When waiting for child processes using "wait" or if "set -T" is in effect, a
signal interrupts the wait. Make sure there is no window where the signal
handler may be invoked (setting a flag) just before going to sleep.
There is a similar race condition in the shell language, but scripts can
avoid it by exiting from the trap handler or enforcing synchronization using
a fifo.
If SIGCHLD is not trapped, a signal handler must be installed for it. Only
install this handler for the duration of the wait to avoid triggering
unexpected [EINTR] errors elsewhere.
Note that for some reason only SIGINT and SIGQUIT interrupt a "wait"
command. This remains the case.
Examples:
export x=~
now expands the tilde
local y=$1
is now safe, even if $1 contains IFS characters or metacharacters.
For a word to "look like an assignment", it must start with a name followed
by an equals sign, none of which may be quoted.
The special treatment applies when the first word (potentially after
"command") is "export", "readonly" or "local". There may be quoting
characters but no expansions. If "local" is overridden with a function there
is no special treatment ("export" and "readonly" cannot be overridden with a
function).
If things like
local arr=(1 2 3)
are ever allowed in the future, they cannot call a "local" function. This
would either be a run-time error or it would call the builtin.
This matches Austin Group bug #351, planned for the next issue of POSIX.1.
PR: bin/166771
On recent versions of NetBSD's libedit, el_gets
now sets el_len to -1 on error so we can
distinguish between a NULL string and an error.
This fixes sh from exiting with newer versions
of libedit now allowing EINTR to return.
Obtained from: NetBSD
Reviewed by: jilles
MFC after: 3 weeks
1. Avoid a cd back into ${.CURDIR} to run mkbuiltins when we know make
will first cd into ${.OBJDIR}. Keep the cwd to what make sets it to.
2. Don't tell mkbuiltins where to write to (= ${.OBJDIR}), but where to
get sources from (= ${.CURDIR}). This to compensate for point 1.
This fixes a problem with bmake's mk files that optimize ${.OBJDIR} to
expand to "." after changing cwd, not taking into account that the
target is pretty much undoing that and not getting the full path to the
object tree anymore.
quotation. Also make sure we have the same amount of columns in each row as
the number of columns we specify in the head arguments.
Reviewed by: brueffer
This uses vfork() for simple commands and command substitutions containing a
single simple command, invoking an external program under certain conditions
(no redirections or variable assignments, non-interactive shell, no job
control). These restrictions limit the amount of code executed in a vforked
child.
There is a large speedup (for example 35%) in microbenchmarks. The
difference in buildkernel is smaller (for example 0.5%) but still
statistically significant. See
http://lists.freebsd.org/pipermail/freebsd-hackers/2012-January/037581.html
for some numbers.
The use of vfork() can be disabled by setting a variable named
SH_DISABLE_VFORK.
In the first command of a 'for', $? should be the exit status of the last
pipeline (command substitution in the word list or command before 'for'),
not always 0.
Before this fix, only the first statement of the trap was executed if
evalskip was set. This is for example the case when:
o "-e" is set for this shell
o a trap is set on EXIT
o a function returns 1 and causes the script to abort
Reviewed by: jilles
MFC after: 2 weeks
Also, rework evalcase() to not evaluate any tree. Instead, return the
NCLISTFALLTHRU node and handle it in evaltree().
Fixed bugs:
* If a ;& list with non-zero exit status is followed by an empty ;; or final
list, the exit status of the case command should be equal to the exit
status of the ;& list, not 0.
* An empty ;& case should not reset $?.
* If no pattern is matched, POSIX says the exit status shall be 0 (even if
there are command substitutions).
* If a pattern is matched and there are no command substitutions, the first
command should see the $? from before the case command, not always 0.
The errno message display added in r222292 did not take attempting to
cd to a non-directory or something that cannot be stat()ed into account.
PR: bin/164070
MFC after: 10 days
This improves performance for globs where a slash or another component
follows a component with metacharacters by eliminating unnecessary attempts
to open directories that are not.
This is not necessary: errors are already caught in evalbackcmd() and
forcelocal handles changes to variables.
Note that this depends on r223024.
MFC after: 4 weeks
Free expanded case text before executing commands.
Remove impossible evalskip checks (expanding an argument cannot set
evalskip anymore since $(break) and the like are properly executed in a
subshell environment).
Because sh executes commands in subshell environments without forking in
more and more cases (particularly from 8.0 on), it makes sense to describe
subshell environments more precisely using ideas from POSIX, together with
some FreeBSD-specific items.
In particular, the hash and times builtins may not behave as if their state
is copied for a subshell environment while leaving the parent shell
environment unchanged.
* Shell patterns are also for ${var#pat} and the like.
* An '!' by itself will not trigger pathname generation so do not call it a
meta-character, even though it has a special meaning directly after an
'['.
* Character ranges are locale-dependent.
* A '^' will complement a character class like '!' but is non-standard.
MFC after: 1 week
POSIX requires a -h option to sh and set, to locate and remember utilities
invoked by functions as they are defined. Given that this
locate-and-remember process is optional elsewhere, it seems safe enough to
make this option do nothing.
POSIX does not specify a long name for this option. Follow ksh in calling it
"trackall".
Replacing ;; with the new control operator ;& will cause the next list to be
executed as well without checking its pattern, continuing until a list ends
with ;; or until the end of the case statement. This is like omitting
"break" in a C "switch" statement.
The sequence ;& was formerly invalid.
This feature is proposed for the next POSIX issue in Austin Group issue
#449.
