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From 8eefbac3b67756f0dfe9d68741d70015023b5216 Mon Sep 17 00:00:00 2001
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From: Martin Milata <mmilata@redhat.com>
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Date: Fri, 17 Jul 2015 12:52:49 +0200
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Subject: [PATCH] Create core backtrace in unwind hook
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Related to #829.
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We need to implement #882 in order for this to work. This change
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requires (yet unreleased) satyr-0.16.
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The feature is turned off by default, you need to pass
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--enable-dump-time-unwind to configure in order to enable it.
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Signed-off-by: Martin Milata <mmilata@redhat.com>
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Conflicts:
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	src/hooks/abrt-hook-ccpp.c
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---
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 configure.ac                        |  12 ++++
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 doc/abrt-CCpp.conf.txt              |  18 ++++++
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 src/hooks/CCpp.conf                 |  15 +++++
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 src/hooks/abrt-hook-ccpp.c          | 108 ++++++++++++++++++++++++------------
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 src/hooks/abrt-install-ccpp-hook.in |   4 +-
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 5 files changed, 121 insertions(+), 36 deletions(-)
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diff --git a/configure.ac b/configure.ac
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index 56b8ad8..330dd9c 100644
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--- a/configure.ac
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+++ b/configure.ac
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@@ -232,6 +232,18 @@ AC_ARG_ENABLE([native-unwinder],
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 [fi]
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+# Perform stack unwind on live/dying process in the core handler?
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+
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+AC_ARG_ENABLE([dump-time-unwind],
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+    AS_HELP_STRING([--enable-dump-time-unwind],
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+        [create core stack trace while the crashed process is still in memory (default is no)]),
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+    [], [enable_dump_time_unwind=no])
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+
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+[if test "$enable_native_unwinder" = "yes" -a "$enable_dump_time_unwind" = "yes"]
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+[then]
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+    AC_DEFINE([ENABLE_DUMP_TIME_UNWIND], [1], [Create core stacktrace while the process is still in memory.])
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+[fi]
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+
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 AC_SUBST(CONF_DIR)
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 AC_SUBST(DEFAULT_CONF_DIR)
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 AC_SUBST(VAR_RUN)
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diff --git a/doc/abrt-CCpp.conf.txt b/doc/abrt-CCpp.conf.txt
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index ad3830b..498d53d 100644
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--- a/doc/abrt-CCpp.conf.txt
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+++ b/doc/abrt-CCpp.conf.txt
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@@ -19,12 +19,30 @@ SaveBinaryImage = 'yes' / 'no' ...::
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    Useful, for example, when _deleted binary_ segfaults.
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    Default is 'no'.
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+CreateCoreBacktrace = 'yes' / 'no' ...::
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+   When this option is set to 'yes', core backtrace is generated
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+   from the memory image of the crashing process. Only the crash
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+   thread is present in the backtrace. This feature requires
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+   kernel 3.18 or newer, otherwise the core backtrace is not
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+   created.
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+   Default is 'yes'.
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+
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+SaveFullCore = 'yes' / 'no' ...::
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+   Save full coredump? If set to 'no', coredump won't be saved
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+   and you won't be able to report the crash to Bugzilla. Only
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+   useful with 'CreateCoreBacktrace' set to 'yes'. Please
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+   note that if this option is set to 'no' and MakeCompatCore
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+   is set to 'yes', the core is still written to the current
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+   directory.
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+   Default is 'yes'.
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+
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 VerboseLog = NUM::
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    Used to make the hook more verbose
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 SEE ALSO
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 --------
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 abrt.conf(5)
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+abrt-action-generate-core-backtrace(1)
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 AUTHORS
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 -------
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diff --git a/src/hooks/CCpp.conf b/src/hooks/CCpp.conf
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index d199116..b1a0a22 100644
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--- a/src/hooks/CCpp.conf
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+++ b/src/hooks/CCpp.conf
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@@ -8,6 +8,21 @@ MakeCompatCore = yes
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 # (useful, for example, when _deleted binary_ segfaults)
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 SaveBinaryImage = no
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+# When this option is set to 'yes', core backtrace is generated
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+# from the memory image of the crashing process. Only the crash
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+# thread is present in the backtrace. This feature requires
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+# kernel 3.18 or newer, otherwise the core backtrace is not
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+# created.
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+CreateCoreBacktrace = yes
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+
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+# Save full coredump? If set to 'no', coredump won't be saved
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+# and you won't be able to report the crash to Bugzilla. Only
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+# useful with CreateCoreBacktrace set to 'yes'. Please
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+# note that if this option is set to 'no' and MakeCompatCore
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+# is set to 'yes', the core is still written to the current
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+# directory.
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+SaveFullCore = yes
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+
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 # Used for debugging the hook
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 #VerboseLog = 2
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diff --git a/src/hooks/abrt-hook-ccpp.c b/src/hooks/abrt-hook-ccpp.c
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index 2dd9ac6..b5f00f6 100644
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--- a/src/hooks/abrt-hook-ccpp.c
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+++ b/src/hooks/abrt-hook-ccpp.c
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@@ -22,6 +22,11 @@
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 #include "libabrt.h"
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 #include <selinux/selinux.h>
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+#ifdef ENABLE_DUMP_TIME_UNWIND
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+#include <satyr/abrt.h>
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+#include <satyr/utils.h>
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+#endif /* ENABLE_DUMP_TIME_UNWIND */
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+
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 #define  DUMP_SUID_UNSAFE 1
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 #define  DUMP_SUID_SAFE 2
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@@ -155,13 +160,13 @@ static struct dump_dir *dd;
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  * %g - gid
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  * %t - UNIX time of dump
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  * %e - executable filename
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- * %h - hostname
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+ * %i - crash thread tid
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  * %% - output one "%"
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  */
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 /* Hook must be installed with exactly the same sequence of %c specifiers.
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  * Last one, %h, may be omitted (we can find it out).
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  */
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-static const char percent_specifiers[] = "%scpugteh";
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+static const char percent_specifiers[] = "%scpugtei";
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 static char *core_basename = (char*) "core";
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 static char* get_executable(pid_t pid, int *fd_p)
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@@ -580,6 +585,24 @@ static int create_or_die(const char *filename, int user_core_fd)
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     perror_msg_and_die("Can't open '%s'", filename);
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 }
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+static void create_core_backtrace(pid_t tid, const char *executable, int signal_no, const char *dd_path)
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+{
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+#ifdef ENABLE_DUMP_TIME_UNWIND
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+    if (g_verbose > 1)
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+        sr_debug_parser = true;
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+
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+    char *error_message = NULL;
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+    bool success = sr_abrt_create_core_stacktrace_from_core_hook(dd_path, tid, executable,
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+                                                                 signal_no, &error_message);
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+
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+    if (!success)
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+    {
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+        log("Failed to create core_backtrace: %s", error_message);
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+        free(error_message);
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+    }
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+#endif /* ENABLE_DUMP_TIME_UNWIND */
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+}
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+
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 static int create_user_core(int user_core_fd, pid_t pid, off_t ulimit_c)
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 {
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     int err = 1;
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@@ -619,9 +642,9 @@ int main(int argc, char** argv)
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     if (argc < 8)
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     {
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-        /* percent specifier:         %s   %c              %p  %u  %g  %t   %e          %h */
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+        /* percent specifier:         %s   %c              %p  %u  %g  %t   %e          %i */
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         /* argv:                  [0] [1]  [2]             [3] [4] [5] [6]  [7]         [8]*/
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-        error_msg_and_die("Usage: %s SIGNO CORE_SIZE_LIMIT PID UID GID TIME BINARY_NAME [HOSTNAME]", argv[0]);
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+        error_msg_and_die("Usage: %s SIGNO CORE_SIZE_LIMIT PID UID GID TIME BINARY_NAME [TID]", argv[0]);
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     }
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     /* Not needed on 2.6.30.
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@@ -646,6 +669,8 @@ int main(int argc, char** argv)
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     /* ... and plugins/CCpp.conf */
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     bool setting_MakeCompatCore;
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     bool setting_SaveBinaryImage;
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+    bool setting_SaveFullCore;
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+    bool setting_CreateCoreBacktrace;
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     {
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         map_string_t *settings = new_map_string();
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         load_abrt_plugin_conf_file("CCpp.conf", settings);
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@@ -654,6 +679,10 @@ int main(int argc, char** argv)
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         setting_MakeCompatCore = value && string_to_bool(value);
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         value = get_map_string_item_or_NULL(settings, "SaveBinaryImage");
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         setting_SaveBinaryImage = value && string_to_bool(value);
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+        value = get_map_string_item_or_NULL(settings, "SaveFullCore");
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+        setting_SaveFullCore = value ? string_to_bool(value) : true;
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+        value = get_map_string_item_or_NULL(settings, "CreateCoreBacktrace");
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+        setting_CreateCoreBacktrace = value ? string_to_bool(value) : true;
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         value = get_map_string_item_or_NULL(settings, "VerboseLog");
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         if (value)
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             g_verbose = xatoi_positive(value);
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@@ -686,11 +715,10 @@ int main(int argc, char** argv)
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             free(s);
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     }
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-    struct utsname uts;
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-    if (!argv[8]) /* no HOSTNAME? */
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+    pid_t tid = 0;
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+    if (argv[8])
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     {
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-        uname(&uts;;
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-        argv[8] = uts.nodename;
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+        tid = xatoi_positive(argv[8]);
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     }
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     char path[PATH_MAX];
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@@ -906,36 +934,42 @@ int main(int argc, char** argv)
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             off_t sz = copyfd_eof(src_fd_binary, dst_fd, COPYFD_SPARSE);
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             if (fsync(dst_fd) != 0 || close(dst_fd) != 0 || sz < 0)
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             {
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-                dd_delete(dd);
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-                error_msg_and_die("Error saving '%s'", path);
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+                dd_delete(dd); error_msg_and_die("Error saving '%s'", path);
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             }
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             close(src_fd_binary);
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         }
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-        strcpy(path + path_len, "/"FILENAME_COREDUMP);
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-        int abrt_core_fd = create_or_die(path, user_core_fd);
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-
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-        /* We write both coredumps at once.
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-         * We can't write user coredump first, since it might be truncated
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-         * and thus can't be copied and used as abrt coredump;
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-         * and if we write abrt coredump first and then copy it as user one,
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-         * then we have a race when process exits but coredump does not exist yet:
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-         * $ echo -e '#include<signal.h>\nmain(){raise(SIGSEGV);}' | gcc -o test -x c -
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-         * $ rm -f core*; ulimit -c unlimited; ./test; ls -l core*
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-         * 21631 Segmentation fault (core dumped) ./test
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-         * ls: cannot access core*: No such file or directory <=== BAD
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-         */
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-        off_t core_size = copyfd_sparse(STDIN_FILENO, abrt_core_fd, user_core_fd, ulimit_c);
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-
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-        close_user_core(user_core_fd, core_size);
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-
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-        if (fsync(abrt_core_fd) != 0 || close(abrt_core_fd) != 0 || core_size < 0)
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+        off_t core_size = 0;
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+        if (setting_SaveFullCore)
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         {
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-            unlink(path);
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-            dd_delete(dd);
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-            /* copyfd_sparse logs the error including errno string,
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-             * but it does not log file name */
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-            error_msg_and_die("Error writing '%s'", path);
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+            strcpy(path + path_len, "/"FILENAME_COREDUMP);
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+            int abrt_core_fd = create_or_die(path, user_core_fd);
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+
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+            /* We write both coredumps at once.
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+             * We can't write user coredump first, since it might be truncated
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+             * and thus can't be copied and used as abrt coredump;
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+             * and if we write abrt coredump first and then copy it as user one,
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+             * then we have a race when process exits but coredump does not exist yet:
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+             * $ echo -e '#include<signal.h>\nmain(){raise(SIGSEGV);}' | gcc -o test -x c -
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+             * $ rm -f core*; ulimit -c unlimited; ./test; ls -l core*
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+             * 21631 Segmentation fault (core dumped) ./test
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+             * ls: cannot access core*: No such file or directory <=== BAD
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+             */
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+            core_size = copyfd_sparse(STDIN_FILENO, abrt_core_fd, user_core_fd, ulimit_c);
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+            close_user_core(user_core_fd, core_size);
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+            if (fsync(abrt_core_fd) != 0 || close(abrt_core_fd) != 0 || core_size < 0)
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+            {
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+                unlink(path);
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+                dd_delete(dd);
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+                /* copyfd_sparse logs the error including errno string,
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+                 * but it does not log file name */
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+                error_msg_and_die("Error writing '%s'", path);
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+            }
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+        }
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+        else
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+        {
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+            /* User core is created even if WriteFullCore is off. */
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+            create_user_core(user_core_fd, pid, ulimit_c);
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         }
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 /* Because of #1211835 and #1126850 */
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@@ -977,6 +1011,10 @@ int main(int argc, char** argv)
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         /* And finally set the right uid and gid */
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         dd_reset_ownership(dd);
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+        /* Perform crash-time unwind of the guilty thread. */
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+        if (tid > 0 && setting_CreateCoreBacktrace)
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+            create_core_backtrace(tid, executable, signal_no, dd->dd_dirname);
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+
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         /* We close dumpdir before we start catering for crash storm case.
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          * Otherwise, delete_dump_dir's from other concurrent
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          * CCpp's won't be able to delete our dump (their delete_dump_dir
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@@ -990,7 +1028,9 @@ int main(int argc, char** argv)
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             strcpy(path, newpath);
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         free(newpath);
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-        log("Saved core dump of pid %lu (%s) to %s (%llu bytes)", (long)pid, executable, path, (long long)core_size);
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+        if (core_size > 0)
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+            log_notice("Saved core dump of pid %lu (%s) to %s (%llu bytes)",
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+                       (long)pid, executable, path, (long long)core_size);
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         notify_new_path(path);
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diff --git a/src/hooks/abrt-install-ccpp-hook.in b/src/hooks/abrt-install-ccpp-hook.in
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index aa01231..d4ed4a5 100755
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--- a/src/hooks/abrt-install-ccpp-hook.in
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+++ b/src/hooks/abrt-install-ccpp-hook.in
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@@ -11,9 +11,9 @@ SAVED_PATTERN_DIR="@VAR_RUN@/abrt"
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 SAVED_PATTERN_FILE="@VAR_RUN@/abrt/saved_core_pattern"
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 HOOK_BIN="@libexecdir@/abrt-hook-ccpp"
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 # Must match percent_specifiers[] order in abrt-hook-ccpp.c:
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-PATTERN="|$HOOK_BIN %s %c %p %u %g %t %e"
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+PATTERN="|$HOOK_BIN %s %c %p %u %g %t %e %i"
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 # Same, but with bogus "executable name" parameter
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-PATTERN1="|$HOOK_BIN %s %c %p %u %g %t e"
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+PATTERN1="|$HOOK_BIN %s %c %p %u %g %t e %i"
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 # core_pipe_limit specifies how many dump_helpers can run at the same time
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 # 0 - means unlimited, but it's not guaranteed that /proc/<pid> of crashing
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-- 
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2.4.3
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