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Possible bug in allegro utf8 function
archlinka
Member #17,215
December 2019

Hi, I was just looking to Allegro source code and foundsome strange situation. Or it's also possible that I just do not understand the code:

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1/* Function: al_ustr_find_set 2 */ 3int al_ustr_find_set(const ALLEGRO_USTR *us, int start_pos, 4 const ALLEGRO_USTR *accept) 5{ 6 int rc; 7 int32_t c, d; 8 int pos; 9 int set_pos; 10 11 /* Fast path for ASCII characters. */ 12 if (all_ascii(accept)) { 13 rc = _al_binchr(us, start_pos, accept); 14 return (rc == _AL_BSTR_ERR) ? -1 : rc; 15 } 16 17 /* Non-ASCII. */ 18 pos = 0; 19 while ((c = al_ustr_get(us, pos)) != -1) { 20 if (c == -2) { 21 /* Invalid byte sequence. */ 22 pos++; 23 continue; 24 } 25 26 set_pos = 0; 27 while ((d = al_ustr_get_next(accept, &set_pos)) != -1) { 28 if (c == d) 29 return pos; 30 } 31 32 pos += al_utf8_width(c); 33 } 34 35 return -1; 36}

It should find first occurrence of code point starting at pos start_pos. The thing I do not understand is that the argument start_pos is used only in one place in the function and that's the ASCII only branch. But not in the non ASCII. Is it bug or just there is something I do not see?

amarillion
Member #940
January 2001
avatar

I think you're right, this looks like a bug.

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Peter Hull
Member #1,136
March 2001

I agree, if you've got time please could you create an issue on the github?
https://github.com/liballeg/allegro5/issues

Thanks.
(p.s. looks like it would be easily fixed, too!)

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