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- /*
- * Copyright (C) 2000-2011 Erik Andersen <andersen@uclibc.org>
- *
- * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
- */
- #ifndef _CANCEL_H
- #define _CANCEL_H
- /*
- * Usage of this header:
- * 1. define a static or hidden function __NC(NAME) - expands to __NAME_nocancel
- * 2. if it is hidden, add the prototype to the appropiate header where NAME has
- * it's prototype (guarded by _LIBC)
- * 3. add a CANCELLABLE_SYSCALL(...) line at the end, this will create the function
- * NAME (as weak) with enabled cancellation for NPTL, for
- * LT it will also create a strong_alias to __libc_NAME to be used in libpthread
- * 4. if you need libc_hidden_(weak|def) line, use instead lt_libc_hidden, this will
- * take care of the correct type, weak or strong depending on the THREADS type
- * 5. If the implementation can't be done using CANCELLABLE_SYSCALL (like for fcntl)
- * you need to manually add lt_strong_alias() line too, to optionally create the
- * __libc_NAME alias
- * 6. if functions are needed to implement __NC(NAME), that themselves are cancellable,
- * decide how the cancellation should be solved, two variants are possible:
- * a. use the other function as __NC(FUNC), this way you access the non-cancellable
- * variant and provide by CANCELLABLE_SYSCALL(...) the dedicated cancellation for NAME.
- * be aware, that for this case __NC(FUNC) has to be hidden (not static)
- * b. use the other function with it's name (FUNC) and add LIBC_CANCEL_HANDLED(); at
- * the end of file with a comment telling us which function took care of the cancellation
- * Note: LIBC_CANCEL_HANDLED() is noop on uClibc, glibc uses it only for tests, we use
- * it only for "documentation".
- *
- * For now the use of this file is limited to libc, will expand later to support libpthread
- * and librt as well.
- */
- #include <features.h>
- #define __NC(name) _NC(name)
- #define _NC(name) __##name##_nocancel
- #define __NC_OLD(name) _NC_OLD(name)
- #define _NC_OLD(name) __libc_##name
- #define __NC_PROTO(name) extern __typeof(name) __NC(name) attribute_hidden;
- #define __NC_OLD_PROTO(name) extern __typeof(name) __NC_OLD(name);
- #if defined __UCLIBC_HAS_THREADS__ && !defined __UCLIBC_HAS_LINUXTHREADS__
- # define __NEW_THREADS 1
- #else
- # define SINGLE_THREAD_P 1
- #endif
- #ifdef __NEW_THREADS
- # include <sysdep-cancel.h>
- # define CANCELLABLE_SYSCALL(res_type, name, param_list, params) \
- res_type weak_function name param_list \
- { \
- int oldtype; \
- res_type result; \
- if (SINGLE_THREAD_P) \
- return __NC(name) params; \
- oldtype = LIBC_CANCEL_ASYNC(); \
- result = __NC(name) params; \
- LIBC_CANCEL_RESET(oldtype); \
- return result; \
- }
- # define lt_strong_alias(name)
- # define lt_libc_hidden(name) libc_hidden_def(name)
- #elif defined __UCLIBC_HAS_LINUXTHREADS__
- # define CANCELLABLE_SYSCALL(res_type, name, param_list, params) \
- weak_alias(__NC(name),name) \
- lt_strong_alias(name)
- # define lt_strong_alias(name) \
- __NC_OLD_PROTO(name) \
- strong_alias(name,__NC_OLD(name))
- # define lt_libc_hidden(name) libc_hidden_weak(name)
- #else
- # define CANCELLABLE_SYSCALL(res_type, name, param_list, params) \
- strong_alias(__NC(name),name)
- # define lt_strong_alias(name)
- # define lt_libc_hidden(name) libc_hidden_def(name)
- #endif
- /* disable it, useless, glibc uses it only for tests */
- # undef LIBC_CANCEL_HANDLED
- # define LIBC_CANCEL_HANDLED()
- #endif
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