sys/linux, sys/freebsd: apply more ignore_return attributes

1. Apply ignore_return to semctl$GETVAL which produces random errno
values on linux and freebsd.

2. Apply ignore_return to prctl and remove the custom code in executor.

3. Remove the custom errno ignoring code in fuchsia executor.
The calls are already marked as ignore_return, so this is just a leftover.

4. Only reset errno for ignore_return.
The syscall can still return a resource (maybe).
We only need to reset errno for fallback coverage.

3 files changed, 4 insertions, 22 deletions

diff --git a/executor/executor.cc b/executor/executor.cc
index b221c2070..2f90e4092 100644
--- a/executor/executor.cc
+++ b/executor/executor.cc
@@ -1112,12 +1112,9 @@ void execute_call(thread_t* th)
 	errno = EFAULT;
 	NONFAILING(th->res = execute_syscall(call, th->args));
 	th->reserrno = errno;
-	if (th->res == -1 && th->reserrno == 0)
-		th->reserrno = EINVAL; // our syz syscalls may misbehave
-	if (call->attrs.ignore_return) {
-		th->res = 0;
-		th->reserrno = 0;
-	}
+	// Our pseudo-syscalls may misbehave.
+	if ((th->res == -1 && th->reserrno == 0) || call->attrs.ignore_return)
+		th->reserrno = EINVAL;
 	// Reset the flag before the first possible fail().
 	th->soft_fail_state = false;
 
diff --git a/executor/executor_fuchsia.h b/executor/executor_fuchsia.h
index 84ebac44d..88a1ccff5 100644
--- a/executor/executor_fuchsia.h
+++ b/executor/executor_fuchsia.h
@@ -22,15 +22,6 @@ static intptr_t execute_syscall(const call_t* c, intptr_t a[kMaxArgs])
 {
 	intptr_t res = c->call(a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8]);
 	if (strncmp(c->name, "zx_", 3) == 0) {
-		// Convert zircon error convention to the libc convention that executor expects.
-		// The following calls return arbitrary integers instead of error codes.
-		if (res == ZX_OK ||
-		    !strcmp(c->name, "zx_debuglog_read") ||
-		    !strcmp(c->name, "zx_clock_get") ||
-		    !strcmp(c->name, "zx_clock_get_monotonic") ||
-		    !strcmp(c->name, "zx_deadline_after") ||
-		    !strcmp(c->name, "zx_ticks_get"))
-			return 0;
 		errno = (-res) & 0x7f;
 		return -1;
 	}
diff --git a/executor/executor_linux.h b/executor/executor_linux.h
index 8f0dc579a..8c5a19ef7 100644
--- a/executor/executor_linux.h
+++ b/executor/executor_linux.h
@@ -84,13 +84,7 @@ static intptr_t execute_syscall(const call_t* c, intptr_t a[kMaxArgs])
 {
 	if (c->call)
 		return c->call(a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8]);
-	intptr_t res = syscall(c->sys_nr, a[0], a[1], a[2], a[3], a[4], a[5]);
-	// Some prctl commands don't respect the normal convention for return values
-	// (e.g. PR_GET_TIMERSLACK, but there are more) and may produce all possible
-	// errno values. This conflicts with fallback coverage.
-	if (!flag_coverage && res == -1 && !strcmp(c->name, "prctl"))
-		errno = EINVAL;
-	return res;
+	return syscall(c->sys_nr, a[0], a[1], a[2], a[3], a[4], a[5]);
 }
 
 static void cover_open(cover_t* cov, bool extra)