In particular, this makes things like ${#foo[0]} and ${#foo[@]} errors
rather than silent equivalents of ${#foo}.
PR: bin/151720
Submitted by: Mark Johnston
Exp-run done by: pav (with some other sh(1) changes)
If execve() returns an [ENOEXEC] error, check if the file is binary before
trying to execute it using sh. A file is considered binary if at least one
of the first 256 bytes is '\0'.
In particular, trying to execute ELF binaries for the wrong architecture now
fails with an "Exec format error" message instead of syntax errors and
potentially strange results.
An error message is written, the builtin is not executed, nonzero exit
status is returned but the shell does not abort.
This was already checked for special builtins and external commands, with
the same consequences except that the shell aborts for special builtins.
Obtained from: NetBSD
Apart from detecting breakage earlier or at all, this also fixes a segfault
in the testsuite. The "handling" of the breakage left an invalid internal
representation in some cases.
Examples:
echo a; do echo b
echo `) echo a`
echo `date; do do do`
Exp-run done by: pav (with some other sh(1) changes)
Redirection errors on subshells already did not abort the shell because
the redirection is executed in the subshell.
Other shells seem to agree that these redirection errors should not abort
the shell.
Also ensure that the redirections will be cleaned up properly in cases like
command eval '{ shift x; } 2>/dev/null'
Example:
{ echo bad; } </var/empty/x; echo good
Although simple commands without a command word (only assignments and/or
redirections) are much like special builtins, POSIX and most shells seem to
agree that redirection errors should not abort the shell in this case. Of
course, the assignments persist and assignment errors are fatal.
To get the old behaviour portably, use the ':' special builtin.
To get the new behaviour portably, given that there are no assignments, use
the 'true' regular builtin.
We currently ignore readonly status for assignments before regular builtins
and external programs (these assignments are not persistent anyway), so just
check that the readonly variable really is not changed.
The test depends on the command builtin changes for 'command :'.
* avoid unnecessary fork
* allow executing builtins via command
* executing a special builtin via command removes its special properties
Obtained from: NetBSD (parts)
Due to the amount of code removed by this, it seems that allowing unmatched
quotes was a deliberate imitation of System V sh and real ksh. Most other
shells do not allow unmatched quotes (e.g. bash, zsh, pdksh, NetBSD /bin/sh,
dash).
PR: bin/137657
