From: Steve <srb@unixsh.com>
To: tuhs@tuhs.org
Subject: [TUHS] GOTO etc
Date: Sun, 12 Mar 2023 14:23:51 -0400 [thread overview]
Message-ID: <eac9d81f-5350-3094-9141-51456ec2c645@unixsh.com> (raw)
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Dennis added setjmp() and longjmp() so the shell could handle errors in a reasonable way.
There are two places where setjmp was used in the original shell (7th edition) code as I recall.
Both at the top level
in main.c.
The idea came from Algol68 but I do not know where it was originally invented. longjmp() was used
in the "exitsh"
function that got called on the exit command, default trap routine and a fault with no trap set.
It was also used when executing a subshell to avoid a fork and exec. In this case the setjmp() was
at top level
in the initial sh setup.
Hope this makes sense. But these were two different uses. One for error recovery and one to reset
the execution environment
back to initial state.
Steve
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next reply other threads:[~2023-03-12 18:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-12 18:23 Steve [this message]
2023-03-12 20:06 ` [TUHS] " Bakul Shah
2023-03-12 21:10 ` Paul Winalski
2023-03-16 20:35 ` Steve Bourne
2023-03-19 15:41 [TUHS] " Steve
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