bash drops errexit option in sourced file

[Robert Schiele]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc -I/home/abuild/rpmbuild/BUILD/bash-4.2
-L/home/abuild/rpmbuild/BUILD/bash-4.2/../readline-6.2
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64'
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-suse-linux-gnu'
-DCONF_VENDOR='suse' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash'
-DSHELL -DHAVE_CONFIG_H   -I.  -I. -I./include -I./lib
-fmessage-length=0 -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector
-funwind-tables -fasynchronous-unwind-tables -g  -D_GNU_SOURCE
-DRECYCLES_PIDS -Wall -g -std=gnu89 -Wuninitialized -Wextra
-Wno-unprototyped-calls -Wno-switch-enum -Wno-unused-variable
-Wno-unused-parameter -ftree-loop-linear -pipe -fprofile-use
uname output: Linux linux-e1lq 3.4.11-2.16-desktop #1 SMP PREEMPT Wed
Sep 26 17:05:00 UTC 2012 (259fc87) x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-suse-linux-gnu

Bash Version: 4.2
Patch Level: 24
Release Status: release

Description:
While normally sourced files have identical options set like the
invoking environment this is not true if the sourcing is done from
within a function foo that was called with something like:

foo && true

The following example demonstrates this:

$ cat bug
#!/bin/bash
set -e

int()
{
echo A: $-
. source
echo D: $-
}

echo Broken:
int && true

echo OK:
int
$ cat source
echo B: $-
false
echo C: $-
$ bash bug
Broken:
A: ehB
B: hB
C: hB
D: ehB
OK:
A: ehB
B: ehB
$

This error showed up in bash 4.0 first and was not present in 3.2 or older.

As you can see in the invocation "int && true" the flag is still set
inside the function but magically disappears once the file is sourced,
while in the second incocation "int" everything behaves as expected.
Apparently something gets broken when the exit on error is temporarily
disabled for the chained command "int && true" because while it gets
properly restored within the function itself it disappears again when
sourcing the other file.

This problem was also reported already as
https://savannah.gnu.org/support/index.php?108191 already but Werner
Fink suggested to report via bashbug.

Repeat-By:
Invoke the scripts as described in the details section.

Re: bash drops errexit option in sourced file

[Robert Schiele]

On Mon, Dec 3, 2012 at 4:25 PM, Chet Ramey  wrote:
> Since the `source' command is called in a context where all commands within
> it should have the `errexit' flag disabled, bash chooses to satisfy this
> requirement by turning off the flag that (internally) represents errexit.
> Under most circumstances, however, that state is externally visible as the
> value of the -e option.
>
> Note that the behavior of suppressing the effect of the errexit option is
> correct.  The value of the -e option in $- should be unaffected, though.

Ah, now I start to understand how this is supposed to work. I also
realized that it is not possible within the function to turn on the
flag again with another internal set -e. Is that also part of the
design, meaning there is no way to have an effective set -e within a
function in case it was called in that context?

Robert