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119 lines
2.3 KiB
C
119 lines
2.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* status.c
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*
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* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
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*
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* Monitor status of a PostgreSQL server.
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres_fe.h"
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#include <signal.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "pg_probackup.h"
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/* PID can be negative for standalone backend */
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typedef long pgpid_t;
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static pgpid_t get_pgpid(void);
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static bool postmaster_is_alive(pid_t pid);
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/*
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* get_pgpid
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*
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* Get PID of postmaster, by scanning postmaster.pid.
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*/
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static pgpid_t
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get_pgpid(void)
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{
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FILE *pidf;
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long pid;
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char pid_file[MAXPGPATH];
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snprintf(pid_file, lengthof(pid_file), "%s/postmaster.pid", pgdata);
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pidf = fopen(pid_file, "r");
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if (pidf == NULL)
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{
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/* No pid file, not an error on startup */
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if (errno == ENOENT)
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return 0;
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else
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{
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elog(ERROR, "could not open PID file \"%s\": %s",
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pid_file, strerror(errno));
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}
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}
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if (fscanf(pidf, "%ld", &pid) != 1)
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{
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/* Is the file empty? */
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if (ftell(pidf) == 0 && feof(pidf))
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elog(ERROR, "the PID file \"%s\" is empty",
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pid_file);
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else
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elog(ERROR, "invalid data in PID file \"%s\"\n",
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pid_file);
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}
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fclose(pidf);
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return (pgpid_t) pid;
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}
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/*
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* postmaster_is_alive
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*
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* Check whether postmaster is alive or not.
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*/
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static bool
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postmaster_is_alive(pid_t pid)
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{
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/*
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* Test to see if the process is still there. Note that we do not
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* consider an EPERM failure to mean that the process is still there;
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* EPERM must mean that the given PID belongs to some other userid, and
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* considering the permissions on $PGDATA, that means it's not the
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* postmaster we are after.
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*
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* Don't believe that our own PID or parent shell's PID is the postmaster,
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* either. (Windows hasn't got getppid(), though.)
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*/
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if (pid == getpid())
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return false;
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#ifndef WIN32
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if (pid == getppid())
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return false;
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#endif
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if (kill(pid, 0) == 0)
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return true;
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return false;
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}
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/*
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* is_pg_running
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*
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*
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*/
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bool
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is_pg_running(void)
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{
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pgpid_t pid;
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pid = get_pgpid();
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/* 0 means no pid file */
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if (pid == 0)
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return false;
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/* Case of a standalone backend */
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if (pid < 0)
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pid = -pid;
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/* Check if postmaster is alive */
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return postmaster_is_alive((pid_t) pid);
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}
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