ok
Mini Shell
#include "ruby.h"
#if defined( RUBY_19 ) || defined( RUBY_2 )
#include <ruby/util.h>
#else
#include "util.h"
#endif
#include "lsapilib.h"
#include <errno.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <signal.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <unistd.h>
#include <sys/mman.h>
#include <fcntl.h>
/* RUBY_EXTERN VALUE ruby_errinfo; */
RUBY_EXTERN VALUE rb_stdin;
RUBY_EXTERN VALUE rb_stdout;
#if RUBY_VERSION_CODE < 180
RUBY_EXTERN VALUE rb_defout;
#endif
static VALUE orig_stdin;
static VALUE orig_stdout;
static VALUE orig_stderr;
#if RUBY_VERSION_CODE < 180
static VALUE orig_defout;
#endif
static VALUE orig_env;
static VALUE env_copy;
static VALUE lsapi_env;
static int MAX_BODYBUF_LENGTH = (10 * 1024 * 1024);
/* static VALUE lsapi_objrefs; */
typedef struct lsapi_data
{
LSAPI_Request * req;
VALUE env;
ssize_t (* fn_write)( LSAPI_Request *, const char * , size_t );
}lsapi_data;
static VALUE cLSAPI;
static VALUE s_req = Qnil;
static lsapi_data * s_req_data;
static VALUE s_req_stderr = Qnil;
static lsapi_data * s_stderr_data;
static pid_t s_pid = 0;
typedef struct lsapi_body
{
char *bodyBuf; //we put small one into memory, otherwise, into a memory mapping file, and we still use the bodyBuf to access this mapping
int bodyLen; //expected length got form content-length
int bodyCurrentLen; //current length by read() readBodyToReqBuf
int curPos;
}lsapi_body;
static lsapi_body s_body;
static char sTempFile[1024] = {0};
/*
* static void lsapi_ruby_setenv(const char *name, const char *value)
* {
* if (!name) return;
*
* if (value && *value)
* ruby_setenv(name, value);
* else
* ruby_unsetenv(name);
} * *
*/
static void lsapi_mark( lsapi_data * data )
{
rb_gc_mark( data->env );
}
/*
* static void lsapi_free_data( lsapi_data * data )
* {
* free( data );
} * *
*/
static int add_env_rails( const char * pKey, int keyLen, const char * pValue, int valLen,
void * arg )
{
char * p;
int len;
/* Fixup some environment variables for rails */
switch( *pKey )
{
case 'Q':
if ( strcmp( pKey, "QUERY_STRING" ) == 0 )
{
if ( !*pValue )
return 1;
}
break;
case 'R':
if (( *(pKey+8) == 'U' )&&( strcmp( pKey, "REQUEST_URI" ) == 0 ))
{
p = strchr( pValue, '?' );
if ( p )
{
len = valLen - ( p - pValue ) - 1;
/*
* valLen = p - pValue;
*p++ = 0;
*/
}
else
{
p = (char *)pValue + valLen;
len = 0;
}
rb_hash_aset( lsapi_env,rb_tainted_str_new("PATH_INFO", 9),
rb_tainted_str_new(pValue, p - pValue));
rb_hash_aset( lsapi_env,rb_tainted_str_new("REQUEST_PATH", 12),
rb_tainted_str_new(pValue, p - pValue));
if ( *p == '?' )
++p;
rb_hash_aset( lsapi_env,rb_tainted_str_new("QUERY_STRING", 12),
rb_tainted_str_new(p, len));
}
break;
case 'S':
if ( strcmp( pKey, "SCRIPT_NAME" ) == 0 )
{
pValue = "/";
valLen = 1;
}
break;
case 'P':
if ( strcmp( pKey, "PATH_INFO" ) == 0 )
return 1;
default:
break;
}
/* lsapi_ruby_setenv(pKey, pValue ); */
rb_hash_aset( lsapi_env,rb_tainted_str_new(pKey, keyLen),
rb_tainted_str_new(pValue, valLen));
return 1;
}
static int add_env_no_fix( const char * pKey, int keyLen, const char * pValue, int valLen,
void * arg )
{
rb_hash_aset( lsapi_env,rb_tainted_str_new(pKey, keyLen),
rb_tainted_str_new(pValue, valLen));
return 1;
}
typedef int (*fn_add_env)( const char * pKey, int keyLen, const char * pValue, int valLen,
void * arg );
fn_add_env s_fn_add_env = add_env_no_fix;
static void clear_env()
{
/* rb_funcall( lsapi_env, rb_intern( "clear" ), 0 ); */
rb_funcall( lsapi_env, rb_intern( "replace" ), 1, env_copy );
}
static void setup_cgi_env( lsapi_data * data )
{
clear_env();
LSAPI_ForeachHeader_r( data->req, s_fn_add_env, data );
LSAPI_ForeachEnv_r( data->req, s_fn_add_env, data );
}
static VALUE lsapi_s_accept( VALUE self )
{
int pid;
if ( LSAPI_Prefork_Accept_r( &g_req ) == -1 )
return Qnil;
else
{
if (s_body.bodyBuf != NULL)
free (s_body.bodyBuf);
s_body.bodyBuf = NULL;
s_body.bodyLen = -1;
s_body.bodyCurrentLen = 0;
s_body.curPos = 0;
pid = getpid();
if ( pid != s_pid )
{
s_pid = pid;
rb_funcall( Qnil, rb_intern( "srand" ), 0 );
}
setup_cgi_env( s_req_data );
return s_req;
}
}
static VALUE lsapi_s_accept_new_conn(VALUE self)
{
if (LSAPI_Accept_Before_Fork(&g_req) == -1 )
return Qnil;
else
return s_req;
}
static VALUE lsapi_s_postfork_child(VALUE self)
{
LSAPI_Postfork_Child(&g_req);
return s_req;
}
static VALUE lsapi_s_postfork_parent(VALUE self)
{
LSAPI_Postfork_Parent(&g_req);
return s_req;
}
/*
* static int chdir_file( const char * pFile )
* {
* char * p = strrchr( pFile, '/' );
* int ret;
* if ( !p )
* return -1;
*p = 0;
ret = chdir( pFile );
*p = '/';
return ret;
}
*/
static VALUE lsapi_eval_string_wrap(VALUE self, VALUE str)
{
if (rb_safe_level() >= 4)
{
Check_Type(str, T_STRING);
}
else
{
SafeStringValue(str);
}
return rb_eval_string_wrap(StringValuePtr(str), NULL);
}
static VALUE lsapi_process( VALUE self )
{
/* lsapi_data *data;
const char * pScriptPath;
Data_Get_Struct(self,lsapi_data, data);
pScriptPath = LSAPI_GetScriptFileName_r( data->req );
*/
/*
* if ( chdir_file( pScriptPath ) == -1 )
* {
* lsapi_send_error( 404 );
* }
* rb_load_file( pScriptPath );
*/
return Qnil;
}
static VALUE lsapi_putc(VALUE self, VALUE c)
{
char ch = NUM2CHR(c);
lsapi_data *data;
Data_Get_Struct(self,lsapi_data, data);
if ( (*data->fn_write)( data->req, &ch, 1 ) == 1 )
return c;
else
return INT2NUM( EOF );
}
static VALUE lsapi_write( VALUE self, VALUE str )
{
lsapi_data *data;
int len;
Data_Get_Struct(self,lsapi_data, data);
/* len = LSAPI_Write_r( data->req, RSTRING_PTR(str), RSTRING_LEN(str) ); */
if (TYPE(str) != T_STRING)
str = rb_obj_as_string(str);
len = (*data->fn_write)( data->req, RSTRING_PTR(str), RSTRING_LEN(str) );
return INT2NUM( len );
}
static VALUE lsapi_print( int argc, VALUE *argv, VALUE out )
{
int i;
VALUE line;
/* if no argument given, print `$_' */
if (argc == 0)
{
argc = 1;
line = rb_lastline_get();
argv = &line;
}
for (i = 0; i<argc; i++)
{
if (!NIL_P(rb_output_fs) && i>0)
{
lsapi_write(out, rb_output_fs);
}
switch (TYPE(argv[i]))
{
case T_NIL:
lsapi_write(out, rb_str_new2("nil"));
break;
default:
lsapi_write(out, argv[i]);
break;
}
}
if (!NIL_P(rb_output_rs))
{
lsapi_write(out, rb_output_rs);
}
return Qnil;
}
static VALUE lsapi_printf(int argc, VALUE *argv, VALUE out)
{
lsapi_write(out, rb_f_sprintf(argc, argv));
return Qnil;
}
static VALUE lsapi_puts _((int, VALUE*, VALUE));
#if defined( RUBY_19 ) || defined( RUBY_2 )
static VALUE lsapi_puts_ary(VALUE ary, VALUE out, int recur )
{
VALUE tmp;
long i;
if (recur)
{
tmp = rb_str_new2("[...]");
rb_io_puts(1, &tmp, out);
return Qnil;
}
for (i=0; i<RARRAY_LEN(ary); i++)
{
tmp = RARRAY_PTR(ary)[i];
rb_io_puts(1, &tmp, out);
}
return Qnil;
}
#else
static VALUE lsapi_puts_ary(VALUE ary, VALUE out)
{
VALUE tmp;
int i;
for (i=0; i<RARRAY_LEN(ary); i++)
{
tmp = RARRAY_PTR(ary)[i];
if (rb_inspecting_p(tmp))
{
tmp = rb_str_new2("[...]");
}
lsapi_puts(1, &tmp, out);
}
return Qnil;
}
#endif
static VALUE lsapi_puts(int argc, VALUE *argv, VALUE out)
{
int i;
VALUE line;
/* if no argument given, print newline. */
if (argc == 0)
{
lsapi_write(out, rb_default_rs);
return Qnil;
}
for (i=0; i<argc; i++)
{
switch (TYPE(argv[i]))
{
case T_NIL:
line = rb_str_new2("nil");
break;
case T_ARRAY:
#if defined( RUBY_19 ) || defined( RUBY_2 )
rb_exec_recursive(lsapi_puts_ary, argv[i], out);
#else
rb_protect_inspect(lsapi_puts_ary, argv[i], out);
#endif
continue;
default:
line = argv[i];
break;
}
line = rb_obj_as_string(line);
lsapi_write(out, line);
if (*( RSTRING_PTR(line) + RSTRING_LEN(line) - 1 ) != '\n')
{
lsapi_write(out, rb_default_rs);
}
}
return Qnil;
}
static VALUE lsapi_addstr(VALUE out, VALUE str)
{
lsapi_write(out, str);
return out;
}
static VALUE lsapi_flush( VALUE self )
{
/*
* lsapi_data *data;
* Data_Get_Struct(self,lsapi_data, data);
*/
LSAPI_Flush_r( &g_req );
return Qnil;
}
static VALUE lsapi_getc( VALUE self )
{
int ch;
/*
* lsapi_data *data;
* Data_Get_Struct(self,lsapi_data, data);
*/
if (rb_safe_level() >= 4 && !OBJ_TAINTED(self))
{
rb_raise(rb_eSecurityError, "Insecure: operation on untainted IO");
}
ch = LSAPI_ReqBodyGetChar_r( &g_req );
if ( ch == EOF )
return Qnil;
return INT2NUM( ch );
}
static inline int isBodyWriteToFile()
{
return ((s_body.bodyLen >= MAX_BODYBUF_LENGTH)? (1): (0));
}
//create a temp file and open it, if failed, fd = -1
static inline int createTempFile()
{
int fd = -1;
char *sfn = strdup(sTempFile);
if ((fd = mkstemp(sfn)) == -1)
{
fprintf(stderr, "%s: %s\n", sfn, strerror(errno));
}
else
unlink(sfn);
free(sfn);
return fd;
}
//return 1 if error occured!
//if already created, always OK (0)
static int createBodyBuf()
{
int fd = -1;
if (s_body.bodyLen == -1)
{
s_body.bodyLen = LSAPI_GetReqBodyLen_r(&g_req);
//Error if get a zeor length, should not happen
if (s_body.bodyLen < 0)
{
//Wrong bode length will be treated as 0
s_body.bodyLen = 0;
}
if (s_body.bodyLen > 0)
{
if (isBodyWriteToFile())
{
//create file mapping
fd = createTempFile();
if (fd == -1)
{
return 1;
}
if (ftruncate(fd, s_body.bodyLen) == 0)
{
perror("ftruncate() failed. \n");
close(fd);
return 1;
}
s_body.bodyBuf = mmap(NULL, s_body.bodyLen, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (s_body.bodyBuf == MAP_FAILED)
{
perror("File mapping failed. \n");
close(fd);
return 1;
}
close(fd); //close since needn't it anymore
}
else
{
s_body.bodyBuf = (char *)calloc(s_body.bodyLen, sizeof(char));
if (s_body.bodyBuf == NULL)
{
perror("Memory calloc error");
return 1;
}
}
}
}
return 0;
}
static inline int isAllBodyRead()
{
return (s_body.bodyCurrentLen < s_body.bodyLen)? 0 : 1;
}
static inline int isEofBodyBuf()
{
return (s_body.curPos < s_body.bodyLen) ? 0 : 1;
}
//try to read length as times pagesize (such as 8KB * N)
static int readBodyBuf(const int needRead)
{
const int blockSize = 8192;
char *buff = s_body.bodyBuf + s_body.bodyCurrentLen;
int nRead;
int readMore = (needRead + blockSize -1) / blockSize * blockSize;
int remain = LSAPI_GetReqBodyRemain_r( &g_req );
//Only when not enough left, needReadChange will be changed!!!
if (remain < readMore)
readMore = remain;
if ( readMore <= 0 )
return 0;
nRead = LSAPI_ReadReqBody_r(&g_req, buff, readMore);
if ( nRead > 0 )
s_body.bodyCurrentLen += nRead;
return nRead;
}
static VALUE lsapi_gets( VALUE self )
{
VALUE str;
const int blkSize = 4096;
int n;
char *p = NULL;
if (rb_safe_level() >= 4 && !OBJ_TAINTED(self))
{
rb_raise(rb_eSecurityError, "Insecure: operation on untainted IO");
}
if (createBodyBuf() == 1)
{
return Qnil;
}
//comment:
while((p = memmem(s_body.bodyBuf + s_body.curPos, s_body.bodyCurrentLen - s_body.curPos, "\n", 1)) == NULL)
{
if (isAllBodyRead() == 1)
break;
//read one page and check, then reply
readBodyBuf(blkSize);
}
p = memmem(s_body.bodyBuf + s_body.curPos, s_body.bodyCurrentLen - s_body.curPos, "\n", 1);
if (p != NULL)
n = p - s_body.bodyBuf - s_body.curPos + 1;
else
n = s_body.bodyCurrentLen - s_body.curPos;
str = rb_str_buf_new( n );
OBJ_TAINT(str);
if (n > 0)
{
rb_str_buf_cat( str, s_body.bodyBuf + s_body.curPos, n );
s_body.curPos += n;
}
return str;
}
static VALUE lsapi_read(int argc, VALUE *argv, VALUE self)
{
VALUE str;
int n;
int needRead;
int nRead;
if (rb_safe_level() >= 4 && !OBJ_TAINTED(self))
{
rb_raise(rb_eSecurityError, "Insecure: operation on untainted IO");
}
if (createBodyBuf() == 1)
{
return Qnil;
}
//we need to consider these 4 cases:
//1, need all data since argc == 0, we may have all data 2, or not
//3, need a length of data (argv >= 1), we may have enough data already read, 4, or not
if (argc == 0)
n = s_body.bodyLen - s_body.curPos;
else
{
n = NUM2INT(argv[0]); //request that length from currentpos
if (n < 0)
return Qnil;
if (n > s_body.bodyLen - s_body.curPos)
n = s_body.bodyLen - s_body.curPos;
}
needRead = s_body.curPos + n - s_body.bodyCurrentLen;
if (needRead < 0)
needRead = 0;
str = rb_str_buf_new( n );
OBJ_TAINT(str);
if (n == 0)
return str;
//copy already have part first
if (n - needRead != 0)
{
rb_str_buf_cat( str, s_body.bodyBuf + s_body.curPos, n - needRead);
s_body.curPos += (n - needRead);
}
if (needRead > 0)
{
//try to read needRead, but may be less (changed) when read the end of the data
nRead = readBodyBuf(needRead);
if (nRead > 0)
{
n = ((nRead < needRead) ? nRead : needRead);
rb_str_buf_cat( str, s_body.bodyBuf + s_body.curPos, n );
s_body.curPos += n;
}
}
return str;
}
static VALUE lsapi_rewind(VALUE self)
{
s_body.curPos = 0;
return self;
}
static VALUE lsapi_each(int argc, VALUE *argv, VALUE self)
{
VALUE str;
lsapi_rewind(self);
while(isEofBodyBuf() != 1)
{
str = lsapi_gets(self);
rb_yield(str);
}
return self;
}
static VALUE lsapi_eof(VALUE self)
{
/*
* lsapi_data *data;
*
* if (rb_safe_level() >= 4 && !OBJ_TAINTED(self))
* {
* rb_raise(rb_eSecurityError, "Insecure: operation on untainted IO");
}
Data_Get_Struct(self, lsapi_data, data);
*/
return (LSAPI_GetReqBodyRemain_r( &g_req ) <= 0) ? Qtrue : Qfalse;
}
static VALUE lsapi_binmode(VALUE self)
{
return self;
}
static VALUE lsapi_isatty(VALUE self)
{
return Qfalse;
}
static VALUE lsapi_sync(VALUE self)
{
return Qfalse;
}
static VALUE lsapi_setsync(VALUE self,VALUE sync)
{
return Qfalse;
}
static VALUE lsapi_close(VALUE self)
{
LSAPI_Flush_r( &g_req );
if (isBodyWriteToFile())
{
//msync(s_body.bodyBuf, s_body.bodyLen, MS_SYNC);
//sleep(5);
munmap(s_body.bodyBuf, s_body.bodyLen);
}
else
free(s_body.bodyBuf);
s_body.bodyBuf = NULL;
s_body.bodyLen = -1;
s_body.bodyCurrentLen = 0;
s_body.curPos = 0;
//Should the temp be deleted here?!
return Qnil;
}
static VALUE lsapi_reopen( int argc, VALUE *argv, VALUE self)
{
VALUE orig_verbose;
if ( self == s_req_stderr )
{
/* constant silence hack */
orig_verbose = (VALUE)ruby_verbose;
ruby_verbose = Qnil;
rb_define_global_const("STDERR", orig_stderr);
ruby_verbose = (VALUE)orig_verbose;
return rb_funcall2( orig_stderr, rb_intern( "reopen" ), argc, argv );
}
return self;
}
static void readMaxBodyBufLength()
{
int n;
const char *p = getenv( "LSAPI_MAX_BODYBUF_LENGTH" );
if ( p )
{
n = atoi( p );
if (n > 0)
{
if (strstr(p, "M") || strstr(p, "m"))
MAX_BODYBUF_LENGTH = n * 1024 * 1024;
else if (strstr(p, "K") || strstr(p, "k"))
MAX_BODYBUF_LENGTH = n * 1024;
else
MAX_BODYBUF_LENGTH = n;
}
}
}
static void readTempFileTemplate()
{
const char *p = getenv( "LSAPI_TEMPFILE" );
if (p == NULL || strlen(p) > 1024 - 7)
p = "/tmp/lsapi.XXXXXX";
strcpy(sTempFile, p);
if (strlen(p) <= 6 || strcmp(p + (strlen(p) - 6), "XXXXXX") != 0)
strcat(sTempFile, ".XXXXXX");
}
static void initBodyBuf()
{
s_body.bodyBuf = NULL;
s_body.bodyLen = -1;
s_body.bodyCurrentLen = 0;
s_body.curPos = 0;
}
void Init_lsapi()
{
VALUE orig_verbose;
char * p;
int prefork = 0;
LSAPI_Init();
initBodyBuf();
readMaxBodyBufLength();
readTempFileTemplate();
p = getenv("LSAPI_CHILDREN");
if (p && atoi(p) > 1)
prefork = 1;
#ifdef rb_thread_select
LSAPI_Init_Env_Parameters( rb_thread_select );
#else
LSAPI_Init_Env_Parameters( select );
#endif
s_pid = getpid();
p = getenv( "RACK_ROOT" );
if ( p )
{
if ( chdir( p ) == -1 )
perror( "chdir()" );
}
if ( p || getenv( "RACK_ENV" ) )
s_fn_add_env = add_env_rails;
orig_stdin = rb_stdin;
orig_stdout = rb_stdout;
orig_stderr = rb_stderr;
#if RUBY_VERSION_CODE < 180
orig_defout = rb_defout;
#endif
orig_env = rb_const_get( rb_cObject, rb_intern("ENV") );
env_copy = rb_funcall( orig_env, rb_intern( "to_hash" ), 0 );
/* tell the garbage collector it is a global variable, do not recycle it. */
rb_global_variable(&env_copy);
rb_hash_aset( env_copy,rb_tainted_str_new("GATEWAY_Irewindable_input.rbNTERFACE", 17),
rb_tainted_str_new("CGI/1.2", 7));
rb_define_global_function("eval_string_wrap", lsapi_eval_string_wrap, 1);
cLSAPI = rb_define_class("LSAPI", rb_cObject);
rb_define_singleton_method(cLSAPI, "accept", lsapi_s_accept, 0);
if (prefork)
{
rb_define_singleton_method(cLSAPI, "accept_new_connection", lsapi_s_accept_new_conn, 0);
rb_define_singleton_method(cLSAPI, "postfork_child", lsapi_s_postfork_child, 0);
rb_define_singleton_method(cLSAPI, "postfork_parent", lsapi_s_postfork_parent, 0);
}
rb_define_method(cLSAPI, "process", lsapi_process, 0 );
/* rb_define_method(cLSAPI, "initialize", lsapi_initialize, 0); */
rb_define_method(cLSAPI, "putc", lsapi_putc, 1);
rb_define_method(cLSAPI, "write", lsapi_write, 1);
rb_define_method(cLSAPI, "print", lsapi_print, -1);
rb_define_method(cLSAPI, "printf", lsapi_printf, -1);
rb_define_method(cLSAPI, "puts", lsapi_puts, -1);
rb_define_method(cLSAPI, "<<", lsapi_addstr, 1);
rb_define_method(cLSAPI, "flush", lsapi_flush, 0);
rb_define_method(cLSAPI, "getc", lsapi_getc, 0);
/* rb_define_method(cLSAPI, "ungetc", lsapi_ungetc, 1); */
rb_define_method(cLSAPI, "gets", lsapi_gets, 0);
//TEST: adding readline function to make irb happy?
/*rb_define_method(cLSAPI, "readline", lsapi_gets, 0); */
rb_define_method(cLSAPI, "read", lsapi_read, -1);
rb_define_method(cLSAPI, "rewind", lsapi_rewind, 0);
rb_define_method(cLSAPI, "each", lsapi_each, 0);
rb_define_method(cLSAPI, "eof", lsapi_eof, 0);
rb_define_method(cLSAPI, "eof?", lsapi_eof, 0);
rb_define_method(cLSAPI, "close", lsapi_close, 0);
/* rb_define_method(cLSAPI, "closed?", lsapi_closed, 0); */
rb_define_method(cLSAPI, "binmode", lsapi_binmode, 0);
rb_define_method(cLSAPI, "isatty", lsapi_isatty, 0);
rb_define_method(cLSAPI, "tty?", lsapi_isatty, 0);
rb_define_method(cLSAPI, "sync", lsapi_sync, 0);
rb_define_method(cLSAPI, "sync=", lsapi_setsync, 1);
rb_define_method(cLSAPI, "reopen", lsapi_reopen, -1 );
s_req = Data_Make_Struct( cLSAPI, lsapi_data, lsapi_mark, free, s_req_data );
s_req_data->req = &g_req;
s_req_data->fn_write = LSAPI_Write_r;
rb_stdin = rb_stdout = s_req;
#if RUBY_VERSION_CODE < 180
rb_defout = s_req;
#endif
rb_global_variable(&s_req );
s_req_stderr = Data_Make_Struct( cLSAPI, lsapi_data, lsapi_mark, free, s_stderr_data );
s_stderr_data->req = &g_req;
s_stderr_data->fn_write = LSAPI_Write_Stderr_r;
rb_stderr = s_req_stderr;
rb_global_variable(&s_req_stderr );
/* constant silence hack */
orig_verbose = (VALUE)ruby_verbose;
ruby_verbose = Qnil;
lsapi_env = rb_hash_new();
clear_env();
/* redefine ENV using a hash table, should be faster than char **environment */
rb_define_global_const("ENV", lsapi_env);
rb_define_global_const("STDERR", rb_stderr);
ruby_verbose = (VALUE)orig_verbose;
return;
}
Zerion Mini Shell 1.0