This allows scripts to check for a nonzero exit status on the
'print', 'printf' and 'echo' builtins and prevent possible infinite
loops if SIGPIPE is ignored.
sfsync() was already returning a negative value on I/O error, so
all we need to do is add a check. The stream buffer will need to be
filled before an I/O error can be detected, but this is the same on
other shells. See manual page: src/lib/libast/man/sfio.3
Ref.: https://github.com/att/ast/issues/1093https://github.com/att/ast/pull/1363
src/cmd/ksh93/bltins/print.c: b_print():
- Make sure an error result from sfsync() is reflected in the
output builtin's exit status (exitval).
- Write an I/O error message (e_io) if the exit status is nonzero.
src/cmd/ksh93/data/msg.c, src/cmd/ksh93/include/io.h:
- Add the e_io[] error message.
src/cmd/ksh93/tests/builtins.sh:
- Add I/O error regression test, checking for the correct error
message and exit status. All three output builtins use the same
b_print() function so we only need to test one.
src/cmd/ksh93/tests/basic.sh,
src/cmd/ksh93/tests/coprocess.sh:
- Redirect stderr on a few 'print' commands to /dev/null; these
now issue an expected I/O error. This does not cause failures.
NEWS, TODO:
- Update.
(cherry picked from commit 9011fa933552e483dab460f7dd1593d64e059d94)
ksh used to redirect standard output by default when no file
descriptor was specified with the rarely used '<>' reading/writing
redirection operator. It now redirects standard input by default,
as POSIX specifies and as all other POSIX shells do. To redirect
standard output for reading and writing, you now need '1<>'.
Ref.: https://github.com/att/ast/issues/75http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_07_07
(cherry picked from commit 29afc16c47824fc79ed092ae7704c525b1db6a0a)
