| Bug #93767 | INSTALL COMPONENT fails - handled segfault during installation nothing in log | ||
|---|---|---|---|
| Submitted: | 30 Dec 2018 22:22 | Modified: | 25 Feb 2019 13:14 |
| Reporter: | Justin Swanhart | Email Updates: | |
| Status: | Can't repeat | Impact on me: | |
| Category: | MySQL Server | Severity: | S2 (Serious) |
| Version: | 8.0.13 (git source) | OS: | Debian (9.6) |
| Assigned to: | CPU Architecture: | x86 | |
[30 Dec 2018 22:27]
Justin Swanhart
changed the title to indicate the handled segfault
[30 Dec 2018 22:54]
Justin Swanhart
I commented out the body of query_injection_point() to see if that would change anything, but it still segfaults.
[11 Jan 2019 15:16]
MySQL Verification Team
Hello Justin, Let me know how are you !!!!! Both, our mutual friend from Bulgaria and I are delighted that you are trying to write components. Regarding the one that you have displayed for us here, I do have some bad news for you. I am afraid that you are assuming that you can, in a component, alter internal state of another component. Unfortunately, this is simply not possible with components. Plugins can do that for other plugins, but this does not work with components. I will provide you here with one useful URL for the documentation: https://dev.mysql.com/doc/dev/mysql-server/latest/ Hoping to hear from you soon !!!!!
[21 Jan 2019 18:23]
Justin Swanhart
Hi, There is only one component here. I'm not trying to modify the state of another component, everything is normal library calls. I've modified sql_cilent.h and sql_client.cc in my installation, so this code won't compile out of the box. I will provide a simpler example with an empty function (remember I tried with the body commented out) to demonstrate the problem more clearly.
[21 Jan 2019 19:10]
Justin Swanhart
Okay, so it turns out this happens when you try to install a component that is not found, instead of a nice error message like 'could not locate component'... I suggest you improve the error messages around component installation in that case. Now I can't figure out how to install my component. It is installed in /usr/local/mysql/lib/plugin/libplugin_shim.so All of the following fail: mysql> install component 'file://shim'; ERROR 3529 (HY000): Cannot load component from specified URN: 'file://shim'. mysql> install component 'file://plugin_shim'; ERROR 3529 (HY000): Cannot load component from specified URN: 'file://plugin_shim'. mysql> install component 'file://libplugin_shim'; ERROR 3529 (HY000): Cannot load component from specified URN: 'file://libplugin_shim'. How do I load my shared library. Is it named wrong?
[21 Jan 2019 20:01]
Justin Swanhart
From the docs you gave I must be missing something. I'll look at the example/ directory to see what I'm missing.
[22 Jan 2019 13:19]
MySQL Verification Team
First of all, waiting on the example. Second, try giving a full path of your component in its subdirectory under components/ directory.
[23 Feb 2019 1:00]
Bugs System
No feedback was provided for this bug for over a month, so it is being suspended automatically. If you are able to provide the information that was originally requested, please do so and change the status of the bug back to "Open".
Description: I have created a C++ service using the component framework. This service won't install with INSTALL COMPONENT: mysql> install component 'file://sql_shim'; ERROR 3529 (HY000): Cannot load component from specified URN: 'file://sql_shim' When I attach gdb I get a handled segfaul in PFS: Thread 43 "mysqld" received signal SIGSEGV, Segmentation fault. my_thread_get_THR_PFS () at /root/warpsql-server/storage/perfschema/pfs.cc:2094 2094 static inline PFS_thread *my_thread_get_THR_PFS() { return THR_PFS; } (gdb) handle_fatal_signal (sig=11) at /root/warpsql-server/sql/signal_handler.cc:80 80 extern "C" void handle_fatal_signal(int sig) { (gdb) 81 if (segfaulted) { (gdb) 96 const time_t curr_time = time(NULL); (gdb) bt #0 handle_fatal_signal (sig=11) at /root/warpsql-server/sql/signal_handler.cc:96 #1 <signal handler called> #2 my_thread_get_THR_PFS () at /root/warpsql-server/storage/perfschema/pfs.cc:2094 #3 pfs_set_thread_start_time_v1 (start_time=1546208093) at /root/warpsql-server/storage/perfschema/pfs.cc:3127 #4 0x000055555626445c in THD::set_time (this=0x7fff60000b50) at /root/warpsql-server/sql/sql_class.h:2582 #5 dispatch_command (thd=0x7fff60000b50, com_data=0x7fffdc1ebd40, command=COM_QUERY) at /root/warpsql-server/sql/sql_parse.cc:1445 #6 0x0000555556267b50 in do_command (thd=thd@entry=0x7fff60000b50) at /root/warpsql-server/sql/sql_parse.cc:1260 #7 0x0000555556364528 in handle_connection (arg=arg@entry=0x555558ce45c0) at /root/warpsql-server/sql/conn_handler/connection_handler_per_thread.cc:308 #8 0x00005555575a0ddf in pfs_spawn_thread (arg=0x555558f859b0) at /root/warpsql-server/storage/perfschema/pfs.cc:2836 #9 0x00007ffff7bc3494 in start_thread (arg=0x7fffdc1ec700) at pthread_create.c:333 #10 0x00007ffff6114acf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97 (gdb) How to repeat: here is the header: #ifndef MYSQL_SHIM_SERVICE_H #define MYSQL_SHIM_SERVICE_H #include "mysql/components/service_implementation.h" #include "../../components/mysql_server/server_component.h" #include "mysql/psi/psi_memory.h" #include <locale> #include "sql/sql_parse.h" #include "sql/sql_class.h" #include "sql/sql_client.h" void my_plugin_shim_init(); class my_plugin_shim_imp { public: /* service implementations */ /** Query rewriter that allows queries to run on the THD inside of the plugin to get internal resultsets using SQLClient @param [in] thd - the THD object on which to run queries @param [in] com_data - the original COM_DATA* from the do_command function @param [in] command - the original command from the do_command function @param [out] new_com_data - pointer to a new COM_DATA to run when the function returns @param [out] new_command - pointer to a new enum_server_command to run when the function returns @return return value indicates wether or not the command was rewritten @retval false no rewrite @retval true query was rewritten */ static DEFINE_BOOL_METHOD(query_injection_point,(THD* thd, COM_DATA *com_data, enum enum_server_command command, COM_DATA* new_com_data, enum enum_server_command* new_command)); }; #endif /* MYSQL_SHIM_SERVICE_H */ And here is the implementation: #include "../../components/mysql_server/my_plugin_shim.h" PSI_memory_key key_memory_shim_iterator; /** Its a dummy initialization function. And it will be called from mysql_component_infrastructure_init(). Else linker, is cutting out (as library optimization) the string service code because libsql code is not calling any functions of it. */ void my_plugin_shim_init() { return; } /* Query rewriter that allows queries to run on the THD inside of the plugin to get internal resultsets using SQLClient @param [in] thd - the THD object on which to run queries @param [in] com_data - the original COM_DATA* from the do_command function @param [in] command - the original command from the do_command function @param [out] new_com_data - pointer to a new COM_DATA to run when the function returns @param [out] new_command - pointer to a new enum_server_command to run when the function returns @return return value indicates wether or not the command was rewritten @retval false no rewrite @retval true query was rewritten */ DEFINE_BOOL_METHOD(my_plugin_shim_imp::query_injection_point,(THD* thd, COM_DATA *com_data, enum enum_server_command command, COM_DATA* new_com_data, enum enum_server_command* new_command)) { std::string new_query; SQLClient conn(thd); SQLCursor* stmt; SQLRow* row; try { /* example rewrite rule for SHOW PASSWORD*/ if(command == COM_QUERY) { std::locale loc; std::string old_query(com_data->com_query.query,com_data->com_query.length); for(unsigned int i=0;i<com_data->com_query.length;++i) { old_query[i] = std::toupper(old_query[i], loc); } if(old_query == "SHOW PASSWORD") { if(conn.query("pw,user","select authentication_string as pw,user from mysql.user where concat(user,'@',host) = USER() or user = USER() LIMIT 1", &stmt)) { if(stmt != NULL) { if((row = stmt->next())) { new_query = "SELECT '" + row->at(0) + "'"; } } else { delete stmt; return false; } } else { return false; } /* replace the command sent to the server */ if(new_query != "") { thd->get_protocol_classic()->create_command(new_com_data, COM_QUERY, (uchar *) strdup(new_query.c_str()), new_query.length()); *new_command = COM_QUERY; } else { if(stmt) delete stmt; return false; } if(stmt) delete stmt; return true; } } /* don't replace command */ return false; } catch (...) { if(stmt != NULL) delete stmt; mysql_components_handle_std_exception(__func__); return false; } return true; }; Here is the CMakeLists.txt - I've put the code in sql/shim: IF(WITHOUT_SERVER) MESSAGE(STATUS "The shim plugin is for server only") RETURN() ENDIF() SET(MYSQL_SHIM_SOURCES my_plugin_shim.cc ) ADD_CONVENIENCE_LIBRARY(plugin_shim ${MYSQL_SHIM_SOURCES}) IF(INSTALL_STATIC_LIBRARIES) INSTALL(TARGETS plugin_shim DESTINATION ${INSTALL_LIBDIR} COMPONENT Development) ENDIF() ADD_DEPENDENCIES(plugin_shim GenError) Suggested fix: Not sure. I don't know why the PFS segfaults.