[patch] linux-low.c: handle android bionic ptrace

[dje at google dot com (Doug Evans)]

Hi.

The next thing getting in the way of compiling gdbserver on android
is calls to ptrace.

The signature of ptrace on Bionic is:

extern long ptrace(int request, pid_t pid, void *addr, void *data);

The linux manpage defines it as:

long ptrace(enum __ptrace_request request, pid_t pid,
            void *addr, void *data);

But glibc defines it as a variadic function:

extern long int ptrace (enum __ptrace_request __request, ...) __THROW;

This patch changes PTRACE_ARG3_TYPE from long to void *,
adds PTRACE_ARG4_TYPE, and updates all the calls to ptrace
that need explicit casting.

I will check it in tomorrow if there are no objections.
Tested with --target_board=native-gdbserver on amd64-linux.

2010-01-20  Doug Evans  <dje@google.com>

	* linux-low.c (PTRACE_ARG3_TYPE): Change from long to void*.
	(PTRACE_ARG4_TYPE): New macro.
	(handle_extended_wait): Cast ptrace arg4 to PTRACE_ARG4_TYPE.
	(linux_wait_for_event_1, linux_resume_one_lwp): Ditto.
	(fetch_register): Cast to uintptr_t before casting to PTRACE_ARG3_TYPE.
	(usr_store_inferior_registers): Ditto.
	(linux_read_memory, linux_write_memory): Ditto.
	(linux_test_for_tracefork): Ditto.

Index: linux-low.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/linux-low.c,v
retrieving revision 1.124
diff -u -p -r1.124 linux-low.c
--- linux-low.c	20 Jan 2010 18:29:39 -0000	1.124
+++ linux-low.c	20 Jan 2010 21:25:13 -0000
@@ -153,7 +153,8 @@ struct pending_signals
   struct pending_signals *prev;
 };
 
-#define PTRACE_ARG3_TYPE long
+#define PTRACE_ARG3_TYPE void *
+#define PTRACE_ARG4_TYPE void *
 #define PTRACE_XFER_TYPE long
 
 #ifdef HAVE_LINUX_REGSETS
@@ -385,7 +386,7 @@ handle_extended_wait (struct lwp_info *e
 	    warning ("wait returned unexpected status 0x%x", status);
 	}
 
-      ptrace (PTRACE_SETOPTIONS, new_pid, 0, PTRACE_O_TRACECLONE);
+      ptrace (PTRACE_SETOPTIONS, new_pid, 0, (PTRACE_ARG4_TYPE) PTRACE_O_TRACECLONE);
 
       ptid = ptid_build (pid_of (event_child), new_pid, 0);
       new_lwp = (struct lwp_info *) add_lwp (ptid);
@@ -1181,7 +1182,7 @@ linux_wait_for_event_1 (ptid_t ptid, int
       if (event_child->must_set_ptrace_flags)
 	{
 	  ptrace (PTRACE_SETOPTIONS, lwpid_of (event_child),
-		  0, PTRACE_O_TRACECLONE);
+		  0, (PTRACE_ARG4_TYPE) PTRACE_O_TRACECLONE);
 	  event_child->must_set_ptrace_flags = 0;
 	}
 
@@ -1862,7 +1863,10 @@ linux_resume_one_lwp (struct lwp_info *l
   errno = 0;
   lwp->stopped = 0;
   lwp->stepping = step;
-  ptrace (step ? PTRACE_SINGLESTEP : PTRACE_CONT, lwpid_of (lwp), 0, signal);
+  ptrace (step ? PTRACE_SINGLESTEP : PTRACE_CONT, lwpid_of (lwp), 0,
+	  /* Coerce to a uintptr_t first to avoid potential gcc warning
+	     of coercing an 8 byte integer to a 4 byte pointer.  */
+	  (PTRACE_ARG4_TYPE) (uintptr_t) signal);
 
   current_inferior = saved_inferior;
   if (errno)
@@ -2145,7 +2149,10 @@ fetch_register (int regno)
     {
       errno = 0;
       *(PTRACE_XFER_TYPE *) (buf + i) =
-	ptrace (PTRACE_PEEKUSER, pid, (PTRACE_ARG3_TYPE) regaddr, 0);
+	ptrace (PTRACE_PEEKUSER, pid,
+		/* Coerce to a uintptr_t first to avoid potential gcc warning
+		   of coercing an 8 byte integer to a 4 byte pointer.  */
+		(PTRACE_ARG3_TYPE) (uintptr_t) regaddr, 0);
       regaddr += sizeof (PTRACE_XFER_TYPE);
       if (errno != 0)
 	{
@@ -2215,8 +2222,11 @@ usr_store_inferior_registers (int regno)
       for (i = 0; i < size; i += sizeof (PTRACE_XFER_TYPE))
 	{
 	  errno = 0;
-	  ptrace (PTRACE_POKEUSER, pid, (PTRACE_ARG3_TYPE) regaddr,
-		  *(PTRACE_XFER_TYPE *) (buf + i));
+	  ptrace (PTRACE_POKEUSER, pid,
+		/* Coerce to a uintptr_t first to avoid potential gcc warning
+		   about coercing an 8 byte integer to a 4 byte pointer.  */
+		  (PTRACE_ARG3_TYPE) (uintptr_t) regaddr,
+		  (PTRACE_ARG4_TYPE) *(PTRACE_XFER_TYPE *) (buf + i));
 	  if (errno != 0)
 	    {
 	      /* At this point, ESRCH should mean the process is
@@ -2468,7 +2478,10 @@ linux_read_memory (CORE_ADDR memaddr, un
   for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
     {
       errno = 0;
-      buffer[i] = ptrace (PTRACE_PEEKTEXT, pid, (PTRACE_ARG3_TYPE) addr, 0);
+      /* Coerce the 3rd arg to a uintptr_t first to avoid potential gcc warning
+	 about coercing an 8 byte integer to a 4 byte pointer.  */
+      buffer[i] = ptrace (PTRACE_PEEKTEXT, pid,
+			  (PTRACE_ARG3_TYPE) (uintptr_t) addr, 0);
       if (errno)
 	return errno;
     }
@@ -2515,14 +2528,19 @@ linux_write_memory (CORE_ADDR memaddr, c
 
   /* Fill start and end extra bytes of buffer with existing memory data.  */
 
-  buffer[0] = ptrace (PTRACE_PEEKTEXT, pid, (PTRACE_ARG3_TYPE) addr, 0);
+  /* Coerce the 3rd arg to a uintptr_t first to avoid potential gcc warning
+     about coercing an 8 byte integer to a 4 byte pointer.  */
+  buffer[0] = ptrace (PTRACE_PEEKTEXT, pid,
+		      (PTRACE_ARG3_TYPE) (uintptr_t) addr, 0);
 
   if (count > 1)
     {
       buffer[count - 1]
 	= ptrace (PTRACE_PEEKTEXT, pid,
-		  (PTRACE_ARG3_TYPE) (addr + (count - 1)
-				      * sizeof (PTRACE_XFER_TYPE)),
+		  /* Coerce to a uintptr_t first to avoid potential gcc warning
+		     about coercing an 8 byte integer to a 4 byte pointer.  */
+		  (PTRACE_ARG3_TYPE) (uintptr_t) (addr + (count - 1)
+						  * sizeof (PTRACE_XFER_TYPE)),
 		  0);
     }
 
@@ -2535,7 +2553,11 @@ linux_write_memory (CORE_ADDR memaddr, c
   for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
     {
       errno = 0;
-      ptrace (PTRACE_POKETEXT, pid, (PTRACE_ARG3_TYPE) addr, buffer[i]);
+      ptrace (PTRACE_POKETEXT, pid,
+	      /* Coerce to a uintptr_t first to avoid potential gcc warning
+		 about coercing an 8 byte integer to a 4 byte pointer.  */
+	      (PTRACE_ARG3_TYPE) (uintptr_t) addr,
+	      (PTRACE_ARG4_TYPE) buffer[i]);
       if (errno)
 	return errno;
     }
@@ -2602,7 +2624,8 @@ linux_test_for_tracefork (void)
   if (! WIFSTOPPED (status))
     error ("linux_test_for_tracefork: waitpid: unexpected status %d.", status);
 
-  ret = ptrace (PTRACE_SETOPTIONS, child_pid, 0, PTRACE_O_TRACEFORK);
+  ret = ptrace (PTRACE_SETOPTIONS, child_pid, 0,
+		(PTRACE_ARG4_TYPE) PTRACE_O_TRACEFORK);
   if (ret != 0)
     {
       ret = ptrace (PTRACE_KILL, child_pid, 0, 0);