Blame SOURCES/net-snmp-5.7.2-extend-close.patch

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Bug 1252048 - net-snmp snmpd fork() overhead [fix available]
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Backported from:
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commit f0e87f4918ffc41e03f707e9670ea422cd154a9b
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Author: Bart Van Assche <bvanassche@acm.org>
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Date:   Sat Jan 31 12:05:24 2015 +0100
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    CHANGES: snmpd: BUG: 2596: Reduce fork() overhead
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    Avoid that the close() loop that is executed after a fork() delays
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    the pass/extend API on systems with a large maximum number of files
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    by reducing the number of iterations of this loop on Linux systems.
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    See also http://sourceforge.net/p/net-snmp/bugs/2596.
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    Reported-by: andymf <andymf@users.sf.net>
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diff -up net-snmp-5.7.2/agent/mibgroup/util_funcs.c.test net-snmp-5.7.2/agent/mibgroup/util_funcs.c
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--- net-snmp-5.7.2/agent/mibgroup/util_funcs.c.test	2012-10-10 00:28:58.000000000 +0200
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+++ net-snmp-5.7.2/agent/mibgroup/util_funcs.c	2015-08-18 10:15:18.888767023 +0200
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@@ -480,8 +480,7 @@ get_exec_pipes(char *cmd, int *fdIn, int
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         /*
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          * close all non-standard open file descriptors 
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          */
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-        for (cnt = getdtablesize() - 1; cnt >= 2; --cnt)
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-            (void) close(cnt);
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+        netsnmp_close_fds(1);
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         (void) dup(1);          /* stderr */
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         for (cnt = 1, cptr1 = cmd, cptr2 = argvs; *cptr1 != 0;
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diff -up net-snmp-5.7.2/agent/mibgroup/utilities/execute.c.test net-snmp-5.7.2/agent/mibgroup/utilities/execute.c
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--- net-snmp-5.7.2/agent/mibgroup/utilities/execute.c.test	2012-10-10 00:28:58.000000000 +0200
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+++ net-snmp-5.7.2/agent/mibgroup/utilities/execute.c	2015-08-18 10:15:18.889767028 +0200
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@@ -22,6 +22,9 @@
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 #if HAVE_FCNTL_H
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 #include <fcntl.h>
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 #endif
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+#if HAVE_DIRENT_H
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+#include <dirent.h>
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+#endif
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 #if HAVE_SYS_WAIT_H
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 #include <sys/wait.h>
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 #endif
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@@ -207,8 +210,8 @@ run_exec_command( char *command, char *i
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         close(opipe[0]);
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         close(2);
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         dup(1);
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-        for (i = getdtablesize()-1; i>2; i--)
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-            close(i);
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+
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+        netsnmp_close_fds(2);
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         /*
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          * Set up the argv array and execute it
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@@ -406,3 +409,30 @@ run_exec_command( char *command, char *i
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     return run_shell_command( command, input, output, out_len );
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 #endif
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 }
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+
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+/**
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+ * Close all file descriptors larger than @fd.
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+ */
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+void netsnmp_close_fds(int fd)
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+{
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+#if defined(HAVE_FORK)
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+    DIR            *dir;
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+    struct dirent  *ent;
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+    int             i, largest_fd = -1;
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+
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+    if ((dir = opendir("/proc/self/fd"))) {
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+        while ((ent = readdir(dir))) {
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+            if (sscanf(ent->d_name, "%d", &i) == 1) {
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+                if (i > largest_fd)
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+                    largest_fd = i;
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+            }
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+        }
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+        closedir(dir);
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+    } else {
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+        largest_fd = getdtablesize() - 1;
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+    }
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+
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+    for (i = largest_fd; i > fd && i > 0; i--)
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+        close(i);
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+#endif
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+}
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diff -up net-snmp-5.7.2/agent/mibgroup/utilities/execute.h.test net-snmp-5.7.2/agent/mibgroup/utilities/execute.h
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--- net-snmp-5.7.2/agent/mibgroup/utilities/execute.h.test	2012-10-10 00:28:58.000000000 +0200
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+++ net-snmp-5.7.2/agent/mibgroup/utilities/execute.h	2015-08-18 10:15:18.889767028 +0200
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@@ -3,6 +3,7 @@
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 config_belongs_in(agent_module)
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+void netsnmp_close_fds(int fd);
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 int run_shell_command(char *command, char *input,
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                       char *output,  int  *out_len);
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 int run_exec_command( char *command, char *input,
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diff -up net-snmp-5.7.2/agent/snmpd.c.test net-snmp-5.7.2/agent/snmpd.c
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--- net-snmp-5.7.2/agent/snmpd.c.test	2015-08-18 10:15:08.450714809 +0200
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+++ net-snmp-5.7.2/agent/snmpd.c	2015-08-18 10:17:31.579430763 +0200
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@@ -143,6 +143,7 @@ typedef long    fd_mask;
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 #include <net-snmp/agent/agent_module_config.h>
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 #include <net-snmp/agent/mib_module_config.h>
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+#include "utilities/execute.h" /* netsnmp_close_fds() */
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 #include "snmpd.h"
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 #include <net-snmp/agent/mib_modules.h>
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@@ -451,7 +452,6 @@ main(int argc, char *argv[])
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     FILE           *PID;
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 #endif
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-#ifndef WIN32
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 #ifndef NETSNMP_NO_SYSYSTEMD
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     /* check if systemd has sockets for us and don't close them */
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     prepared_sockets = netsnmp_sd_listen_fds(0);
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@@ -462,11 +462,8 @@ main(int argc, char *argv[])
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      * inherited from the shell.
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      */
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     if (!prepared_sockets) {
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-        for (i = getdtablesize() - 1; i > 2; --i) {
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-            (void) close(i);
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-        }
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+        netsnmp_close_fds(2);
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     }
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-#endif /* #WIN32 */
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     /*
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      * register signals ASAP to prevent default action (usually core)
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diff -up net-snmp-5.7.2/apps/snmptrapd.c.test net-snmp-5.7.2/apps/snmptrapd.c
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--- net-snmp-5.7.2/apps/snmptrapd.c.test	2015-08-18 10:15:08.450714809 +0200
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+++ net-snmp-5.7.2/apps/snmptrapd.c	2015-08-18 10:18:15.454650235 +0200
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@@ -97,6 +97,7 @@ SOFTWARE.
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 #include <net-snmp/net-snmp-includes.h>
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 #include <net-snmp/agent/net-snmp-agent-includes.h>
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 #include <net-snmp/library/fd_event_manager.h>
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+#include "utilities/execute.h" /* netsnmp_close_fds() */
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 #include "snmptrapd_handlers.h"
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 #include "snmptrapd_log.h"
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 #include "snmptrapd_auth.h"
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@@ -662,7 +663,6 @@ main(int argc, char *argv[])
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     int             prepared_sockets = 0;
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-#ifndef WIN32
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 #ifndef NETSNMP_NO_SYSTEMD
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     /* check if systemd has sockets for us and don't close them */
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     prepared_sockets = netsnmp_sd_listen_fds(0);
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@@ -672,11 +672,8 @@ main(int argc, char *argv[])
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      * inherited from the shell.
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      */
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     if (!prepared_sockets) {
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-        for (i = getdtablesize() - 1; i > 2; --i) {
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-            (void) close(i);
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-        }
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+        netsnmp_close_fds(2);
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     }
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-#endif /* #WIN32 */
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 #ifdef SIGTERM
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     signal(SIGTERM, term_handler);
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@@ -1382,18 +1379,6 @@ trapd_update_config(void)
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     read_configs();
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 }
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-
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-#if !defined(HAVE_GETDTABLESIZE) && !defined(WIN32)
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-#include <sys/resource.h>
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-int
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-getdtablesize(void)
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-{
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-    struct rlimit   rl;
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-    getrlimit(RLIMIT_NOFILE, &rl);
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-    return (rl.rlim_cur);
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-}
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-#endif
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-
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 /*
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  * Windows Service Related functions 
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  */