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syscall(3)'s return type should be long.

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This doesn't require us to change any of the syscall implementations
because (a) the LP32 ones have sizeof(int) == sizeof(long) anyway,
which is how we never noticed this bug before and (b) the LP64 ones
all use a 64-bit register for the result (and for the syscall number
too).

Bug: https://code.google.com/p/android/issues/detail?id=73952
Change-Id: I9866c3579a7a94de27bfbe80ad7a822c3183c7fb
This commit is contained in:
Elliott Hughes 2014-07-28 12:24:22 -07:00
parent 8c66fd798e
commit 21972b61ec
2 changed files with 10 additions and 1 deletions
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2
libc/include/sys/syscall.h
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@ -37,7 +37,7 @@
__BEGIN_DECLS
int syscall(int number, ...);
long syscall(long number, ...);
__END_DECLS

9
tests/unistd_test.cpp
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@ -20,6 +20,7 @@
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/syscall.h>
@ -212,6 +213,14 @@ TEST(unistd, read_EBADF) {
ASSERT_EQ(EBADF, errno);
}
TEST(unistd, syscall_long) {
// Check that syscall(3) correctly returns long results.
// https://code.google.com/p/android/issues/detail?id=73952
// We assume that the break is > 4GiB, but this is potentially flaky.
uintptr_t p = reinterpret_cast<uintptr_t>(sbrk(0));
ASSERT_EQ(p, static_cast<uintptr_t>(syscall(__NR_brk, 0)));
}
TEST(unistd, alarm) {
ASSERT_EQ(0U, alarm(0));
}