taken from iopreds.c: alias handling
This commit is contained in:
Vítor Santos Costa
parent
8ec89c5bef
commit
bd572cbb59
435
os/alias.c
Normal file
435
os/alias.c
Normal file
@ -0,0 +1,435 @@
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/*************************************************************************
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* *
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* YAP Prolog *
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* *
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* Yap Prolog was developed at NCCUP - Universidade do Porto *
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* *
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* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
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* *
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**************************************************************************
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* *
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* File: iopreds.c *
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* Last rev: 5/2/88 *
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* mods: *
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* comments: Input/Output C implemented predicates *
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* *
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*************************************************************************/
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#ifdef SCCS
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static char SccsId[] = "%W% %G%";
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#endif
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/** Aliases
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* This file defines the main operations on aliases, a second name for a file. Aliases are always
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* textual constants (atoms).
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*
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* Their first advantage is that they allow cleaning up code, by separating name from operation, eg
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* YAP has a loop stream used to run the main top-level, which can be std0 originally but then
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* changed to a pipe, a file, or a memory region. Other important streams are the user streams. Finally,
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* the debugger uses debugger input and output.
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*
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* Predefined stream aliases are:
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* + user: special alias, initially refers to all the three standard streams.
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* + `user_input: initially refers to the stdandard input stream;
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* + `user_output: initially refers to the stdandard output stream;
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* + `user_error: initially refers to the stdandard error stream. Often this is the same device
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* as `stderr`, just accessed in different ways.
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* + loop_stream: refers to the stream for the file or object being current consulted
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* + debugger_input: refers to the stream used to send debugger commands, by default `user_input`.
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* It must always be interactive.
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*/
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#include "Yap.h"
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#if HAVE_FCNTL_H
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/* for O_BINARY and O_TEXT in WIN32 */
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#include <fcntl.h>
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#endif
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#include "Yatom.h"
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#include "YapHeap.h"
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#include "yapio.h"
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#include "eval.h"
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#include "YapText.h"
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#include <stdlib.h>
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#if HAVE_STDARG_H
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#include <stdarg.h>
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#endif
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#if HAVE_CTYPE_H
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#include <ctype.h>
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#endif
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#if HAVE_WCTYPE_H
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#include <wctype.h>
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#endif
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#if HAVE_SYS_PARAM_H
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#include <sys/param.h>
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#endif
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#if HAVE_SYS_TIME_H
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#include <sys/time.h>
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#endif
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#if HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#ifdef HAVE_SYS_STAT_H
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#include <sys/stat.h>
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#endif
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#if HAVE_SYS_SELECT_H && !_MSC_VER && !defined(__MINGW32__)
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#include <sys/select.h>
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#endif
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#if HAVE_STRING_H
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#include <string.h>
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#endif
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#if HAVE_SIGNAL_H
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#include <signal.h>
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#endif
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#ifdef _WIN32
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#if HAVE_IO_H
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/* Windows */
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#include <io.h>
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#endif
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#endif
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#if !HAVE_STRNCAT
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#define strncat(X,Y,Z) strcat(X,Y)
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#endif
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#if !HAVE_STRNCPY
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#define strncpy(X,Y,Z) strcpy(X,Y)
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#endif
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#if _MSC_VER || defined(__MINGW32__)
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#if HAVE_SOCKET
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#include <winsock2.h>
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#endif
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#include <windows.h>
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#ifndef S_ISDIR
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#define S_ISDIR(x) (((x)&_S_IFDIR)==_S_IFDIR)
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#endif
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#endif
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#include "iopreds.h"
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#if _MSC_VER || defined(__MINGW32__)
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#define SYSTEM_STAT _stat
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#else
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#define SYSTEM_STAT stat
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#endif
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static Atom FetchAlias (int sno);
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static bool ExistsAliasForStream (int sno, Atom al);
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static Int add_alias_to_stream (USES_REGS1)
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{
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Term tname = Deref(ARG1);
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Term tstream = Deref(ARG2);
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Atom at;
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Int sno;
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if (IsVarTerm(tname)) {
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Yap_Error(INSTANTIATION_ERROR, tname, "$add_alias_to_stream");
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return (FALSE);
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} else if (!IsAtomTerm (tname)) {
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Yap_Error(TYPE_ERROR_ATOM, tname, "$add_alias_to_stream");
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return (FALSE);
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}
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if (IsVarTerm(tstream)) {
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Yap_Error(INSTANTIATION_ERROR, tstream, "$add_alias_to_stream");
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return (FALSE);
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} else if (!IsApplTerm (tstream) || FunctorOfTerm (tstream) != FunctorStream ||
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!IsIntTerm(ArgOfTerm(1,tstream))) {
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Yap_Error(DOMAIN_ERROR_STREAM_OR_ALIAS, tstream, "$add_alias_to_stream");
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return (FALSE);
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}
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at = AtomOfTerm(tname);
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sno = (int)IntOfTerm(ArgOfTerm(1,tstream));
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if (Yap_AddAlias(at, sno))
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return(TRUE);
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/* we could not create the alias, time to close the stream */
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Yap_CloseStream(sno);
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Yap_Error(PERMISSION_ERROR_NEW_ALIAS_FOR_STREAM, tname, "open/3");
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return (FALSE);
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}
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static Int check_if_valid_new_alias (USES_REGS1)
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{
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Term tname = Deref(ARG1);
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Atom at;
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if (IsVarTerm(tname)) {
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Yap_Error(INSTANTIATION_ERROR, tname, "$add_alias_to_stream");
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return (FALSE);
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} else if (!IsAtomTerm (tname)) {
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Yap_Error(TYPE_ERROR_ATOM, tname, "$add_alias_to_stream");
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return (FALSE);
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}
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at = AtomOfTerm(tname);
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return(Yap_CheckAlias(at) == -1);
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}
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bool
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Yap_FetchStreamAlias (int sno, Term t2 USES_REGS)
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{
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if (IsVarTerm(t2)) {
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Atom at = FetchAlias(sno);
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if (at == NULL)
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return false;
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else {
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return Yap_unify_constant(t2, MkAtomTerm(at));
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}
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} else if (IsAtomTerm(t2)) {
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Atom at = AtomOfTerm(t2);
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return ExistsAliasForStream(sno,at);
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} else {
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Yap_Error(TYPE_ERROR_ATOM, t2, "stream_property(_,alias( ))");
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return false;
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}
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}
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static void
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ExtendAliasArray(void)
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{
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CACHE_REGS
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AliasDesc new;
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UInt new_size = LOCAL_SzOfFileAliases+ALIASES_BLOCK_SIZE;
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new = (AliasDesc)Yap_AllocCodeSpace(sizeof(AliasDesc *)*new_size);
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memcpy((void *)new, (void *)LOCAL_FileAliases, sizeof(AliasDesc *)*LOCAL_SzOfFileAliases);
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Yap_FreeCodeSpace((ADDR) LOCAL_FileAliases);
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LOCAL_FileAliases = new;
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LOCAL_SzOfFileAliases = new_size;
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}
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void
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Yap_SetAlias (Atom arg, int sno)
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{
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CACHE_REGS
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AliasDesc aliasp = LOCAL_FileAliases, aliasp_max = LOCAL_FileAliases+LOCAL_NOfFileAliases;
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while (aliasp < aliasp_max) {
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// replace alias
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if (aliasp->name == arg) {
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Int alno = aliasp-LOCAL_FileAliases;
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aliasp->alias_stream = sno;
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if (!(GLOBAL_Stream[sno].status &
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(Null_Stream_f|InMemory_Stream_f|Socket_Stream_f))) {
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switch(alno) {
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case 0:
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Yap_stdin = GLOBAL_Stream[sno].file;
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break;
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case 1:
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Yap_stdout = GLOBAL_Stream[sno].file;
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break;
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case 2:
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Yap_stderr = GLOBAL_Stream[sno].file;
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#if HAVE_SETBUF
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setvbuf (GLOBAL_Stream[sno].file, NULL, _IONBF, 0);
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#endif /* HAVE_SETBUF */
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break;
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default:
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break;
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}
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}
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return;
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}
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aliasp++;
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}
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// set new alias
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/* we have not found an alias, create one */
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if (aliasp == LOCAL_FileAliases+ LOCAL_SzOfFileAliases)
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ExtendAliasArray();
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LOCAL_NOfFileAliases++;
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aliasp->name = arg;
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aliasp->alias_stream = sno;
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}
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/* purge all aliases for stream sno */
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void
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Yap_DeleteAliases (int sno)
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{
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CACHE_REGS
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AliasDesc aliasp = LOCAL_FileAliases, aliasp_max = LOCAL_FileAliases+ LOCAL_NOfFileAliases, new_aliasp = aliasp;
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while (aliasp < aliasp_max) {
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if (aliasp->alias_stream == sno) {
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if (aliasp - LOCAL_FileAliases < 3) {
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/* get back to std streams, but keep alias around */
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Int alno = aliasp-LOCAL_FileAliases;
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new_aliasp->alias_stream = alno;
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switch(alno) {
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case 0:
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Yap_stdin = stdin;
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break;
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case 1:
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Yap_stdout = stdout;
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break;
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case 2:
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Yap_stderr = stderr;
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break; /* just put something here */
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}
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new_aliasp++;
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} else {
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LOCAL_NOfFileAliases--;
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}
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} else {
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/* avoid holes in alias array */
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if (new_aliasp != aliasp) {
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new_aliasp->alias_stream = aliasp->alias_stream;
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new_aliasp->name = aliasp->name;
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}
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new_aliasp++;
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}
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aliasp++;
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}
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}
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/* check if name is an alias */
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int
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Yap_CheckAlias (Atom arg)
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{
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CACHE_REGS
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AliasDesc aliasp = LOCAL_FileAliases, aliasp_max = LOCAL_FileAliases+LOCAL_NOfFileAliases;
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while (aliasp < aliasp_max) {
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if (aliasp->name == arg) {
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return(aliasp->alias_stream);
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}
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aliasp++;
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}
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return(-1);
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}
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/* check if stream has an alias */
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static Atom
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FetchAlias (int sno)
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{
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CACHE_REGS
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AliasDesc aliasp = LOCAL_FileAliases, aliasp_max = LOCAL_FileAliases+LOCAL_NOfFileAliases;
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while (aliasp < aliasp_max) {
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if (aliasp->alias_stream == sno) {
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return(aliasp->name);
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}
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aliasp++;
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}
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return(AtomFoundVar);
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}
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/* check if arg is an alias */
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static bool
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ExistsAliasForStream (int sno, Atom al)
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{
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CACHE_REGS
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AliasDesc aliasp = LOCAL_FileAliases, aliasp_max = LOCAL_FileAliases+LOCAL_NOfFileAliases;
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while (aliasp < aliasp_max) {
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if (aliasp->alias_stream == sno && aliasp->name == al) {
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return true;
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}
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aliasp++;
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}
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return false;
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}
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/* check if arg is an alias */
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bool
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Yap_FindStreamForAlias (Atom al)
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{
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CACHE_REGS
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AliasDesc aliasp = LOCAL_FileAliases,
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aliasp_max = LOCAL_FileAliases+LOCAL_NOfFileAliases;
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while (aliasp < aliasp_max) {
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if (aliasp->name == al) {
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return aliasp->alias_stream;
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}
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aliasp++;
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}
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return true;
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}
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/* create a new alias arg for stream sno */
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int
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Yap_RemoveAlias (Atom arg, int sno)
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{
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CACHE_REGS
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AliasDesc aliasp = LOCAL_FileAliases, aliasp_max = LOCAL_FileAliases+LOCAL_NOfFileAliases;
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while (aliasp < aliasp_max) {
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if (aliasp->name == arg) {
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if (aliasp->alias_stream != sno) {
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return(FALSE);
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}
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return(TRUE);
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}
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aliasp++;
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}
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/* we have not found an alias neither a hole */
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if (aliasp == LOCAL_FileAliases+LOCAL_SzOfFileAliases)
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ExtendAliasArray();
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LOCAL_NOfFileAliases++;
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aliasp->name = arg;
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aliasp->alias_stream = sno;
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return(TRUE);
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}
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/* create a new alias arg for stream sno */
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bool
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Yap_AddAlias (Atom arg, int sno)
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{
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CACHE_REGS
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AliasDesc aliasp = LOCAL_FileAliases, aliasp_max = LOCAL_FileAliases+LOCAL_NOfFileAliases;
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while (aliasp < aliasp_max) {
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if (aliasp->name == arg) {
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aliasp->alias_stream = sno;
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return true;
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}
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aliasp++;
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}
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/* we have not found an alias neither a hole */
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if (aliasp == LOCAL_FileAliases+LOCAL_SzOfFileAliases)
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ExtendAliasArray();
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LOCAL_NOfFileAliases++;
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aliasp->name = arg;
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aliasp->alias_stream = sno;
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return true;
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}
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/* create a new alias arg for stream sno */
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struct AliasDescS *
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Yap_InitStandardAliases(void)
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{
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/* init standard aliases */
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/* alloca alias array */
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LOCAL_FileAliases = (AliasDesc)Yap_AllocCodeSpace(sizeof(struct AliasDescS)*ALIASES_BLOCK_SIZE);
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if (LOCAL_FileAliases == NULL)
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return NULL;
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LOCAL_FileAliases[0].name = AtomUserIn;
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LOCAL_FileAliases[0].alias_stream = 0;
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LOCAL_FileAliases[1].name = AtomUserOut;
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LOCAL_FileAliases[1].alias_stream = 1;
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LOCAL_FileAliases[2].name = AtomUserErr;
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LOCAL_FileAliases[2].alias_stream = 2;
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LOCAL_FileAliases[3].name = AtomLoopStream;
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LOCAL_FileAliases[3].alias_stream = 0;
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LOCAL_FileAliases[4].name = AtomDebuggerInput;
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LOCAL_FileAliases[4].alias_stream = 0;
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LOCAL_NOfFileAliases = 5;
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LOCAL_SzOfFileAliases = ALIASES_BLOCK_SIZE;
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return LOCAL_FileAliases;
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}
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/* create a new alias arg for stream sno */
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void
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Yap_InitAliases(void)
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{
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Yap_InitCPred ("$check_if_valid_new_alias", 1, check_if_valid_new_alias, TestPredFlag|SafePredFlag|SyncPredFlag|HiddenPredFlag);
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Yap_InitCPred ("$add_alias_to_stream", 2, add_alias_to_stream, SafePredFlag|SyncPredFlag|HiddenPredFlag);
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}
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Block a user