From 0f669af4d7180b12142a41117ae2459d6960dd31 Mon Sep 17 00:00:00 2001
From: Martin Milata <mmilata@redhat.com>
Date: Mon, 1 Dec 2014 12:05:36 +0100
Subject: [PATCH] Create core backtrace in unwind hook

Related to #829.

We need to implement #882 in order for this to work. This change
requires (yet unreleased) satyr-0.16.

The feature is turned off by default, you need to pass
--enable-dump-time-unwind to configure in order to enable it.

Signed-off-by: Martin Milata <mmilata@redhat.com>
---
 configure.ac                                       |  12 ++
 doc/abrt-CCpp.conf.txt                             |  18 +++
 .../en-US/Automatic_Bug_Reporting_Tool_ABRT.xml    |   2 +-
 src/hooks/CCpp.conf                                |  15 +++
 src/hooks/abrt-hook-ccpp.c                         | 126 ++++++++++++++-------
 src/hooks/abrt-install-ccpp-hook.in                |   4 +-
 6 files changed, 132 insertions(+), 45 deletions(-)

diff --git a/configure.ac b/configure.ac
index 71d7c18..d7e0ea5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -266,6 +266,18 @@ AC_ARG_ENABLE([addon-vmcore],
 	AM_CONDITIONAL(BUILD_ADDON_VMCORE, false)
 [fi]
 
+# Perform stack unwind on live/dying process in the core handler?
+
+AC_ARG_ENABLE([dump-time-unwind],
+    AS_HELP_STRING([--enable-dump-time-unwind],
+        [create core stack trace while the crashed process is still in memory (default is no)]),
+    [], [enable_dump_time_unwind=no])
+
+[if test "$enable_native_unwinder" = "yes" -a "$enable_dump_time_unwind" = "yes"]
+[then]
+    AC_DEFINE([ENABLE_DUMP_TIME_UNWIND], [1], [Create core stacktrace while the process is still in memory.])
+[fi]
+
 AC_SUBST(CONF_DIR)
 AC_SUBST(DEFAULT_CONF_DIR)
 AC_SUBST(VAR_RUN)
diff --git a/doc/abrt-CCpp.conf.txt b/doc/abrt-CCpp.conf.txt
index ad3830b..498d53d 100644
--- a/doc/abrt-CCpp.conf.txt
+++ b/doc/abrt-CCpp.conf.txt
@@ -19,12 +19,30 @@ SaveBinaryImage = 'yes' / 'no' ...::
    Useful, for example, when _deleted binary_ segfaults.
    Default is 'no'.
 
+CreateCoreBacktrace = 'yes' / 'no' ...::
+   When this option is set to 'yes', core backtrace is generated
+   from the memory image of the crashing process. Only the crash
+   thread is present in the backtrace. This feature requires
+   kernel 3.18 or newer, otherwise the core backtrace is not
+   created.
+   Default is 'yes'.
+
+SaveFullCore = 'yes' / 'no' ...::
+   Save full coredump? If set to 'no', coredump won't be saved
+   and you won't be able to report the crash to Bugzilla. Only
+   useful with 'CreateCoreBacktrace' set to 'yes'. Please
+   note that if this option is set to 'no' and MakeCompatCore
+   is set to 'yes', the core is still written to the current
+   directory.
+   Default is 'yes'.
+
 VerboseLog = NUM::
    Used to make the hook more verbose
 
 SEE ALSO
 --------
 abrt.conf(5)
+abrt-action-generate-core-backtrace(1)
 
 AUTHORS
 -------
diff --git a/doc/deployment/en-US/Automatic_Bug_Reporting_Tool_ABRT.xml b/doc/deployment/en-US/Automatic_Bug_Reporting_Tool_ABRT.xml
index e11307a..daee375 100644
--- a/doc/deployment/en-US/Automatic_Bug_Reporting_Tool_ABRT.xml
+++ b/doc/deployment/en-US/Automatic_Bug_Reporting_Tool_ABRT.xml
@@ -187,7 +187,7 @@ Starting abrt daemon:                                      [  OK  ]</screen>
     	<para>
     	  Please note that installing <application>ABRT</application> packages overwrites the <filename>/proc/sys/kernel/core_pattern</filename> file which can contain a template used to name core dump files. The content of this file will be overwritten to:
     	</para>
-    	<programlisting language="Bash">|/usr/libexec/abrt-hook-ccpp %s %c %p %u %g %t e</programlisting>
+    	<programlisting language="Bash">|/usr/libexec/abrt-hook-ccpp %s %c %p %u %g %t e %i</programlisting>
     </warning>
     <para>
       Finally, if you run ABRT in a graphical desktop environment, you can verify that the <systemitem class="service">ABRT notification applet</systemitem> is running:
diff --git a/src/hooks/CCpp.conf b/src/hooks/CCpp.conf
index d199116..b1a0a22 100644
--- a/src/hooks/CCpp.conf
+++ b/src/hooks/CCpp.conf
@@ -8,6 +8,21 @@ MakeCompatCore = yes
 # (useful, for example, when _deleted binary_ segfaults)
 SaveBinaryImage = no
 
+# When this option is set to 'yes', core backtrace is generated
+# from the memory image of the crashing process. Only the crash
+# thread is present in the backtrace. This feature requires
+# kernel 3.18 or newer, otherwise the core backtrace is not
+# created.
+CreateCoreBacktrace = yes
+
+# Save full coredump? If set to 'no', coredump won't be saved
+# and you won't be able to report the crash to Bugzilla. Only
+# useful with CreateCoreBacktrace set to 'yes'. Please
+# note that if this option is set to 'no' and MakeCompatCore
+# is set to 'yes', the core is still written to the current
+# directory.
+SaveFullCore = yes
+
 # Used for debugging the hook
 #VerboseLog = 2
 
diff --git a/src/hooks/abrt-hook-ccpp.c b/src/hooks/abrt-hook-ccpp.c
index 3785d89..57c56a7 100644
--- a/src/hooks/abrt-hook-ccpp.c
+++ b/src/hooks/abrt-hook-ccpp.c
@@ -21,6 +21,11 @@
 #include <sys/utsname.h>
 #include "libabrt.h"
 
+#ifdef ENABLE_DUMP_TIME_UNWIND
+#include <satyr/abrt.h>
+#include <satyr/utils.h>
+#endif /* ENABLE_DUMP_TIME_UNWIND */
+
 #define  DUMP_SUID_UNSAFE 1
 #define  DUMP_SUID_SAFE 2
 
@@ -151,13 +156,13 @@ static struct dump_dir *dd;
  * %g - gid
  * %t - UNIX time of dump
  * %e - executable filename
- * %h - hostname
+ * %i - crash thread tid
  * %% - output one "%"
  */
 /* Hook must be installed with exactly the same sequence of %c specifiers.
  * Last one, %h, may be omitted (we can find it out).
  */
-static const char percent_specifiers[] = "%scpugteh";
+static const char percent_specifiers[] = "%scpugtei";
 static char *core_basename = (char*) "core";
 /*
  * Used for error messages only.
@@ -453,6 +458,24 @@ static int create_or_die(const char *filename, int user_core_fd)
     perror_msg_and_die("Can't open '%s'", filename);
 }
 
+static void create_core_backtrace(pid_t tid, const char *executable, int signal_no, const char *dd_path)
+{
+#ifdef ENABLE_DUMP_TIME_UNWIND
+    if (g_verbose > 1)
+        sr_debug_parser = true;
+
+    char *error_message = NULL;
+    bool success = sr_abrt_create_core_stacktrace_from_core_hook(dd_path, tid, executable,
+                                                                 signal_no, &error_message);
+
+    if (!success)
+    {
+        log("Failed to create core_backtrace: %s", error_message);
+        free(error_message);
+    }
+#endif /* ENABLE_DUMP_TIME_UNWIND */
+}
+
 static int create_user_core(int user_core_fd, pid_t pid, off_t ulimit_c)
 {
     if (user_core_fd >= 0)
@@ -493,9 +516,9 @@ int main(int argc, char** argv)
 
     if (argc < 8)
     {
-        /* percent specifier:         %s   %c              %p  %u  %g  %t   %e          %h */
+        /* percent specifier:         %s   %c              %p  %u  %g  %t   %e          %i */
         /* argv:                  [0] [1]  [2]             [3] [4] [5] [6]  [7]         [8]*/
-        error_msg_and_die("Usage: %s SIGNO CORE_SIZE_LIMIT PID UID GID TIME BINARY_NAME [HOSTNAME]", argv[0]);
+        error_msg_and_die("Usage: %s SIGNO CORE_SIZE_LIMIT PID UID GID TIME BINARY_NAME [TID]", argv[0]);
     }
 
     /* Not needed on 2.6.30.
@@ -520,6 +543,8 @@ int main(int argc, char** argv)
     /* ... and plugins/CCpp.conf */
     bool setting_MakeCompatCore;
     bool setting_SaveBinaryImage;
+    bool setting_SaveFullCore;
+    bool setting_CreateCoreBacktrace;
     {
         map_string_t *settings = new_map_string();
         load_abrt_plugin_conf_file("CCpp.conf", settings);
@@ -528,6 +553,10 @@ int main(int argc, char** argv)
         setting_MakeCompatCore = value && string_to_bool(value);
         value = get_map_string_item_or_NULL(settings, "SaveBinaryImage");
         setting_SaveBinaryImage = value && string_to_bool(value);
+        value = get_map_string_item_or_NULL(settings, "SaveFullCore");
+        setting_SaveFullCore = value ? string_to_bool(value) : true;
+        value = get_map_string_item_or_NULL(settings, "CreateCoreBacktrace");
+        setting_CreateCoreBacktrace = value ? string_to_bool(value) : true;
         value = get_map_string_item_or_NULL(settings, "VerboseLog");
         if (value)
             g_verbose = xatoi_positive(value);
@@ -560,11 +589,10 @@ int main(int argc, char** argv)
             free(s);
     }
 
-    struct utsname uts;
-    if (!argv[8]) /* no HOSTNAME? */
+    pid_t tid = 0;
+    if (argv[8])
     {
-        uname(&uts);
-        argv[8] = uts.nodename;
+        tid = xatoi_positive(argv[8]);
     }
 
     char path[PATH_MAX];
@@ -769,49 +797,57 @@ int main(int argc, char** argv)
             off_t sz = copyfd_eof(src_fd_binary, dst_fd, COPYFD_SPARSE);
             if (fsync(dst_fd) != 0 || close(dst_fd) != 0 || sz < 0)
             {
-                dd_delete(dd);
-                error_msg_and_die("Error saving '%s'", path);
+                dd_delete(dd); error_msg_and_die("Error saving '%s'", path);
             }
             close(src_fd_binary);
         }
 
-        strcpy(path + path_len, "/"FILENAME_COREDUMP);
-        int abrt_core_fd = create_or_die(path, user_core_fd);
-
-        /* We write both coredumps at once.
-         * We can't write user coredump first, since it might be truncated
-         * and thus can't be copied and used as abrt coredump;
-         * and if we write abrt coredump first and then copy it as user one,
-         * then we have a race when process exits but coredump does not exist yet:
-         * $ echo -e '#include<signal.h>\nmain(){raise(SIGSEGV);}' | gcc -o test -x c -
-         * $ rm -f core*; ulimit -c unlimited; ./test; ls -l core*
-         * 21631 Segmentation fault (core dumped) ./test
-         * ls: cannot access core*: No such file or directory <=== BAD
-         */
-        off_t core_size = copyfd_sparse(STDIN_FILENO, abrt_core_fd, user_core_fd, ulimit_c);
-        if (fsync(abrt_core_fd) != 0 || close(abrt_core_fd) != 0 || core_size < 0)
+        off_t core_size = 0;
+        if (setting_SaveFullCore)
         {
-            unlink(path);
-            dd_delete(dd);
-            if (user_core_fd >= 0)
+            strcpy(path + path_len, "/"FILENAME_COREDUMP);
+            int abrt_core_fd = create_or_die(path, user_core_fd);
+
+            /* We write both coredumps at once.
+             * We can't write user coredump first, since it might be truncated
+             * and thus can't be copied and used as abrt coredump;
+             * and if we write abrt coredump first and then copy it as user one,
+             * then we have a race when process exits but coredump does not exist yet:
+             * $ echo -e '#include<signal.h>\nmain(){raise(SIGSEGV);}' | gcc -o test -x c -
+             * $ rm -f core*; ulimit -c unlimited; ./test; ls -l core*
+             * 21631 Segmentation fault (core dumped) ./test
+             * ls: cannot access core*: No such file or directory <=== BAD
+             */
+            core_size = copyfd_sparse(STDIN_FILENO, abrt_core_fd, user_core_fd, ulimit_c);
+            if (fsync(abrt_core_fd) != 0 || close(abrt_core_fd) != 0 || core_size < 0)
             {
+                unlink(path);
+                dd_delete(dd);
+                if (user_core_fd >= 0)
+                {
+                    xchdir(user_pwd);
+                    unlink(core_basename);
+                }
+                /* copyfd_sparse logs the error including errno string,
+                 * but it does not log file name */
+                error_msg_and_die("Error writing '%s'", path);
+            }
+            if (user_core_fd >= 0
+                /* error writing user coredump? */
+             && (fsync(user_core_fd) != 0 || close(user_core_fd) != 0
+                /* user coredump is too big? */
+                || (ulimit_c == 0 /* paranoia */ || core_size > ulimit_c)
+                )
+            ) {
+                /* nuke it (silently) */
                 xchdir(user_pwd);
                 unlink(core_basename);
             }
-            /* copyfd_sparse logs the error including errno string,
-             * but it does not log file name */
-            error_msg_and_die("Error writing '%s'", path);
         }
-        if (user_core_fd >= 0
-            /* error writing user coredump? */
-         && (fsync(user_core_fd) != 0 || close(user_core_fd) != 0
-            /* user coredump is too big? */
-            || (ulimit_c == 0 /* paranoia */ || core_size > ulimit_c)
-            )
-        ) {
-            /* nuke it (silently) */
-            xchdir(user_pwd);
-            unlink(core_basename);
+        else
+        {
+            /* User core is created even if WriteFullCore is off. */
+            create_user_core(user_core_fd, pid, ulimit_c);
         }
 
         /* Save JVM crash log if it exists. (JVM's coredump per se
@@ -847,6 +883,10 @@ int main(int argc, char** argv)
             }
         }
 
+        /* Perform crash-time unwind of the guilty thread. */
+        if (tid > 0 && setting_CreateCoreBacktrace)
+            create_core_backtrace(tid, executable, signal_no, dd->dd_dirname);
+
         /* We close dumpdir before we start catering for crash storm case.
          * Otherwise, delete_dump_dir's from other concurrent
          * CCpp's won't be able to delete our dump (their delete_dump_dir
@@ -860,7 +900,9 @@ int main(int argc, char** argv)
             strcpy(path, newpath);
         free(newpath);
 
-        log_notice("Saved core dump of pid %lu (%s) to %s (%llu bytes)", (long)pid, executable, path, (long long)core_size);
+        if (core_size > 0)
+            log_notice("Saved core dump of pid %lu (%s) to %s (%llu bytes)",
+                       (long)pid, executable, path, (long long)core_size);
 
         notify_new_path(path);
 
diff --git a/src/hooks/abrt-install-ccpp-hook.in b/src/hooks/abrt-install-ccpp-hook.in
index aa01231..d4ed4a5 100755
--- a/src/hooks/abrt-install-ccpp-hook.in
+++ b/src/hooks/abrt-install-ccpp-hook.in
@@ -11,9 +11,9 @@ SAVED_PATTERN_DIR="@VAR_RUN@/abrt"
 SAVED_PATTERN_FILE="@VAR_RUN@/abrt/saved_core_pattern"
 HOOK_BIN="@libexecdir@/abrt-hook-ccpp"
 # Must match percent_specifiers[] order in abrt-hook-ccpp.c:
-PATTERN="|$HOOK_BIN %s %c %p %u %g %t %e"
+PATTERN="|$HOOK_BIN %s %c %p %u %g %t %e %i"
 # Same, but with bogus "executable name" parameter
-PATTERN1="|$HOOK_BIN %s %c %p %u %g %t e"
+PATTERN1="|$HOOK_BIN %s %c %p %u %g %t e %i"
 
 # core_pipe_limit specifies how many dump_helpers can run at the same time
 # 0 - means unlimited, but it's not guaranteed that /proc/<pid> of crashing
-- 
2.1.0

