+++ /dev/null
-
-
- Pginterface 2.0
-
-Attached is a copy of the Postgres support routines I wrote to allow me
-to more cleanly interface to the libpg library, more like a 4gl SQL
-interface.
-
-It has several features that may be useful for others:
-
-I have simplified the C code that calls libpq by wrapping all the
-functionality of libpq in calls to connectdb(), doquery(), fetch(),
-fetchwithnulls() and disconnectdb(). Each call returns a structure or
-value, so if you need to do more work with the result, you can. Also, I
-have a global variable that allows you to disable the error checking I
-have added to the doquery() routine.
-
-I have added a function called fetch(), which allows you to pass
-pointers as parameters, and on return the variables are filled with the
-data from the binary cursor you opened. These binary cursors are not
-useful if you are running the query engine on a system with a different
-architecture than the database server. If you pass a NULL pointer, the
-column is skipped, and you can use libpq to handle it as you wish.
-
-I have used sigprocmask() to block the reception of certain signals
-while the program is executing SQL queries. This prevents a user
-pressing Control-C from stopping all the back ends. It blocks SIGHUP,
-SIGINT, and SIGTERM, but does not block SIGQUIT or obviously kill -9.
-If your platform does not support sigprocmask(), you can remove those
-function calls. ( Am I correct that abnormal termination can cause
-shared memory resynchronization?)
-
-There is a demo program called pginsert that demonstrates how the
-library can be used.
-
-You can create a library of pginterface.c and halt.c, and just include
-pginterface.h in your source code.
-
-I am willing to maintain this if people find problems or want additional
-functionality.
-
+++ /dev/null
-/*
- * insert.c
- *
-*/
-
-#include
-#include
-#include
-#include
-#include "halt.h"
-#include "pginterface.h"
-
-int
-main(int argc, char **argv)
-{
- char query[4000];
- int row = 1;
- int aint;
- float afloat;
- double adouble;
- char achar[11],
- achar16[17],
- abpchar[11],
- avarchar[51],
- atext[51];
- time_t aabstime;
-
- if (argc != 2)
- halt("Usage: %s database\n", argv[0]);
-
- connectdb(argv[1], NULL, NULL, NULL, NULL);
-
- on_error_continue();
- doquery("DROP TABLE testfetch");
- on_error_stop();
-
- doquery("\
- CREATE TABLE testfetch( \
- aint int4, \
- afloat float4, \
- adouble float8, \
- achar char, \
- achar16 char16, \
- abpchar char(10), \
- avarchar varchar(50), \
- atext text, \
- aabstime abstime) \
- ");
-
- while (1)
- {
- sprintf(query, "INSERT INTO testfetch VALUES ( \
- %d, \
- 2322.12, \
- '923121.0323'::float8, \
- 'A', \
- 'Betty', \
- 'Charley', \
- 'Doug', \
- 'Ernie', \
- 'now' )", row);
- doquery(query);
-
- doquery("BEGIN WORK");
- doquery("DECLARE c_testfetch BINARY CURSOR FOR \
- SELECT * FROM testfetch");
-
- doquery("FETCH ALL IN c_testfetch");
-
- while (fetch(
- &aint,
- &afloat,
- &adouble,
- achar,
- achar16,
- abpchar,
- avarchar,
- atext,
- &aabstime) != END_OF_TUPLES)
- printf("int %d\nfloat %f\ndouble %f\nchar %s\nchar16 %s\n\
-bpchar %s\nvarchar %s\ntext %s\nabstime %s",
- aint,
- afloat,
- adouble,
- achar,
- achar16,
- abpchar,
- avarchar,
- atext,
- ctime(&aabstime));
-
-
- doquery("CLOSE c_testfetch");
- doquery("COMMIT WORK");
- printf("--- %-d rows inserted so far\n", row);
-
- row++;
- }
-
- disconnectdb();
- return 0;
-}
+++ /dev/null
-/*
- * pginterface.c
- *
-*/
-
-#include
-#include
-#include
-#include
-
-#include
-#include "halt.h"
-#include "pginterface.h"
-
-static void sig_disconnect();
-static void set_signals();
-
-#define NUL '\0'
-
-/* GLOBAL VARIABLES */
-static PGconn *conn;
-static PGresult *res = NULL;
-
-#define ON_ERROR_STOP 0
-#define ON_ERROR_CONTINUE 1
-
-static int on_error_state = ON_ERROR_STOP;
-
-/* LOCAL VARIABLES */
-static sigset_t block_sigs,
- unblock_sigs;
-static int tuple;
-
-/*
-**
-** connectdb - returns PGconn structure
-**
-*/
-PGconn *
-connectdb(char *dbName,
- char *pghost,
- char *pgport,
- char *pgoptions,
- char *pgtty)
-{
- /* make a connection to the database */
- conn = PQsetdb(pghost, pgport, pgoptions, pgtty, dbName);
- if (PQstatus(conn) == CONNECTION_BAD)
- halt("Connection to database '%s' failed.\n%s\n", dbName,
- PQerrorMessage(conn));
- set_signals();
- return conn;
-}
-
-/*
-**
-** disconnectdb
-**
-*/
-void
-disconnectdb()
-{
- PQfinish(conn);
-}
-
-/*
-**
-** doquery - returns PGresult structure
-**
-*/
-PGresult *
-doquery(char *query)
-{
- if (res != NULL)
- PQclear(res);
-
- sigprocmask(SIG_SETMASK, &block_sigs, NULL);
- res = PQexec(conn, query);
- sigprocmask(SIG_SETMASK, &unblock_sigs, NULL);
-
- if (on_error_state == ON_ERROR_STOP &&
- (res == NULL ||
- PQresultStatus(res) == PGRES_BAD_RESPONSE ||
- PQresultStatus(res) == PGRES_NONFATAL_ERROR ||
- PQresultStatus(res) == PGRES_FATAL_ERROR))
- {
- if (res != NULL)
- fprintf(stderr, "query error: %s\n", PQcmdStatus(res));
- else
- fprintf(stderr, "connection error: %s\n", PQerrorMessage(conn));
- PQfinish(conn);
- halt("failed request: %s\n", query);
- }
- tuple = 0;
- return res;
-}
-
-/*
-**
-** fetch - returns tuple number (starts at 0), or the value END_OF_TUPLES
-** NULL pointers are skipped
-**
-*/
-int
-fetch(void *param,...)
-{
- va_list ap;
- int arg,
- num_fields;
-
- num_fields = PQnfields(res);
-
- if (tuple >= PQntuples(res))
- return END_OF_TUPLES;
-
- va_start(ap, param);
- for (arg = 0; arg < num_fields; arg++)
- {
- if (param != NULL)
- {
- if (PQfsize(res, arg) == -1)
- {
- memcpy(param, PQgetvalue(res, tuple, arg), PQgetlength(res, tuple, arg));
- ((char *) param)[PQgetlength(res, tuple, arg)] = NUL;
- }
- else
- memcpy(param, PQgetvalue(res, tuple, arg), PQfsize(res, arg));
- }
- param = va_arg(ap, char *);
- }
- va_end(ap);
- return tuple++;
-}
-
-/*
-**
-** fetchwithnulls - returns tuple number (starts at 0),
-** or the value END_OF_TUPLES
-** Returns true or false into null indicator variables
-** NULL pointers are skipped
-*/
-int
-fetchwithnulls(void *param,...)
-{
- va_list ap;
- int arg,
- num_fields;
-
- num_fields = PQnfields(res);
-
- if (tuple >= PQntuples(res))
- return END_OF_TUPLES;
-
- va_start(ap, param);
- for (arg = 0; arg < num_fields; arg++)
- {
- if (param != NULL)
- {
- if (PQfsize(res, arg) == -1)
- {
- memcpy(param, PQgetvalue(res, tuple, arg), PQgetlength(res, tuple, arg));
- ((char *) param)[PQgetlength(res, tuple, arg)] = NUL;
- }
- else
- memcpy(param, PQgetvalue(res, tuple, arg), PQfsize(res, arg));
- }
- param = va_arg(ap, char *);
- if (PQgetisnull(res, tuple, arg) != 0)
- *(int *) param = 1;
- else
- *(int *) param = 0;
- param = va_arg(ap, char *);
- }
- va_end(ap);
- return tuple++;
-}
-
-/*
-**
-** on_error_stop
-**
-*/
-void
-on_error_stop()
-{
- on_error_state = ON_ERROR_STOP;
-}
-
-/*
-**
-** on_error_continue
-**
-*/
-void
-on_error_continue()
-{
- on_error_state = ON_ERROR_CONTINUE;
-}
-
-/*
-**
-** sig_disconnect
-**
-*/
-static void
-sig_disconnect()
-{
- fprintf(stderr, "exiting...\n");
- PQfinish(conn);
- exit(1);
-}
-
-/*
-**
-** set_signals
-**
-*/
-static void
-set_signals()
-{
- sigemptyset(&block_sigs);
- sigemptyset(&unblock_sigs);
- sigaddset(&block_sigs, SIGTERM);
- sigaddset(&block_sigs, SIGHUP);
- sigaddset(&block_sigs, SIGINT);
-/* sigaddset(&block_sigs,SIGQUIT); no block */
- sigprocmask(SIG_SETMASK, &unblock_sigs, NULL);
- signal(SIGTERM, sig_disconnect);
- signal(SIGHUP, sig_disconnect);
- signal(SIGINT, sig_disconnect);
- signal(SIGQUIT, sig_disconnect);
-}
+++ /dev/null
-/*
- * pgnulltest.c
- *
-*/
-
-#define TEST_NON_NULLS
-
-#include
-#include
-#include
-#include
-#include
-
-int
-main(int argc, char **argv)
-{
- char query[4000];
- int row = 1;
- int aint;
- float afloat;
- double adouble;
- char achar[11],
- achar16[17],
- abpchar[11],
- avarchar[51],
- atext[51];
- time_t aabstime;
- int aint_null,
- afloat_null,
- adouble_null,
- achar_null,
- achar16_null,
- abpchar_null,
- avarchar_null,
- atext_null,
- aabstime_null;
-
- if (argc != 2)
- halt("Usage: %s database\n", argv[0]);
-
- connectdb(argv[1], NULL, NULL, NULL, NULL);
-
- on_error_continue();
- doquery("DROP TABLE testfetch");
- on_error_stop();
-
- doquery("\
- CREATE TABLE testfetch( \
- aint int4, \
- afloat float4, \
- adouble float8, \
- achar char, \
- achar16 char16, \
- abpchar char(10), \
- avarchar varchar(50), \
- atext text, \
- aabstime abstime) \
- ");
-
-#ifdef TEST_NON_NULLS
- sprintf(query, "INSERT INTO testfetch VALUES ( \
- 0, \
- 0, \
- 0, \
- '', \
- '', \
- '', \
- '', \
- '', \
- '');");
-#else
- sprintf(query, "INSERT INTO testfetch VALUES ( \
- NULL, \
- NULL, \
- NULL, \
- NULL, \
- NULL, \
- NULL, \
- NULL, \
- NULL, \
- NULL);");
-#endif
- doquery(query);
-
- doquery("BEGIN WORK");
- doquery("DECLARE c_testfetch BINARY CURSOR FOR \
- SELECT * FROM testfetch");
-
- doquery("FETCH ALL IN c_testfetch");
-
- if (fetchwithnulls(
- &aint,
- &aint_null,
- &afloat,
- &afloat_null,
- &adouble,
- &adouble_null,
- achar,
- &achar_null,
- achar16,
- &achar16_null,
- abpchar,
- &abpchar_null,
- avarchar,
- &avarchar_null,
- atext,
- &atext_null,
- &aabstime,
- &aabstime_null) != END_OF_TUPLES)
- printf("int %d\nfloat %f\ndouble %f\nchar %s\nchar16 %s\n\
-bpchar %s\nvarchar %s\ntext %s\nabstime %s\n",
- aint,
- afloat,
- adouble,
- achar,
- achar16,
- abpchar,
- avarchar,
- atext,
- ctime(&aabstime));
- printf("NULL:\nint %d\nfloat %d\ndouble %d\nchar %d\nchar16 %d\n\
-bpchar %d\nvarchar %d\ntext %d\nabstime %d\n",
- aint_null,
- afloat_null,
- adouble_null,
- achar_null,
- achar16_null,
- abpchar_null,
- avarchar_null,
- atext_null,
- aabstime_null);
-
-
- doquery("CLOSE c_testfetch");
- doquery("COMMIT WORK");
- printf("--- %-d rows inserted so far\n", row);
-
- row++;
-
- disconnectdb();
- return 0;
-}
+++ /dev/null
-/*
- * wordcount.c
- *
-*/
-
-#include
-#include
-#include
-#include "halt.h"
-#include
-#include "pginterface.h"
-
-int
-main(int argc, char **argv)
-{
- char query[4000];
- int row = 0;
- int count;
- char line[4000];
-
- if (argc != 2)
- halt("Usage: %s database\n", argv[0]);
-
- connectdb(argv[1], NULL, NULL, NULL, NULL);
- on_error_continue();
- doquery("DROP TABLE words");
- on_error_stop();
-
- doquery("\
- CREATE TABLE words( \
- matches int4, \
- word text ) \
- ");
- doquery("\
- CREATE INDEX i_words_1 ON words USING btree ( \
- word text_ops )\
- ");
-
- while (1)
- {
- if (scanf("%s", line) != 1)
- break;
- doquery("BEGIN WORK");
- sprintf(query, "\
- DECLARE c_words BINARY CURSOR FOR \
- SELECT count(*) \
- FROM words \
- WHERE word = '%s'", line);
- doquery(query);
- doquery("FETCH ALL IN c_words");
-
- while (fetch(&count) == END_OF_TUPLES)
- count = 0;
- doquery("CLOSE c_words");
- doquery("COMMIT WORK");
-
- if (count == 0)
- sprintf(query, "\
- INSERT INTO words \
- VALUES (1, '%s')", line);
- else
- sprintf(query, "\
- UPDATE words \
- SET matches = matches + 1 \
- WHERE word = '%s'", line);
- doquery(query);
- row++;
- }
-
- disconnectdb();
- return 0;
-}
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