libc: Fix cancellation handling in some C functions

According to POSIX.1-2008 standard, the following syscalls shall be
cancellation points : waitid, sleep, fdatasync, ppoll.
Further, if generic syscall is not available and stubs are
configured, provide the stub implementation for function.

Signed-off-by: Salvatore Cro <salvatore.cro@st.com>
Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>

5 files changed, 78 insertions, 8 deletions

diff --git a/libc/sysdeps/linux/common/Makefile.in b/libc/sysdeps/linux/common/Makefile.in
index 4f0a72c09..1711e8025 100644
--- a/libc/sysdeps/linux/common/Makefile.in
+++ b/libc/sysdeps/linux/common/Makefile.in
@@ -27,7 +27,7 @@ endif
 ifneq ($(UCLIBC_LINUX_SPECIFIC),y)
 # we need these internally: fstatfs.c statfs.c
 CSRC := $(filter-out capget.c capset.c inotify.c ioperm.c iopl.c madvise.c \
-	modify_ldt.c personality.c prctl.c readahead.c reboot.c \
+	modify_ldt.c personality.c ppoll.c prctl.c readahead.c reboot.c \
 	remap_file_pages.c sched_getaffinity.c sched_setaffinity.c \
 	sendfile64.c sendfile.c setfsgid.c setfsuid.c setresuid.c \
 	splice.c vmsplice.c tee.c signalfd.c swapoff.c swapon.c \
diff --git a/libc/sysdeps/linux/common/fdatasync.c b/libc/sysdeps/linux/common/fdatasync.c
index a40f3e00c..19d37b6e0 100644
--- a/libc/sysdeps/linux/common/fdatasync.c
+++ b/libc/sysdeps/linux/common/fdatasync.c
@@ -14,4 +14,37 @@
 # define __NR_fdatasync __NR_osf_fdatasync
 #endif
 
-_syscall1(int, fdatasync, int, fd)
+#ifdef __NR_fdatasync
+
+# ifdef __UCLIBC_HAS_THREADS_NATIVE__
+# include <sysdep-cancel.h>
+# else
+# define SINGLE_THREAD_P 1
+# endif
+
+#define __NR___syscall_fdatasync __NR_fdatasync
+
+static __always_inline
+_syscall1(int, __syscall_fdatasync, int, fd)
+
+int fdatasync(int fd)
+{
+	if (SINGLE_THREAD_P)
+		return __syscall_fdatasync(fd);
+
+# ifdef __UCLIBC_HAS_THREADS_NATIVE__
+	int oldtype = LIBC_CANCEL_ASYNC ();
+	int result = __syscall_fdatasync(fd);
+	LIBC_CANCEL_RESET (oldtype);
+	return result;
+# endif
+}
+
+#elif defined __UCLIBC_HAS_STUBS__
+/* no syscall available, so provide a stub */
+int fdatasync(int fd)
+{
+	__set_errno(ENOSYS);
+	return -1;
+}
+#endif
diff --git a/libc/sysdeps/linux/common/ppoll.c b/libc/sysdeps/linux/common/ppoll.c
index 02c8013a5..09b2b1539 100644
--- a/libc/sysdeps/linux/common/ppoll.c
+++ b/libc/sysdeps/linux/common/ppoll.c
@@ -24,6 +24,12 @@
 #include <stddef.h>
 
 #if defined __NR_ppoll && defined __UCLIBC_LINUX_SPECIFIC__
+# ifdef __UCLIBC_HAS_THREADS_NATIVE__
+#  include <sysdep-cancel.h>
+# else
+#  define SINGLE_THREAD_P 1
+# endif
+
 int
 ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *timeout,
        const sigset_t *sigmask)
@@ -35,8 +41,15 @@ ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *timeout,
 		tval = *timeout;
 		timeout = &tval;
 	}
+  if (SINGLE_THREAD_P)
+		return INLINE_SYSCALL(ppoll, 5, fds, nfds, timeout, sigmask, _NSIG / 8);
 
-	return INLINE_SYSCALL(ppoll, 5, fds, nfds, timeout, sigmask, _NSIG / 8);
+# ifdef __UCLIBC_HAS_THREADS_NATIVE__
+	int oldtype = LIBC_CANCEL_ASYNC ();
+	int result = INLINE_SYSCALL(ppoll, 5, fds, nfds, timeout, sigmask, _NSIG / 8);
+	LIBC_CANCEL_RESET (oldtype);
+	return result;
+# endif
 }
 libc_hidden_def(ppoll)
 #endif
diff --git a/libc/sysdeps/linux/common/waitid.c b/libc/sysdeps/linux/common/waitid.c
index af55c914a..c8115f9a5 100644
--- a/libc/sysdeps/linux/common/waitid.c
+++ b/libc/sysdeps/linux/common/waitid.c
@@ -14,20 +14,37 @@
 # include <sys/syscall.h>
 
 # ifdef __NR_waitid
+
+#  ifdef __UCLIBC_HAS_THREADS_NATIVE__
+#  include <sysdep-cancel.h>
+#  else
+#  define SINGLE_THREAD_P 1
+#  endif
+
 /* The waitid() POSIX interface takes 4 arguments, but the kernel function
  * actually takes 5.  The fifth is a pointer to struct rusage.  Make sure
  * we pass NULL rather than letting whatever was in the register bleed up.
  */
 #define __NR_waitid5 __NR_waitid
-static _syscall5(int, waitid5, idtype_t, idtype, id_t, id, siginfo_t*, infop,
+static __always_inline
+_syscall5(int, waitid5, idtype_t, idtype, id_t, id, siginfo_t*, infop,
                  int, options, struct rusage*, ru)
 # endif
 
 int waitid(idtype_t idtype, id_t id, siginfo_t *infop, int options)
 {
 # ifdef __NR_waitid
-	return waitid5(idtype, id, infop, options, NULL);
-# else
+ if (SINGLE_THREAD_P)
+		return waitid5(idtype, id, infop, options, NULL);
+
+#  ifdef __UCLIBC_HAS_THREADS_NATIVE__
+	int oldtype = LIBC_CANCEL_ASYNC ();
+	int result = waitid5(idtype, id, infop, options, NULL);
+	LIBC_CANCEL_RESET (oldtype);
+	return result;
+#  endif
+
+# elif defined __NR_waitpid
 	switch (idtype) {
 		case P_PID:
 			if (id <= 0)
@@ -56,7 +73,9 @@ int waitid(idtype_t idtype, id_t id, siginfo_t *infop, int options)
 	if (infop->si_pid < 0)
 		return infop->si_pid;
 	return 0;
+# else
+ __set_errno(ENOSYS);
+ return -1;
 # endif
 }
-
 #endif
diff --git a/libc/unistd/sleep.c b/libc/unistd/sleep.c
index 0c0416e6d..b0031f022 100644
--- a/libc/unistd/sleep.c
+++ b/libc/unistd/sleep.c
@@ -54,7 +54,12 @@ unsigned int sleep (unsigned int seconds)
 
     /* This is not necessary but some buggy programs depend on this.  */
     if (seconds == 0)
-	return 0;
+	{
+# ifdef CANCELLATION_P
+		CANCELLATION_P (THREAD_SELF);
+# endif
+		return 0;
+	}
 
     /* Linux will wake up the system call, nanosleep, when SIGCHLD
        arrives even if SIGCHLD is ignored.  We have to deal with it