Date: Wed, 26 Dec 2018 23:46:37 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 234430] bc(1) writes error messages to standard output instead of standard error Message-ID: <bug-234430-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D234430 Bug ID: 234430 Summary: bc(1) writes error messages to standard output instead of standard error Product: Base System Version: 12.0-STABLE Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: bin Assignee: bugs@FreeBSD.org Reporter: mcdutchie@hotmail.com Upon encountering a parsing error, bc(1) passes an error message on to dc(1), which writes the error message to standard output along with the normal output. That is a bug. Error messages should go to standard error instead, as POSIX specifies: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html#tag_20_09= _10 GNU 'bc', Solaris 'bc', and (as of 2017) OpenBSD 'bc' act like POSIX says a= nd write error messages to standard error. Bizarrely, the exit status of bc(1) is left unspecified: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html#tag_20_09= _18 And indeed, all versions of 'bc' exit with status 0 if there is an input error such as a parsing error, so the exit status cannot be used to catch it. That leaves examining standard error as the only method for a program calling bc(1), such as a shell script, to distinguish between an error state and normal operation. That is, with this bug, there is no way at all. The following example shell function transparently hardens bc(1) by intercepting standard error and exiting the program or subshell if an error was produced. bc() { _bc_err=3D$(command -p bc "$@" 2>&1 1>&3) [ -z "${_bc_err}" ] && return printf '%s\n' "$0: bc(1) caught errors:" "${_bc_err}" 1>&2 exit 127 } 3>&1 This bug was fixed on OpenBSD 'bc' back in Feburary 2017. I figured FreeBSD would eventually pull in that fix since FreeBSD 'bc' is based on OpenBSD 'b= c', but as of FreeBSD 12.0 that hasn't happened. The OpenBSD patch that fixes the bug is here: https://marc.info/?l=3Dopenbsd-tech&m=3D148767278323276&w=3D2 --=20 You are receiving this mail because: You are the assignee for the bug.=
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