Re: [fsverity-utils PATCH 1/2] Use pkg-config to get libcrypto build flags

[Luca Boccassi <luca.boccassi@gmail.com>]

On Fri, 2020-10-23 at 21:07 -0700, Eric Biggers wrote:
> On Thu, Oct 22, 2020 at 06:59:33PM +0100, luca.boccassi@gmail.com wrote:
> > From: Luca Boccassi <luca.boccassi@microsoft.com>
> > 
> > Especially when cross-compiling or other such cases, it might be necessary
> > to pass additional compiler flags. This is commonly done via pkg-config,
> > so use it if available, and fall back to the hardcoded -lcrypto if not.
> > 
> > Signed-off-by: Luca Boccassi <luca.boccassi@microsoft.com>
> > ---
> >  Makefile | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Makefile b/Makefile
> > index 3fc1bec..122c0a2 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -58,6 +58,7 @@ BINDIR          ?= $(PREFIX)/bin
> >  INCDIR          ?= $(PREFIX)/include
> >  LIBDIR          ?= $(PREFIX)/lib
> >  DESTDIR         ?=
> > +PKGCONF         ?= pkg-config
> >  
> >  # Rebuild if a user-specified setting that affects the build changed.
> >  .build-config: FORCE
> > @@ -69,7 +70,8 @@ DESTDIR         ?=
> >  
> >  DEFAULT_TARGETS :=
> >  COMMON_HEADERS  := $(wildcard common/*.h)
> > -LDLIBS          := -lcrypto
> > +LDLIBS          := $(shell $(PKGCONF) libcrypto --libs 2>/dev/null || echo -lcrypto)
> > +CFLAGS          += $(shell $(PKGCONF) libcrypto --cflags 2>/dev/null || echo)
> 
> There should be a way to prevent pkg-config from being used if someone wants to
> link to a local copy of libcrypto.  One might expect setting PKGCONF to an empty
> string to work, and it kind of does, but then the shell command executes
> "libcrypto", which is strange.  How about quoting "$(PKGCONF)" so that the shell
> command is guaranteed to fail as expected in that case?
> 
> - Eric

Sure, done in v2.

-- 
Kind regards,
Luca Boccassi