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peterepetere
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Treat empty connection parameters as is, in particular to enable overriding
environment variables with "nothing". Empty host parameter indicates Unix socket.
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‎doc/src/sgml/libpq.sgml

Lines changed: 35 additions & 40 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$Header: /cvsroot/pgsql/doc/src/sgml/libpq.sgml,v 1.41 2000/09/29 20:21:34 petere Exp $
2+
$Header: /cvsroot/pgsql/doc/src/sgml/libpq.sgml,v 1.42 2000/10/03 19:16:16 petere Exp $
33
-->
44

55
<chapter id="libpq-chapter">
@@ -38,21 +38,22 @@ $Header: /cvsroot/pgsql/doc/src/sgml/libpq.sgml,v 1.41 2000/09/29 20:21:34 peter
3838
<filename>libpq</filename> library.
3939
</para>
4040

41-
<sect1 id="libpq-connect">
42-
<title>Database Connection Functions</title>
41+
<sect1 id="libpq-connect">
42+
<title>Database Connection Functions</title>
4343

44-
<para>
45-
The following routines deal with making a connection to
46-
a <productname>Postgres</productname> backend server. The application
47-
program can have several backend connections open at one time.
48-
(One reason to do that is to access more than one database.)
49-
Each connection is represented by a PGconn object which is obtained
50-
from PQconnectdb() or PQsetdbLogin(). Note that these functions
51-
will always return a non-null object pointer, unless perhaps
52-
there is too little memory even to allocate the PGconn object.
53-
The PQstatus function should be called
54-
to check whether a connection was successfully made
55-
before queries are sent via the connection object.
44+
<para>
45+
The following routines deal with making a connection to a
46+
<productname>Postgres</productname> backend server. The
47+
application program can have several backend connections open at
48+
one time. (One reason to do that is to access more than one
49+
database.) Each connection is represented by a
50+
<structname>PGconn</> object which is obtained from
51+
<function>PQconnectdb</> or <function>PQsetdbLogin</>. Note that
52+
these functions will always return a non-null object pointer,
53+
unless perhaps there is too little memory even to allocate the
54+
<structname>PGconn</> object. The <function>PQstatus</> function
55+
should be called to check whether a connection was successfully
56+
made before queries are sent via the connection object.
5657

5758
<itemizedlist>
5859
<listitem>
@@ -87,9 +88,8 @@ PGconn *PQconnectdb(const char *conninfo)
8788
<listitem>
8889
<para>
8990
Name of host to connect to. If a non-zero-length string is
90-
specified, TCP/IP
91-
communication is used. Using this parameter causes a hostname look-up.
92-
See hostaddr.
91+
specified, TCP/IP communication is used, else Unix sockets.
92+
Using this parameter causes a hostname look-up. See hostaddr.
9393
</para>
9494
</listitem>
9595
</varlistentry>
@@ -1930,22 +1930,22 @@ call <function>fe_setauthsvc</function> at all.
19301930

19311931
</sect1>
19321932

1933-
<sect1 id="libpq-sample">
1934-
<title>Sample Programs</title>
19351933

1936-
<sect2>
1937-
<title>Sample Program 1</title>
1934+
<sect1 id="libpq-example">
1935+
<title>Example Programs</title>
1936+
1937+
<example id="libpq-example-1">
1938+
<title>libpq Example Program 1</title>
19381939

1939-
<para>
19401940
<programlisting>
19411941
/*
1942-
* testlibpq.c Test the C version of Libpq, the Postgres frontend
1943-
* library.
1944-
*
1942+
* testlibpq.c
19451943
*
1944+
* Test the C version of libpq, the PostgreSQL frontend
1945+
* library.
19461946
*/
19471947
#include &lt;stdio.h&gt;
1948-
#include "libpq-fe.h"
1948+
#include &lt;libpq-fe.h&gt;
19491949

19501950
void
19511951
exit_nicely(PGconn *conn)
@@ -2065,13 +2065,11 @@ main()
20652065

20662066
}
20672067
</programlisting>
2068-
</para>
2069-
</sect2>
2068+
</example>
20702069

2071-
<sect2>
2072-
<title>Sample Program 2</title>
2070+
<example id="libpq-example-2">
2071+
<title>libpq Example Program 2</title>
20732072

2074-
<para>
20752073
<programlisting>
20762074
/*
20772075
* testlibpq2.c
@@ -2187,13 +2185,11 @@ main()
21872185
return 0;
21882186
}
21892187
</programlisting>
2190-
</para>
2191-
</sect2>
2188+
</example>
21922189

2193-
<sect2>
2194-
<title>Sample Program 3</title>
2190+
<example id="libpq-example-3">
2191+
<title>libpq Example Program 3</>
21952192

2196-
<para>
21972193
<programlisting>
21982194
/*
21992195
* testlibpq3.c Test the C version of Libpq, the Postgres frontend
@@ -2370,10 +2366,9 @@ main()
23702366
return 0;
23712367
}
23722368
</programlisting>
2373-
</para>
2369+
</example>
23742370

2375-
</sect2>
2376-
</sect1>
2371+
</sect1>
23772372
</chapter>
23782373

23792374
<!-- Keep this comment at the end of the file

‎src/interfaces/libpq/fe-connect.c

Lines changed: 10 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-connect.c,v 1.136 2000/10/03 03:39:46 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-connect.c,v 1.137 2000/10/03 19:16:17 petere Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -416,15 +416,12 @@ PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
416416
if (conn == NULL)
417417
return (PGconn *) NULL;
418418

419-
if ((pghost == NULL) || pghost[0] == '\0')
420-
{
421-
if ((tmp = getenv("PGHOST")) != NULL)
422-
conn->pghost = strdup(tmp);
423-
}
424-
else
419+
if (pghost)
425420
conn->pghost = strdup(pghost);
421+
else if ((tmp = getenv("PGHOST")) != NULL)
422+
conn->pghost = strdup(tmp);
426423

427-
if ((pgport == NULL) || pgport[0] == '\0')
424+
if (pgport == NULL)
428425
{
429426
if ((tmp = getenv("PGPORT")) == NULL)
430427
tmp = DEF_PGPORT_STR;
@@ -433,7 +430,7 @@ PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
433430
else
434431
conn->pgport = strdup(pgport);
435432

436-
if ((pgtty == NULL) || pgtty[0] == '\0')
433+
if (pgtty == NULL)
437434
{
438435
if ((tmp = getenv("PGTTY")) == NULL)
439436
tmp = DefaultTty;
@@ -442,7 +439,7 @@ PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
442439
else
443440
conn->pgtty = strdup(pgtty);
444441

445-
if ((pgoptions == NULL) || pgoptions[0] == '\0')
442+
if (pgoptions == NULL)
446443
{
447444
if ((tmp = getenv("PGOPTIONS")) == NULL)
448445
tmp = DefaultOption;
@@ -476,7 +473,7 @@ PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
476473
else
477474
conn->pgpass = strdup(DefaultPassword);
478475

479-
if ((dbName == NULL) || dbName[0] == '\0')
476+
if (dbName == NULL)
480477
{
481478
if ((tmp = getenv("PGDATABASE")) != NULL)
482479
conn->dbName = strdup(tmp);
@@ -705,7 +702,7 @@ connectDBStart(PGconn *conn)
705702

706703
MemSet((char *) &conn->raddr, 0, sizeof(conn->raddr));
707704

708-
if (conn->pghostaddr != NULL)
705+
if (conn->pghostaddr != NULL && conn->pghostaddr[0] != '\0')
709706
{
710707
/* Using pghostaddr avoids a hostname lookup */
711708
/* Note that this supports IPv4 only */
@@ -724,7 +721,7 @@ connectDBStart(PGconn *conn)
724721
memmove((char *) &(conn->raddr.in.sin_addr),
725722
(char *) &addr, sizeof(addr));
726723
}
727-
else if (conn->pghost != NULL)
724+
else if (conn->pghost != NULL && conn->pghost[0] != '\0')
728725
{
729726
/* Using pghost, so we have to look-up the hostname */
730727
struct hostent *hp;

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