miscinit.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

			}
		}

		/*
		 * 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 \"ipcclean\", \"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)));
	}
	if (close(fd))
	{
		int			save_errno = errno;

		unlink(filename);
		errno = save_errno;
		ereport(FATAL,
				(errcode_for_file_access(),
				 errmsg("could not write lock file \"%s\": %m", filename)));
	}

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

/*
 * Create the data directory lockfile.
 *
 * When this is called, we must have already switched the working
 * directory to DataDir, so we can just use a relative path.  This
 * helps ensure that we are locking the directory we should be.
 */
void
CreateDataDirLockFile(bool amPostmaster)
{
	CreateLockFile(DIRECTORY_LOCK_FILE, amPostmaster, true, DataDir);
}

/*
 * Create a lockfile for the specified Unix socket file.
 */
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.
 *
 * 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];

	fd = open(DIRECTORY_LOCK_FILE, O_RDWR | PG_BINARY, 0);
	if (fd < 0)
	{
		ereport(LOG,
				(errcode_for_file_access(),
				 errmsg("could not open file \"%s\": %m",
						DIRECTORY_LOCK_FILE)));
		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",
						DIRECTORY_LOCK_FILE)));
		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\"", DIRECTORY_LOCK_FILE);
		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",
						DIRECTORY_LOCK_FILE)));
		close(fd);
		return;
	}
	if (close(fd))
	{
		ereport(LOG,
				(errcode_for_file_access(),
				 errmsg("could not write to file \"%s\": %m",
						DIRECTORY_LOCK_FILE)));
	}
}


/*-------------------------------------------------------------------------
 *				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
 *-------------------------------------------------------------------------
 */

typedef void (*func_ptr) ();

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

		canonicalize_path(filename);
		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);
	list_free(elemlist);
}