syscall_emul: fix warn_once behavior

The current ignoreWarnOnceFunc doesn't really work as expected,
since it will only generate one warning total, for whichever
"warn-once" syscall is invoked first.  This patch fixes that
behavior by keeping a "warned" flag in the SyscallDesc object,
allowing suitably flagged syscalls to warn exactly once per
syscall.

1 files changed, 9 insertions, 11 deletions

diff --git a/src/sim/syscall_emul.cc b/src/sim/syscall_emul.cc
index 8f3d08cd7..b1d3edde4 100644
--- a/src/sim/syscall_emul.cc
+++ b/src/sim/syscall_emul.cc
@@ -99,20 +99,18 @@ ignoreFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
            ThreadContext *tc)
 {
     int index = 0;
-    warn("ignoring syscall %s(%d, ...)", desc->name,
-         process->getSyscallArg(tc, index));
+    const char *extra_text = "";
 
-    return 0;
-}
+    if (desc->warnOnce()) {
+        if (desc->warned)
+            return 0;
 
+        desc->warned = true;
+        extra_text = "\n      (further warnings will be suppressed)";
+    }
 
-SyscallReturn
-ignoreWarnOnceFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
-           ThreadContext *tc)
-{
-    int index = 0;
-    warn_once("ignoring syscall %s(%d, ...)", desc->name,
-              process->getSyscallArg(tc, index));
+    warn("ignoring syscall %s(%d, ...)%s", desc->name,
+         process->getSyscallArg(tc, index), extra_text);
 
     return 0;
 }