d024d4c895
This fixes two bugs: issuing the 'exit' command with a value > 256 would cause ksh 93u+ to kill itself with the corresponding signal (try 'exit 265' to SIGKILL your interactive shell), and, if the last command of a script exits due to a signal, the shell would repeat that signal to itself, causing any parent ksh to also be killed. Discussion: https://bugzilla.redhat.com/show_bug.cgi?id=1469624 https://rainbow.chard.org/2017/03/21/ksh-deliberately-segfaults-if-the-last-command-in-a-script-crashes/ This commit is loosely based on a patch applied to the 93v- beta and the abandoned ksh2020, but that patch was incomplete & broken: $ ksh-2020.0.0 -c 'exit 265'; echo $? 137 Expected: 9. Since the exit was *not* due to a signal, the value should simply be cropped to the 8 bits supported by the OS. src/cmd/ksh93/bltins/cflow.c: b_exit(): - For the 'exit' builtin command, bitwise-AND the argument to 'exit' with SH_EXITMASK (8 bits, crop to 0-255) before passing it on to sh_exit(). This restores the behaviour of <=2011 ksh93 versions and is in line with all other POSIX shells. It also fixes this bogosity: $ (exit 265); echo $? # non-forked subshell 265 $ (ulimit -t unlimited; exit 265); echo $? # forked subshell 9 Forked or non-forked should make no difference at all (see commit message a0e0e29e for why). src/cmd/ksh93/sh/fault.c: sh_done(): - If the current exit status is equal to the status for the last signal that was received from a child process, remove the SH_EXITSIG (9th) bit, so that the shell doesn't kill itself. - If the shell's last child process exits due to a signal, exit with a portable 8-bit exit status (128 + signal number). This avoids the exit status being < 128 by being cropped to 8 bits. src/cmd/ksh93/tests/signal.sh: - Add regression test for exit with status > 256. - Add regression test verifying the shell no longer kills itself. (cherry picked from commit 98e0fc94393e175ce6adfee390327c320795bf12) |
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KornShell 93u+m
This repository is used to develop bugfixes to the last stable release (93u+ 2012-08-01) of ksh93, formerly developed by AT&T Software Technology (AST). The sources in this repository were forked from the Github AST repository which is no longer under active development.
To see what's fixed, see NEWS and click on commit messages for full details.
To see what's left to fix, see TODO.
Policy
- No new features. Bug fixes only.
- No major rewrites. No refactoring code that is not fully understood.
- No changes in documented behaviour, except if required for compliance with the POSIX shell language standard which David Korn intended for ksh to follow.
- No 100% bug compatibility. Broken and undocumented behaviour gets fixed.
- No bureaucracy, no formalities. Just fix it, or report it: create issues, send pull requests. Every interested party is invited to contribute.
- To help increase everyone's understanding of this code base, fixes and significant changes should be fully documented in commit messages.
Why?
Between 2017 and 2020 there was an ultimately unsuccessful attempt to breathe new life into the KornShell by extensively refactoring the last unstable AST beta version (93v-). While that ksh2020 branch is now abandoned and still has many critical bugs, it also had a lot of bugs fixed. More importantly, the AST issue tracker now contains a lot of documentation on how to fix those bugs, which makes it possible to backport many of them to the last stable release instead.
In February 2020, having concluded the AST 93v- beta was too broken to base new work on, others decided to start a new fork based on the last stable 93u+ 2012-08-01 release. Unfortunately, as of June 2020, the new ksh-community organisation is yet to see any significant activity four months after its bootstrapping. I hope that will change; I am ready to join efforts with them at any time, as well as anyone else who wants to contribute.
The last stable ksh93 release from 2012 is the least buggy release currently available, but it still has many serious bugs. So it is well past time to start fixing those bugs, leave the rest of the code alone, and get an improved release out there.
Build
After cloning this repo, cd to the top directory of it and run:
./bin/package make
If you have trouble or want to tune the binaries, you may pass additional compiler and linker flags by appending it to the command shown above. E.g.:
./bin/package make \
SHELL=/bin/bash CCFLAGS="-xc99 -D_XPG6 -m64 -xO4" LDFLAGS="-m64"
For more information run
bin/package help
Many other commands in this repo self-document via the --help, --man and
--html options; those that do have no separate manual page.
Test
After compiling, you can run the regression tests. Start by reading the information printed by:
./bin/shtests --man