[patch] gdbserver: Detect and return errors reading memory

["Nathan J. Williams" <nathanw@wasabisystems.com>]

As I promised last week, here is a patch to check for errors reading
memory in gdbserver and propagate that error back to the host gdb.

        - Nathan

2004-03-01  Nathan J. Williams  <nathanw@wasabisystems.com>

	* linux-low.c (linux_read_memory): Change return type to
	int. Check for and return error from ptrace().
	* target.c (read_inferior_memory): Change return type to int. Pass
	back return status from the_target->read_memory().
	* target.h (struct target_ops): Adapt *read_memory() prototype.
	Update comment.
	(read_inferior_memory): Adapt prototype.
	* server.c (main): Return an error packet if
	read_inferior_memory() returns an error.

Index: linux-low.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/linux-low.c,v
retrieving revision 1.29
diff -u -p -r1.29 linux-low.c
--- linux-low.c	29 Feb 2004 16:47:15 -0000	1.29
+++ linux-low.c	1 Mar 2004 20:47:58 -0000
@@ -1281,7 +1281,7 @@ linux_store_registers (int regno)
 /* Copy LEN bytes from inferior's memory starting at MEMADDR
    to debugger memory starting at MYADDR.  */
 
-static void
+static int
 linux_read_memory (CORE_ADDR memaddr, char *myaddr, int len)
 {
   register int i;
@@ -1298,11 +1298,16 @@ linux_read_memory (CORE_ADDR memaddr, ch
   /* Read all the longwords */
   for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
     {
+      errno = 0;
       buffer[i] = ptrace (PTRACE_PEEKTEXT, inferior_pid, (PTRACE_ARG3_TYPE) addr, 0);
+      if (errno)
+	return errno;
     }
 
   /* Copy appropriate bytes out of the buffer.  */
   memcpy (myaddr, (char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)), len);
+
+  return 0;
 }
 
 /* Copy LEN bytes of data from debugger memory at MYADDR
Index: target.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/target.c,v
retrieving revision 1.3
diff -u -p -r1.3 target.c
--- target.c	11 Jun 2002 17:32:40 -0000	1.3
+++ target.c	1 Mar 2004 20:47:58 -0000
@@ -57,11 +57,13 @@ set_desired_inferior (int use_general)
     current_inferior = found;
 }
 
-void
+int
 read_inferior_memory (CORE_ADDR memaddr, char *myaddr, int len)
 {
-  (*the_target->read_memory) (memaddr, myaddr, len);
+  int res;
+  res = (*the_target->read_memory) (memaddr, myaddr, len);
   check_mem_read (memaddr, myaddr, len);
+  return res;
 }
 
 int
Index: target.h
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/target.h,v
retrieving revision 1.10
diff -u -p -r1.10 target.h
--- target.h	26 Feb 2004 15:08:47 -0000	1.10
+++ target.h	1 Mar 2004 20:47:58 -0000
@@ -102,9 +102,11 @@ struct target_ops
   /* Read memory from the inferior process.  This should generally be
      called through read_inferior_memory, which handles breakpoint shadowing.
 
-     Read LEN bytes at MEMADDR into a buffer at MYADDR.  */
+     Read LEN bytes at MEMADDR into a buffer at MYADDR.
+  
+     Returns 0 on success and errno on failure.  */
 
-  void (*read_memory) (CORE_ADDR memaddr, char *myaddr, int len);
+  int (*read_memory) (CORE_ADDR memaddr, char *myaddr, int len);
 
   /* Write memory to the inferior process.  This should generally be
      called through write_inferior_memory, which handles breakpoint shadowing.
@@ -160,7 +162,7 @@ void set_target_ops (struct target_ops *
 
 unsigned char mywait (char *statusp, int connected_wait);
 
-void read_inferior_memory (CORE_ADDR memaddr, char *myaddr, int len);
+int read_inferior_memory (CORE_ADDR memaddr, char *myaddr, int len);
 
 int write_inferior_memory (CORE_ADDR memaddr, const char *myaddr, int len);
 
Index: server.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/server.c,v
retrieving revision 1.20
diff -u -p -r1.20 server.c
--- server.c	29 Feb 2004 16:49:38 -0000	1.20
+++ server.c	1 Mar 2004 20:47:58 -0000
@@ -462,8 +462,10 @@ main (int argc, char *argv[])
 	      break;
 	    case 'm':
 	      decode_m_packet (&own_buf[1], &mem_addr, &len);
-	      read_inferior_memory (mem_addr, mem_buf, len);
-	      convert_int_to_ascii (mem_buf, own_buf, len);
+	      if (read_inferior_memory (mem_addr, mem_buf, len) == 0)
+		convert_int_to_ascii (mem_buf, own_buf, len);
+	      else
+		write_enn (own_buf);
 	      break;
 	    case 'M':
 	      decode_M_packet (&own_buf[1], &mem_addr, &len, mem_buf);