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