cleanup various minor issues reported by nsz

the changes to syscall_ret are mostly no-ops in the generated code,
just cleanup of type issues and removal of some implementation-defined
behavior. the one exception is the change in the comparison value,
which is fixed so that 0xf...f000 (which in principle could be a valid
return value for mmap, although probably never in reality) is not
treated as an error return.

include/sys/syscall.h

@@ -4,7 +4,7 @@
 extern "C" {
 #endif
 
-long __syscall_ret(long);
+long __syscall_ret(unsigned long);
 long __syscall(long, ...);
 long syscall(long, ...);
 

include/time.h

@@ -85,7 +85,6 @@ int clock_settime (clockid_t, const struct timespec *);
 int clock_nanosleep (clockid_t, int, const struct timespec *, struct timespec *);
 int clock_getcpuclockid (pid_t, clockid_t *);
 
-/* FIXME..?? */
 struct sigevent;
 int timer_create (clockid_t, struct sigevent *, timer_t *);
 int timer_delete (timer_t);

src/internal/syscall_ret.c

@@ -3,9 +3,9 @@
 
 long __syscall_ret(unsigned long r)
 {
-	if (r >= (unsigned long)-1 - 4096) {
-		errno = -(long)r;
+	if (r > -4096UL) {
+		errno = -r;
 		return -1;
 	}
-	return (long)r;
+	return r;
 }

src/linux/sbrk.c

@@ -1,7 +1,7 @@
-#include <stddef.h>
+#include <stdint.h>
 #include "syscall.h"
 
-void *sbrk(ptrdiff_t inc)
+void *sbrk(intptr_t inc)
 {
 	unsigned long cur = syscall(SYS_brk, 0);
 	if (inc && syscall(SYS_brk, cur+inc) != cur+inc) return (void *)-1;

src/time/__asctime.c

@@ -1,6 +1,7 @@
 #include <time.h>
 #include <stdio.h>
 #include <langinfo.h>
+#include "atomic.h"
 
 const char *__langinfo(nl_item);
 
@@ -21,7 +22,7 @@ char *__asctime(const struct tm *tm, char *buf)
 		 * application developers that they may not be so lucky
 		 * on other implementations (e.g. stack smashing..).
 		 */
-		*(volatile int*)0 = 0;
+		a_crash();
 	}
 	return buf;
 }

src/unistd/setpgid.c

@@ -1,7 +1,7 @@
 #include <unistd.h>
 #include "syscall.h"
 
-pid_t setpgid(pid_t pid, pid_t pgid)
+int setpgid(pid_t pid, pid_t pgid)
 {
 	return syscall(SYS_setpgid, pid, pgid);
 }