PostgreSQL Source Code git master
Macros | Functions
signalfuncs.c File Reference
#include "postgres.h"
#include <signal.h>
#include "catalog/pg_authid.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/syslogger.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "utils/acl.h"
#include "utils/fmgrprotos.h"
Include dependency graph for signalfuncs.c:

Go to the source code of this file.

Macros

#define  SIGNAL_BACKEND_SUCCESS   0
 
#define  SIGNAL_BACKEND_ERROR   1
 
#define  SIGNAL_BACKEND_NOPERMISSION   2
 
#define  SIGNAL_BACKEND_NOSUPERUSER   3
 
#define  SIGNAL_BACKEND_NOAUTOVAC   4
 

Functions

static int  pg_signal_backend (int pid, int sig)
 
Datum  pg_cancel_backend (PG_FUNCTION_ARGS)
 
static bool  pg_wait_until_termination (int pid, int64 timeout)
 
Datum  pg_terminate_backend (PG_FUNCTION_ARGS)
 
Datum  pg_reload_conf (PG_FUNCTION_ARGS)
 
Datum  pg_rotate_logfile (PG_FUNCTION_ARGS)
 

Macro Definition Documentation

◆ SIGNAL_BACKEND_ERROR

#define SIGNAL_BACKEND_ERROR   1

Definition at line 46 of file signalfuncs.c.

◆ SIGNAL_BACKEND_NOAUTOVAC

#define SIGNAL_BACKEND_NOAUTOVAC   4

Definition at line 49 of file signalfuncs.c.

◆ SIGNAL_BACKEND_NOPERMISSION

#define SIGNAL_BACKEND_NOPERMISSION   2

Definition at line 47 of file signalfuncs.c.

◆ SIGNAL_BACKEND_NOSUPERUSER

#define SIGNAL_BACKEND_NOSUPERUSER   3

Definition at line 48 of file signalfuncs.c.

◆ SIGNAL_BACKEND_SUCCESS

#define SIGNAL_BACKEND_SUCCESS   0

Definition at line 45 of file signalfuncs.c.

Function Documentation

◆ pg_cancel_backend()

Datum pg_cancel_backend ( PG_FUNCTION_ARGS  )

Definition at line 136 of file signalfuncs.c.

137{
138 int r = pg_signal_backend(PG_GETARG_INT32(0), SIGINT);
139
142 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
143 errmsg("permission denied to cancel query"),
144 errdetail("Only roles with the %s attribute may cancel queries of roles with the %s attribute.",
145 "SUPERUSER", "SUPERUSER")));
146
149 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
150 errmsg("permission denied to cancel query"),
151 errdetail("Only roles with privileges of the \"%s\" role may cancel autovacuum workers.",
152 "pg_signal_autovacuum_worker")));
153
156 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
157 errmsg("permission denied to cancel query"),
158 errdetail("Only roles with privileges of the role whose query is being canceled or with privileges of the \"%s\" role may cancel this query.",
159 "pg_signal_backend")));
160
162}
int errdetail(const char *fmt,...)
Definition: elog.c:1207
int errcode(int sqlerrcode)
Definition: elog.c:854
int errmsg(const char *fmt,...)
Definition: elog.c:1071
#define ERROR
Definition: elog.h:39
#define ereport(elevel,...)
Definition: elog.h:150
#define PG_GETARG_INT32(n)
Definition: fmgr.h:269
#define PG_RETURN_BOOL(x)
Definition: fmgr.h:359
static int pg_signal_backend(int pid, int sig)
Definition: signalfuncs.c:51
#define SIGNAL_BACKEND_SUCCESS
Definition: signalfuncs.c:45
#define SIGNAL_BACKEND_NOPERMISSION
Definition: signalfuncs.c:47
#define SIGNAL_BACKEND_NOSUPERUSER
Definition: signalfuncs.c:48
#define SIGNAL_BACKEND_NOAUTOVAC
Definition: signalfuncs.c:49

References ereport, errcode(), errdetail(), errmsg(), ERROR, PG_GETARG_INT32, PG_RETURN_BOOL, pg_signal_backend(), SIGNAL_BACKEND_NOAUTOVAC, SIGNAL_BACKEND_NOPERMISSION, SIGNAL_BACKEND_NOSUPERUSER, and SIGNAL_BACKEND_SUCCESS.

◆ pg_reload_conf()

Datum pg_reload_conf ( PG_FUNCTION_ARGS  )

Definition at line 288 of file signalfuncs.c.

289{
291 {
293 (errmsg("failed to send signal to postmaster: %m")));
294 PG_RETURN_BOOL(false);
295 }
296
297 PG_RETURN_BOOL(true);
298}
#define WARNING
Definition: elog.h:36
pid_t PostmasterPid
Definition: globals.c:106
#define SIGHUP
Definition: win32_port.h:158
#define kill(pid, sig)
Definition: win32_port.h:493

References ereport, errmsg(), kill, PG_RETURN_BOOL, PostmasterPid, SIGHUP, and WARNING.

◆ pg_rotate_logfile()

Datum pg_rotate_logfile ( PG_FUNCTION_ARGS  )

Definition at line 308 of file signalfuncs.c.

309{
311 {
313 (errmsg("rotation not possible because log collection not active")));
314 PG_RETURN_BOOL(false);
315 }
316
318 PG_RETURN_BOOL(true);
319}
void SendPostmasterSignal(PMSignalReason reason)
Definition: pmsignal.c:165
@ PMSIGNAL_ROTATE_LOGFILE
Definition: pmsignal.h:38
bool Logging_collector
Definition: syslogger.c:70

References ereport, errmsg(), Logging_collector, PG_RETURN_BOOL, PMSIGNAL_ROTATE_LOGFILE, SendPostmasterSignal(), and WARNING.

◆ pg_signal_backend()

static int pg_signal_backend ( int  pid,
int  sig 
)
static

Definition at line 51 of file signalfuncs.c.

52{
53 PGPROC *proc = BackendPidGetProc(pid);
54
55 /*
56 * BackendPidGetProc returns NULL if the pid isn't valid; but by the time
57 * we reach kill(), a process for which we get a valid proc here might
58 * have terminated on its own. There's no way to acquire a lock on an
59 * arbitrary process to prevent that. But since so far all the callers of
60 * this mechanism involve some request for ending the process anyway, that
61 * it might end on its own first is not a problem.
62 *
63 * Note that proc will also be NULL if the pid refers to an auxiliary
64 * process or the postmaster (neither of which can be signaled via
65 * pg_signal_backend()).
66 */
67 if (proc == NULL)
68 {
69 /*
70 * This is just a warning so a loop-through-resultset will not abort
71 * if one backend terminated on its own during the run.
72 */
74 (errmsg("PID %d is not a PostgreSQL backend process", pid)));
75
77 }
78
79 /*
80 * Only allow superusers to signal superuser-owned backends. Any process
81 * not advertising a role might have the importance of a superuser-owned
82 * backend, so treat it that way. As an exception, we allow roles with
83 * privileges of pg_signal_autovacuum_worker to signal autovacuum workers
84 * (which do not advertise a role).
85 *
86 * Otherwise, users can signal backends for roles they have privileges of.
87 */
88 if (!OidIsValid(proc->roleId) || superuser_arg(proc->roleId))
89 {
90 ProcNumber procNumber = GetNumberFromPGProc(proc);
92
93 if (backendType == B_AUTOVAC_WORKER)
94 {
95 if (!has_privs_of_role(GetUserId(), ROLE_PG_SIGNAL_AUTOVACUUM_WORKER))
97 }
98 else if (!superuser())
100 }
101 else if (!has_privs_of_role(GetUserId(), proc->roleId) &&
102 !has_privs_of_role(GetUserId(), ROLE_PG_SIGNAL_BACKEND))
104
105 /*
106 * Can the process we just validated above end, followed by the pid being
107 * recycled for a new process, before reaching here? Then we'd be trying
108 * to kill the wrong thing. Seems near impossible when sequential pid
109 * assignment and wraparound is used. Perhaps it could happen on a system
110 * where pid re-use is randomized. That race condition possibility seems
111 * too unlikely to worry about.
112 */
113
114 /* If we have setsid(), signal the backend's whole process group */
115#ifdef HAVE_SETSID
116 if (kill(-pid, sig))
117#else
118 if (kill(pid, sig))
119#endif
120 {
121 /* Again, just a warning to allow loops */
123 (errmsg("could not send signal to process %d: %m", pid)));
125 }
127}
bool has_privs_of_role(Oid member, Oid role)
Definition: acl.c:5284
BackendType pgstat_get_backend_type_by_proc_number(ProcNumber procNumber)
#define OidIsValid(objectId)
Definition: c.h:774
BackendType
Definition: miscadmin.h:337
@ B_AUTOVAC_WORKER
Definition: miscadmin.h:344
Oid GetUserId(void)
Definition: miscinit.c:469
static int sig
Definition: pg_ctl.c:80
#define GetNumberFromPGProc(proc)
Definition: proc.h:441
PGPROC * BackendPidGetProc(int pid)
Definition: procarray.c:3158
int ProcNumber
Definition: procnumber.h:24
#define SIGNAL_BACKEND_ERROR
Definition: signalfuncs.c:46
Definition: proc.h:179
Oid roleId
Definition: proc.h:225
bool superuser_arg(Oid roleid)
Definition: superuser.c:56
bool superuser(void)
Definition: superuser.c:46

References B_AUTOVAC_WORKER, BackendPidGetProc(), ereport, errmsg(), GetNumberFromPGProc, GetUserId(), has_privs_of_role(), kill, OidIsValid, pgstat_get_backend_type_by_proc_number(), PGPROC::roleId, sig, SIGNAL_BACKEND_ERROR, SIGNAL_BACKEND_NOAUTOVAC, SIGNAL_BACKEND_NOPERMISSION, SIGNAL_BACKEND_NOSUPERUSER, SIGNAL_BACKEND_SUCCESS, superuser(), superuser_arg(), and WARNING.

Referenced by pg_cancel_backend(), and pg_terminate_backend().

◆ pg_terminate_backend()

Datum pg_terminate_backend ( PG_FUNCTION_ARGS  )

Definition at line 237 of file signalfuncs.c.

238{
239 int pid;
240 int r;
241 int timeout; /* milliseconds */
242
243 pid = PG_GETARG_INT32(0);
244 timeout = PG_GETARG_INT64(1);
245
246 if (timeout < 0)
248 (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
249 errmsg("\"timeout\" must not be negative")));
250
251 r = pg_signal_backend(pid, SIGTERM);
252
255 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
256 errmsg("permission denied to terminate process"),
257 errdetail("Only roles with the %s attribute may terminate processes of roles with the %s attribute.",
258 "SUPERUSER", "SUPERUSER")));
259
262 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
263 errmsg("permission denied to terminate process"),
264 errdetail("Only roles with privileges of the \"%s\" role may terminate autovacuum workers.",
265 "pg_signal_autovacuum_worker")));
266
269 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
270 errmsg("permission denied to terminate process"),
271 errdetail("Only roles with privileges of the role whose process is being terminated or with privileges of the \"%s\" role may terminate this process.",
272 "pg_signal_backend")));
273
274 /* Wait only on success and if actually requested */
275 if (r == SIGNAL_BACKEND_SUCCESS && timeout > 0)
277 else
279}
#define PG_GETARG_INT64(n)
Definition: fmgr.h:283
static bool pg_wait_until_termination(int pid, int64 timeout)
Definition: signalfuncs.c:169

References ereport, errcode(), errdetail(), errmsg(), ERROR, PG_GETARG_INT32, PG_GETARG_INT64, PG_RETURN_BOOL, pg_signal_backend(), pg_wait_until_termination(), SIGNAL_BACKEND_NOAUTOVAC, SIGNAL_BACKEND_NOPERMISSION, SIGNAL_BACKEND_NOSUPERUSER, and SIGNAL_BACKEND_SUCCESS.

◆ pg_wait_until_termination()

static bool pg_wait_until_termination ( int  pid,
int64  timeout 
)
static

Definition at line 169 of file signalfuncs.c.

170{
171 /*
172 * Wait in steps of waittime milliseconds until this function exits or
173 * timeout.
174 */
175 int64 waittime = 100;
176
177 /*
178 * Initially remaining time is the entire timeout specified by the user.
179 */
180 int64 remainingtime = timeout;
181
182 /*
183 * Check existence of the backend. If the backend still exists, then wait
184 * for waittime milliseconds, again check for the existence. Repeat this
185 * until timeout or an error occurs or a pending interrupt such as query
186 * cancel gets processed.
187 */
188 do
189 {
190 if (remainingtime < waittime)
191 waittime = remainingtime;
192
193 if (kill(pid, 0) == -1)
194 {
195 if (errno == ESRCH)
196 return true;
197 else
199 (errcode(ERRCODE_INTERNAL_ERROR),
200 errmsg("could not check the existence of the backend with PID %d: %m",
201 pid)));
202 }
203
204 /* Process interrupts, if any, before waiting */
206
207 (void) WaitLatch(MyLatch,
209 waittime,
210 WAIT_EVENT_BACKEND_TERMINATION);
211
213
214 remainingtime -= waittime;
215 } while (remainingtime > 0);
216
218 (errmsg_plural("backend with PID %d did not terminate within %" PRId64 " millisecond",
219 "backend with PID %d did not terminate within %" PRId64 " milliseconds",
220 timeout,
221 pid, timeout)));
222
223 return false;
224}
int64_t int64
Definition: c.h:535
int errmsg_plural(const char *fmt_singular, const char *fmt_plural, unsigned long n,...)
Definition: elog.c:1184
struct Latch * MyLatch
Definition: globals.c:63
void ResetLatch(Latch *latch)
Definition: latch.c:374
int WaitLatch(Latch *latch, int wakeEvents, long timeout, uint32 wait_event_info)
Definition: latch.c:172
#define CHECK_FOR_INTERRUPTS()
Definition: miscadmin.h:122
#define WL_TIMEOUT
Definition: waiteventset.h:37
#define WL_EXIT_ON_PM_DEATH
Definition: waiteventset.h:39
#define WL_LATCH_SET
Definition: waiteventset.h:34

References CHECK_FOR_INTERRUPTS, ereport, errcode(), errmsg(), errmsg_plural(), ERROR, kill, MyLatch, ResetLatch(), WaitLatch(), WARNING, WL_EXIT_ON_PM_DEATH, WL_LATCH_SET, and WL_TIMEOUT.

Referenced by pg_terminate_backend().

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