Files
cpython-source-deps/env/env_name.c
2017-09-04 13:40:25 -05:00

265 lines
6.2 KiB
C

/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996,2008 Oracle. All rights reserved.
*
* $Id: env_name.c 63573 2008-05-23 21:43:21Z trent.nelson $
*/
#include "db_config.h"
#include "db_int.h"
static int __db_tmp_open __P((ENV *, u_int32_t, char *, DB_FH **));
#define DB_ADDSTR(add) { \
/* \
* The string might be NULL or zero-length, and the p[-1] \
* might indirect to before the beginning of our buffer. \
*/ \
if ((add) != NULL && (add)[0] != '\0') { \
/* If leading slash, start over. */ \
if (__os_abspath(add)) { \
p = str; \
slash = 0; \
} \
/* Append to the current string. */ \
len = strlen(add); \
if (slash) \
*p++ = PATH_SEPARATOR[0]; \
memcpy(p, add, len); \
p += len; \
slash = strchr(PATH_SEPARATOR, p[-1]) == NULL; \
} \
}
/*
* __db_appname --
* Given an optional DB environment, directory and file name and type
* of call, build a path based on the ENV->open rules, and return
* it in allocated space.
*
* PUBLIC: int __db_appname __P((ENV *, APPNAME,
* PUBLIC: const char *, u_int32_t, DB_FH **, char **));
*/
int
__db_appname(env, appname, file, tmp_oflags, fhpp, namep)
ENV *env;
APPNAME appname;
const char *file;
u_int32_t tmp_oflags;
DB_FH **fhpp;
char **namep;
{
DB_ENV *dbenv;
enum { TRY_NOTSET, TRY_DATA_DIR, TRY_ENV_HOME, TRY_CREATE } try_state;
size_t len, str_len;
int data_entry, ret, slash, tmp_create;
const char *a, *b;
char *p, *str;
dbenv = env->dbenv;
try_state = TRY_NOTSET;
a = b = NULL;
data_entry = 0;
tmp_create = 0;
/*
* We don't return a name when creating temporary files, just a file
* handle. Default to an error now.
*/
if (fhpp != NULL)
*fhpp = NULL;
if (namep != NULL)
*namep = NULL;
/*
* Absolute path names are never modified. If the file is an absolute
* path, we're done.
*/
if (file != NULL && __os_abspath(file))
return (__os_strdup(env, file, namep));
/* Everything else is relative to the environment home. */
if (env != NULL)
a = env->db_home;
retry: /*
* DB_APP_NONE:
* DB_HOME/file
* DB_APP_DATA:
* DB_HOME/DB_DATA_DIR/file
* DB_APP_LOG:
* DB_HOME/DB_LOG_DIR/file
* DB_APP_TMP:
* DB_HOME/DB_TMP_DIR/<create>
*/
switch (appname) {
case DB_APP_NONE:
break;
case DB_APP_DATA:
if (env == NULL || dbenv->db_data_dir == NULL) {
try_state = TRY_CREATE;
break;
}
/*
* First, step through the data_dir entries, if any, looking
* for the file.
*/
if ((b = dbenv->db_data_dir[data_entry]) != NULL) {
++data_entry;
try_state = TRY_DATA_DIR;
break;
}
/* Second, look in the environment home directory. */
if (try_state != TRY_ENV_HOME) {
try_state = TRY_ENV_HOME;
break;
}
/* Third, try creation in the first data_dir entry. */
try_state = TRY_CREATE;
b = dbenv->db_data_dir[0];
break;
case DB_APP_LOG:
if (env != NULL)
b = dbenv->db_log_dir;
break;
case DB_APP_TMP:
if (env != NULL)
b = dbenv->db_tmp_dir;
tmp_create = 1;
break;
}
len =
(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(env, 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 (appname == DB_APP_DATA &&
__os_exists(env, str, NULL) != 0 && try_state != TRY_CREATE) {
__os_free(env, str);
b = NULL;
goto retry;
}
/* Create the file if so requested. */
if (tmp_create &&
(ret = __db_tmp_open(env, tmp_oflags, str, fhpp)) != 0) {
__os_free(env, str);
return (ret);
}
if (namep == NULL)
__os_free(env, str);
else
*namep = str;
return (0);
}
/*
* __db_tmp_open --
* Create a temporary file.
*/
static int
__db_tmp_open(env, tmp_oflags, path, fhpp)
ENV *env;
u_int32_t tmp_oflags;
char *path;
DB_FH **fhpp;
{
pid_t pid;
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(env, path, &isdir)) != 0) {
__db_err(env, ret, "%s", path);
return (ret);
}
if (!isdir) {
__db_err(env, EINVAL, "%s", path);
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). */
__os_id(env->dbenv, &pid, NULL);
for (trv = path + strlen(path); *--trv == 'X'; pid /= 10)
*trv = '0' + (u_char)(pid % 10);
firstx = trv + 1;
/* Loop, trying to open a file. */
for (filenum = 1;; filenum++) {
if ((ret = __os_open(env, path, 0,
tmp_oflags | DB_OSO_CREATE | DB_OSO_EXCL | DB_OSO_TEMP,
DB_MODE_600, 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(env, ret, "temporary open: %s", path);
return (ret);
}
/*
* Generate temporary file names in a backwards-compatible way.
* If pid == 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 */
}