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docs: Update libpq and testlo examples

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Josh Kupershmidt
This commit is contained in:
Bruce Momjian 2013-09-10 21:03:11 -04:00
parent 0f59f4a645
commit 2885006afc
2 changed files with 85 additions and 60 deletions
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27
doc/src/sgml/libpq.sgml
View File

@ -7906,12 +7906,17 @@ main(int argc, char **argv)
* *
* INSERT INTO TBL1 VALUES (10); * INSERT INTO TBL1 VALUES (10);
*/ */
#ifdef WIN32
#include <windows.h>
#endif
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
#include <string.h> #include <string.h>
#include <errno.h> #include <errno.h>
#include <sys/time.h> #include <sys/time.h>
#include <libpq-fe.h> #include <sys/types.h>
#include "libpq-fe.h"
static void static void
exit_nicely(PGconn *conn) exit_nicely(PGconn *conn)
@ -8045,11 +8050,17 @@ main(int argc, char **argv)
* t = (8 bytes) 'ho there' * t = (8 bytes) 'ho there'
* b = (5 bytes) \004\003\002\001\000 * b = (5 bytes) \004\003\002\001\000
*/ */
#ifdef WIN32
#include <windows.h>
#endif
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
#include <stdint.h>
#include <string.h> #include <string.h>
#include <sys/types.h> #include <sys/types.h>
#include <libpq-fe.h> #include "libpq-fe.h"
/* for ntohl/htonl */ /* for ntohl/htonl */
#include <netinet/in.h> #include <netinet/in.h>
@ -8160,10 +8171,10 @@ main(int argc, char **argv)
* out-of-line parameters, as well as binary transmission of data. * out-of-line parameters, as well as binary transmission of data.
* *
* This first example transmits the parameters as text, but receives the * This first example transmits the parameters as text, but receives the
* results in binary format. By using out-of-line parameters we can * results in binary format. By using out-of-line parameters we can avoid
* avoid a lot of tedious mucking about with quoting and escaping, even * a lot of tedious mucking about with quoting and escaping, even though
* though the data is text. Notice how we don't have to do anything * the data is text. Notice how we don't have to do anything special with
* special with the quote mark in the parameter value. * the quote mark in the parameter value.
*/ */
/* Here is our out-of-line parameter value */ /* Here is our out-of-line parameter value */
@ -8190,8 +8201,8 @@ main(int argc, char **argv)
PQclear(res); PQclear(res);
/* /*
* In this second example we transmit an integer parameter in binary * In this second example we transmit an integer parameter in binary form,
* form, and again retrieve the results in binary form. * and again retrieve the results in binary form.
* *
* Although we tell PQexecParams we are letting the backend deduce * Although we tell PQexecParams we are letting the backend deduce
* parameter type, we really force the decision by casting the parameter * parameter type, we really force the decision by casting the parameter

118
doc/src/sgml/lobj.sgml
View File

@ -597,27 +597,39 @@ SELECT lo_export(image.raster, '/tmp/motd') FROM image
<example id="lo-example"> <example id="lo-example">
<title>Large Objects with <application>libpq</application> Example Program</title> <title>Large Objects with <application>libpq</application> Example Program</title>
<programlisting><![CDATA[ <programlisting><![CDATA[
/*-------------------------------------------------------------- /*-------------------------------------------------------------------------
* *
* testlo.c-- * testlo.c
* test using large objects with libpq * test using large objects with libpq
* *
* Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
* *
*-------------------------------------------------------------- *
* IDENTIFICATION
* src/test/examples/testlo.c
*
*-------------------------------------------------------------------------
*/ */
#include <stdio.h> #include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "libpq-fe.h" #include "libpq-fe.h"
#include "libpq/libpq-fs.h" #include "libpq/libpq-fs.h"
#define BUFSIZE 1024 #define BUFSIZE 1024
/* /*
* importFile * importFile -
* import file "in_filename" into database as large object "lobjOid" * import file "in_filename" into database as large object "lobjOid"
* *
*/ */
Oid static Oid
importFile(PGconn *conn, char *filename) importFile(PGconn *conn, char *filename)
{ {
Oid lobjId; Oid lobjId;
@ -633,7 +645,7 @@ importFile(PGconn *conn, char *filename)
fd = open(filename, O_RDONLY, 0666); fd = open(filename, O_RDONLY, 0666);
if (fd < 0) if (fd < 0)
{ /* error */ { /* error */
fprintf(stderr, "cannot open unix file %s\n", filename); fprintf(stderr, "cannot open unix file\"%s\"\n", filename);
} }
/* /*
@ -641,7 +653,7 @@ importFile(PGconn *conn, char *filename)
*/ */
lobjId = lo_creat(conn, INV_READ | INV_WRITE); lobjId = lo_creat(conn, INV_READ | INV_WRITE);
if (lobjId == 0) if (lobjId == 0)
fprintf(stderr, "cannot create large object\n"); fprintf(stderr, "cannot create large object");
lobj_fd = lo_open(conn, lobjId, INV_WRITE); lobj_fd = lo_open(conn, lobjId, INV_WRITE);
@ -652,16 +664,16 @@ importFile(PGconn *conn, char *filename)
{ {
tmp = lo_write(conn, lobj_fd, buf, nbytes); tmp = lo_write(conn, lobj_fd, buf, nbytes);
if (tmp < nbytes) if (tmp < nbytes)
fprintf(stderr, "error while reading large object\n"); fprintf(stderr, "error while reading \"%s\"", filename);
} }
(void) close(fd); close(fd);
(void) lo_close(conn, lobj_fd); lo_close(conn, lobj_fd);
return lobjId; return lobjId;
} }
void static void
pickout(PGconn *conn, Oid lobjId, int start, int len) pickout(PGconn *conn, Oid lobjId, int start, int len)
{ {
int lobj_fd; int lobj_fd;
@ -671,10 +683,7 @@ pickout(PGconn *conn, Oid lobjId, int start, int len)
lobj_fd = lo_open(conn, lobjId, INV_READ); lobj_fd = lo_open(conn, lobjId, INV_READ);
if (lobj_fd < 0) if (lobj_fd < 0)
{ fprintf(stderr, "cannot open large object %u", lobjId);
fprintf(stderr, "cannot open large object %d\n",
lobjId);
}
lo_lseek(conn, lobj_fd, start, SEEK_SET); lo_lseek(conn, lobj_fd, start, SEEK_SET);
buf = malloc(len + 1); buf = malloc(len + 1);
@ -683,16 +692,18 @@ pickout(PGconn *conn, Oid lobjId, int start, int len)
while (len - nread > 0) while (len - nread > 0)
{ {
nbytes = lo_read(conn, lobj_fd, buf, len - nread); nbytes = lo_read(conn, lobj_fd, buf, len - nread);
buf[nbytes] = ' '; buf[nbytes] = '\0';
fprintf(stderr, ">>> %s", buf); fprintf(stderr, ">>> %s", buf);
nread += nbytes; nread += nbytes;
if (nbytes <= 0)
break; /* no more data? */
} }
free(buf); free(buf);
fprintf(stderr, "\n"); fprintf(stderr, "\n");
lo_close(conn, lobj_fd); lo_close(conn, lobj_fd);
} }
void static void
overwrite(PGconn *conn, Oid lobjId, int start, int len) overwrite(PGconn *conn, Oid lobjId, int start, int len)
{ {
int lobj_fd; int lobj_fd;
@ -703,35 +714,38 @@ overwrite(PGconn *conn, Oid lobjId, int start, int len)
lobj_fd = lo_open(conn, lobjId, INV_WRITE); lobj_fd = lo_open(conn, lobjId, INV_WRITE);
if (lobj_fd < 0) if (lobj_fd < 0)
{ fprintf(stderr, "cannot open large object %u", lobjId);
fprintf(stderr, "cannot open large object %d\n",
lobjId);
}
lo_lseek(conn, lobj_fd, start, SEEK_SET); lo_lseek(conn, lobj_fd, start, SEEK_SET);
buf = malloc(len + 1); buf = malloc(len + 1);
for (i = 0; i < len; i++) for (i = 0; i < len; i++)
buf[i] = 'X'; buf[i] = 'X';
buf[i] = ' '; buf[i] = '\0';
nwritten = 0; nwritten = 0;
while (len - nwritten > 0) while (len - nwritten > 0)
{ {
nbytes = lo_write(conn, lobj_fd, buf + nwritten, len - nwritten); nbytes = lo_write(conn, lobj_fd, buf + nwritten, len - nwritten);
nwritten += nbytes; nwritten += nbytes;
if (nbytes <= 0)
{
fprintf(stderr, "\nWRITE FAILED!\n");
break;
}
} }
free(buf); free(buf);
fprintf(stderr, "\n"); fprintf(stderr, "\n");
lo_close(conn, lobj_fd); lo_close(conn, lobj_fd);
} }
/* /*
* exportFile * exportFile -
* export large object "lobjOid" to file "out_filename" * export large object "lobjOid" to file "out_filename"
* *
*/ */
void static void
exportFile(PGconn *conn, Oid lobjId, char *filename) exportFile(PGconn *conn, Oid lobjId, char *filename)
{ {
int lobj_fd; int lobj_fd;
@ -745,18 +759,15 @@ exportFile(PGconn *conn, Oid lobjId, char *filename)
*/ */
lobj_fd = lo_open(conn, lobjId, INV_READ); lobj_fd = lo_open(conn, lobjId, INV_READ);
if (lobj_fd < 0) if (lobj_fd < 0)
{ fprintf(stderr, "cannot open large object %u", lobjId);
fprintf(stderr, "cannot open large object %d\n",
lobjId);
}
/* /*
* open the file to be written to * open the file to be written to
*/ */
fd = open(filename, O_CREAT | O_WRONLY, 0666); fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0666);
if (fd < 0) if (fd < 0)
{ /* error */ { /* error */
fprintf(stderr, "cannot open unix file %s\n", fprintf(stderr, "cannot open unix file\"%s\"",
filename); filename);
} }
@ -768,18 +779,18 @@ exportFile(PGconn *conn, Oid lobjId, char *filename)
tmp = write(fd, buf, nbytes); tmp = write(fd, buf, nbytes);
if (tmp < nbytes) if (tmp < nbytes)
{ {
fprintf(stderr, "error while writing %s\n", fprintf(stderr, "error while writing \"%s\"",
filename); filename);
} }
} }
(void) lo_close(conn, lobj_fd); lo_close(conn, lobj_fd);
(void) close(fd); close(fd);
return; return;
} }
void static void
exit_nicely(PGconn *conn) exit_nicely(PGconn *conn)
{ {
PQfinish(conn); PQfinish(conn);
@ -813,37 +824,40 @@ main(int argc, char **argv)
conn = PQsetdb(NULL, NULL, NULL, NULL, database); conn = PQsetdb(NULL, NULL, NULL, NULL, database);
/* check to see that the backend connection was successfully made */ /* check to see that the backend connection was successfully made */
if (PQstatus(conn) == CONNECTION_BAD) if (PQstatus(conn) != CONNECTION_OK)
{ {
fprintf(stderr, "Connection to database '%s' failed.\n", database); fprintf(stderr, "Connection to database failed: %s",
fprintf(stderr, "%s", PQerrorMessage(conn)); PQerrorMessage(conn));
exit_nicely(conn); exit_nicely(conn);
} }
res = PQexec(conn, "begin"); res = PQexec(conn, "begin");
PQclear(res); PQclear(res);
printf("importing file \"%s\" ...\n", in_filename);
printf("importing file %s\n", in_filename);
/* lobjOid = importFile(conn, in_filename); */ /* lobjOid = importFile(conn, in_filename); */
lobjOid = lo_import(conn, in_filename); lobjOid = lo_import(conn, in_filename);
/* if (lobjOid == 0)
printf("as large object %d.\n", lobjOid); fprintf(stderr, "%s\n", PQerrorMessage(conn));
else
{
printf("\tas large object %u.\n", lobjOid);
printf("picking out bytes 1000-2000 of the large object\n"); printf("picking out bytes 1000-2000 of the large object\n");
pickout(conn, lobjOid, 1000, 1000); pickout(conn, lobjOid, 1000, 1000);
printf("overwriting bytes 1000-2000 of the large object with X's\n"); printf("overwriting bytes 1000-2000 of the large object with X's\n");
overwrite(conn, lobjOid, 1000, 1000); overwrite(conn, lobjOid, 1000, 1000);
*/
printf("exporting large object to file %s\n", out_filename); printf("exporting large object to file \"%s\" ...\n", out_filename);
/* exportFile(conn, lobjOid, out_filename); */ /* exportFile(conn, lobjOid, out_filename); */
lo_export(conn, lobjOid, out_filename); if (lo_export(conn, lobjOid, out_filename) < 0)
fprintf(stderr, "%s\n", PQerrorMessage(conn));
}
res = PQexec(conn, "end"); res = PQexec(conn, "end");
PQclear(res); PQclear(res);
PQfinish(conn); PQfinish(conn);
exit(0); return 0;
} }
]]> ]]>
</programlisting> </programlisting>