env_open.c

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	    (a == NULL ? 0 : strlen(a) + 1) +
	    (b == NULL ? 0 : strlen(b) + 1) +
	    (file == NULL ? 0 : strlen(file) + 1);

	/*
	 * Allocate space to hold the current path information, as well as any
	 * temporary space that we're going to need to create a temporary file
	 * name.
	 */
#define	DB_TRAIL	"BDBXXXXX"
	str_len = len + sizeof(DB_TRAIL) + 10;
	if ((ret = __os_malloc(dbenv, str_len, &str)) != 0)
		return (ret);

	slash = 0;
	p = str;
	DB_ADDSTR(a);
	DB_ADDSTR(b);
	DB_ADDSTR(file);
	*p = '\0';

	/*
	 * If we're opening a data file, see if it exists.  If it does,
	 * return it, otherwise, try and find another one to open.
	 */
	if (__os_exists(str, NULL) != 0 && data_entry != -1) {
		__os_free(dbenv, str);
		b = NULL;
		goto retry;
	}

	/* Create the file if so requested. */
	if (tmp_create &&
	    (ret = __db_tmp_open(dbenv, tmp_oflags, str, fhpp)) != 0) {
		__os_free(dbenv, str);
		return (ret);
	}

	if (namep == NULL)
		__os_free(dbenv, str);
	else
		*namep = str;
	return (0);
}

/*
 * __db_home --
 *	Find the database home.
 *
 * PUBLIC:	int __db_home __P((DB_ENV *, const char *, u_int32_t));
 */
int
__db_home(dbenv, db_home, flags)
	DB_ENV *dbenv;
	const char *db_home;
	u_int32_t flags;
{
	const char *p;

	/*
	 * Use db_home by default, this allows utilities to reasonably
	 * override the environment either explicitly or by using a -h
	 * option.  Otherwise, use the environment if it's permitted
	 * and initialized.
	 */
	if ((p = db_home) == NULL &&
	    (LF_ISSET(DB_USE_ENVIRON) ||
	    (LF_ISSET(DB_USE_ENVIRON_ROOT) && __os_isroot())) &&
	    (p = getenv("DB_HOME")) != NULL && p[0] == '\0') {
		__db_err(dbenv, "illegal DB_HOME environment variable");
		return (EINVAL);
	}

	return (p == NULL ? 0 : __os_strdup(dbenv, p, &dbenv->db_home));
}

#define	__DB_OVFL(v, max)						\
	if (v > max) {							\
		__v = v;						\
		__max = max;						\
		goto toobig;						\
	}

/*
 * __db_parse --
 *	Parse a single NAME VALUE pair.
 */
static int
__db_parse(dbenv, s)
	DB_ENV *dbenv;
	char *s;
{
	u_long __max, __v, v1, v2, v3;
	u_int32_t flags;
	char *name, *p, *value, v4;

	/*
	 * !!!
	 * The constant 40 is hard-coded into format arguments to sscanf
	 * below, it can't be changed here without changing it there, too.
	 * The additional bytes are for a trailing nul byte and because we
	 * are reading user input -- I don't want to risk any off-by-ones.
	 */
	char arg[40 + 5];

	/*
	 * Name/value pairs are parsed as two white-space separated strings.
	 * Leading and trailing white-space is trimmed from the value, but
	 * it may contain embedded white-space.  Note: we use the isspace(3)
	 * macro because it's more portable, but that means that you can use
	 * characters like form-feed to separate the strings.
	 */
	name = s;
	for (p = name; *p != '\0' && !isspace((int)*p); ++p)
		;
	if (*p == '\0' || p == name)
		goto illegal;
	*p = '\0';
	for (++p; isspace((int)*p); ++p)
		;
	if (*p == '\0')
		goto illegal;
	value = p;
	for (++p; *p != '\0'; ++p)
		;
	for (--p; isspace((int)*p); --p)
		;
	++p;
	if (p == value) {
illegal:	__db_err(dbenv, "mis-formatted name-value pair: %s", s);
		return (EINVAL);
	}
	*p = '\0';

	if (!strcasecmp(name, "set_cachesize")) {
		if (sscanf(value, "%lu %lu %lu %c", &v1, &v2, &v3, &v4) != 3)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		__DB_OVFL(v2, UINT32_MAX);
		__DB_OVFL(v3, 10000);
		return (__memp_set_cachesize(
		    dbenv, (u_int32_t)v1, (u_int32_t)v2, (int)v3));
	}

	if (!strcasecmp(name, "set_data_dir") ||
	    !strcasecmp(name, "db_data_dir"))		/* Compatibility. */
		return (__dbenv_set_data_dir(dbenv, value));

	if (!strcasecmp(name, "set_intermediate_dir")) {/* Undocumented. */
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
#ifdef INT_MAX
		__DB_OVFL(v1, INT_MAX);
#endif
		return (__dbenv_set_intermediate_dir(dbenv, (int)v1, 0));
	}

	if (!strcasecmp(name, "set_flags")) {
		if (sscanf(value, "%40s %c", arg, &v4) != 1)
			goto badarg;

		if (!strcasecmp(value, "db_auto_commit"))
			return (__dbenv_set_flags(dbenv, DB_AUTO_COMMIT, 1));
		if (!strcasecmp(value, "db_cdb_alldb"))
			return (__dbenv_set_flags(dbenv, DB_CDB_ALLDB, 1));
		if (!strcasecmp(value, "db_direct_db"))
			return (__dbenv_set_flags(dbenv, DB_DIRECT_DB, 1));
		if (!strcasecmp(value, "db_direct_log"))
			return (__dbenv_set_flags(dbenv, DB_DIRECT_LOG, 1));
		if (!strcasecmp(value, "db_dsync_log"))
			return (__dbenv_set_flags(dbenv, DB_DSYNC_LOG, 1));
		if (!strcasecmp(value, "db_log_autoremove"))
			return (__dbenv_set_flags(dbenv, DB_LOG_AUTOREMOVE, 1));
		if (!strcasecmp(value, "db_log_inmemory"))
			return (__dbenv_set_flags(dbenv, DB_LOG_INMEMORY, 1));
		if (!strcasecmp(value, "db_nolocking"))
			return (__dbenv_set_flags(dbenv, DB_NOLOCKING, 1));
		if (!strcasecmp(value, "db_nommap"))
			return (__dbenv_set_flags(dbenv, DB_NOMMAP, 1));
		if (!strcasecmp(value, "db_nopanic"))
			return (__dbenv_set_flags(dbenv, DB_NOPANIC, 1));
		if (!strcasecmp(value, "db_overwrite"))
			return (__dbenv_set_flags(dbenv, DB_OVERWRITE, 1));
		if (!strcasecmp(value, "db_region_init"))
			return (__dbenv_set_flags(dbenv, DB_REGION_INIT, 1));
		if (!strcasecmp(value, "db_txn_nosync"))
			return (__dbenv_set_flags(dbenv, DB_TXN_NOSYNC, 1));
		if (!strcasecmp(value, "db_txn_write_nosync"))
			return (
			    __dbenv_set_flags(dbenv, DB_TXN_WRITE_NOSYNC, 1));
		if (!strcasecmp(value, "db_yieldcpu"))
			return (__dbenv_set_flags(dbenv, DB_YIELDCPU, 1));
		goto badarg;
	}

	if (!strcasecmp(name, "set_lg_bsize")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__log_set_lg_bsize(dbenv, (u_int32_t)v1));
	}

	if (!strcasecmp(name, "set_lg_max")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__log_set_lg_max(dbenv, (u_int32_t)v1));
	}

	if (!strcasecmp(name, "set_lg_regionmax")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__log_set_lg_regionmax(dbenv, (u_int32_t)v1));
	}

	if (!strcasecmp(name, "set_lg_dir") ||
	    !strcasecmp(name, "db_log_dir"))		/* Compatibility. */
		return (__log_set_lg_dir(dbenv, value));

	if (!strcasecmp(name, "set_lk_detect")) {
		if (sscanf(value, "%40s %c", arg, &v4) != 1)
			goto badarg;
		if (!strcasecmp(value, "db_lock_default"))
			flags = DB_LOCK_DEFAULT;
		else if (!strcasecmp(value, "db_lock_expire"))
			flags = DB_LOCK_EXPIRE;
		else if (!strcasecmp(value, "db_lock_maxlocks"))
			flags = DB_LOCK_MAXLOCKS;
		else if (!strcasecmp(value, "db_lock_maxwrite"))
			flags = DB_LOCK_MAXWRITE;
		else if (!strcasecmp(value, "db_lock_minlocks"))
			flags = DB_LOCK_MINLOCKS;
		else if (!strcasecmp(value, "db_lock_minwrite"))
			flags = DB_LOCK_MINWRITE;
		else if (!strcasecmp(value, "db_lock_oldest"))
			flags = DB_LOCK_OLDEST;
		else if (!strcasecmp(value, "db_lock_random"))
			flags = DB_LOCK_RANDOM;
		else if (!strcasecmp(value, "db_lock_youngest"))
			flags = DB_LOCK_YOUNGEST;
		else
			goto badarg;
		return (__lock_set_lk_detect(dbenv, flags));
	}

	if (!strcasecmp(name, "set_lk_max")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__lock_set_lk_max(dbenv, (u_int32_t)v1));
	}

	if (!strcasecmp(name, "set_lk_max_locks")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__lock_set_lk_max_locks(dbenv, (u_int32_t)v1));
	}

	if (!strcasecmp(name, "set_lk_max_lockers")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__lock_set_lk_max_lockers(dbenv, (u_int32_t)v1));
	}

	if (!strcasecmp(name, "set_lk_max_objects")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__lock_set_lk_max_objects(dbenv, (u_int32_t)v1));
	}

	if (!strcasecmp(name, "set_lock_timeout")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__lock_set_env_timeout(
		    dbenv, (u_int32_t)v1, DB_SET_LOCK_TIMEOUT));
	}

	if (!strcasecmp(name, "set_mp_max_openfd")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, INT_MAX);
		return (__memp_set_mp_max_openfd(dbenv, (int)v1));
	}

	if (!strcasecmp(name, "set_mp_max_write")) {
		if (sscanf(value, "%lu %lu %c", &v1, &v2, &v4) != 2)
			goto badarg;
		__DB_OVFL(v1, INT_MAX);
		__DB_OVFL(v2, INT_MAX);
		return (__memp_set_mp_max_write(dbenv, (int)v1, (int)v2));
	}

	if (!strcasecmp(name, "set_mp_mmapsize")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__memp_set_mp_mmapsize(dbenv, (u_int32_t)v1));
	}

	if (!strcasecmp(name, "set_region_init")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1 || v1 != 1)
			goto badarg;
		return (__dbenv_set_flags(
		    dbenv, DB_REGION_INIT, v1 == 0 ? 0 : 1));
	}

	if (!strcasecmp(name, "set_shm_key")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		return (__dbenv_set_shm_key(dbenv, (long)v1));
	}

	if (!strcasecmp(name, "set_tas_spins")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__dbenv_set_tas_spins(dbenv, (u_int32_t)v1));
	}

	if (!strcasecmp(name, "set_tmp_dir") ||
	    !strcasecmp(name, "db_tmp_dir"))		/* Compatibility.*/
		return (__dbenv_set_tmp_dir(dbenv, value));

	if (!strcasecmp(name, "set_tx_max")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__txn_set_tx_max(dbenv, (u_int32_t)v1));
	}

	if (!strcasecmp(name, "set_txn_timeout")) {
		if (sscanf(value, "%lu %c", &v1, &v4) != 1)
			goto badarg;
		__DB_OVFL(v1, UINT32_MAX);
		return (__lock_set_env_timeout(
		    dbenv, (u_int32_t)v1, DB_SET_TXN_TIMEOUT));
	}

	if (!strcasecmp(name, "set_verbose")) {
		if (sscanf(value, "%40s %c", arg, &v4) != 1)
			goto badarg;

		else if (!strcasecmp(value, "db_verb_deadlock"))
			flags = DB_VERB_DEADLOCK;
		else if (!strcasecmp(value, "db_verb_recovery"))
			flags = DB_VERB_RECOVERY;
		else if (!strcasecmp(value, "db_verb_replication"))
			flags = DB_VERB_REPLICATION;
		else if (!strcasecmp(value, "db_verb_waitsfor"))
			flags = DB_VERB_WAITSFOR;
		else
			goto badarg;
		return (__dbenv_set_verbose(dbenv, flags, 1));
	}

	__db_err(dbenv, "unrecognized name-value pair: %s", s);
	return (EINVAL);

badarg:	__db_err(dbenv, "incorrect arguments for name-value pair: %s", s);
	return (EINVAL);

toobig:	__db_err(dbenv,
	    "%s: %lu larger than maximum value %lu", s, __v, __max);
	return (EINVAL);
}

/*
 * __db_tmp_open --
 *	Create a temporary file.
 */
static int
__db_tmp_open(dbenv, tmp_oflags, path, fhpp)
	DB_ENV *dbenv;
	u_int32_t tmp_oflags;
	char *path;
	DB_FH **fhpp;
{
	u_int32_t id;
	int filenum, i, isdir, ret;
	char *firstx, *trv;

	/*
	 * Check the target directory; if you have six X's and it doesn't
	 * exist, this runs for a *very* long time.
	 */
	if ((ret = __os_exists(path, &isdir)) != 0) {
		__db_err(dbenv, "%s: %s", path, db_strerror(ret));
		return (ret);
	}
	if (!isdir) {
		__db_err(dbenv, "%s: %s", path, db_strerror(EINVAL));
		return (EINVAL);
	}

	/* Build the path. */
	(void)strncat(path, PATH_SEPARATOR, 1);
	(void)strcat(path, DB_TRAIL);

	/* Replace the X's with the process ID (in decimal). */
	for (trv = path + strlen(path), __os_id(&id); *--trv == 'X'; id /= 10)
		*trv = '0' + (id % 10);
	firstx = trv + 1;

	/* Loop, trying to open a file. */
	for (filenum = 1;; filenum++) {
		if ((ret = __os_open(dbenv, path,
		    tmp_oflags | DB_OSO_CREATE | DB_OSO_EXCL | DB_OSO_TEMP,
		    __db_omode("rw----"), fhpp)) == 0)
			return (0);

		/*
		 * !!!:
		 * If we don't get an EEXIST error, then there's something
		 * seriously wrong.  Unfortunately, if the implementation
		 * doesn't return EEXIST for O_CREAT and O_EXCL regardless
		 * of other possible errors, we've lost.
		 */
		if (ret != EEXIST) {
			__db_err(dbenv,
			    "tmp_open: %s: %s", path, db_strerror(ret));
			return (ret);
		}

		/*
		 * Generate temporary file names in a backwards-compatible way.
		 * If id == 12345, the result is:
		 *   <path>/DB12345 (tried above, the first time through).
		 *   <path>/DBa2345 ...  <path>/DBz2345
		 *   <path>/DBaa345 ...  <path>/DBaz345
		 *   <path>/DBba345, and so on.
		 *
		 * XXX
		 * This algorithm is O(n**2) -- that is, creating 100 temporary
		 * files requires 5,000 opens, creating 1000 files requires
		 * 500,000.  If applications open a lot of temporary files, we
		 * could improve performance by switching to timestamp-based
		 * file names.
		 */
		for (i = filenum, trv = firstx; i > 0; i = (i - 1) / 26)
			if (*trv++ == '\0')
				return (EINVAL);

		for (i = filenum; i > 0; i = (i - 1) / 26)
			*--trv = 'a' + ((i - 1) % 26);
	}
	/* NOTREACHED */
}