Mike Bird via tde-devels wrote: > On Mon May 8 2023 23:18:45 deloptes via tde-devels wrote: >> Mike Bird via tde-devels wrote: >> > %as is looking for a float so let's ignore that. >> >> I found out %as means do not store (strip) the terminator \0. > > Do you have a man page for that? The test code is not written > to handle non-terminated strings. How would it know the lengths? > There is some documentation to the code but not in this regards. >> > If we switch back to %s it's looking for a string which would be >> > great except no memory has been allocated for the strings. >> > >> > The attached works with both gcc and clang but the important thing >> > to remember is NEVER NEVER NEVER use scanf or any variant thereof. >> >> What do you mean it works with gcc? I have debian with gcc-10 and it does >> following: > > My test.c attached to my previous email - sorry I should have chosen a > different name to avoid confusion - works with gcc-10 and clang-11 in > Debian 11.7 Bullseye. > OK, thank you! >> $ ./test >> String: interpreter usb 0x04b8 >> 0x0142 /usr/lib/esci/libesci-interpreter-perfection-v330 >> /usr/share/esci/esfwad.bin vendor 4b8 >> product 142 >> library (null) >> firmware (null) >> >> > https://dwheeler.com/secure-programs/Secure-Programs-HOWTO/dangers-c.html >> >> I am not the owner of this code. It was working for the past 6y and as >> reported when compiled last year in Buster it works as well, but now >> compiled in Bullseye is not working. >> For me it is not the matter of using it or not, but a change somewhere >> either in gcc (Buster was using gcc-8) or in the libraries. >> >> Also regarding the memory allocated. You are right. It is working if I >> allocate memory and use %s instead of %as. >> Why, oh, why?! >> >> Is there some kind of flag or option for the compiler? > > %a currently means floating point. > > %as used to be a non-standard and incompatible way of asking for > memory to be assigned for the strings but it won't work unless you > use special flags. The standards-compliant way to assign memory > while scanning is %ms. > > So a simple fix would be to change %as to %ms but it's hard to get > it right - you have to free(3) the allocated memory but only if the > sscanf actually some memory. The attached test3.c shows how to do > this in this simple case. > > --Mike This was the solution. The code takes care of freeing the memory, but your example is excellent one. Thank you -- FCD6 3719 0FFB F1BF 38EA 4727 5348 5F1F DCFE BCB0 ____________________________________________________ tde-devels mailing list -- devels@xxxxxxxxxxxxxxxxxx To unsubscribe send an email to devels-leave@xxxxxxxxxxxxxxxxxx Web mail archive available at https://mail.trinitydesktop.org/mailman3/hyperkitty/list/devels@xxxxxxxxxxxxxxxxxx
