Use strwinerror in gdb/windows-nat.c

When working on windows-nat.c, it's useful to see an error message in
addition to the error number given by GetLastError.  This patch moves
strwinerror from gdbserver to gdbsupport, and then updates
windows-nat.c to use it.  A couple of minor changes to strwinerror
(constify the return type and use the ARRAY_SIZE macro) are also
included.

2 files changed, 70 insertions, 0 deletions

diff --git a/gdbsupport/errors.cc b/gdbsupport/errors.cc
index 703b221..b98d015 100644
--- a/gdbsupport/errors.cc
+++ b/gdbsupport/errors.cc
@@ -19,6 +19,9 @@
 
 #include "common-defs.h"
 #include "errors.h"
+#ifdef USE_WIN32API
+#include <windows.h>
+#endif /* USE_WIN32API */
 
 /* See gdbsupport/errors.h.  */
 
@@ -67,3 +70,54 @@ internal_warning (const char *file, int line, const char *fmt, ...)
   internal_vwarning (file, line, fmt, ap);
   va_end (ap);
 }
+
+#ifdef USE_WIN32API
+
+/* See errors.h.  */
+
+const char *
+strwinerror (ULONGEST error)
+{
+  static char buf[1024];
+  TCHAR *msgbuf;
+  DWORD lasterr = GetLastError ();
+  DWORD chars = FormatMessage (FORMAT_MESSAGE_FROM_SYSTEM
+			       | FORMAT_MESSAGE_ALLOCATE_BUFFER,
+			       NULL,
+			       error,
+			       0, /* Default language */
+			       (LPTSTR) &msgbuf,
+			       0,
+			       NULL);
+  if (chars != 0)
+    {
+      /* If there is an \r\n appended, zap it.  */
+      if (chars >= 2
+	  && msgbuf[chars - 2] == '\r'
+	  && msgbuf[chars - 1] == '\n')
+	{
+	  chars -= 2;
+	  msgbuf[chars] = 0;
+	}
+
+      if (chars > ARRAY_SIZE (buf) - 1)
+	{
+	  chars = ARRAY_SIZE (buf) - 1;
+	  msgbuf [chars] = 0;
+	}
+
+#ifdef UNICODE
+      wcstombs (buf, msgbuf, chars + 1);
+#else
+      strncpy (buf, msgbuf, chars + 1);
+#endif
+      LocalFree (msgbuf);
+    }
+  else
+    sprintf (buf, "unknown win32 error (%u)", (unsigned) error);
+
+  SetLastError (lasterr);
+  return buf;
+}
+
+#endif /* USE_WIN32API */
diff --git a/gdbsupport/errors.h b/gdbsupport/errors.h
index 47965ea..9a671d3 100644
--- a/gdbsupport/errors.h
+++ b/gdbsupport/errors.h
@@ -91,4 +91,20 @@ extern void malloc_failure (long size) ATTRIBUTE_NORETURN;
 
 extern void flush_streams ();
 
+#ifdef USE_WIN32API
+
+/* Map the Windows error number in ERROR to a locale-dependent error
+   message string and return a pointer to it.  Typically, the values
+   for ERROR come from GetLastError.
+
+   The string pointed to shall not be modified by the application,
+   but may be overwritten by a subsequent call to strwinerror
+
+   The strwinerror function does not change the current setting
+   of GetLastError.  */
+
+extern const char *strwinerror (ULONGEST error);
+
+#endif /* USE_WIN32API */
+
 #endif /* COMMON_ERRORS_H */