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threading: fix race conditions when interrupted while pushing in the bindings stack
If ecl_bds_push or ecl_bds_bind were interrupted by a call to
ecl_bds_unwind, segementation faults could occur, because
env->bds_top->symbol may not have pointed to a valid symbol.
Also, memory corruption was possible if the functions were
interrupted after setting slot->symbol but before setting
slot->value.
This commit is contained in:
Marius Gerbershagen
parent
fac5f3f7fc
commit
6ce7ebc19f
4 changed files with 92 additions and 29 deletions
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@ -322,14 +322,19 @@ ecl_bds_bind(cl_env_ptr env, cl_object s, cl_object v)
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location = env->thread_local_bindings + index;
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slot = ++env->bds_top;
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if (slot >= env->bds_limit) slot = ecl_bds_overflow();
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ecl_disable_interrupts_env(env);
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slot->symbol = s;
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slot->value = *location;
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*location = v;
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ecl_enable_interrupts_env(env);
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#else
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ecl_bds_check(env);
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(++(env->bds_top))->symbol = s;
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env->bds_top->value = s->symbol.value; \
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ecl_bds_ptr slot = ++(env->bds_top);
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ecl_disable_interrupts_env(env);
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slot->symbol = s;
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slot->value = s->symbol.value;
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s->symbol.value = v;
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ecl_enable_interrupts_env(env);
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#endif
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}
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@ -346,13 +351,18 @@ ecl_bds_push(cl_env_ptr env, cl_object s)
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location = env->thread_local_bindings + index;
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slot = ++env->bds_top;
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if (slot >= env->bds_limit) slot = ecl_bds_overflow();
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ecl_disable_interrupts_env(env);
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slot->symbol = s;
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slot->value = *location;
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if (*location == ECL_NO_TL_BINDING) *location = s->symbol.value;
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ecl_enable_interrupts_env(env);
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#else
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ecl_bds_check(env);
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(++(env->bds_top))->symbol = s;
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env->bds_top->value = s->symbol.value;
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ecl_bds_ptr slot = ++(env->bds_top);
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ecl_disable_interrupts_env(env);
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slot->symbol = s;
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slot->value = s->symbol.value;
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ecl_enable_interrupts_env(env);
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#endif
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}
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34
src/h/ecl-atomic-ops.h
Normal file
34
src/h/ecl-atomic-ops.h
Normal file
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@ -0,0 +1,34 @@
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/* -*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*- */
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/* vim: set filetype=c tabstop=8 shiftwidth=4 expandtab: */
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/*
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ecl-atomic-ops.h -- Wrapper around libatomic_ops functions
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*/
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/*
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Copyright (c) 2001, Juan Jose Garcia Ripoll.
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ECL is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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See file '../Copyright' for full details.
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*/
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#ifndef ECL_ATOMIC_OPS_H
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#define ECL_ATOMIC_OPS_H
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#ifdef ECL_THREADS
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# define AO_REQUIRE_CAS
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# ifdef ECL_LIBATOMIC_OPS_H
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# include <ecl/atomic_ops.h>
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# else
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# include <atomic_ops.h>
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# endif
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#else
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# define AO_load(x) (x)
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# define AO_store(x,y) ((x)=(y))
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# define AO_store_full(x,y) ((x)=(y))
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#endif
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#endif /* ECL_ATOMIC_OPS_H */
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@ -420,17 +420,7 @@ extern void cl_write_object(cl_object x, cl_object stream);
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# define ECL_WITH_GLOBAL_ENV_WRLOCK_END
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#endif /* ECL_RWLOCK */
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#ifdef ECL_THREADS
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# define AO_REQUIRE_CAS
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# ifdef ECL_LIBATOMIC_OPS_H
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# include <ecl/atomic_ops.h>
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# else
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# include <atomic_ops.h>
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# endif
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#else
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# define AO_load(x) (x)
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# define AO_store(x,y) ((x)=(y))
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#endif
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#include <ecl/ecl-atomic-ops.h>
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/* read.d */
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#ifdef ECL_UNICODE
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@ -17,6 +17,11 @@
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See file '../Copyright' for full details.
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*/
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#ifndef ECL_STACKS_H
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#define ECL_STACKS_H
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#include <ecl/ecl-atomic-ops.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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@ -76,18 +81,29 @@ static inline void ecl_bds_bind_inl(cl_env_ptr env, cl_object s, cl_object v)
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ecl_bds_bind(env,s,v);
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} else {
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location = env->thread_local_bindings + index;
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/* First, we push a dummy symbol in the stack to
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* prevent segfaults when we are interrupted with a
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* call to ecl_bds_unwind. */
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AO_store_full((AO_t*)&(env->bds_top+1)->symbol,(AO_t)ECL_DUMMY_TAG);
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slot = ++env->bds_top;
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if (slot >= env->bds_limit) slot = ecl_bds_overflow();
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/* Then we disable interrupts to ensure that
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* ecl_bds_unwind doesn't overwrite the symbol with
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* some random value. */
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ecl_disable_interrupts_env(env);
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slot->symbol = s;
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slot->value = *location;
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*location = v;
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ecl_enable_interrupts_env(env);
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}
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# else
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slot = ++env->bds_top;
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if (slot >= env->bds_limit) slot = ecl_bds_overflow();
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ecl_disable_interrupts_env(env);
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slot->symbol = s;
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slot->value = s->symbol.value;
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s->symbol.value = v;
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ecl_enable_interrupts_env(env);
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# endif /* !ECL_THREADS */
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}
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@ -101,17 +117,22 @@ static inline void ecl_bds_push_inl(cl_env_ptr env, cl_object s)
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ecl_bds_push(env, s);
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} else {
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location = env->thread_local_bindings + index;
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AO_store_full((AO_t*)&(env->bds_top+1)->symbol,(AO_t)ECL_DUMMY_TAG);
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slot = ++env->bds_top;
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if (slot >= env->bds_limit) slot = ecl_bds_overflow();
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ecl_disable_interrupts_env(env);
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slot->symbol = s;
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slot->value = *location;
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if (*location == ECL_NO_TL_BINDING) *location = s->symbol.value;
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ecl_enable_interrupts_env(env);
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}
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# else
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slot = ++env->bds_top;
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if (slot >= env->bds_limit) slot = ecl_bds_overflow();
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ecl_disable_interrupts_env(env);
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slot->symbol = s;
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slot->value = s->symbol.value;
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ecl_enable_interrupts_env(env);
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# endif /* !ECL_THREADS */
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}
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@ -154,21 +175,27 @@ static inline cl_object *ecl_bds_ref_inl(cl_env_ptr env, cl_object s)
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# define ecl_bds_unwind1 ecl_bds_unwind1_inl
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#else /* !__GNUC__ */
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# ifndef ECL_THREADS
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# define ecl_bds_bind(env,sym,val) do { \
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const cl_env_ptr env_copy = (env); \
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const cl_object s = (sym); \
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const cl_object v = (val); \
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ecl_bds_check(env_copy); \
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(++(env_copy->bds_top))->symbol = s, \
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env_copy->bds_top->value = s->symbol.value; \
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s->symbol.value = v; } while (0)
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# define ecl_bds_bind(env,sym,val) do { \
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const cl_env_ptr env_copy = (env); \
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const cl_object s = (sym); \
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const cl_object v = (val); \
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ecl_bds_check(env_copy); \
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ecl_bds_ptr slot = ++(env_copy->bds_top); \
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ecl_disable_interrupts_env(env_copy); \
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slot->symbol = s; \
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slot->value = s->symbol.value; \
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s->symbol.value = v; \
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ecl_enable_interrupts_env(env_copy); } while (0)
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# define ecl_bds_push(env,sym) do { \
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const cl_env_ptr env_copy = (env); \
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const cl_object s = (sym); \
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const cl_object v = s->symbol.value; \
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ecl_bds_check(env_copy); \
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(++(env_copy->bds_top))->symbol = s, \
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env_copy->bds_top->value = s->symbol.value; } while (0);
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const cl_env_ptr env_copy = (env); \
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const cl_object s = (sym); \
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const cl_object v = s->symbol.value; \
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ecl_bds_check(env_copy); \
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ecl_bds_ptr slot = ++(env_copy->bds_top); \
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ecl_disable_interrupts_env(env_copy); \
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slot->symbol = s; \
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slot->value = s->symbol.value; \
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ecl_enable_interrupts_env(env_copy); } while (0);
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# define ecl_bds_unwind1(env) do { \
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const cl_env_ptr env_copy = (env); \
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const cl_object s = env_copy->bds_top->symbol; \
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@ -484,3 +511,5 @@ extern ECL_API ecl_frame_ptr _ecl_frs_push(register cl_env_ptr, register cl_obje
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#ifdef __cplusplus
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}
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#endif
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#endif /* ECL_STACKS_H */
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