[PATCH v3 1/2] gdb/regcache: return REG_UNAVAILABLE in raw_read if NOT_AVAILABLE_ERROR is seen

[Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>]

In regcache's raw_read, it is possible that 'raw_update' fails with an
exception.  This could happen, for instance, if the debugged thread is
already exited and the target cannot fetch its registers.  Catch the
exception and return REG_UNAVAILABLE if the error is of kind
NOT_AVAILABLE_ERROR.  This makes clients' lives easier.

Regression-tested on X86_64-Linux.
---
 gdb/regcache.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/gdb/regcache.c b/gdb/regcache.c
index 00d7a10e289..c57d2e4c345 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -598,7 +598,17 @@ enum register_status
 readable_regcache::raw_read (int regnum, gdb_byte *buf)
 {
   gdb_assert (buf != NULL);
-  raw_update (regnum);
+  try
+    {
+      raw_update (regnum);
+    }
+  catch (const gdb_exception_error &ex)
+    {
+      if (ex.error != NOT_AVAILABLE_ERROR)
+	throw;
+
+      m_register_status[regnum] = REG_UNAVAILABLE;
+    }
 
   if (m_register_status[regnum] != REG_VALID)
     memset (buf, 0, m_descr->sizeof_register[regnum]);
-- 
2.33.1

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