miscinit.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 947 行 · 第 1/2 页

	 * We need a loop here because of race conditions.	But don't loop
	 * forever (for example, a non-writable $PGDATA directory might cause
	 * a failure that won't go away).  100 tries seems like plenty.
	 */
	for (ntries = 0;; ntries++)
	{
		/*
		 * Try to create the lock file --- O_EXCL makes this atomic.
		 */
		fd = open(filename, O_RDWR | O_CREAT | O_EXCL, 0600);
		if (fd >= 0)
			break;				/* Success; exit the retry loop */

		/*
		 * Couldn't create the pid file. Probably it already exists.
		 */
		if ((errno != EEXIST && errno != EACCES) || ntries > 100)
			ereport(FATAL,
					(errcode_for_file_access(),
					 errmsg("could not create lock file \"%s\": %m",
							filename)));

		/*
		 * Read the file to get the old owner's PID.  Note race condition
		 * here: file might have been deleted since we tried to create it.
		 */
		fd = open(filename, O_RDONLY, 0600);
		if (fd < 0)
		{
			if (errno == ENOENT)
				continue;		/* race condition; try again */
			ereport(FATAL,
					(errcode_for_file_access(),
					 errmsg("could not open lock file \"%s\": %m",
							filename)));
		}
		if ((len = read(fd, buffer, sizeof(buffer) - 1)) <= 0)
			ereport(FATAL,
					(errcode_for_file_access(),
					 errmsg("could not read lock file \"%s\": %m",
							filename)));
		close(fd);

		buffer[len] = '\0';
		encoded_pid = atoi(buffer);

		/* if pid < 0, the pid is for postgres, not postmaster */
		other_pid = (pid_t) (encoded_pid < 0 ? -encoded_pid : encoded_pid);

		if (other_pid <= 0)
			elog(FATAL, "bogus data in lock file \"%s\"", filename);

		/*
		 * Check to see if the other process still exists
		 *
		 * Normally kill() will fail with ESRCH if the given PID doesn't
		 * exist.  BeOS returns EINVAL for some silly reason, however.
		 */
		if (other_pid != my_pid)
		{
			if (kill(other_pid, 0) == 0 ||
				(errno != ESRCH
#ifdef __BEOS__
				 && errno != EINVAL
#endif
				 ))
			{
				/* lockfile belongs to a live process */
				ereport(FATAL,
						(errcode(ERRCODE_LOCK_FILE_EXISTS),
						 errmsg("lock file \"%s\" already exists",
								filename),
						 isDDLock ?
					 errhint("Is another %s (PID %d) running in data directory \"%s\"?",
						   (encoded_pid < 0 ? "postgres" : "postmaster"),
							 (int) other_pid, refName) :
						 errhint("Is another %s (PID %d) using socket file \"%s\"?",
						   (encoded_pid < 0 ? "postgres" : "postmaster"),
								 (int) other_pid, refName)));
			}
		}

		/*
		 * No, the creating process did not exist.	However, it could be
		 * that the postmaster crashed (or more likely was kill -9'd by a
		 * clueless admin) but has left orphan backends behind.  Check for
		 * this by looking to see if there is an associated shmem segment
		 * that is still in use.
		 */
		if (isDDLock)
		{
			char	   *ptr;
			unsigned long id1,
						id2;

			ptr = strchr(buffer, '\n');
			if (ptr != NULL &&
				(ptr = strchr(ptr + 1, '\n')) != NULL)
			{
				ptr++;
				if (sscanf(ptr, "%lu %lu", &id1, &id2) == 2)
				{
					if (PGSharedMemoryIsInUse(id1, id2))
						ereport(FATAL,
								(errcode(ERRCODE_LOCK_FILE_EXISTS),
							   errmsg("pre-existing shared memory block "
									  "(key %lu, ID %lu) is still in use",
									  id1, id2),
							   errhint("If you're sure there are no old "
									   "server processes still running, remove "
									   "the shared memory block with "
									   "the command \"ipcrm\", or just delete the file \"%s\".",
									   filename)));
				}
			}
		}

		/*
		 * Looks like nobody's home.  Unlink the file and try again to
		 * create it.  Need a loop because of possible race condition
		 * against other would-be creators.
		 */
		if (unlink(filename) < 0)
			ereport(FATAL,
					(errcode_for_file_access(),
					 errmsg("could not remove old lock file \"%s\": %m",
							filename),
					 errhint("The file seems accidentally left over, but "
						  "it could not be removed. Please remove the file "
							 "by hand and try again.")));
	}

	/*
	 * Successfully created the file, now fill it.
	 */
	snprintf(buffer, sizeof(buffer), "%d\n%s\n",
			 amPostmaster ? (int) my_pid : -((int) my_pid),
			 DataDir);
	errno = 0;
	if (write(fd, buffer, strlen(buffer)) != strlen(buffer))
	{
		int			save_errno = errno;

		close(fd);
		unlink(filename);
		/* if write didn't set errno, assume problem is no disk space */
		errno = save_errno ? save_errno : ENOSPC;
		ereport(FATAL,
				(errcode_for_file_access(),
			  errmsg("could not write lock file \"%s\": %m", filename)));
	}
	close(fd);

	/*
	 * Arrange for automatic removal of lockfile at proc_exit.
	 */
	on_proc_exit(UnlinkLockFile, PointerGetDatum(strdup(filename)));
}

void
CreateDataDirLockFile(const char *datadir, bool amPostmaster)
{
	char		lockfile[MAXPGPATH];

	snprintf(lockfile, sizeof(lockfile), "%s/postmaster.pid", datadir);
	CreateLockFile(lockfile, amPostmaster, true, datadir);
	/* Save name of lockfile for RecordSharedMemoryInLockFile */
	strcpy(directoryLockFile, lockfile);
}

void
CreateSocketLockFile(const char *socketfile, bool amPostmaster)
{
	char		lockfile[MAXPGPATH];

	snprintf(lockfile, sizeof(lockfile), "%s.lock", socketfile);
	CreateLockFile(lockfile, amPostmaster, false, socketfile);
	/* Save name of lockfile for TouchSocketLockFile */
	strcpy(socketLockFile, lockfile);
}

/*
 * TouchSocketLockFile -- mark socket lock file as recently accessed
 *
 * This routine should be called every so often to ensure that the lock file
 * has a recent mod or access date.  That saves it
 * from being removed by overenthusiastic /tmp-directory-cleaner daemons.
 * (Another reason we should never have put the socket file in /tmp...)
 */
void
TouchSocketLockFile(void)
{
	/* Do nothing if we did not create a socket... */
	if (socketLockFile[0] != '\0')
	{
		/*
		 * utime() is POSIX standard, utimes() is a common alternative; if
		 * we have neither, fall back to actually reading the file (which
		 * only sets the access time not mod time, but that should be
		 * enough in most cases).  In all paths, we ignore errors.
		 */
#ifdef HAVE_UTIME
		utime(socketLockFile, NULL);
#else							/* !HAVE_UTIME */
#ifdef HAVE_UTIMES
		utimes(socketLockFile, NULL);
#else							/* !HAVE_UTIMES */
		int			fd;
		char		buffer[1];

		fd = open(socketLockFile, O_RDONLY | PG_BINARY, 0);
		if (fd >= 0)
		{
			read(fd, buffer, sizeof(buffer));
			close(fd);
		}
#endif   /* HAVE_UTIMES */
#endif   /* HAVE_UTIME */
	}
}

/*
 * Append information about a shared memory segment to the data directory
 * lock file (if we have created one).
 *
 * This may be called multiple times in the life of a postmaster, if we
 * delete and recreate shmem due to backend crash.	Therefore, be prepared
 * to overwrite existing information.  (As of 7.1, a postmaster only creates
 * one shm seg at a time; but for the purposes here, if we did have more than
 * one then any one of them would do anyway.)
 */
void
RecordSharedMemoryInLockFile(unsigned long id1, unsigned long id2)
{
	int			fd;
	int			len;
	char	   *ptr;
	char		buffer[BLCKSZ];

	/*
	 * Do nothing if we did not create a lockfile (probably because we are
	 * running standalone).
	 */
	if (directoryLockFile[0] == '\0')
		return;

	fd = open(directoryLockFile, O_RDWR | PG_BINARY, 0);
	if (fd < 0)
	{
		ereport(LOG,
				(errcode_for_file_access(),
				 errmsg("could not open file \"%s\": %m",
						directoryLockFile)));
		return;
	}
	len = read(fd, buffer, sizeof(buffer) - 100);
	if (len <= 0)
	{
		ereport(LOG,
				(errcode_for_file_access(),
				 errmsg("could not read from file \"%s\": %m",
						directoryLockFile)));
		close(fd);
		return;
	}
	buffer[len] = '\0';

	/*
	 * Skip over first two lines (PID and path).
	 */
	ptr = strchr(buffer, '\n');
	if (ptr == NULL ||
		(ptr = strchr(ptr + 1, '\n')) == NULL)
	{
		elog(LOG, "bogus data in \"%s\"", directoryLockFile);
		close(fd);
		return;
	}
	ptr++;

	/*
	 * Append key information.	Format to try to keep it the same length
	 * always (trailing junk won't hurt, but might confuse humans).
	 */
	sprintf(ptr, "%9lu %9lu\n", id1, id2);

	/*
	 * And rewrite the data.  Since we write in a single kernel call, this
	 * update should appear atomic to onlookers.
	 */
	len = strlen(buffer);
	errno = 0;
	if (lseek(fd, (off_t) 0, SEEK_SET) != 0 ||
		(int) write(fd, buffer, len) != len)
	{
		/* if write didn't set errno, assume problem is no disk space */
		if (errno == 0)
			errno = ENOSPC;
		ereport(LOG,
				(errcode_for_file_access(),
				 errmsg("could not write to file \"%s\": %m",
						directoryLockFile)));
		close(fd);
		return;
	}
	close(fd);
}


/*-------------------------------------------------------------------------
 *				Version checking support
 *-------------------------------------------------------------------------
 */

/*
 * Determine whether the PG_VERSION file in directory `path' indicates
 * a data version compatible with the version of this program.
 *
 * If compatible, return. Otherwise, ereport(FATAL).
 */
void
ValidatePgVersion(const char *path)
{
	char		full_path[MAXPGPATH];
	FILE	   *file;
	int			ret;
	long		file_major,
				file_minor;
	long		my_major = 0,
				my_minor = 0;
	char	   *endptr;
	const char *version_string = PG_VERSION;

	my_major = strtol(version_string, &endptr, 10);
	if (*endptr == '.')
		my_minor = strtol(endptr + 1, NULL, 10);

	snprintf(full_path, sizeof(full_path), "%s/PG_VERSION", path);

	file = AllocateFile(full_path, "r");
	if (!file)
	{
		if (errno == ENOENT)
			ereport(FATAL,
					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
					 errmsg("\"%s\" is not a valid data directory",
							path),
					 errdetail("File \"%s\" is missing.", full_path)));
		else
			ereport(FATAL,
					(errcode_for_file_access(),
					 errmsg("could not open file \"%s\": %m", full_path)));
	}

	ret = fscanf(file, "%ld.%ld", &file_major, &file_minor);
	if (ret != 2)
		ereport(FATAL,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("\"%s\" is not a valid data directory",
						path),
				 errdetail("File \"%s\" does not contain valid data.",
						   full_path),
				 errhint("You may need to initdb.")));

	FreeFile(file);

	if (my_major != file_major || my_minor != file_minor)
		ereport(FATAL,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("database files are incompatible with server"),
				 errdetail("The data directory was initialized by PostgreSQL version %ld.%ld, "
						 "which is not compatible with this version %s.",
						   file_major, file_minor, version_string)));
}

/*-------------------------------------------------------------------------
 *				Library preload support
 *-------------------------------------------------------------------------
 */

#if defined(__mc68000__) && defined(__ELF__)
typedef int32 ((*func_ptr) ());

#else
typedef char *((*func_ptr) ());
#endif

/*
 * process any libraries that should be preloaded and
 * optionally pre-initialized
 */
void
process_preload_libraries(char *preload_libraries_string)
{
	char	   *rawstring;
	List	   *elemlist;
	List	   *l;

	if (preload_libraries_string == NULL)
		return;

	/* Need a modifiable copy of string */
	rawstring = pstrdup(preload_libraries_string);

	/* Parse string into list of identifiers */
	if (!SplitIdentifierString(rawstring, ',', &elemlist))
	{
		/* syntax error in list */
		pfree(rawstring);
		freeList(elemlist);
		ereport(LOG,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("invalid list syntax for parameter \"preload_libraries\"")));
		return;
	}

	foreach(l, elemlist)
	{
		char	   *tok = (char *) lfirst(l);
		char	   *sep = strstr(tok, ":");
		char	   *filename = NULL;
		char	   *funcname = NULL;
		func_ptr	initfunc;

		if (sep)
		{
			/*
			 * a colon separator implies there is an initialization
			 * function that we need to run in addition to loading the
			 * library
			 */
			size_t		filename_len = sep - tok;
			size_t		funcname_len = strlen(tok) - filename_len - 1;

			filename = (char *) palloc(filename_len + 1);
			memcpy(filename, tok, filename_len);
			filename[filename_len] = '\0';

			funcname = (char *) palloc(funcname_len + 1);
			strcpy(funcname, sep + 1);
		}
		else
		{
			/*
			 * no separator -- just load the library
			 */
			filename = pstrdup(tok);
			funcname = NULL;
		}

		initfunc = (func_ptr) load_external_function(filename, funcname,
													 true, NULL);
		if (initfunc)
			(*initfunc) ();

		if (funcname)
			ereport(LOG,
					(errmsg("preloaded library \"%s\" with initialization function \"%s\"",
							filename, funcname)));
		else
			ereport(LOG,
					(errmsg("preloaded library \"%s\"",
							filename)));

		pfree(filename);
		if (funcname)
			pfree(funcname);
	}

	pfree(rawstring);
	freeList(elemlist);
}