* target.c (target_read_until_error): New.

[deliverable/binutils-gdb.git] / gdb / target.c

diff --git a/gdb/target.c b/gdb/target.c
index 6b009a8e76cfb1322a9a0c28b44d2aee394dbfb7..b2f7be7f7f7bd74a82b611d60db9afad9e78db8d 100644 (file)
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -1451,6 +1451,72 @@ target_read (struct target_ops *ops,
   return len;
 }
 
+LONGEST
+target_read_until_error (struct target_ops *ops,
+                        enum target_object object,
+                        const char *annex, gdb_byte *buf,
+                        ULONGEST offset, LONGEST len)
+{
+  LONGEST xfered = 0;
+  while (xfered < len)
+    {
+      LONGEST xfer = target_read_partial (ops, object, annex,
+                                         (gdb_byte *) buf + xfered,
+                                         offset + xfered, len - xfered);
+      /* Call an observer, notifying them of the xfer progress?  */
+      if (xfer == 0)
+       return xfered;
+      if (xfer < 0)
+       {
+         /* We've got an error.  Try to read in smaller blocks.  */
+         ULONGEST start = offset + xfered;
+         ULONGEST remaining = len - xfered;
+         ULONGEST half;
+
+         /* If an attempt was made to read a random memory address,
+            it's likely that the very first byte is not accessible.
+            Try reading the first byte, to avoid doing log N tries
+            below.  */
+         xfer = target_read_partial (ops, object, annex, 
+                                     (gdb_byte *) buf + xfered, start, 1);
+         if (xfer <= 0)
+           return xfered;
+         start += 1;
+         remaining -= 1;
+         half = remaining/2;
+         
+         while (half > 0)
+           {
+             xfer = target_read_partial (ops, object, annex,
+                                         (gdb_byte *) buf + xfered,
+                                         start, half);
+             if (xfer == 0)
+               return xfered;
+             if (xfer < 0)
+               {
+                 remaining = half;               
+               }
+             else
+               {
+                 /* We have successfully read the first half.  So, the
+                    error must be in the second half.  Adjust start and
+                    remaining to point at the second half.  */
+                 xfered += xfer;
+                 start += xfer;
+                 remaining -= xfer;
+               }
+             half = remaining/2;
+           }
+
+         return xfered;
+       }
+      xfered += xfer;
+      QUIT;
+    }
+  return len;
+}
+
+
 /* An alternative to target_write with progress callbacks.  */
 
 LONGEST