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Merge branch 'bug26779_033' into bug26779_035

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This commit is contained in:
Nick Mathewson 2018-08-08 15:50:29 -04:00
commit 26f1167e71
4 changed files with 37 additions and 9 deletions
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4
changes/bug26779 Normal file
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@ -0,0 +1,4 @@
o Minor features (bug workaround):
- Compile correctly on systems that provide the C11 stdatomic.h header,
but where C11 atomic functions don't actually compile.
Closes ticket 26779; workaround for Debian issue 903709.

20
configure.ac
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@ -1658,6 +1658,26 @@ AC_CHECK_SIZEOF(socklen_t, , [AC_INCLUDES_DEFAULT()
AC_CHECK_SIZEOF(cell_t)
# Let's see if stdatomic works. (There are some debian clangs that screw it
# up; see Tor bug #26779 and debian bug 903709.)
AC_CACHE_CHECK([whether C11 stdatomic.h actually works],
tor_cv_stdatomic_works,
[AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
#include <stdatomic.h>
struct x { atomic_size_t y; };
void try_atomic_init(struct x *xx)
{
atomic_init(&xx->y, 99);
atomic_fetch_add(&xx->y, 1);
}
]])], [tor_cv_stdatomic_works=yes], [tor_cv_stdatomic_works=no])])
if test "$tor_cv_stdatomic_works" = "yes"; then
AC_DEFINE(STDATOMIC_WORKS, 1, [Set to 1 if we can compile a simple stdatomic example.])
elif test "$ac_cv_header_stdatomic_h" = "yes"; then
AC_MSG_WARN([Your compiler provides the stdatomic.h header, but it doesn't seem to work. I'll pretend it isn't there. If you are using Clang on Debian, maybe this is because of https://bugs.debian.org/903709 ])
fi
# Now make sure that NULL can be represented as zero bytes.
AC_CACHE_CHECK([whether memset(0) sets pointers to NULL], tor_cv_null_is_zero,
[AC_RUN_IFELSE([AC_LANG_SOURCE(

4
src/lib/thread/compat_threads.c
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@ -57,7 +57,7 @@ in_main_thread(void)
return main_thread_id == tor_get_thread_id();
}
#ifndef HAVE_STDATOMIC_H
#ifndef HAVE_WORKING_STDATOMIC
/** Initialize a new atomic counter with the value 0 */
void
atomic_counter_init(atomic_counter_t *counter)
@ -108,4 +108,4 @@ atomic_counter_exchange(atomic_counter_t *counter, size_t newval)
tor_mutex_release(&counter->mutex);
return oldval;
}
#endif /* !defined(HAVE_STDATOMIC_H) */
#endif /* !defined(HAVE_WORKING_STDATOMIC) */

18
src/lib/thread/threads.h
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@ -16,7 +16,11 @@
#include "lib/testsupport/testsupport.h"
#include "lib/lock/compat_mutex.h"
#ifdef HAVE_STDATOMIC_H
#if defined(HAVE_STDATOMIC_H) && defined(STDATOMIC_WORKS)
#define HAVE_WORKING_STDATOMIC
#endif
#ifdef HAVE_WORKING_STDATOMIC
#include <stdatomic.h>
#endif
@ -98,18 +102,18 @@ void tor_threadlocal_set(tor_threadlocal_t *threadlocal, void *value);
/**
* Atomic counter type; holds a size_t value.
*/
#ifdef HAVE_STDATOMIC_H
#ifdef HAVE_WORKING_STDATOMIC
typedef struct atomic_counter_t {
atomic_size_t val;
} atomic_counter_t;
#define ATOMIC_LINKAGE static
#else /* !(defined(HAVE_STDATOMIC_H)) */
#else /* !(defined(HAVE_WORKING_STDATOMIC)) */
typedef struct atomic_counter_t {
tor_mutex_t mutex;
size_t val;
} atomic_counter_t;
#define ATOMIC_LINKAGE
#endif /* defined(HAVE_STDATOMIC_H) */
#endif /* defined(HAVE_WORKING_STDATOMIC) */
ATOMIC_LINKAGE void atomic_counter_init(atomic_counter_t *counter);
ATOMIC_LINKAGE void atomic_counter_destroy(atomic_counter_t *counter);
@ -120,7 +124,7 @@ ATOMIC_LINKAGE size_t atomic_counter_exchange(atomic_counter_t *counter,
size_t newval);
#undef ATOMIC_LINKAGE
#ifdef HAVE_STDATOMIC_H
#ifdef HAVE_WORKING_STDATOMIC
/** Initialize a new atomic counter with the value 0 */
static inline void
atomic_counter_init(atomic_counter_t *counter)
@ -158,7 +162,7 @@ atomic_counter_exchange(atomic_counter_t *counter, size_t newval)
return atomic_exchange(&counter->val, newval);
}
#else /* !(defined(HAVE_STDATOMIC_H)) */
#endif /* defined(HAVE_STDATOMIC_H) */
#else /* !(defined(HAVE_WORKING_STDATOMIC)) */
#endif /* defined(HAVE_WORKING_STDATOMIC) */
#endif /* !defined(TOR_COMPAT_THREADS_H) */