--- Begin Message ---
On Sat, 24 Jul 2021 00:11:27 +0100
Denis Ovsienko via tcpdump-workers
wrote:
> There are more related corner cases of varying severity,
> some of which I might have time to describe later.
So, as promised... Several warnings are now documented in the build
scripts (look for TCPSLICE_TAINTED=yes and TCPDUMP_TAINTED=yes).
Another problem that is briefly mentioned in a comment is tcpdump build
issues on Solaris specific to CMake and system libpcap. Hopefully my
notes have captured the details right.
# Solaris 10 with Sun C #
The pre-compile libpcap feature test programs link with the system
libpcap.so fine and run fine. The tcpdump binary links fine, but fails
to run:
$ /tmp/tcpdump_build_matrix.XXtwaqbh/bin/tcpdump --version
ld.so.1: tcpdump: fatal: libpcap.so.1: open failed: No such file or
directory
$ ldd /tmp/tcpdump_build_matrix.XXyKaiEo/bin/tcpdump
libpcap.so.1 => (file not found)
libsocket.so.1 =>/lib/libsocket.so.1
libnsl.so.1 => /lib/libnsl.so.1
libsmi.so.2 => (file not found)
libc.so.1 => /lib/libc.so.1
libmp.so.2 =>/lib/libmp.so.2
libmd.so.1 =>/lib/libmd.so.1
libscf.so.1 => /lib/libscf.so.1
libdoor.so.1 => /lib/libdoor.so.1
libuutil.so.1 => /lib/libuutil.so.1
libgen.so.1 => /lib/libgen.so.1
libm.so.2 => /lib/libm.so.2
/platform/SUNW,SPARC-Enterprise-T5220/lib/libc_psr.so.1
/platform/SUNW,SPARC-Enterprise-T5220/lib/libmd_psr.so.1
$ pcap-config --libs
-L/opt/csw/lib -R/opt/csw/lib -lpcap
It looks like the test programs use the runpath, but tcpdump does not.
# Solaris 11 with GCC #
This is the opposite: the pre-compile libpcap feature test programs
fail to link so all libpcap feature tests fail. However, libpcap is
detected as available and the build process resorts to missing/ and
produces a binary of tcpdump that is mostly functional:
$ /tmp/tcpdump_build_matrix.XX06MD.a/bin/tcpdump -D
/tmp/tcpdump_build_matrix.XX06MD.a/bin/tcpdump: illegal option -- D
The problem seems to be that the feature test linking instead of using
the flags returned by pcap-config points exactly to the 32-bit version
of libpcap and fails:
$ pcap-config --libs
-L/usr/lib -lpcap
/usr/bin/gcc
-DCHECK_FUNCTION_EXISTS=pcap_list_datalinks
CMakeFiles/cmTC_d38b1.dir/CheckFunctionExists.c.o -o cmTC_d38b1
/usr/lib/libpcap.so
ld: fatal: file /usr/lib/libpcap.so: wrong ELF class: ELFCLASS32
collect2: error: ld returned 1 exit status
It likely has to do with these CMake variables:
TCPDUMP_LINK_LIBRARIES=/usr/lib/libpcap.so;socket;nsl
PCAP_LIBRARIES=/usr/lib/libpcap.so
Soon after that tcpdump linking does not force the 32-bit library and
works:
/usr/bin/gccCMakeFiles/tcpdump.dir/fptype.c.o
CMakeFiles/tcpdump.dir/tcpdump.c.o CMakeFiles/tcpdump.dir/bpf_dump.c.o
CMakeFiles/tcpdump.dir/missing/pcap_dump_ftell.c.o
CMakeFiles/tcpdump.dir/missing/datalinks.c.o
CMakeFiles/tcpdump.dir/missing/dlnames.c.o -o tcpdump libnetdissect.a
-lpcap -lsocket -lnsl
This automatically uses the 64-bit library (not in /usr/lib).
Autoconf build does not have the problem with feature tests because it
uses exactly what pcap-config has returned and lets the linker figure
the details out:
configure:6157: checking for pcap_findalldevs
configure:6157: gcc -o conftest -I/usr/inet6/include -g -O2
conftest.c -L/usr/lib -lpcap -lsocket -lnsl >&5
configure:6157: $? = 0
Sun C does not have the problem with feature tests: CMake invokes it
same way as GCC, but Sun C manages to produce feature test programs
that work as expected:
/opt/solarisstudio12.4/bin/suncc
-DCHECK_FUNCTION_EXISTS=pcap_list_datalinks
CMakeFiles/cmTC_97fb2.dir/CheckFunctionExists.c.o -o cmTC_97fb2
/usr/lib/libpcap.so
This looks like some heuristics or a short-cut built into Sun C, but it
seems wrong to depend on it. Moreover, Sun C does not have to guess hard
for tcpdump linking because the flags are just correct:
/opt/solarisstudio12.4/bin/sunccCMakeFiles/tcpdump.dir/fptype.c.o
CMakeFiles/tcpdump.dir/tcpdump.c.o -o tcpdump libnetdissect.a -lpcap
-lsocket -lnsl
--
Denis Ovsienko
--- End Message ---
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