On Wed, Feb 16, 2022 at 12:39:06PM +0100, Thomas Huth wrote: > > > - $SED -re 's/[0-9]{4}-[0-9]{2}-[0-9]{2} > > > [0-9]{2}:[0-9]{2}:[0-9]{2}/yyyy-mm-dd hh:mm:ss/' > > > + gsed -re 's/[0-9]{4}-[0-9]{2}-[0-9]{2} > > > [0-9]{2}:[0-9]{2}:[0-9]{2}/yyyy-mm-dd hh:mm:ss/' > > > > GNU sed recommends spelling it 'sed -E', not 'sed -r', when using > > extended regex. Older POSIX did not support either spelling, but the > > next version will require -E, as many implementations have it now: > > https://www.austingroupbugs.net/view.php?id=528 > > Thanks for the pointer ... I originally checked "man 1p sed" on > my system and did not see -r or -E in there, so I thought that > this must be really something specific to GNU sed. But now that > you've mentioned this, I just double-checked the build environments > that we support with QEMU, and seems like -E should be supported > everywhere:
Yay. > > So I think it should be safe to change these spots that are > using "-r" to "sed -E" (and not use gsed here). > > > Other than the fact that this was easier to write with ERE, I'm not > > seeing any other GNU-only extensions in use here; but I'd recommend > > that as long as we're touching the line, we spell it 'gsed -Ee' > > instead of -re (here, and in several other places). > > > > > _filter_qom_path() > > > { > > > - $SED -e '/Attached to:/s/\device[[0-9]\+\]/device[N]/g' > > > + gsed -e '/Attached to:/s/\device[[0-9]\+\]/device[N]/g' > > > > Here, it is our use of \+ that is a GNU sed extension, although it is > > fairly easy (but verbose) to translate that one to portable sed > > (<PAT>\+ is the same as <PAT><PAT>*). So gsed is correct. Then again, since we claim 'sed -E' is portable, we can get the + operator everywhere by using ERE instead of BRE (and with fewer leaning toothpicks, another reason I like ERE better than BRE). On the > > other hand, the use of [[0-9]\+\] looks ugly - it probably does NOT > > match what we meant (we have a bracket expression '[...]' that matches > > the 11 characters [ and 0-9, then '\+' to match that bracket > > expression 1 or more times, then '\]' which in its context is > > identical to ']' to match a closing ], since only opening [ needs \ > > escaping for literal treatment). What we probably meant is: > > > > '/Attached to:/s/\device\[[0-9][0-9]*]/device[N]/g' > > > > at which point normal sed would do. > > Ok ... but I'd prefer to clean such spots rather in a second step, > to make sure not to introduce bugs and to make the review easier. Yeah, fixing bugs and cleaning up consistent use of sed/gsed/$SED are worth separating. > > > _filter_qemu_io() > > > { > > > - _filter_win32 | $SED -e "s/[0-9]* ops\; [0-9/:. sec]* ([0-9/.inf]* > > > [EPTGMKiBbytes]*\/sec and [0-9/.inf]* ops\/sec)/X ops\; XX:XX:XX.X (XXX > > > YYY\/sec and XXX ops\/sec)/" \ > > > + _filter_win32 | gsed -e "s/[0-9]* ops\; [0-9/:. sec]* ([0-9/.inf]* > > > [EPTGMKiBbytes]*\/sec and [0-9/.inf]* ops\/sec)/X ops\; XX:XX:XX.X (XXX > > > YYY\/sec and XXX ops\/sec)/" \ > > > -e "s/: line [0-9][0-9]*: *[0-9][0-9]*\( Aborted\| > > > Killed\)/:\1/" \ > > > -e "s/qemu-io> //g" > > > > I'm not seeing anything specific to GNU sed in this (long) sed script; > > can we relax this one to plain 'sed'? Use of s#some/text## might be > > easier than having to s/some\/text//, but that's not essential. > > If I switch that to plain sed, I'm getting errors like this on NetBSD: > > --- /home/qemu/qemu-test.is2SLq/src/tests/qemu-iotests/046.out > +++ 11296-046.out.bad > @@ -66,6 +66,7 @@ > 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > wrote 65536/65536 bytes at offset 2031616 > 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > + > Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=6442450944 > backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT Huh; not sure what happened that I didn't see. But I trust your tests as a more canonical version of "it worked on this platform's sed" than my "I don't see anything blantantly non-POSIX" ;) > > == Some concurrent requests touching the same cluster == > > So I'll keep gsed here for now - we need it for _filter_qemu_io > anyway since it's calling _filter_win32 that currently needs > gsed, too. Yeah, I think your patch is big enough to prove there are places where it really is easier to rely on gsed than to try and be portable. > > > > @@ -142,7 +142,7 @@ _do_filter_img_create() > > > # precedes ", fmt=") and the options part ($options, which starts > > > # with "fmt=") > > > # (And just echo everything before the first "^Formatting") > > > - readarray formatting_line < <($SED -e 's/, fmt=/\n/') > > > + readarray formatting_line < <(gsed -e 's/, fmt=/\n/') > > > > This one looks like it should work with plain 'sed'. > > Using normal sed does not really work for me here. For example > with NetBSD, I get errors like this: > > --- /home/qemu/qemu-test.cSYvEb/src/tests/qemu-iotests/027.out > +++ 13694-027.out.bad > @@ -1,5 +1,5 @@ > QA output created by 027 > -Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 > +Formatting 'TEST_DIR/t.IMGFMT'nIMGFMT cluster_size=65536 extended_l2=off > compression_type=zlib size=134217728 lazy_refcounts=off refcount_bits=16, fmt= Hmm. I had to go and re-read POSIX. Okay, POSIX says that 's/...\n.../.../' is required to match a newline in the pattern space, but for the substitution, \n is not required to work, and instead, you would write: s/.../\ / to portably substitute a literal newline into the output. But that is unwieldy in a script, so using gsed is indeed the best approach. > > I found one or two issues that need to be fixed, and a couple of > > "might as well improve them while touching the line anyway", but > > overall I like where this is headed. > > Thanks a lot of your review and suggestions, I'll respin a v2 with the > updates... Looking forward to it. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org