[flashrom] [PATCH] More robust libpci detection

[Carl-Daniel Hailfinger]

On 28.02.2010 16:30, Idwer Vollering wrote:
> 2010/2/26 Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>
>   
>> Idwer reported problems with the current libpci check on
>>
>> FreeBSD 8.0-RELEASE i386
>>
>> This is caused by a strict linker. Parsing linker error messages is an
>> exercise in futility, so I implemented fallback library detection with
>> $CC --print-file-name.
>> This fallback will fail on llvm-clang (llvm bug 5137), but such machines
>> hopefully have a more permissive linker and will never hit that code path.
>> The fallback will also fail on NetBSD where we should look for
>> libpciutils instead, but that hopefully doesn't have a strict linker
>> either.
>>
>> Side note: The configure checks in the Makefile are now so unwieldy that
>> a separate configure script will definitely improve readability.
>>
>> Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>
>>
>>     
> $ gmake
> Checking for a C compiler... found.
> Checking for libpci headers... found.
> Checking for libpci (method 1)... not found.
> Checking for dynamic libpci (method 2)... not found.
> not found.
>
> Please install libpci (package pciutils).
> See README for more information.
>
> unavailable.
>
> Please install libpci (package pciutils).
> See README for more information.
>   

Ouch. Turns out the patch had one error message too many, a missing
semicolon and missing LDFLAGS in some CC calls.
New version
.
Idwer reported problems with the current libpci check on
FreeBSD 8.0-RELEASE i386
This is caused by a strict linker. Parsing linker error messages is an
exercise in futility, so I implemented fallback library detection with
$CC --print-file-name.
This fallback may cause false positives/negatives on llvm-clang (llvm
bug 5137), but such machines hopefully have a more permissive linker and
will never hit that code path.
The fallback will be unreliable on NetBSD where we should look for
libpciutils instead, but that hopefully doesn't have a strict linker
either. A fix is easy (replace libpci with PCI_LIB_NAME), but outside
the scope of this patch.
Tested with error injection at various levels.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>

Index: flashrom-libpci_robust_detection/Makefile
===================================================================
--- flashrom-libpci_robust_detection/Makefile	(Revision 919)
+++ flashrom-libpci_robust_detection/Makefile	(Arbeitskopie)
@@ -251,21 +251,28 @@
 		echo "Please install libpci headers (package pciutils-devel).";	\
 		echo "See README for more information."; echo;			\
 		rm -f .test.c .test.o; exit 1)
-	@printf "Checking for libpci... "
+	@printf "Checking for libpci (method 1)... "
 	@$(shell ( echo "#include <pci/pci.h>";		   \
 		   echo "int main(int argc, char **argv)"; \
 		   echo "{ return 0; }"; ) > .test1.c )
-	@$(CC) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) .test1.c -o .test1 -lpci $(LIBS) >/dev/null 2>&1 &&	\
-		echo "found." || ( echo "not found."; echo;				\
-		echo "Please install libpci (package pciutils).";			\
-		echo "See README for more information."; echo;				\
-		rm -f .test1.c .test1; exit 1)
+	@$(CC) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) .test1.c -o .test1 $(LIBS) >/dev/null 2>&1 &&	\
+		echo "found." || ( echo "not found.";		\
+		$(CC) $(LDFLAGS) --print-file-name=libpci.so >/dev/null 2>&1 && (		\
+		printf "Checking for dynamic libpci (method 2)... ";		\
+		$(CC) $(LDFLAGS) --print-file-name=libpci.so 2>/dev/null | grep -q / &&	\
+		echo "found." || ( echo "not found.";				\
+		printf "Checking for static libpci (method 2)... ";		\
+		$(CC) $(LDFLAGS) --print-file-name=libpci.a 2>/dev/null | grep -q / &&	\
+		echo "found." || ( echo "not found."; echo;			\
+		echo "Please install libpci (package pciutils).";		\
+		echo "See README for more information."; echo;			\
+		rm -f .test1.c .test1; exit 1) ) ) )
 	@printf "Checking if libpci is sufficient... "
 	@printf "" > .libdeps
-	@$(CC) $(LDFLAGS) .test.o -o .test -lpci $(LIBS) >/dev/null 2>&1 &&				\
+	@$(CC) $(LDFLAGS) .test.o -o .test $(LIBS) >/dev/null 2>&1 &&				\
 		echo "yes." || ( echo "no.";							\
 		printf "Checking if libz is present and supplies all needed symbols...";	\
-		$(CC) $(LDFLAGS) .test.o -o .test -lpci -lz $(LIBS) >/dev/null 2>&1 &&		\
+		$(CC) $(LDFLAGS) .test.o -o .test $(LIBS) -lz >/dev/null 2>&1 &&		\
 		( echo "yes."; echo "NEEDLIBZ := yes" > .libdeps ) || ( echo "no."; echo;	\
 		echo "Please install libz.";			\
 		echo "See README for more information."; echo;				\


-- 
"I do consider assignment statements and pointer variables to be among
computer science's most valuable treasures."
-- Donald E. Knuth