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cleanup: remove redundant sh.st.execbrk flag

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The 'break' and 'continue' flow control commands use three int
variables in the scoped sh.st struct:

	sh.st.execbrk:	nonzero if 'break' or 'continue' are used
	sh.st.breakcnt:	number of levels to 'break'/'continue'
			(negative if 'continue')
	sh.st.loopcnt:	loop level counter for 'break'/'continue'

Reading the code that sets and uses these (in bltins/cflow.c and
sh/xec.c) makes it fairly obvious that the sh.st.execbrk flag is
redundant; it is zero if no 'break' or 'continue' should happen,
but the same is true for sh.st.breakcnt.

This commit simplifies the code by removing sh.st.execbrk.
It also adds some comments clarifying the use of the other two.

Trivia: the ancient "Version 06/03/86a" ksh source code was
recently discovered. It uses global execbrk, breakcnt and loopcnt
variables with the same redundancy. More evidence that the AT&T
team always lacked a question-everything department...
https://minnie.tuhs.org/pipermail/tuhs/2020-December/022640.html
https://github.com/weiss/original-bsd/blob/master/local/toolchest/ksh/sh/builtin.c
https://github.com/weiss/original-bsd/blob/master/local/toolchest/ksh/sh/xec.c
This commit is contained in:
Martijn Dekker 2022-07-03 12:21:51 +02:00
parent 400806afa6
commit 24c3d77e3c
4 changed files with 17 additions and 14 deletions
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4
src/cmd/ksh93/sh/main.c
View file

@ -437,7 +437,7 @@ static void exfile(register Sfio_t *iop,register int fno)
sh_iorestore(0,jmpval);
hist_flush(sh.hist_ptr);
sfsync(sh.outpool);
sh.st.execbrk = sh.st.breakcnt = 0;
sh.st.breakcnt = 0;
/* check for return from profile or env file */
if(sh_isstate(SH_PROFILE) && (jmpval==SH_JMPFUN || jmpval==SH_JMPEXIT))
{
@ -604,7 +604,7 @@ static void exfile(register Sfio_t *iop,register int fno)
{
execflags |= sh_state(SH_NOFORK);
}
sh.st.execbrk = 0;
sh.st.breakcnt = 0;
sh_exec(t,execflags);
if(sh.forked)
{