[binutils-gdb/gdb-8.0-branch] PR gdb/22046: Fix T-stopped detach regression on old Linux kernels

[Jan Kratochvil <jkratoch at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=c247e38d78a98f85066e4a61032ee742d08a0579

commit c247e38d78a98f85066e4a61032ee742d08a0579
Author: Jan Kratochvil <jan.kratochvil@redhat.com>
Date:   Fri Sep 1 06:13:40 2017 +0200

    PR gdb/22046: Fix T-stopped detach regression on old Linux kernels
    
    On <=RHEL6 hosts Fedora/RHEL GDB started to 'kill -STOP' all processes it
    detached.  Even those not originally T-stopped.  This is a Fedora-specific
    patch which is based on upstream GDB's PROC_STATE_STOPPED state.
    
    I believe (I did not verify) this patch did regress it:
    commit d617208bb06bd461b52ce041d89f7127e3044762
    Author: Pedro Alves <palves@redhat.com>
    Date:   Mon Jul 25 12:42:17 2016 +0100
        linux-procfs: Introduce enum proc_state
    
    As originally there was strstr() but now there is strcmp() and so the missing
    trailing '\n' no longer matches.
    
    The Bug was found by Michal Kolar.
    
    Reproducibility:
    $ gdb -p $PID
    (gdb) quit
    $ ...
    
    Actual results:
    ===
    RHEL6.9 x86_64 # scl enable devtoolset-7 bash
    RHEL6.9 x86_64 # which gdb
    /opt/rh/devtoolset-7/root/usr/bin/gdb
    RHEL6.9 x86_64 # ./testcase.sh
    24737 pts/0    S+     0:00 /bin/sleep 4
    24737 pts/0    T+     0:00 /bin/sleep 4
    RHEL6.9 x86_64 #
    ===
    
    Expected results:
    ===
    RHEL6.9 x86_64 # which gdb
    /usr/bin/gdb
    RHEL6.9 x86_64 # ./testcase.sh
    24708 pts/0    S+     0:00 /bin/sleep 4
    24708 pts/0    S+     0:00 /bin/sleep 4
    ./testcase.sh: line 20: kill: (24708) - No such process
    RHEL6.9 x86_64 #
    ===
    
    gdb/ChangeLog
    2017-09-01  Jan Kratochvil  <jan.kratochvil@redhat.com>
    
    	PR gdb/22046
    	* nat/linux-procfs.c (parse_proc_status_state): Fix PROC_STATE_STOPPED
    	detection.

Diff:
---
 gdb/ChangeLog          | 6 ++++++
 gdb/nat/linux-procfs.c | 6 +++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 97299e6..5eef1c9 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2017-09-01  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	PR gdb/22046
+	* nat/linux-procfs.c (parse_proc_status_state): Fix PROC_STATE_STOPPED
+	detection.
+
 2017-08-28  Simon Marchi  <simon.marchi@ericsson.com>
 
 	PR gdb/21827
diff --git a/gdb/nat/linux-procfs.c b/gdb/nat/linux-procfs.c
index 5290045..c68c4dc 100644
--- a/gdb/nat/linux-procfs.c
+++ b/gdb/nat/linux-procfs.c
@@ -106,10 +106,10 @@ parse_proc_status_state (const char *state)
       return PROC_STATE_TRACING_STOP;
     case 'T':
       /* Before Linux 2.6.33, tracing stop used uppercase T.  */
-      if (strcmp (state, "T (tracing stop)") == 0)
-	return PROC_STATE_TRACING_STOP;
-      else
+      if (strcmp (state, "T (stopped)\n") == 0)
 	return PROC_STATE_STOPPED;
+      else /* "T (tracing stop)\n" */
+	return PROC_STATE_TRACING_STOP;
     case 'X':
       return PROC_STATE_DEAD;
     case 'Z':