From 57809e5e5a506664eb54433ded81ab0785168a83 Mon Sep 17 00:00:00 2001 From: Jan Kratochvil Date: Wed, 27 Apr 2016 21:27:40 +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 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 * 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 2016-04-26 Jan Kratochvil * remote.c (remote_start_remote): Detect PACKET_vFile_setfs.support. --- gdb/ChangeLog | 4 ++++ gdb/remote.c | 19 +++++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 165c2a3..5cf8a5f 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,7 @@ +2016-04-27 Jan Kratochvil + + * remote.c (remote_start_remote): Detect PACKET_vFile_setfs.support. + 2016-04-27 Martin Galvan * c-valprint.c (c_value_print): Always convert val back to reference diff --git a/gdb/remote.c b/gdb/remote.c index 4c18b4f..1f0d67c 100644 --- a/gdb/remote.c +++ b/gdb/remote.c @@ -4031,6 +4031,25 @@ remote_start_remote (int from_tty, struct target_ops *target, int extended_p) if (packet_support (PACKET_QAllow) != PACKET_DISABLE) remote_set_permissions (target); + /* 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. + Disable "vFile:setfs:" in such case. Do not disable other 'v' packets as + other "vFile" packets get correctly detected even on gdbserver < 7.7. */ + { + const char v_mustreplyempty[] = "vMustReplyEmpty"; + + putpkt (v_mustreplyempty); + getpkt (&rs->buf, &rs->buf_size, 0); + if (strcmp (rs->buf, "OK") == 0) + remote_protocol_packets[PACKET_vFile_setfs].support = PACKET_DISABLE; + else if (strcmp (rs->buf, "") != 0) + 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, -- 2.7.4