--- Begin Message ---
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- Date: Wed, 6 Apr 2016 17:13:12 +0200
- Subject: [PATCH] Workaround gdbserver<7.7 for setfs
With current FSF GDB HEAD and old FSF gdbserver I expected I could do:
gdb -ex 'file target:/root/redhat/threadit' -ex 'target remote :1234'
(supplying that unsupported qXfer:exec-file:read by "file")
But that does not work because:
Sending packet: $vFile:setfs:0#bf...Packet received: OK
Packet vFile:setfs (hostio-setfs) is supported
...
Sending packet: $vFile:setfs:104#24...Packet received: OK
"target:/root/redhat/threadit": could not open as an executable file: Invalid argument
GDB documentation says:
The valid responses to Host I/O packets are:
An empty response indicates that this operation is not recognized.
This "empty response" vs. "OK" was a bug in gdbserver < 7.7. It was fixed by:
commit e7f0d979dd5cc4f8b658df892e93db69d6d660b7
Author: Yao Qi <yao@codesourcery.com>
Date: Tue Dec 10 21:59:20 2013 +0800
Fix a bug in matching notifications.
Message-ID: <1386684626-11415-1-git-send-email-yao@codesourcery.com>
https://sourceware.org/ml/gdb-patches/2013-12/msg00373.html
2013-12-10 Yao Qi <yao@codesourcery.com>
* notif.c (handle_notif_ack): Return 0 if no notification
matches.
with unpatched old FSF gdbserver and patched FSF GDB HEAD:
gdb -ex 'file target:/root/redhat/threadit' -ex 'target remote :1234'
Sending packet: $vFile:setfs:0#bf...Packet received: OK
Packet vFile:setfs (hostio-setfs) is NOT supported
...
(gdb) info sharedlibrary
From To Syms Read Shared Object Library
0x00007ffff7ddbae0 0x00007ffff7df627a Yes (*) target:/lib64/ld-linux-x86-64.so.2
0x00007ffff7bc48a0 0x00007ffff7bcf514 Yes (*) target:/lib64/libpthread.so.0
gdb/ChangeLog
2016-04-06 Jan Kratochvil <jan.kratochvil@redhat.com>
* remote.c (struct remote_state): New field unknown_v_replies_ok.
(packet_config_support): Read it.
(remote_start_remote): Set it.
---
gdb/ChangeLog | 6 ++++++
gdb/remote.c | 31 +++++++++++++++++++++++++++++++
2 files changed, 37 insertions(+)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e362360..e3848ec 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
2016-04-06 Jan Kratochvil <jan.kratochvil@redhat.com>
+ * remote.c (struct remote_state): New field unknown_v_replies_ok.
+ (packet_config_support): Read it.
+ (remote_start_remote): Set it.
+
+2016-04-06 Jan Kratochvil <jan.kratochvil@redhat.com>
+
* remote.c: Revert check-in by a mistake in the previous commit.
2016-04-06 Jan Kratochvil <jan.kratochvil@redhat.com>
diff --git a/gdb/remote.c b/gdb/remote.c
index 5c407b6..ea7f5b8 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -426,6 +426,15 @@ struct remote_state
request/reply nature of the RSP. We only cache data for a single
file descriptor at a time. */
struct readahead_cache readahead_cache;
+
+ /* gdbserver < 7.7 (before its fix from 2013-12-11) did reply to any
+ unknown 'v' packet with string "OK". "OK" gets interpreted by GDB
+ as a reply to known packet. For packet "vFile:setfs:" it is an
+ invalid reply and GDB would return error in
+ remote_hostio_set_filesystem, making remote files access impossible.
+ If this variable is non-zero it means the remote gdbserver is buggy
+ and any not yet detected packets are assumed as unsupported. */
+ int unknown_v_replies_ok;
};
/* Private data that we'll store in (struct thread_info)->private. */
@@ -1519,6 +1528,13 @@ packet_config_support (struct packet_config *config)
case AUTO_BOOLEAN_FALSE:
return PACKET_DISABLE;
case AUTO_BOOLEAN_AUTO:
+ {
+ struct remote_state *rs = get_remote_state ();
+
+ if (rs->unknown_v_replies_ok && config->name != NULL
+ && config->name[0] == 'v')
+ return PACKET_DISABLE;
+ }
return config->support;
default:
gdb_assert_not_reached (_("bad switch"));
@@ -4023,6 +4039,21 @@ remote_start_remote (int from_tty, struct target_ops *target, int extended_p)
if (packet_support (PACKET_QAllow) != PACKET_DISABLE)
remote_set_permissions (target);
+ /* See unknown_v_replies_ok description. */
+ {
+ const char v_mustreplyempty[] = "vMustReplyEmpty";
+
+ putpkt (v_mustreplyempty);
+ getpkt (&rs->buf, &rs->buf_size, 0);
+ if (strcmp (rs->buf, "OK") == 0)
+ rs->unknown_v_replies_ok = 1;
+ else if (strcmp (rs->buf, "") == 0)
+ rs->unknown_v_replies_ok = 0;
+ else
+ error (_("Remote replied unexpectedly to '%s': %s"), v_mustreplyempty,
+ rs->buf);
+ }
+
/* Next, we possibly activate noack mode.
If the QStartNoAckMode packet configuration is set to AUTO,
--
2.5.5
--- End Message ---