Fix a GDB assert failure on windows

A GDB internal error is found on native mingw32 target.

(gdb) run
../../binutils-gdb/gdb/target.c:1483: internal-error:
target_xfer_partial: Assertion `*xfered_len > 0' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)

This error was introduced by the following snippet in commit
9b409511d07fe375284701af34909fb539029caf

> @@ -2536,27 +2538,30 @@ windows_xfer_shared_libraries (struct target_ops *ops,
>      }
>
>    obstack_free (&obstack, NULL);
> -  return len;
> +  *xfered_len = (ULONGEST) len;
> +  return TARGET_XFER_OK;
>  }

In the original code, len is returned, which could be 0, but after that
commit, only TARGET_XFER_OK is returned, which is wrong.  If len is 0,
TARGET_XFER_EOF should be returned.  (it is 0 in enum
target_xfer_status declaration).

gdb:

2014-02-24  Yuanhui Zhang  <asmwarrior@gmail.com>

	* windows-nat.c (windows_xfer_shared_libraries): Return
	TARGET_XFER_EOF if LEN is zero to fix an assert failure when
	requested object is TARGET_OBJECT_LIBRARIES.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5fdbf4f31403d2acf49b594d9d84272b0974f33c..bc8573c1d047e7eda4113d131a2454ef0a2fab65 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2014-02-24  Yuanhui Zhang  <asmwarrior@gmail.com>
+
+       * windows-nat.c (windows_xfer_shared_libraries): Return
+       TARGET_XFER_EOF if LEN is zero to fix an assert failure when
+       requested object is TARGET_OBJECT_LIBRARIES.
+
 2014-02-24  Yao Qi  <yao@codesourcery.com>
 
        * target.h (enum target_xfer_status)

diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index 4366aab64b1b6f1cb0b5fa7c85ed9f770a776753..6c45d0a0a6648aa7b5c9351e623cc5d246ae5d29 100644 (file)
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -2501,7 +2501,7 @@ windows_xfer_shared_libraries (struct target_ops *ops,
 
   obstack_free (&obstack, NULL);
   *xfered_len = (ULONGEST) len;
-  return TARGET_XFER_OK;
+  return len != 0 ? TARGET_XFER_OK : TARGET_XFER_EOF;
 }
 
 static enum target_xfer_status