;
}
else
{
PQclear(res);
return -1;
}
}
/*
* lo_creat
* create a new large object
* the mode is ignored (once upon a time it had a use)
*
* returns the oid of the large object created or
* InvalidOid upon failure
*/
Oid
lo_creat(PGconn *conn, int mode)
{
PQArgBlock argv[1];
PGresult *res;
int retval;
int result_len;
if (conn->lobjfuncs == NULL)
{
if (lo_initialize(conn) < 0)
return InvalidOid;
}
argv[0].isint = 1;
argv[0].len = 4;
argv[0].u.integer = mode;
res = PQfn(conn, conn->lobjfuncs->fn_lo_creat,
&retval, &result_len, 1, argv, 1);
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return (Oid) retval;
}
else
{
PQclear(res);
return InvalidOid;
}
}
/*
* lo_create
* create a new large object
* if lobjId isn't InvalidOid, it specifies the OID to (attempt to) create
*
* returns the oid of the large object created or
* InvalidOid upon failure
*/
Oid
lo_create(PGconn *conn, Oid lobjId)
{
PQArgBlock argv[1];
PGresult *res;
int retval;
int result_len;
if (conn->lobjfuncs == NULL)
{
if (lo_initialize(conn) < 0)
return InvalidOid;
}
/* Must check this on-the-fly because it's not there pre-8.1 */
if (conn->lobjfuncs->fn_lo_create == 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("cannot determine OID of function lo_create\n"));
return InvalidOid;
}
argv[0].isint = 1;
argv[0].len = 4;
argv[0].u.integer = lobjId;
res = PQfn(conn, conn->lobjfuncs->fn_lo_create,
&retval, &result_len, 1, argv, 1);
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return (Oid) retval;
}
else
{
PQclear(res);
return InvalidOid;
}
}
/*
* lo_tell
* returns the current seek location of the large object
*
*/
int
lo_tell(PGconn *conn, int fd)
{
int retval;
PQArgBlock argv[1];
PGresult *res;
int result_len;
if (conn->lobjfuncs == NULL)
{
if (lo_initialize(conn) < 0)
return -1;
}
argv[0].isint = 1;
argv[0].len = 4;
argv[0].u.integer = fd;
res = PQfn(conn, conn->lobjfuncs->fn_lo_tell,
&retval, &result_len, 1, argv, 1);
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return retval;
}
else
{
PQclear(res);
return -1;
}
}
/*
* lo_unlink
* delete a file
*
*/
int
lo_unlink(PGconn *conn, Oid lobjId)
{
PQArgBlock argv[1];
PGresult *res;
int result_len;
int retval;
if (conn->lobjfuncs == NULL)
{
if (lo_initialize(conn) < 0)
return -1;
}
argv[0].isint = 1;
argv[0].len = 4;
argv[0].u.integer = lobjId;
res = PQfn(conn, conn->lobjfuncs->fn_lo_unlink,
&retval, &result_len, 1, argv, 1);
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return retval;
}
else
{
PQclear(res);
return -1;
}
}
/*
* lo_import -
* imports a file as an (inversion) large object.
*
* returns the oid of that object upon success,
* returns InvalidOid upon failure
*/
Oid
lo_import(PGconn *conn, const char *filename)
{
return lo_import_internal(conn, filename, InvalidOid);
}
/*
* lo_import_with_oid -
* imports a file as an (inversion) large object.
* large object id can be specified.
*
* returns the oid of that object upon success,
* returns InvalidOid upon failure
*/
Oid
lo_import_with_oid(PGconn *conn, const char *filename, Oid lobjId)
{
return lo_import_internal(conn, filename, lobjId);
}
static Oid
lo_import_internal(PGconn *conn, const char *filename, const Oid oid)
{
int fd;
int nbytes,
tmp;
char buf[LO_BUFSIZE];
Oid lobjOid;
int lobj;
char sebuf[256];
/*
* open the file to be read in
*/
fd = open(filename, O_RDONLY | PG_BINARY, 0666);
if (fd < 0)
{ /* error */
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not open file \"%s\": %s\n"),
filename, pqStrerror(errno, sebuf, sizeof(sebuf)));
return InvalidOid;
}
/*
* create an inversion object
*/
if (oid == InvalidOid)
lobjOid = lo_creat(conn, INV_READ | INV_WRITE);
else
lobjOid = lo_create(conn, oid);
if (lobjOid == InvalidOid)
{
/* we assume lo_create() already set a suitable error message */
(void) close(fd);
return InvalidOid;
}
lobj = lo_open(conn, lobjOid, INV_WRITE);
if (lobj == -1)
{
/* we assume lo_open() already set a suitable error message */
(void) close(fd);
return InvalidOid;
}
/*
* read in from the file and write to the large object
*/
while ((nbytes = read(fd, buf, LO_BUFSIZE)) > 0)
{
tmp = lo_write(conn, lobj, buf, nbytes);
if (tmp != nbytes)
{
/*
* If lo_write() failed, we are now in an aborted transaction so
* there's no need for lo_close(); furthermore, if we tried it
* we'd overwrite the useful error result with a useless one. So
* just nail the doors shut and get out of town.
*/
(void) close(fd);
return InvalidOid;
}
}
if (nbytes < 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not read from file \"%s\": %s\n"),
filename, pqStrerror(errno, sebuf, sizeof(sebuf)));
lobjOid = InvalidOid;
}
(void) close(fd);
if (lo_close(conn, lobj) != 0)
{
/* we assume lo_close() already set a suitable error message */
return InvalidOid;
}
return lobjOid;
}
/*
* lo_export -
* exports an (inversion) large object.
* returns -1 upon failure, 1 if OK
*/
int
lo_export(PGconn *conn, Oid lobjId, const char *filename)
{
int result = 1;
int fd;
int nbytes,
tmp;
char buf[LO_BUFSIZE];
int lobj;
char sebuf[256];
/*
* open the large object.
*/
lobj = lo_open(conn, lobjId, INV_READ);
if (lobj == -1)
{
/* we assume lo_open() already set a suitable error message */
return -1;
}
/*
* create the file to be written to
*/
fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC | PG_BINARY, 0666);
if (fd < 0)
{ /* error */
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not open file \"%s\": %s\n"),
filename, pqStrerror(errno, sebuf, sizeof(sebuf)));
(void) lo_close(conn, lobj);
return -1;
}
/*
* read in from the large object and write to the file
*/
while ((nbytes = lo_read(conn, lobj, buf, LO_BUFSIZE)) > 0)
{
tmp = write(fd, buf, nbytes);
if (tmp != nbytes)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not write to file \"%s\": %s\n"),
filename, pqStrerror(errno, sebuf, sizeof(sebuf)));
(void) lo_close(conn, lobj);
(void) close(fd);
return -1;
}
}
/*
* If lo_read() failed, we are now in an aborted transaction so there's no
* need for lo_close(); furthermore, if we tried it we'd overwrite the
* useful error result with a useless one. So skip lo_close() if we got a
* failure result.
*/
if (nbytes < 0 ||
lo_close(conn, lobj) != 0)
{
/* assume lo_read() or lo_close() left a suitable error message */
result = -1;
}
if (close(fd))
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not write to file \"%s\": %s\n"),
filename, pqStrerror(errno, sebuf, sizeof(sebuf)));
result = -1;
}
return result;
}
/*
* lo_initialize
*
* Initialize the large object interface for an existing connection.
* We ask the backend about the functions OID's in pg_proc for all
* functions that are required for large object operations.
*/
static int
lo_initialize(PGconn *conn)
{
PGresult *res;
PGlobjfuncs *lobjfuncs;
int n;
const char *query;
const char *fname;
Oid foid;
/*
* Allocate the structure to hold the functions OID's
*/
lobjfuncs = (PGlobjfuncs *) malloc(sizeof(PGlobjfuncs));
if (lobjfuncs == NULL)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("out of memory\n"));
return -1;
}
MemSet((char *) lobjfuncs, 0, sizeof(PGlobjfuncs));
/*
* Execute the query to get all the functions at once. In 7.3 and later
* we need to be schema-safe. lo_create only exists in 8.1 and up.
* lo_truncate only exists in 8.3 and up.
*/
if (conn->sversion >= 70300)
query = "select proname, oid from pg_catalog.pg_proc "
"where proname in ("
"'lo_open', "
"'lo_close', "
"'lo_creat', "
"'lo_create', "
"'lo_unlink', "
"'lo_lseek', "
"'lo_tell', "
"'lo_truncate', "
"'loread', "
"'lowrite') "
"and pronamespace = (select oid from pg_catalog.pg_namespace "
"where nspname = 'pg_catalog')";
else
query = "select proname, oid from pg_proc "
"where proname = 'lo_open' "
"or proname = 'lo_close' "
"or proname = 'lo_creat' "
"or proname = 'lo_unlink' "
"or proname = 'lo_lseek' "
"or proname = 'lo_tell' "
"or proname = 'loread' "
"or proname = 'lowrite'";
res = PQexec(conn, query);
if (res == NULL)
{
free(lobjfuncs);
return -1;
}
if (res->resultStatus != PGRES_TUPLES_OK)
{
free(lobjfuncs);
PQclear(res);
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("query to initialize large object functions did not return data\n"));
return -1;
}
/*
* Examine the result and put the OID's into the struct
*/
for (n = 0; n < PQntuples(res); n++)
{
fname = PQgetvalue(res, n, 0);
foid = (Oid) atoi(PQgetvalue(res, n, 1));
if (!strcmp(fname, "lo_open"))
lobjfuncs->fn_lo_open = foid;
else if (!strcmp(fname, "lo_close"))
lobjfuncs->fn_lo_close = foid;
else if (!strcmp(fname, "lo_creat"))
lobjfuncs->fn_lo_creat = foid;
else if (!strcmp(fname, "lo_create"))
lobjfuncs->fn_lo_create = foid;
else if (!strcmp(fname, "lo_unlink"))
lobjfuncs->fn_lo_unlink = foid;
else if (!strcmp(fname, "lo_lseek"))
lobjfuncs->fn_lo_lseek = foid;
else if (!strcmp(fname, "lo_tell"))
lobjfuncs->fn_lo_tell = foid;
else if (!strcmp(fname, "lo_truncate"))
lobjfuncs->fn_lo_truncate = foid;
else if (!strcmp(fname, "loread"))
lobjfuncs->fn_lo_read = foid;
else if (!strcmp(fname, "lowrite"))
lobjfuncs->fn_lo_write = foid;
}
PQclear(res);
/*
* Finally check that we really got all large object interface functions
*/
if (lobjfuncs->fn_lo_open == 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("cannot determine OID of function lo_open\n"));
free(lobjfuncs);
return -1;
}
if (lobjfuncs->fn_lo_close == 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("cannot determine OID of function lo_close\n"));
free(lobjfuncs);
return -1;
}
if (lobjfuncs->fn_lo_creat == 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("cannot determine OID of function lo_creat\n"));
free(lobjfuncs);
return -1;
}
if (lobjfuncs->fn_lo_unlink == 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("cannot determine OID of function lo_unlink\n"));
free(lobjfuncs);
return -1;
}
if (lobjfuncs->fn_lo_lseek == 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("cannot determine OID of function lo_lseek\n"));
free(lobjfuncs);
return -1;
}
if (lobjfuncs->fn_lo_tell == 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("cannot determine OID of function lo_tell\n"));
free(lobjfuncs);
return -1;
}
if (lobjfuncs->fn_lo_read == 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("cannot determine OID of function loread\n"));
free(lobjfuncs);
return -1;
}
if (lobjfuncs->fn_lo_write == 0)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("cannot determine OID of function lowrite\n"));
free(lobjfuncs);
return -1;
}
/*
* Put the structure into the connection control
*/
conn->lobjfuncs = lobjfuncs;
return 0;
}
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