Properly handle the wait4 syscall failure on kernels that don't
support the __WALL flag.
diff --git a/server/ptrace.c b/server/ptrace.c
index dafa698..a185ca7 100644
--- a/server/ptrace.c
+++ b/server/ptrace.c
@@ -66,10 +66,6 @@
inline static int ptrace(int req, ...) { errno = EPERM; return -1; /*FAIL*/ }
#endif /* HAVE_SYS_PTRACE_H */
-#ifndef __WALL
-#define __WALL 0
-#endif
-
static const int use_ptrace = 1; /* set to 0 to disable ptrace */
/* handle a status returned by wait4 */
@@ -108,6 +104,23 @@
return 0;
}
+/* wait4 wrapper to handle missing __WALL flag in older kernels */
+static inline pid_t wait4_wrapper( pid_t pid, int *status, int options, struct rusage *usage )
+{
+#ifdef __WALL
+ static int wall_flag = __WALL;
+
+ for (;;)
+ {
+ pid_t ret = wait4( pid, status, options | wall_flag, usage );
+ if (ret != -1 || !wall_flag || errno != EINVAL) return ret;
+ wall_flag = 0;
+ }
+#else
+ return wait4( pid, status, options, usage );
+#endif
+}
+
/* handle a SIGCHLD signal */
void sigchld_callback(void)
{
@@ -115,7 +128,7 @@
for (;;)
{
- if (!(pid = wait4( -1, &status, WUNTRACED | WNOHANG | __WALL, NULL ))) break;
+ if (!(pid = wait4_wrapper( -1, &status, WUNTRACED | WNOHANG, NULL ))) break;
if (pid != -1) handle_child_status( get_thread_from_pid(pid), pid, status, -1 );
else break;
}
@@ -128,7 +141,7 @@
do
{
- if ((res = wait4( get_ptrace_pid(thread), &status, WUNTRACED | __WALL, NULL )) == -1)
+ if ((res = wait4_wrapper( get_ptrace_pid(thread), &status, WUNTRACED, NULL )) == -1)
{
if (errno == ECHILD) /* must have died */
{
