Re: svn commit: r228157 - head/usr.bin/make

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From
Max Khon <fjoe@FreeBSD.org>
Date
1 Dec 2011 07:50:28
Subject
Re: svn commit: r228157 - head/usr.bin/make
Message-ID
CADe0-4mJMTuEjY9Bv0r04ET0eb2hHTZ7WvQGobGsg4XJbXfF+A@mail.gmail.com


[ Hide this part ]
Alexander,

On Thu, Dec 1, 2011 at 12:03 PM, Max Khon <fjoe@freebsd.org> wrote:

it would also be nice, if at some point, somebody could dive into the code
>>> to
>>> see why 'make buildkernel' will let clang produce coloured output, but
>>> 'make -j(N>1) buildkernel' doesn't (and why adding a -B switch to that
>>> command
>>> fixes it).
>>>
>>
>> This one is simple: job make (-jX) runs commands with stdin/stdout/stderr
>> redirected to pipes.
>> -B turns on compat mode for job make.
>>
>> This can be demonstrated by running make with -jX or -jX -B with the
>> following Makefile:
>> --- cut here ---
>> all:
>> @if [ -t 1 ]; then echo "stdout is a tty"; else echo "stdout is
>> not a tty"; fi
>> --- cut here ---
>>
>> If you really want to see colored output in -jX case you should teach
>> clang to output ANSI color sequences not only in isatty(1) case, but also
>> when MAKE_JOBS_FIFO environment variable is present (it is set when make
>> runs in job mode).
>>
>
> This will not work for the cases when make(1) is itself redirected.
> Something like attached patch should work, but it blocks sometimes in
> "ttyout" state for some reason (needs more work).
>

It hangs when tty_drain() is called when make(1) closes slave pty. Looks
like a race condition there when tty_wait() is called from tty_drain().

If I exchange pty master and slave hangs disappear. So attached patch works
for me.
It may add performance penalty but I think that the impact will be
negligible.

Max


[ Hide this part ]
Index: usr.bin/make/Makefile
===================================================================
--- usr.bin/make/Makefile (revision 228157)
+++ usr.bin/make/Makefile (working copy)
@@ -7,6 +7,8 @@
SRCS= arch.c buf.c cond.c dir.c for.c hash.c hash_tables.c job.c \
lst.c main.c make.c parse.c proc.c shell.c str.c suff.c targ.c \
util.c var.c
+DPADD= ${LIBUTIL}
+LDADD= -lutil

NO_SHARED?= YES

Index: usr.bin/make/job.c
===================================================================
--- usr.bin/make/job.c (revision 228157)
+++ usr.bin/make/job.c (working copy)
@@ -115,6 +115,7 @@
#include <fcntl.h>
#include <inttypes.h>
#include <limits.h>
+#include <libutil.h>
#include <paths.h>
#include <string.h>
#include <signal.h>
@@ -1798,8 +1799,13 @@
if (usePipes) {
int fd[2];

- if (pipe(fd) == -1)
- Punt("Cannot create pipe: %s", strerror(errno));
+ if (isatty(1)) {
+ if (openpty(fd + 1, fd + 0, NULL, NULL, NULL) == -1)
+ Punt("Cannot open pty: %s", strerror(errno));
+ } else {
+ if (pipe(fd) == -1)
+ Punt("Cannot create pipe: %s", strerror(errno));
+ }
job->inPipe = fd[0];
job->outPipe = fd[1];
fcntl(job->inPipe, F_SETFD, 1);


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