Re: [PATCH 3/7] procfs.c: Don't install a deprecated_xfer_memory method

[Joel Brobecker <brobecker@adacore.com>]

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Hi Pedro,

> >>> 2014-02-19  Pedro Alves  <palves@redhat.com>
> >>>
> >>> 	* procfs.c (procfs_target): Don't install procfs_xfer_memory as
> >>> 	deprecated_xfer_memory hook.
> >>> 	(procfs_xfer_partial): Call procfs_xfer_memory instead
> >>> 	of the deprecated_xfer_memory target hook.
> >>> 	(procfs_xfer_memory): Adjust interface as a to_xfer_partial
> >>> 	helper.
> >>
> >> FYI: I tried to test it, but the sparc-solaris debugger appears to be
> >> badly broken at the moment, and I won't have much time left this week
> >> to investigate the failures, so I'll schedule that for next week.

It turns out that your patch fixes the breakage as a side-effect.
Since it's bad breakage, I pushed the patch immediately, after having
updated the revision log:

This removes yet another instance of a deprecated_xfer_memory user,
and fixes a nasty regression as a side-effect:

    (gdb) start
    Temporary breakpoint 1 at 0x19070: file simple_main.adb, line 4.
    Starting program: /[...]/simple_main
    Warning:
    Cannot insert breakpoint 1.
    Cannot access memory at address 0x19070
    Cannot insert breakpoint -3.
    Temporarily disabling shared library breakpoints:
    breakpoint #-3

The regression was introduced by the to_xfer_partial transition
to return a status enum.  procfs_xfer_partial was updated but
not the case where object is TARGET_OBJECT_MEMORY.  As result,
procfs_xfer_partial was returning the length xfered rather than
the status, and the xfered buffer was left uninitialized.

gdb/
2014-02-19  Pedro Alves  <palves@redhat.com>

        * procfs.c (procfs_target): Don't install procfs_xfer_memory as
        deprecated_xfer_memory hook.
        (procfs_xfer_partial): Call procfs_xfer_memory instead
        of the deprecated_xfer_memory target hook.
        (procfs_xfer_memory): Adjust interface as a to_xfer_partial
        helper.

Tested on sparc-solaris, and pushed.

I still see one regression, which I will now investigate separately.
Thanks for the patch!

-- 
Joel

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From e96027e0d9b0a600aabd2c1c7cfdde6ce6d076e8 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Wed, 19 Feb 2014 20:29:31 +0000
Subject: [PATCH] procfs.c: Don't install a deprecated_xfer_memory method

This removes yet another instance of a deprecated_xfer_memory user,
and fixes a nasty regression as a side-effect:

    (gdb) start
    Temporary breakpoint 1 at 0x19070: file simple_main.adb, line 4.
    Starting program: /[...]/simple_main
    Warning:
    Cannot insert breakpoint 1.
    Cannot access memory at address 0x19070
    Cannot insert breakpoint -3.
    Temporarily disabling shared library breakpoints:
    breakpoint #-3

The regression was introduced by the to_xfer_partial transition
to return a status enum.  procfs_xfer_partial was updated but
not the case where object is TARGET_OBJECT_MEMORY.  As result,
procfs_xfer_partial was returning the length xfered rather than
the status, and the xfered buffer was left uninitialized.

gdb/
2014-02-19  Pedro Alves  <palves@redhat.com>

	* procfs.c (procfs_target): Don't install procfs_xfer_memory as
	deprecated_xfer_memory hook.
	(procfs_xfer_partial): Call procfs_xfer_memory instead
	of the deprecated_xfer_memory target hook.
	(procfs_xfer_memory): Adjust interface as a to_xfer_partial
	helper.
---
 gdb/ChangeLog |    9 +++++++
 gdb/procfs.c  |   73 +++++++++++++++++++++------------------------------------
 2 files changed, 36 insertions(+), 46 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index bc8573c..b642ac9 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2014-02-24  Pedro Alves  <palves@redhat.com>
+
+	* procfs.c (procfs_target): Don't install procfs_xfer_memory as
+	deprecated_xfer_memory hook.
+	(procfs_xfer_partial): Call procfs_xfer_memory instead
+	of the deprecated_xfer_memory target hook.
+	(procfs_xfer_memory): Adjust interface as a to_xfer_partial
+	helper.
+
 2014-02-24  Yuanhui Zhang  <asmwarrior@gmail.com>
 
 	* windows-nat.c (windows_xfer_shared_libraries): Return
diff --git a/gdb/procfs.c b/gdb/procfs.c
index 822e1e0..8204747 100644
--- a/gdb/procfs.c
+++ b/gdb/procfs.c
@@ -127,9 +127,10 @@ static void procfs_create_inferior (struct target_ops *, char *,
 				    char *, char **, int);
 static ptid_t procfs_wait (struct target_ops *,
 			   ptid_t, struct target_waitstatus *, int);
-static int procfs_xfer_memory (CORE_ADDR, gdb_byte *, int, int,
-			       struct mem_attrib *attrib,
-			       struct target_ops *);
+static enum target_xfer_status procfs_xfer_memory (gdb_byte *,
+						   const gdb_byte *,
+						   ULONGEST, ULONGEST,
+						   ULONGEST *);
 static target_xfer_partial_ftype procfs_xfer_partial;
 
 static int procfs_thread_alive (struct target_ops *ops, ptid_t);
@@ -197,7 +198,6 @@ procfs_target (void)
   t->to_fetch_registers = procfs_fetch_registers;
   t->to_store_registers = procfs_store_registers;
   t->to_xfer_partial = procfs_xfer_partial;
-  t->deprecated_xfer_memory = procfs_xfer_memory;
   t->to_pass_signals = procfs_pass_signals;
   t->to_files_info = procfs_files_info;
   t->to_stop = procfs_stop;
@@ -3986,13 +3986,7 @@ procfs_xfer_partial (struct target_ops *ops, enum target_object object,
   switch (object)
     {
     case TARGET_OBJECT_MEMORY:
-      if (readbuf)
-	return (*ops->deprecated_xfer_memory) (offset, readbuf,
-					       len, 0/*read*/, NULL, ops);
-      if (writebuf)
-	return (*ops->deprecated_xfer_memory) (offset, (gdb_byte *) writebuf,
-					       len, 1/*write*/, NULL, ops);
-      return TARGET_XFER_E_IO;
+      return procfs_xfer_memory (readbuf, writebuf, offset, len, xfered_len);
 
 #ifdef NEW_PROC_API
     case TARGET_OBJECT_AUXV:
@@ -4009,23 +4003,15 @@ procfs_xfer_partial (struct target_ops *ops, enum target_object object,
     }
 }
 
+/* Helper for procfs_xfer_partial that handles memory transfers.
+   Arguments are like target_xfer_partial.  */
 
-/* Transfer LEN bytes between GDB address MYADDR and target address
-   MEMADDR.  If DOWRITE is non-zero, transfer them to the target,
-   otherwise transfer them from the target.  TARGET is unused.
-
-   The return value is 0 if an error occurred or no bytes were
-   transferred.  Otherwise, it will be a positive value which
-   indicates the number of bytes transferred between gdb and the
-   target.  (Note that the interface also makes provisions for
-   negative values, but this capability isn't implemented here.)  */
-
-static int
-procfs_xfer_memory (CORE_ADDR memaddr, gdb_byte *myaddr, int len, int dowrite,
-		    struct mem_attrib *attrib, struct target_ops *target)
+static enum target_xfer_status
+procfs_xfer_memory (gdb_byte *readbuf, const gdb_byte *writebuf,
+		    ULONGEST memaddr, ULONGEST len, ULONGEST *xfered_len)
 {
   procinfo *pi;
-  int nbytes = 0;
+  int nbytes;
 
   /* Find procinfo for main process.  */
   pi = find_procinfo_or_die (ptid_get_pid (inferior_ptid), 0);
@@ -4033,31 +4019,26 @@ procfs_xfer_memory (CORE_ADDR memaddr, gdb_byte *myaddr, int len, int dowrite,
       open_procinfo_files (pi, FD_AS) == 0)
     {
       proc_warn (pi, "xfer_memory, open_proc_files", __LINE__);
-      return 0;
+      return TARGET_XFER_E_IO;
     }
 
-  if (lseek (pi->as_fd, (off_t) memaddr, SEEK_SET) == (off_t) memaddr)
+  if (lseek (pi->as_fd, (off_t) memaddr, SEEK_SET) != (off_t) memaddr)
+    return TARGET_XFER_E_IO;
+
+  if (writebuf != NULL)
     {
-      if (dowrite)
-	{
-#ifdef NEW_PROC_API
-	  PROCFS_NOTE ("write memory:\n");
-#else
-	  PROCFS_NOTE ("write memory:\n");
-#endif
-	  nbytes = write (pi->as_fd, myaddr, len);
-	}
-      else
-	{
-	  PROCFS_NOTE ("read  memory:\n");
-	  nbytes = read (pi->as_fd, myaddr, len);
-	}
-      if (nbytes < 0)
-	{
-	  nbytes = 0;
-	}
+      PROCFS_NOTE ("write memory:\n");
+      nbytes = write (pi->as_fd, writebuf, len);
+    }
+  else
+    {
+      PROCFS_NOTE ("read  memory:\n");
+      nbytes = read (pi->as_fd, readbuf, len);
     }
-  return nbytes;
+  if (nbytes <= 0)
+    return TARGET_XFER_E_IO;
+  *xfered_len = nbytes;
+  return TARGET_XFER_OK;
 }
 
 /* Called by target_resume before making child runnable.  Mark cached
-- 
1.7.9.5