[Tarantool-patches] [PATCH luajit] Add compatibility string coercion for fp:seek() argument.

[Sergey Bronnikov]

Hello,

thanks for the patch! LGTM

Sergey

On 7/21/26 10:59, Sergey Kaplun wrote:
> From: Mike Pall <mike>
>
> Reported by Magnus Wibeck.
>
> (cherry picked from commit d508715ab657261e8437a52c1b1966c20ab1631d)
>
> In LuaJIT the second `fp:seek()` argument (offset) doesn't coerce from a
> string to an integer value, unlike PUC-Rio Lua 5.1 does.
>
> This patch adds missing coercion.
>
> Sergey Kaplun:
> * added the description and the test for the problem
>
> Part of tarantool/tarantool#12880
> ---
>
> Branch:https://github.com/tarantool/luajit/tree/skaplun/lj-1343-fseek-offset-coercion
> Related issues:
> *https://github.com/LuaJIT/LuaJIT/issues/1343
> *https://github.com/tarantool/tarantool/issues/12880
>
>   src/Makefile.dep.original                     |  2 +-
>   src/lib_io.c                                  |  4 +++-
>   .../lj-1343-fseek-offset-coercion.test.lua    | 23 +++++++++++++++++++
>   3 files changed, 27 insertions(+), 2 deletions(-)
>   create mode 100644 test/tarantool-tests/lj-1343-fseek-offset-coercion.test.lua
>
> diff --git a/src/Makefile.dep.original b/src/Makefile.dep.original
> index 436685f5..acc6b3ba 100644
> --- a/src/Makefile.dep.original
> +++ b/src/Makefile.dep.original
> @@ -21,7 +21,7 @@ lib_ffi.o: lib_ffi.c lua.h luaconf.h lauxlib.h lualib.h lj_obj.h lj_def.h \
>   lib_init.o: lib_init.c lua.h luaconf.h lauxlib.h lualib.h lmisclib.h lj_arch.h
>   lib_io.o: lib_io.c lua.h luaconf.h lauxlib.h lualib.h lj_obj.h lj_def.h \
>    lj_arch.h lj_gc.h lj_err.h lj_errmsg.h lj_buf.h lj_str.h lj_state.h \
> - lj_strfmt.h lj_ff.h lj_ffdef.h lj_lib.h lj_libdef.h
> + lj_strfmt.h lj_ff.h lj_ffdef.h lj_lib.h lj_strscan.h lj_libdef.h
>   lib_jit.o: lib_jit.c lua.h luaconf.h lauxlib.h lualib.h lj_obj.h lj_def.h \
>    lj_arch.h lj_gc.h lj_err.h lj_errmsg.h lj_debug.h lj_str.h lj_tab.h \
>    lj_state.h lj_bc.h lj_ctype.h lj_ir.h lj_jit.h lj_ircall.h lj_iropt.h \
> diff --git a/src/lib_io.c b/src/lib_io.c
> index ef39e535..2d0abf78 100644
> --- a/src/lib_io.c
> +++ b/src/lib_io.c
> @@ -25,6 +25,7 @@
>   #include "lj_strfmt.h"
>   #include "lj_ff.h"
>   #include "lj_lib.h"
> +#include "lj_strscan.h"
>   
>   /* Userdata payload for I/O file. */
>   typedef struct IOFileUD {
> @@ -317,13 +318,14 @@ LJLIB_CF(io_method_seek)
>     FILE *fp = io_tofile(L)->fp;
>     int opt = lj_lib_checkopt(L, 2, 1, "\3set\3cur\3end");
>     int64_t ofs = 0;
> -  cTValue *o;
> +  TValue *o;
>     int res;
>     if (opt == 0) opt = SEEK_SET;
>     else if (opt == 1) opt = SEEK_CUR;
>     else if (opt == 2) opt = SEEK_END;
>     o = L->base+2;
>     if (o < L->top) {
> +    if (tvisstr(o)) lj_strscan_num(strV(o), o);
>       if (tvisint(o))
>         ofs = (int64_t)intV(o);
>       else if (tvisnum(o))
> diff --git a/test/tarantool-tests/lj-1343-fseek-offset-coercion.test.lua b/test/tarantool-tests/lj-1343-fseek-offset-coercion.test.lua
> new file mode 100644
> index 00000000..fdfc6ce5
> --- /dev/null
> +++ b/test/tarantool-tests/lj-1343-fseek-offset-coercion.test.lua
> @@ -0,0 +1,23 @@
> +local tap = require('tap')
> +
> +-- The test file to demonstrate LuaJIT's missing coercion for the
> +-- `io.fseek()` offset argument.
> +-- See also:https://github.com/LuaJIT/LuaJIT/issues/1343.
> +
> +local test = tap.test('lj-1343-fseek-offset-coercion')
> +
> +test:plan(2)
> +
> +local f = io.tmpfile()
> +
> +f:write('12345')
> +
> +f:seek('set', 0)
> +f:seek('set', '1')
> +test:is(f:read('*all'), '2345', 'base coercion test')
> +
> +f:seek('set', 0)
> +f:seek('set', '1.9')
> +test:is(f:read('*all'), '2345', 'coercion test for non-integer value')
> +
> +test:done(true)
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