FIX EOF detection in PT_IO-based to_xfer_partial implementation.

At least on OpenBSD PT_IO/PIOD_READ_AUXV can return sucessfully without
transferring any bytes.  Arguably a kernel bug, but interpreting this as EOF
seems sensible.

gdb/ChangeLog:

        * inf-ptrace.c (inf_ptrace_xfer_partial): Return TARGET_XFER_EOF
        if a PT_IO ptrace request returns sucessfully but indicates that 0
        bytes were transferred.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 41397b2..8d91946 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2014-02-12  Mark Kettenis  <kettenis@gnu.org>
+
+       * inf-ptrace.c (inf_ptrace_xfer_partial): Return TARGET_XFER_EOF
+       if a PT_IO ptrace request returns sucessfully but indicates that 0
+       bytes were transferred.
+
 2014-02-12  Pedro Alves  <palves@redhat.com>
            Kevin Buettner <kevinb@redhat.com>
 

diff --git a/gdb/inf-ptrace.c b/gdb/inf-ptrace.c
index 1ab6b0b..1269d24 100644 (file)
--- a/gdb/inf-ptrace.c
+++ b/gdb/inf-ptrace.c
@@ -489,9 +489,9 @@ inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
        errno = 0;
        if (ptrace (PT_IO, pid, (caddr_t)&piod, 0) == 0)
          {
-           *xfered_len = piod.piod_len;
            /* Return the actual number of bytes read or written.  */
-           return TARGET_XFER_OK;
+           *xfered_len = piod.piod_len;
+           return (piod.piod_len == 0) ? TARGET_XFER_EOF : TARGET_XFER_OK;
          }
        /* If the PT_IO request is somehow not supported, fallback on
           using PT_WRITE_D/PT_READ_D.  Otherwise we will return zero
@@ -595,9 +595,9 @@ inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
        errno = 0;
        if (ptrace (PT_IO, pid, (caddr_t)&piod, 0) == 0)
          {
-           *xfered_len = piod.piod_len;
            /* Return the actual number of bytes read or written.  */
-           return TARGET_XFER_OK;
+           *xfered_len = piod.piod_len;
+           return (piod.piod_len == 0) ? TARGET_XFER_EOF : TARGET_XFER_OK;
          }
       }
 #endif