Ramsay JonesIn particular, the subshell feeding the input pipe, using the shell function generate_tens_of_lines(), dies early due to a broken pipe (SIGPIPE). The test-line-buffer command reads all of the data it needs and closes the pipe, but the generate_\ tens_of_lines() function is still attempting to write to the pipe, since it is in an infinite loop. This causes the later "kill $!" to fail, since the process no longer exists.
The infinite loop is caused by the loop variable increment expression, which looks something like this:
: $((i = $i + 1)) || return
This expression does not actually increment the loop variable at all, so $i remains at zero, leading to the infinite loop.
A simple fix, for some shells, would be to remove the '$' from the '$i' within the arithmetic expansion. However, some older shells don't support assignment as part of an arithmetic expansion. Therefore, in order to fix the problem, we replace the loop increment expression with the simpler:
i=$(($i + 1))
which solves the problem, while also being more portable.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk> ---
Junio,
I only remembered last night that I have been skipping some tests on Linux (oops!); this fixes one of the failures for me. One of the reasons for me simply skipping this test, rather than fixing it up earlier, was that it looked like (indeed *is*) another example of a syntax error due to using an older dash shell. (Also, I thought there was some talk of scrapping this test).
However, when I tried bash and an up-to-date dash, the problem changed from a syntax error to an infinite loop! ;-P
The reason for the RFC is that I don't understand why (apparently) I'm the only person seeing this failure; I suspect that a newer version of bash than I have does not have this problem (ie the original arithmetic expansion actually works). dunno :-(
Also, I considered changing the kill statement thus:
- kill $! &&
+ if kill -0 $! 2>/dev/null
+ then
+ kill $!
+ fi &&but I'm not sure that actually helps, and was not necessary to fix the failure for me.
[BTW, the other tests failing for me are t4034 tests #21 (diff driver 'bibtex'), #25 (diff driver 'html); I haven't had time to investigate yet]
ATB, Ramsay Jones
t/t0081-line-buffer.sh | 3 +-- 1 files changed, 1 insertions(+), 2 deletions(-)
Show changes to t/t0081-line-buffer.sh +1 −2
diff --git a/t/t0081-line-buffer.sh b/t/t0081-line-buffer.sh index 5067d1e..9b79e3b 100755 --- a/t/t0081-line-buffer.sh +++ b/t/t0081-line-buffer.sh @@ -25,8 +25,7 @@ generate_tens_of_lines () { do echo "$line" done && - : $((i = $i + 1)) || - return + i=$(($i + 1)) done }
-- 1.7.4
