6749267: Signal handler should save/restore errno

Summary: Save errno before processing signal, then restore it.
Reviewed-by: acorn, sspitsyn

src/os/bsd/vm/os_bsd.cpp

@@ -2887,7 +2887,9 @@ JVM_handle_bsd_signal(int signo, siginfo_t* siginfo,
 
 void signalHandler(int sig, siginfo_t* info, void* uc) {
   assert(info != NULL && uc != NULL, "it must be old kernel");
+  int orig_errno = errno;  // Preserve errno value over signal handler.
   JVM_handle_bsd_signal(sig, info, uc, true);
+  errno = orig_errno;
 }
 
 

src/os/linux/vm/os_linux.cpp

@@ -3653,7 +3653,9 @@ JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
 
 void signalHandler(int sig, siginfo_t* info, void* uc) {
   assert(info != NULL && uc != NULL, "it must be old kernel");
+  int orig_errno = errno;  // Preserve errno value over signal handler.
   JVM_handle_linux_signal(sig, info, uc, true);
+  errno = orig_errno;
 }
 
 

src/os/solaris/vm/os_solaris.cpp

@@ -4317,7 +4317,9 @@ JVM_handle_solaris_signal(int signo, siginfo_t* siginfo, void* ucontext,
 
 
 void signalHandler(int sig, siginfo_t* info, void* ucVoid) {
+  int orig_errno = errno;  // Preserve errno value over signal handler.
   JVM_handle_solaris_signal(sig, info, ucVoid, true);
+  errno = orig_errno;
 }
 
 /* Do not delete - if guarantee is ever removed,  a signal handler (even empty)