Rewrite signal mask decoding without sigset_t

The sigset_t provided by libc is not quite convenient.
In glibc, sigset_t is an array with space for 1024 bits, which is much
more than required: all architectures supported by Linux have only 64
signals except MIPS, which has 128.
In bionic libc, LP32 sigset_t is only 4 bytes long, which is less than
necessary.

With this change, signal mask is decoded without use of intermediate
sigset_t structure, which saves us some cpu cycles in case of glibc with
its inflated sigset_t, and enables build with libcs where sigset_t is
broken.

Old implementation used to check each signal number in the given signal
mask twice using sigismember().
New implementation is based on popcount and next_set_bit() so it's
noticeably faster.

* configure.ac: Check for __builtin_popcount.
* signal.c: Ensure that NSIG >= 32.
(sprintsigmask, sprintsigmask_long, printsigmask): Remove.
(popcount32, sprintsigmask_n): New functions.
(tprintsigmask_addr, sprintsigmask_val, tprintsigmask_val): New macros.
(print_sigset_addr_len, sys_sigsetmask, sys_sigreturn, sys_siggetmask,
sys_sigsuspend, sys_sigprocmask, decode_new_sigaction): Update to use
new signal mask decoding interface.
* tests/sigaction.c (main): Add a test with almost filled signal mask.
* tests/sigaction.awk: Update.
Add multi-personality support to stack_t decoding

stack_t is one of many structures that contain members
whose size differs between 32-bit and 64-bit personalities.

* signal.c (print_stack_t): Decode 32-bit stack_t on a 64-bit host.

Reported-by: Elliott Hughes <enh@google.com>
Remove obsolete ioctlsort.c

The generic version of ioctlsort.c became obsolete after commit
v4.6-240-g5afdf12 that removed its last non-Linux users.

* ioctlsort.c: Remove.
* Makefile.am (EXTRA_DIST): Remove ioctlsort.c.

Reported-by: Elliott Hughes <enh@google.com>
Fix decoding of arm struct stat64 by aarch64 strace.

aarch64's uapi header files have a struct stat but no struct stat64.
To correctly decode a 32-bit process' s struct stat64 we need
HAVE_STAT64, but then the build fails because there is no struct stat64.
Luckily, the aarch64 struct stat is structurally equivalent to the arm
struct stat64, so we can just reuse that.

* file.c [AARCH64] (stat64): Define to stat.

Signed-off-by: Elliott Hughes <enh@google.com>
Add multi-personality support to struct old_sigaction decoding

struct sigaction is another structure that contains members
whose size differs between 32-bit and 64-bit personalities.

* signal.c [HAVE_SIGACTION] (old_sigaction32): New structure.
[HAVE_SIGACTION] (decode_old_sigaction): Decode 32-bit struct
old_sigaction on a 64-bit host.

Signed-off-by: Elliott Hughes <enh@google.com>
sys_fcntl: remove F_FREESP and F_FREESP64 support

F_FREESP and F_FREESP64 fcntl commands are not available in Linux
and therefore the code implementing their decoding is useless.
Besides that, F_FREESP64 decoding is too complicated to support.

* desc.c (fcntlcmds): Remove F_FREESP and F_FREESP64.
Remove F_FREESP64 from the check whether to define struct flock64.
(sys_fcntl): Remove F_FREESP and F_FREESP64 support.
Fix fcntl decoding

Assume that F_SETLK64, F_SETLKW64, and F_GETLK64 are either defined or
not defined altogether.
Do not assume that sizeof(off_t) < sizeof(long long) when F_SETLK64 is
undefined.

This change fixes build with musl libc on x86.

* configure.ac: Define SIZEOF_OFF_T.
* desc.c (USE_PRINTFLOCK64): New macro.
(struct flock64, printflock64): Do not define on X32.
(printflock): Replace X32 specific workaround with SIZEOF_OFF_T check.
Fix printing off_t members of struct flock.
(sys_fcntl): Use USE_PRINTFLOCK64.
aarch64: fix decoding of arm syscall numbers

If an aarch64 strace is tracing a process using the arm personality, it
also needs to call the shuffle_scno function for the ARM-specific
syscalls.

* syscall.c (shuffle_scno): Define on AARCH64.
(get_scno) [AARCH64]: Call shuffle_scno when the tracee is in 32-bit mode.

Signed-off-by: Elliott Hughes <enh@google.com>