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bc: eliminate jump into yyparse() #562

Merged
merged 1 commit into from
Apr 17, 2024
Merged

bc: eliminate jump into yyparse() #562

merged 1 commit into from
Apr 17, 2024

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mknos
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@mknos mknos commented Apr 17, 2024

  • When temporarily enabling warnings in bc I observe warnings for incorrect use of "next"
  • Function yy_err_recover() jumped to a label outside of itself, within yyparse()
  • yyparse() was structured so that it first initialises flags then enters main loop
  • Jumping back to yyparse() was unsafe because the flags would all be cleared again, including $yyssp (yy_err_recover() already adjusts $yyssp)
  • Clear flags before calling yyparse(), and let yyparse() enter the loop immediately so that it's safe to call it from yy_err_recover()
%perl bc # before patch
4++
line 1: syntax error
Exiting subroutine via next at bc line 1387, <STDIN> line 1 (#1)

@mknos
bc: eliminate jump into yyparse()
64c2c3d 
* When temporarily enabling warnings in bc I observe warnings for incorrect use of "next"
* Function yy_err_recover() jumped to a label outside of itself, within yyparse()
* yyparse() was strucured so that it first initialises flags then enters main loop
* Jumping back to yyparse() was unsafe because the flags would all be cleared again, including $yyssp (yy_err_recover() already adjusts $yyssp)
* Clear flags before calling yyparse(), and let yyparse() enter the loop immediately so that it's safe to call it from yy_err_recover()

%perl bc # before patch
4++
line 1: syntax error
Exiting subroutine via next at bc line 1387, <STDIN> line 1 (briandfoy#1)
@github-actions github-actions bot added Type: enhancement improve a feature that already exists Priority: low get to this whenever Program: bc The bc program labels Apr 17, 2024
@briandfoy briandfoy self-assigned this Apr 17, 2024
@briandfoy briandfoy merged commit 72fe391 into briandfoy:master Apr 17, 2024
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changes: fix "Exiting subroutine via next" error

@briandfoy briandfoy added Status: accepted The fix is accepted and removed Priority: low get to this whenever labels Apr 19, 2024
@briandfoy briandfoy added Status: released there is a new release with this fix and removed Status: accepted The fix is accepted labels Apr 30, 2024
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@briandfoy briandfoy briandfoy approved these changes

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Program: bc The bc program Status: released there is a new release with this fix Type: enhancement improve a feature that already exists
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