Allow libpq to do thread-safe SIGPIPE handling. This allows it to
ignore SIGPIPE from send() in libpq, but terminate on any other SIGPIPE, unless the user installs their own signal handler. This is a minor fix because the only time you get SIGPIPE from libpq's send() is when the backend dies.
This commit is contained in:
Bruce Momjian
parent
acc57543de
commit
0150dbdce5
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@ -1,5 +1,5 @@
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<!--
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$PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.144 2003/12/13 23:59:06 neilc Exp $
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$PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.145 2004/01/09 02:02:43 momjian Exp $
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-->
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<chapter id="libpq">
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@ -3587,7 +3587,7 @@ thread-enabled applications.
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One restriction is that no two threads attempt to manipulate the same
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<structname>PGconn</> object at the same time. In particular, you cannot
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issue concurrent commands from different threads through the same
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connection object. (If you need to run concurrent commands, start up
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connection object. (If you need to run concurrent commands, use
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multiple connections.)
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</para>
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@ -3612,6 +3612,25 @@ not thread-safe.<indexterm><primary>crypt</><secondary>thread
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safety</></> It is better to use the <literal>md5</literal> method,
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which is thread-safe on all platforms.
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</para>
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<para>
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<application>libpq</application> must ignore <literal>SIGPIPE</> signals
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generated internally by <function>send()</> calls to backend processes.
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When <productname>PostgreSQL</> is configured without
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<literal>--enable-thread-safety</>, <application>libpq</> sets
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<literal>SIGPIPE</> to <literal>SIG_IGN</> before each
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<function>send()</> call and restores the original signal handler after
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completion. When <literal>--enable-thread-safety</> is used,
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<application>libpq</> installs its own <literal>SIGPIPE</> handler
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before the first database connection if no custom <literal>SIGPIPE</>
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handler has been installed previously. This handler uses thread-local
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storage to determine if a <literal>SIGPIPE</> signal has been generated
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by an internal <function>send()</>. If an application wants to install
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its own <literal>SIGPIPE</> signal handler, it should call
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<function>PQinSend()</> to determine if it should ignore the
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<literal>SIGPIPE</> signal. This function is available in both
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thread-safe and non-thread-safe versions of <application>libpq</>.
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</para>
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</sect1>
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@ -9,7 +9,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/nodes/read.c,v 1.37 2004/01/07 21:12:56 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/nodes/read.c,v 1.38 2004/01/09 02:02:43 momjian Exp $
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*
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* HISTORY
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* AUTHOR DATE MAJOR EVENT
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@ -22,6 +22,7 @@
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#include <ctype.h>
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#include <errno.h>
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#include "nodes/value.h"
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#include "nodes/pg_list.h"
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#include "nodes/readfuncs.h"
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#include "nodes/value.h"
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.266 2004/01/07 18:56:29 neilc Exp $
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* $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.267 2004/01/09 02:02:43 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -43,6 +43,10 @@
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#include <arpa/inet.h>
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#endif
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#ifdef ENABLE_THREAD_SAFETY
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#include <pthread.h>
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#endif
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#include "libpq/ip.h"
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#include "mb/pg_wchar.h"
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@ -66,7 +70,6 @@ long ioctlsocket_ret=1;
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#define DefaultSSLMode "disable"
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#endif
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/* ----------
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* Definition of the conninfo parameters and their fallback resources.
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*
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@ -198,6 +201,7 @@ static char *pwdfMatchesString(char *buf, char *token);
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static char *PasswordFromFile(char *hostname, char *port, char *dbname,
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char *username);
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/*
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* Connecting to a Database
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*
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@ -881,6 +885,12 @@ connectDBStart(PGconn *conn)
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struct addrinfo hint;
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const char *node = NULL;
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int ret;
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#ifdef ENABLE_THREAD_SAFETY
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static pthread_once_t check_sigpipe_once = PTHREAD_ONCE_INIT;
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/* Check only on first connection request */
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pthread_once(&check_sigpipe_once, check_sigpipe_handler);
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#endif
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if (!conn)
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return 0;
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@ -3158,3 +3168,4 @@ PasswordFromFile(char *hostname, char *port, char *dbname, char *username)
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#undef LINELEN
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}
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@ -10,7 +10,7 @@
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* didn't really belong there.
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/interfaces/libpq/fe-print.c,v 1.49 2003/11/29 19:52:12 pgsql Exp $
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* $PostgreSQL: pgsql/src/interfaces/libpq/fe-print.c,v 1.50 2004/01/09 02:02:43 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -90,8 +90,10 @@ PQprint(FILE *fout,
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int fs_len = strlen(po->fieldSep);
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int total_line_length = 0;
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int usePipe = 0;
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pqsigfunc oldsigpipehandler = NULL;
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char *pagerenv;
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#if !defined(ENABLE_THREAD_SAFETY) && !defined(WIN32)
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pqsigfunc oldsigpipehandler = NULL;
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#endif
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#ifdef TIOCGWINSZ
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struct winsize screen_size;
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@ -189,8 +191,12 @@ PQprint(FILE *fout,
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if (fout)
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{
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usePipe = 1;
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#ifdef ENABLE_THREAD_SAFETY
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pthread_setspecific(thread_in_send, "t");
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#else
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#ifndef WIN32
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oldsigpipehandler = pqsignal(SIGPIPE, SIG_IGN);
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#endif
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#endif
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}
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else
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@ -306,7 +312,13 @@ PQprint(FILE *fout,
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_pclose(fout);
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#else
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pclose(fout);
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#endif
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#ifdef ENABLE_THREAD_SAFETY
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pthread_setspecific(thread_in_send, "f");
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#else
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#ifndef WIN32
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pqsignal(SIGPIPE, oldsigpipehandler);
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#endif
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#endif
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}
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if (po->html3 && !po->expanded)
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@ -11,7 +11,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.34 2003/12/18 22:49:26 tgl Exp $
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* $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.35 2004/01/09 02:02:43 momjian Exp $
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*
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* NOTES
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* The client *requires* a valid server certificate. Since
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@ -106,6 +106,10 @@
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#include <arpa/inet.h>
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#endif
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#ifdef ENABLE_THREAD_SAFETY
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#include <pthread.h>
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#endif
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#ifndef HAVE_STRDUP
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#include "strdup.h"
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#endif
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@ -142,6 +146,11 @@ static const char *SSLerrmessage(void);
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static SSL_CTX *SSL_context = NULL;
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#endif
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#ifdef ENABLE_THREAD_SAFETY
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static void sigpipe_handler_ignore_send(int signo);
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pthread_key_t thread_in_send;
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#endif
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/* ------------------------------------------------------------ */
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/* Hardcoded values */
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/* ------------------------------------------------------------ */
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@ -347,9 +356,13 @@ pqsecure_write(PGconn *conn, const void *ptr, size_t len)
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{
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ssize_t n;
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#ifdef ENABLE_THREAD_SAFETY
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pthread_setspecific(thread_in_send, "t");
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#else
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#ifndef WIN32
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pqsigfunc oldsighandler = pqsignal(SIGPIPE, SIG_IGN);
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#endif
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#endif
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#ifdef USE_SSL
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if (conn->ssl)
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@ -407,8 +420,12 @@ pqsecure_write(PGconn *conn, const void *ptr, size_t len)
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#endif
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n = send(conn->sock, ptr, len, 0);
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#ifdef ENABLE_THREAD_SAFETY
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pthread_setspecific(thread_in_send, "f");
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#else
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#ifndef WIN32
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pqsignal(SIGPIPE, oldsighandler);
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#endif
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#endif
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return n;
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@ -1048,3 +1065,59 @@ PQgetssl(PGconn *conn)
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}
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#endif /* USE_SSL */
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#ifdef ENABLE_THREAD_SAFETY
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/*
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* Check SIGPIPE handler and perhaps install our own.
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*/
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void
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check_sigpipe_handler(void)
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{
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pqsigfunc pipehandler;
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/*
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* If the app hasn't set a SIGPIPE handler, define our own
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* that ignores SIGPIPE on libpq send() and does SIG_DFL
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* for other SIGPIPE cases.
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*/
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pipehandler = pqsignalinquire(SIGPIPE);
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if (pipehandler == SIG_DFL) /* not set by application */
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{
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/*
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* Create key first because the signal handler might be called
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* right after being installed.
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*/
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pthread_key_create(&thread_in_send, NULL);
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pqsignal(SIGPIPE, sigpipe_handler_ignore_send);
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}
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}
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/*
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* Threaded SIGPIPE signal handler
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*/
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void
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sigpipe_handler_ignore_send(int signo)
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{
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/* If we have gotten a SIGPIPE outside send(), exit */
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if (!PQinSend())
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exit(128 + SIGPIPE); /* typical return value for SIG_DFL */
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}
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#endif
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/*
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* Indicates whether the current thread is in send()
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* For use by SIGPIPE signal handlers; they should
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* ignore SIGPIPE when libpq is in send(). This means
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* that the backend has died unexpectedly.
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*/
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pqbool
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PQinSend(void)
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{
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#ifdef ENABLE_THREAD_SAFETY
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return (pthread_getspecific(thread_in_send) /* has it been set? */ &&
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*(char *)pthread_getspecific(thread_in_send) == 't') ? true : false;
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#else
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return false; /* No threading, so we can't be in send() */
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#endif
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}
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-fe.h,v 1.101 2003/11/29 22:41:28 pgsql Exp $
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* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-fe.h,v 1.102 2004/01/09 02:02:43 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -450,6 +450,14 @@ extern int PQmblen(const unsigned char *s, int encoding);
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/* Get encoding id from environment variable PGCLIENTENCODING */
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extern int PQenv2encoding(void);
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/* === in fe-secure.c === */
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/*
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* Indicates whether the libpq thread is in send().
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* Used to ignore SIGPIPE if thread is in send().
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*/
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pqbool PQinSend(void);
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#ifdef __cplusplus
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}
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#endif
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@ -12,7 +12,7 @@
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* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.83 2003/11/29 22:41:28 pgsql Exp $
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* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.84 2004/01/09 02:02:43 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -29,6 +29,9 @@
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#include <sys/time.h>
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#endif
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#ifdef ENABLE_THREAD_SAFETY
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#include <pthread.h>
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#endif
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#if defined(WIN32) && (!defined(ssize_t))
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typedef int ssize_t; /* ssize_t doesn't exist in VC (at least
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@ -442,6 +445,10 @@ extern PostgresPollingStatusType pqsecure_open_client(PGconn *);
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extern void pqsecure_close(PGconn *);
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extern ssize_t pqsecure_read(PGconn *, void *ptr, size_t len);
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extern ssize_t pqsecure_write(PGconn *, const void *ptr, size_t len);
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#ifdef ENABLE_THREAD_SAFETY
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extern void check_sigpipe_handler(void);
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extern pthread_key_t thread_in_send;
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#endif
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/*
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* this is so that we can check if a connection is non-blocking internally
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@ -9,7 +9,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/interfaces/libpq/pqsignal.c,v 1.18 2003/11/29 19:52:12 pgsql Exp $
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* $PostgreSQL: pgsql/src/interfaces/libpq/pqsignal.c,v 1.19 2004/01/09 02:02:43 momjian Exp $
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*
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* NOTES
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* This shouldn't be in libpq, but the monitor and some other
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@ -40,3 +40,25 @@ pqsignal(int signo, pqsigfunc func)
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return oact.sa_handler;
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#endif /* !HAVE_POSIX_SIGNALS */
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}
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pqsigfunc
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pqsignalinquire(int signo)
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{
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#if !defined(HAVE_POSIX_SIGNALS)
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pqsigfunc old_sigfunc;
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int old_sigmask;
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/* Prevent signal handler calls during test */
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old_sigmask = sigblock(sigmask(signo));
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old_sigfunc = signal(signo, SIG_DFL);
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signal(signo, old_sigfunc);
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sigblock(old_sigmask);
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return old_sigfunc;
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#else
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struct sigaction oact;
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if (sigaction(signo, NULL, &oact) < 0)
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return SIG_ERR;
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return oact.sa_handler;
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#endif /* !HAVE_POSIX_SIGNALS */
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}
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/interfaces/libpq/pqsignal.h,v 1.16 2003/11/29 22:41:28 pgsql Exp $
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* $PostgreSQL: pgsql/src/interfaces/libpq/pqsignal.h,v 1.17 2004/01/09 02:02:43 momjian Exp $
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*
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* NOTES
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* This shouldn't be in libpq, but the monitor and some other
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@ -24,4 +24,6 @@ typedef void (*pqsigfunc) (int);
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extern pqsigfunc pqsignal(int signo, pqsigfunc func);
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extern pqsigfunc pqsignalinquire(int signo);
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#endif /* PQSIGNAL_H */
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Loading…
Reference in New Issue