On Fri, 14 Oct 2016 16:31:01 -0500 Eric Blake <ebl...@redhat.com> wrote:
> On 10/14/2016 04:26 PM, Greg Kurz wrote: > > Since commit "80dd5c4918ab trace: introduce a formal group name for trace > > events", tracetool generates C variable names and macro definitions out > > of the path to the trace-events-all file. > > > > The current code takes care of turning '/' and '-' characters into > > underscores so that the resulting names are valid C tokens. This is > > enough because these are the only illegal characters that appear in > > a relative path within the QEMU source tree. > > > > Things are different for out of tree builds where the path may contain > > arbitrary character combinations, causing tracetool to generate invalid > > names. > > > > > This patch ensures that only letters [A-Za-z], digits [0-9] and underscores > > are kept. All other characters are turned into underscores. Also, since the > > first character of C symbol names cannot be a digit, an underscore is > > prepended to the group name. > > > > Signed-off-by: Greg Kurz <gr...@kaod.org> > > --- > > scripts/tracetool.py | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/scripts/tracetool.py b/scripts/tracetool.py > > index 629b2593c846..b81b834db924 100755 > > --- a/scripts/tracetool.py > > +++ b/scripts/tracetool.py > > @@ -70,7 +70,7 @@ def make_group_name(filename): > > > > if dirname == "": > > return "common" > > - return re.sub(r"/|-", "_", dirname) > > + return "_" + re.sub(r"[^\w]", "_", dirname) > > This STILL doesn't solve the complaint that the build is now dependent > on the location. Why can't we STRIP off any prefix prior to the in-tree > portion of the naming that we know is sane, instead of munging the > prefix but in the process creating source code that generates with > different lengths? > Heh, because the complaint was about the build break :) > Ideally, compiling twice, once in directory 'a', and the second time in > directory 'aaaaaaaaaaaaaaaaaaaaaaaaaaaa', should not make a noticeable > difference in the final size of the executable due to the difference in > lengths of the debugging symbols used to record the longer name of the > second directory being encoded into lots of macro names. > You're right. I'm okay to look for a way to fix the symbol variable size issue, but I think this patch still makes sense as it makes tracetool less fragile in case we add a directory with an illegal character to the QEMU tree... and it fixes annoying build breaks (Paolo also hit this and asked to revert 80dd5c4918ab in another mail). Cc'ing Peter...
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