> -----Original Message----- > From: Olivier Matz [mailto:[email protected]] > Sent: Friday, January 19, 2018 5:07 PM > To: Xueming(Steven) Li <[email protected]> > Cc: Adrien Mazarguil <[email protected]>; [email protected] > Subject: Re: [PATCH v2] lib/cmdline: init CLI parsing memory > > On Thu, Jan 18, 2018 at 04:29:59AM +0000, Xueming(Steven) Li wrote: > > > > > > > -----Original Message----- > > > From: Olivier Matz [mailto:[email protected]] > > > Sent: Tuesday, January 16, 2018 8:46 PM > > > To: Xueming(Steven) Li <[email protected]> > > > Cc: Adrien Mazarguil <[email protected]>; [email protected] > > > Subject: Re: [PATCH v2] lib/cmdline: init CLI parsing memory > > > > > > Hi Xueming, > > > > > > Sorry for the late response. > > > > > > On Tue, Dec 26, 2017 at 12:57:41PM +0000, Xueming(Steven) Li wrote: > > > > HI Olivier, > > > > > > > > By reading p1 comments carefully, looks like the pointer to result > > > > buffer issue not resolved by result copy. How about this: > > > > > > > > @@ -263,6 +263,7 @@ > > > > #ifdef RTE_LIBRTE_CMDLINE_DEBUG > > > > char debug_buf[BUFSIZ]; > > > > #endif > > > > + char *result_buf = result.buf; > > > > > > > > if (!cl || !buf) > > > > return CMDLINE_PARSE_BAD_ARGS; > > > > @@ -312,16 +313,13 @@ > > > > debug_printf("INST %d\n", inst_num); > > > > > > > > /* fully parsed */ > > > > - tok = match_inst(inst, buf, 0, tmp_result.buf, > > > > - sizeof(tmp_result.buf)); > > > > + tok = match_inst(inst, buf, 0, result_buf, > sizeof(result.buf)); > > > > > > If we don't use tmp_result, it is maybe better to also replace > > > sizeof(result.buf) by CMDLINE_PARSE_RESULT_BUFSIZE > > > > Thanks, would like to send out new version soon > > > > > > > > > > > > > if (tok > 0) /* we matched at least one token */ > > > > err = CMDLINE_PARSE_BAD_ARGS; > > > > > > > > else if (!tok) { > > > > debug_printf("INST fully parsed\n"); > > > > - memcpy(&result, &tmp_result, > > > > - sizeof(result)); > > > > /* skip spaces */ > > > > while (isblank2(*curbuf)) { > > > > curbuf++; > > > > @@ -332,6 +330,7 @@ > > > > if (!f) { > > > > memcpy(&f, &inst->f, sizeof(f)); > > > > memcpy(&data, &inst->data, > sizeof(data)); > > > > + result_buf = tmp_result.buf; > > > > } > > > > else { > > > > /* more than 1 inst matches */ > > > > > > > > > > > > > I guess the issue you are talking about is the one described in > > > "cmdline: fix dynamic tokens parsing" in my previous description? > > > > > > I think this patch is ok, and is probably better than the initial > > > suggestion, because it avoids to copy the buffer. However, I don't > > > understand why the previous patch was wrong, can you detail? > > > > Let me quote your last email: > > " When using dynamic tokens, the result buffer contains pointers > > to some location inside the result buffer. When the content of > > the temporary buffer is copied in the final one, these pointers > > still point to the temporary buffer." > > If pointer exist in buffer, the new copy still pint to the old copy > > which very probably being changed. > > In patch v2, I still think it was correct because there were 2 copies: > > 1/ tok = match_inst(inst, buf, 0, result.buf, sizeof(result.buf)); > > result is set, it may contain pointers to itself > > 2/ result_ok = result; > > result is copied in result_ok > result_ok may contain pointer to result > > 3/ other calls to match_inst(inst, buf, 0, result...) > > this can clobber the result buffer > > 4/ result = result_ok; // before calling f() > > restores the content of result as it was in 1/ > it may contain pointers to itself, which is valid
You are correct, I ignored this step, blind hit. > > Was there another problem I missed? > > > Anyway, I think your v3 is better because it avoids buffer copies. > If it's ok for you, please send a v4 with the small updated regarding > sizeof(result.buf) -> CMDLINE_PARSE_RESULT_BUFSIZE. > > Thanks, > Olivier
