sh: Fix some bugs with backquoted builtins:
- correctly handle error output in $(builtin 2>&1), clarify out1/out2 vs
output/errout in the code
- treat all builtins as regular builtins so errors do

sh: Fix some bugs with backquoted builtins:
- correctly handle error output in $(builtin 2>&1), clarify out1/out2 vs
output/errout in the code
- treat all builtins as regular builtins so errors do not abort the shell
and variable assignments do not persist
- respect the caller's INTOFF

Some bugs still exist:
- expansion errors may still abort the shell
- some side effects of expansions and builtins persist

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sh: Allow command -pv and command -pV (lookup using _PATH_STDPATH).

sh: Ensure funcnest is decremented if there was an error in the function.

This will be important when things like 'command eval f' will be possible.
Currently, the funcnest = 0 assignment in RESET (

sh: Ensure funcnest is decremented if there was an error in the function.

This will be important when things like 'command eval f' will be possible.
Currently, the funcnest = 0 assignment in RESET (called when returning to
the top level after an error in interactive mode) is really sufficient.

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sh: Various warning fixes (from WARNS=6 NO_WERROR=1):
- const
- initializations to silence -Wuninitialized (it was safe anyway)
- remove nested extern declarations
- rename "index" locals to "idx"

Fix some cases where file descriptors from redirections leak to programs.

- Redirecting fds that were not open before kept two copies of the
redirected file.
sh -c '{ :; } 7>/dev/null; fstat -

Fix some cases where file descriptors from redirections leak to programs.

- Redirecting fds that were not open before kept two copies of the
redirected file.
sh -c '{ :; } 7>/dev/null; fstat -p $$; true'
(both fd 7 and 10 remained open)
- File descriptors used to restore things after redirection were not
set close-on-exec, instead they were explicitly closed before executing
a program normally and before executing a shell procedure. The latter
must remain but the former is replaced by close-on-exec.
sh -c 'exec 7</; { exec fstat -p $$; } 7>/dev/null; true'
(fd 10 remained open)

The examples above are simpler than the testsuite because I do not want to
use fstat or procstat in the testsuite.

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Fix various things about SIGINT handling:
* exception handlers are now run with interrupts disabled, which avoids
many race conditions
* fix some cases where SIGINT only aborts one command and cont

Fix various things about SIGINT handling:
* exception handlers are now run with interrupts disabled, which avoids
many race conditions
* fix some cases where SIGINT only aborts one command and continues the
script, in particular if a SIGINT causes an EINTR error which trumped the
interrupt.

Example:
sh -c 'echo < /some/fifo; echo This should not be printed'
The fifo should not have writers. When pressing ctrl+c to abort the open,
the shell used to continue with the next command.

Example:
sh -c '/bin/echo < /some/fifo; echo This should not be printed'
Similar. Note, however, that this particular case did not and does not work
in interactive mode with job control enabled.

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sh: Ensure the same command input file is on top after executing a builtin.

This avoids weirdness when 'fc -e vi' or the like is done and there is a
syntax error in the file. Formerly an interactive

sh: Ensure the same command input file is on top after executing a builtin.

This avoids weirdness when 'fc -e vi' or the like is done and there is a
syntax error in the file. Formerly an interactive shell tried to execute
stuff after the syntax error and exited.

This should also avoid similar issues with 'command eval' and 'command .'
when 'command' is implemented properly as in NetBSD sh.

Special builtins did not have this problem since errors in them cause the
shell to exit or to reset various state such as the current command input
file.

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MFC @199204

MFC r196483,r196634:
sh: Fix crash when undefining or redefining a currently executing function

Add a reference count to function definitions.
Memory may leak if a SIGINT arrives in interactive mode

MFC r196483,r196634:
sh: Fix crash when undefining or redefining a currently executing function

Add a reference count to function definitions.
Memory may leak if a SIGINT arrives in interactive mode at exactly the wrong
time, this will be fixed later by changing SIGINT handling.

PR: bin/137640
Approved by: re (kib)

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sh: Send the "xyz: not found" message to redirected fd 2.
This also fixes that trying to execute a non-regular file with a command
name without '/' returns 127 instead of 126.
The fix is rather simpl

sh: Send the "xyz: not found" message to redirected fd 2.
This also fixes that trying to execute a non-regular file with a command
name without '/' returns 127 instead of 126.
The fix is rather simplistic: treat CMDUNKNOWN as if the command were found
as an external program. The resulting fork is a bit wasteful but executing
unknown commands should not be very frequent.

PR: bin/137659

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Merge from head

- MFC from head@196987

sh: Fix crash with empty functions (f() { }) introduced in r196483

Empty pairs of braces are represented by a NULL node pointer, just like
empty lines at the top level.

Support for empty pairs of b

sh: Fix crash with empty functions (f() { }) introduced in r196483

Empty pairs of braces are represented by a NULL node pointer, just like
empty lines at the top level.

Support for empty pairs of braces may be removed later. They make the code
more complex, have inconsistent behaviour (may or may not change $?), are
not specified by POSIX and are not allowed by some other shells like bash,
dash and ksh93.

Reported by: kan

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sh: Fix crash when undefining or redefining a currently executing function.

Add a reference count to function definitions.
Memory may leak if multiple SIGINTs arrive in interactive mode,
this will b

sh: Fix crash when undefining or redefining a currently executing function.

Add a reference count to function definitions.
Memory may leak if multiple SIGINTs arrive in interactive mode,
this will be fixed later by changing SIGINT handling.

PR: bin/137640

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- MFC

Quote -x tracing output so it is unambiguous.

It is usually but not always suitable for re-input to the shell.

Approved by: ed (mentor) (implicit)

Do not fork for a subshell if it is the last thing this shell is doing
(EV_EXIT). The fork is still done as normal if any traps are active.

In many cases, the fork can be avoided even without this c

Do not fork for a subshell if it is the last thing this shell is doing
(EV_EXIT). The fork is still done as normal if any traps are active.

In many cases, the fork can be avoided even without this change by using {}
instead of (), but in practice many scripts use (), likely because the
syntax is simpler.

Example:
sh -c '(/bin/sleep 10)& sleep 1;ps -p $! -o comm='
Now prints "sleep" instead of "sh". $! is more useful this way.
Most shells (dash, bash, pdksh, ksh93, zsh) seem to print "sleep" for this.

Example:
sh -c '( ( ( (ps jT))))'
Now shows no waiting shell processes instead of four.
Most shells (dash, bash, pdksh, ksh93, zsh) seem to show zero or one.

PR: bin/74404
Approved by: ed (mentor) (implicit)

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sh: Improve handling of setjmp/longjmp volatile:
- remove ineffective and unnecessary (void) &var; [1]
- remove some unnecessary volatile keywords
- add a necessary volatile keyword
- save the old ha

sh: Improve handling of setjmp/longjmp volatile:
- remove ineffective and unnecessary (void) &var; [1]
- remove some unnecessary volatile keywords
- add a necessary volatile keyword
- save the old handler before doing something that could use the saved
value

Submitted by: Christoph Mallon [1]
Approved by: ed (mentor)

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Avoid leaving unnecessary waiting shells in many forms of sh -c COMMAND.

This change only affects strings passed to -c, when the -s
option is not used.

The approach is to check if there may be addi

Avoid leaving unnecessary waiting shells in many forms of sh -c COMMAND.

This change only affects strings passed to -c, when the -s
option is not used.

The approach is to check if there may be additional data
in the string after parsing each command. If there is none,
use the EV_EXIT flag so that a fork may be omitted in
specific cases.

If there are empty lines after the command, the check will
not see the end and forks will not be omitted. The same
thing seems to happen in bash.

Example:
sh -c 'ps lT'
No longer shows a shell process waiting for ps to finish.

PR: bin/113860
Reviewed by: stefanf
Approved by: ed (mentor)

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Don't skip forking for an external command if any traps are active.

Example:
sh -c '(trap "echo trapped" EXIT; sleep 3)'
now correctly prints "trapped".

With this check, it is no longer necessary

Don't skip forking for an external command if any traps are active.

Example:
sh -c '(trap "echo trapped" EXIT; sleep 3)'
now correctly prints "trapped".

With this check, it is no longer necessary to check for -T
explicitly in that case.

This is a useful bugfix by itself and also important because I plan to
skip forking more often.

PR: bin/113860 (part of)
PR: bin/74404 (part of)
Reviewed by: stefanf
Approved by: ed (mentor)

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- Merge from HEAD

correctly test for __GNUC__ macro (non-GCC compilers do not have it defined at all)

Fix the eval command in combination with set -e. Before this change the shell
would always terminate if eval returned with a non-zero exit status regardless
if the status was actually tested. Unfor

Fix the eval command in combination with set -e. Before this change the shell
would always terminate if eval returned with a non-zero exit status regardless
if the status was actually tested. Unfortunately a new file-scope variable
is needed, the alternative would only be to add a new parameter to all
built-ins.

PR: 134881

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- Merge from HEAD

Don't let trailing empty lines overwrite the result of the last command with 0.
This affects the built-ins eval, fc, and trap and also the string passed to sh
with the -c option.

Submitted by: Jille

Don't let trailing empty lines overwrite the result of the last command with 0.
This affects the built-ins eval, fc, and trap and also the string passed to sh
with the -c option.

Submitted by: Jilles Tjoelker

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