[PATCH RFC v1 1/1] Initial support for Lua scripting
Eugene Syromiatnikov
esyr at redhat.com
Thu Jun 15 15:28:53 UTC 2017
On Sat, Jun 10, 2017 at 11:17:29PM +0300, Victor Krapivensky wrote:
> * Makefile.am: Build with LuaJIT if configured so.
> (strace_SOURCES): Add defs_reuse.h.
> * configure.ac: Add new --with-luajit configure option.
> * defs.h: Move code that needs to be fed to LuaJIT's FFI to...
> * defs_reuse.h: ...new file.
> * strace.c: Initial support for Lua scripting.
> (init): New -l option (if built with Lua scripting support).
> (luajit_next_sc, check_lua, luajit_init): New functions.
> (main): run Lua script, if built with Lua scripting support and a script
> was provided.
> ---
> Makefile.am | 6 +++
> configure.ac | 34 +++++++++++++
> defs.h | 34 +------------
> defs_reuse.h | 58 ++++++++++++++++++++++
> strace.c | 160 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 259 insertions(+), 33 deletions(-)
> create mode 100644 defs_reuse.h
>
> diff --git a/Makefile.am b/Makefile.am
> index 3d6eba1e..a7c4bce6 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -100,6 +100,7 @@ strace_SOURCES = \
> copy_file_range.c \
> count.c \
> defs.h \
> + defs_reuse.h \
> desc.c \
> dirent.c \
> dirent64.c \
> @@ -276,6 +277,11 @@ strace_LDFLAGS += $(libunwind_LDFLAGS)
> strace_LDADD += $(libunwind_LIBS)
> endif
>
> +if USE_LUAJIT
> +strace_CPPFLAGS += $(luajit_CFLAGS)
> +strace_LDADD += $(luajit_LIBS)
> +endif
> +
> @CODE_COVERAGE_RULES@
> CODE_COVERAGE_BRANCH_COVERAGE = 1
> CODE_COVERAGE_GENHTML_OPTIONS = $(CODE_COVERAGE_GENHTML_OPTIONS_DEFAULT) \
> diff --git a/configure.ac b/configure.ac
> index dc49d397..b853c294 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -715,6 +715,40 @@ AC_SUBST(dl_LIBS)
>
> AC_PATH_PROG([PERL], [perl])
>
> +dnl LuaJIT scripting support
> +use_luajit=no
> +force_luajit=no
> +luajit_lib=luajit
> +luajit_LIBS=
> +luajit_CFLAGS=
> +AC_ARG_WITH([luajit],
> + [AS_HELP_STRING([--with-luajit],
> + [build with LuaJIT scripting support])],
> + [case "${withval}" in
> + yes) force_luajit=yes ;;
> + check) ;;
> + *) luajit_lib="${withval}" ;;
> + esac],
> + [:]
> +)
> +AS_IF([test "x$luajit_lib" != xno],
> + [AS_IF([test "x$force_luajit" = xyes],
> + [PKG_CHECK_MODULES([luajit], [$luajit_lib], [use_luajit=yes])],
> + [PKG_CHECK_MODULES([luajit], [$luajit_lib], [use_luajit=yes], [:])]
I'd rather move $force_lua check inside the failure branch of
PKG_CHECK_MODULES and use "LUAJIT" as a prefix.
> + )
> + ]
> +)
> +
> +dnl enable LuaJIT
> +AC_MSG_CHECKING([whether to enable Lua scripting])
> +if test "x$use_luajit" = xyes; then
> + AC_DEFINE([USE_LUAJIT], 1, [Enable Lua scripting support])
> + AC_SUBST(luajit_LIBS)
> + AC_SUBST(luajit_CFLAGS)
> +fi
> +AM_CONDITIONAL([USE_LUAJIT], [test "x$use_luajit" = xyes])
> +AC_MSG_RESULT([$use_luajit])
> +
> dnl stack trace with libunwind
> libunwind_CPPFLAGS=
> libunwind_LDFLAGS=
> diff --git a/defs.h b/defs.h
> index 6449bce9..01a8c125 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -208,39 +208,7 @@ struct inject_opts {
> #define MAX_ERRNO_VALUE 4095
> #define INJECT_OPTS_RVAL_DEFAULT (-(MAX_ERRNO_VALUE + 1))
>
> -/* Trace Control Block */
> -struct tcb {
> - int flags; /* See below for TCB_ values */
> - int pid; /* If 0, this tcb is free */
> - int qual_flg; /* qual_flags[scno] or DEFAULT_QUAL_FLAGS + RAW */
> - unsigned long u_error; /* Error code */
> - kernel_ulong_t scno; /* System call number */
> - kernel_ulong_t u_arg[MAX_ARGS]; /* System call arguments */
> - kernel_long_t u_rval; /* Return value */
> -#if SUPPORTED_PERSONALITIES > 1
> - unsigned int currpers; /* Personality at the time of scno update */
> -#endif
> - int sys_func_rval; /* Syscall entry parser's return value */
> - int curcol; /* Output column for this process */
> - FILE *outf; /* Output file for this process */
> - const char *auxstr; /* Auxiliary info from syscall (see RVAL_STR) */
> - void *_priv_data; /* Private data for syscall decoding functions */
> - void (*_free_priv_data)(void *); /* Callback for freeing priv_data */
> - const struct_sysent *s_ent; /* sysent[scno] or dummy struct for bad scno */
> - const struct_sysent *s_prev_ent; /* for "resuming interrupted SYSCALL" msg */
> - struct inject_opts *inject_vec[SUPPORTED_PERSONALITIES];
> - struct timeval stime; /* System time usage as of last process wait */
> - struct timeval dtime; /* Delta for system time usage */
> - struct timeval etime; /* Syscall entry time */
> -
> -#ifdef USE_LIBUNWIND
> - struct UPT_info* libunwind_ui;
> - struct mmap_cache_t* mmap_cache;
> - unsigned int mmap_cache_size;
> - unsigned int mmap_cache_generation;
> - struct queue_t* queue;
> -#endif
> -};
> +#include "defs_reuse.h"
>
> /* TCB flags */
> /* We have attached to this process, but did not see it stopping yet */
> diff --git a/defs_reuse.h b/defs_reuse.h
> new file mode 100644
> index 00000000..a6a8f8ca
> --- /dev/null
> +++ b/defs_reuse.h
> @@ -0,0 +1,58 @@
> +#define STRINGIFY(...) #__VA_ARGS__
> +#ifdef FFI_CDEF
> +# define CONTENT(...) STRINGIFY(__VA_ARGS__)
> +#else
> +# define CONTENT(...) __VA_ARGS__
> +#endif
> +
> +CONTENT(
> +struct tcb {
> + int flags; /* See below for TCB_ values */
> + int pid; /* If 0, this tcb is free */
> + int qual_flg; /* qual_flags[scno] or DEFAULT_QUAL_FLAGS + RAW */
> + unsigned long u_error; /* Error code */
> + kernel_ulong_t scno; /* System call number */
> + kernel_ulong_t u_arg[MAX_ARGS]; /* System call arguments */
> + kernel_long_t u_rval; /* Return value */
> +)
> +
> +#if SUPPORTED_PERSONALITIES > 1
> +CONTENT(
> + unsigned int currpers; /* Personality at the time of scno update */
> +)
> +#endif
> +
> +#ifndef FFI_CDEF
> + int sys_func_rval; /* Syscall entry parser's return value */
> + int curcol; /* Output column for this process */
> + FILE *outf; /* Output file for this process */
> + const char *auxstr; /* Auxiliary info from syscall (see RVAL_STR) */
> + void *_priv_data; /* Private data for syscall decoding functions */
> + void (*_free_priv_data)(void *); /* Callback for freeing priv_data */
> + const struct_sysent *s_ent; /* sysent[scno] or dummy struct for bad scno */
> + const struct_sysent *s_prev_ent; /* for "resuming interrupted SYSCALL" msg */
> + struct inject_opts *inject_vec[SUPPORTED_PERSONALITIES];
> + struct timeval stime; /* System time usage as of last process wait */
> + struct timeval dtime; /* Delta for system time usage */
> + struct timeval etime; /* Syscall entry time */
> +# ifdef USE_LIBUNWIND
> + struct UPT_info* libunwind_ui;
> + struct mmap_cache_t* mmap_cache;
> + unsigned int mmap_cache_size;
> + unsigned int mmap_cache_generation;
> + struct queue_t* queue;
> +# endif
> +#endif /* FFI_CDEF */
> +
> +CONTENT(};)
> +
> +#ifdef USE_LUAJIT
> +CONTENT(
> +struct strace_luajit_funcs {
> + struct tcb * (*next_sc)(void);
> +};
> +)
> +#endif
> +
> +#undef STRINGIFY
> +#undef CONTENT
> diff --git a/strace.c b/strace.c
> index 5a1bcff3..30004444 100644
> --- a/strace.c
> +++ b/strace.c
> @@ -45,6 +45,11 @@
> # include <sys/prctl.h>
> #endif
> #include <asm/unistd.h>
> +#ifdef USE_LUAJIT
> +# include <lua.h>
> +# include <lualib.h>
> +# include <lauxlib.h>
> +#endif
>
> #include "scno.h"
> #include "ptrace.h"
> @@ -166,6 +171,11 @@ static volatile sig_atomic_t interrupted;
> static volatile int interrupted;
> #endif
>
> +#ifdef USE_LUAJIT
> +static lua_State *L = NULL;
I'd prefer to have a bit more verbose variable name.
> +static void luajit_init(const char *scriptfile);
> +#endif
> +
> #ifndef HAVE_STRERROR
>
> #if !HAVE_DECL_SYS_ERRLIST
> @@ -216,6 +226,11 @@ Output format:\n\
> -k obtain stack trace between each syscall (experimental)\n\
> "
> #endif
> +#ifdef USE_LUAJIT
> +"\
> + -l file run a Lua script from FILE\n\
> +"
> +#endif
> "\
> -o file send trace output to FILE instead of stderr\n\
> -q suppress messages about attaching, detaching, etc.\n\
> @@ -1645,6 +1660,9 @@ init(int argc, char *argv[])
> #ifdef USE_LIBUNWIND
> "k"
> #endif
> +#ifdef USE_LUAJIT
> + "l:"
> +#endif
> "D"
> "a:e:o:O:p:s:S:u:E:P:I:")) != EOF) {
> switch (c) {
> @@ -1755,6 +1773,11 @@ init(int argc, char *argv[])
> stack_trace_enabled = true;
> break;
> #endif
> +#ifdef USE_LUAJIT
> + case 'l':
> + luajit_init(optarg);
> + break;
> +#endif
> case 'E':
> if (putenv(optarg) < 0)
> die_out_of_memory();
> @@ -2637,6 +2660,137 @@ terminate(void)
> exit(exit_code);
> }
>
> +#ifdef USE_LUAJIT
I'd probably prefer to have the following functions being defined in
a separate file. It may be even included in-place if it is too burdensome
to fix all the references to the static symbols.
> +static struct tcb *
> +luajit_next_sc(void)
> +{
> + static struct timeval tv = {};
> + static bool first = true;
> +
> +# define MBRESTART(res, sig) \
> + if ((res) >= 0 && ptrace_restart(PTRACE_SYSCALL, current_tcp, sig) < 0) { \
> + /* Note: ptrace_restart emitted error message */ \
> + exit_code = 1; \
> + terminate(); \
> + }
> +
> + if (!first) {
> + unsigned int sig = 0;
> + int res;
> + if (entering(current_tcp)) {
> + res = syscall_entering_trace(current_tcp, &sig);
> + syscall_entering_finish(current_tcp, res);
> + } else {
> + res = syscall_exiting_trace(current_tcp, tv, 1);
> + syscall_exiting_finish(current_tcp);
> + }
> + MBRESTART(res, sig);
> + }
> + first = false;
> +
> + while (1) {
> + int status;
> + siginfo_t si;
> + enum trace_event ret = next_event(&status, &si);
> + if (ret == TE_SYSCALL_STOP) {
> + unsigned int sig = 0;
> + int res;
> + if (entering(current_tcp)) {
> + res = syscall_entering_decode(current_tcp);
> + switch (res) {
> + case 0:
> + break;
> + case 1:
> + return current_tcp;
> + default:
> + res = syscall_entering_trace(current_tcp, &sig);
> + syscall_entering_finish(current_tcp, res);
> + }
> + } else {
> + res = syscall_exiting_decode(current_tcp, &tv);
> + switch (res) {
> + case 0:
> + break;
> + case 1:
> + return current_tcp;
> + default:
> + res = syscall_exiting_trace(current_tcp, tv, res);
> + syscall_exiting_finish(current_tcp);
> + }
> + }
> + MBRESTART(res, sig);
> + } else {
> + if (!dispatch_event(ret, &status, &si)) {
> + terminate();
> + }
> + }
> + }
> +# undef MBRESTART
> +}
> +
> +static void
> +check_lua(int ret)
> +{
> + if (ret == 0)
> + return;
> + const char *msg = lua_tostring(L, -1);
> + if (!msg)
> + msg = "(error object can't be converted to string)";
> + error_msg_and_die("lua: %s", msg);
> +}
> +
> +static void
> +luajit_init(const char *scriptfile)
> +{
> + static struct strace_luajit_funcs funcs = {
> + .next_sc = luajit_next_sc,
> + };
> +
> + if (L)
> + /* already initialized? */
> + error_msg_and_help("multiple -l arguments");
Do you really consider multiple -l arguments in a command line an error
incompatible with continuation of strace execution?
> +
> + if (!(L = luaL_newstate()))
> + die_out_of_memory();
> +
> + luaL_openlibs(L);
> + /* L: - */
> + check_lua(luaL_loadfile(L, scriptfile)); /* L: chunk */
> + lua_getglobal(L, "require"); /* L: chunk require */
> + lua_pushstring(L, "ffi"); /* L: chunk require "ffi" */
> + check_lua(lua_pcall(L, 1, 1, 0)); /* L: chunk ffi */
> + lua_getfield(L, -1, "cdef"); /* L: chunk ffi cdef */
> + luaL_Buffer b;
> + luaL_buffinit(L, &b); /* L: chunk ffi cdef ? */
> + {
> + char buf[128];
> + snprintf(buf, sizeof(buf),
> + "typedef int%zu_t kernel_long_t;"
> + "typedef uint%zu_t kernel_ulong_t;",
> + sizeof(kernel_long_t) * 8,
> + sizeof(kernel_ulong_t) * 8);
> + luaL_addstring(&b, buf); /* L: chunk ffi cdef ? */
> + }
> + luaL_addstring(&b,
> +# define FFI_CDEF
> +# include "defs_reuse.h"
> +# undef FFI_CDEF
> + ); /* L: chunk ffi cdef ? */
> + luaL_pushresult(&b); /* L: chunk ffi cdef str */
> + check_lua(lua_pcall(L, 1, 0, 0)); /* L: chunk ffi */
> + lua_newtable(L); /* L: chunk ffi table */
> + lua_getfield(L, -2, "cast"); /* L: chunk ffi table cast */
> + lua_pushstring(L, "struct strace_luajit_funcs *"); /* L: chunk ffi table cast str */
> + lua_pushlightuserdata(L, &funcs); /* L: chunk ffi table cast str lightuserdata */
> + check_lua(lua_pcall(L, 2, 1, 0)); /* L: chunk ffi table funcs */
> + lua_getfield(L, -1, "next_sc"); /* L: chunk ffi table funcs next_sc */
> + lua_setfield(L, -3, "next_sc"); /* L: chunk ffi table funcs */
> + lua_pop(L, 1); /* L: chunk ffi table */
> + lua_setglobal(L, "strace"); /* L: chunk ffi */
> + lua_pop(L, 1); /* L: chunk */
> +}
> +#endif /* USE_LUAJIT */
> +
> int
> main(int argc, char *argv[])
> {
> @@ -2644,6 +2798,12 @@ main(int argc, char *argv[])
>
> exit_code = !nprocs;
>
> +#ifdef USE_LUAJIT
> + if (L) {
> + /* L: chunk */
> + check_lua(lua_pcall(L, 0, 0, 0)); /* L: - */
> + }
> +#endif
Wouldn't this way non-lua tracing loop being exectuted after Lua one?
> int status;
> siginfo_t si;
> while (dispatch_event(next_event(&status, &si), &status, &si))
> --
> 2.11.0
Overall looks good.
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