Include errors building libModsecurity as WASM module

[M4tteoP]

I'm working on porting the library libModsecurity to use it as a Istio extension. emconfigure and emmake tools seems very promising to accomplish this task, however, I'm stuck on header inclusion errors.
Action performed are just:
./build.sh
emconfigure ./configure
emmake make
Resulting in this error:

/bin/bash ../libtool  --tag=CXX   --mode=compile /home/user/Tesi/extensions/manualBuild/emsdk/upstream/emscripten/em++ -DHAVE_CONFIG_H -I.  -std=c++11 -I.. -g -I../others -fPIC -O3 -I../headers -DWITH_CURL_SSLVERSION_TLSv1_2 -DWITH_CURL -DWITH_GEOIP -I/usr/include          -I/usr/include/libxml2 -DWITH_LIBXML2   -g -O2 -MT parser/libmodsecurity_la-seclang-parser.lo -MD -MP -MF parser/.deps/libmodsecurity_la-seclang-parser.Tpo -c -o parser/libmodsecurity_la-seclang-parser.lo `test -f 'parser/seclang-parser.cc' || echo './'`parser/seclang-parser.cc
libtool: compile:  /home/user/Tesi/extensions/manualBuild/emsdk/upstream/emscripten/em++ -DHAVE_CONFIG_H -I. -std=c++11 -I.. -g -I../others -fPIC -O3 -I../headers -DWITH_CURL_SSLVERSION_TLSv1_2 -DWITH_CURL -DWITH_GEOIP -I/usr/include -I/usr/include/libxml2 -DWITH_LIBXML2 -g -O2 -MT parser/libmodsecurity_la-seclang-parser.lo -MD -MP -MF parser/.deps/libmodsecurity_la-seclang-parser.Tpo -c parser/seclang-parser.cc  -fPIC -DPIC -o parser/.libs/libmodsecurity_la-seclang-parser.o
In file included from parser/seclang-parser.cc:41:
In file included from seclang-parser.yy:11:
In file included from /home/user/Tesi/extensions/manualBuild/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/string:511:
In file included from /home/user/Tesi/extensions/manualBuild/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/string_view:179:
In file included from /home/user/Tesi/extensions/manualBuild/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/__string:57:
In file included from /home/user/Tesi/extensions/manualBuild/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/algorithm:651:
In file included from /home/user/Tesi/extensions/manualBuild/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/cstring:60:
/usr/include/string.h:26:10: fatal error: 'bits/libc-header-start.h' file not found
#include <bits/libc-header-start.h>
         ^~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
em++: error: '/home/user/Tesi/extensions/manualBuild/emsdk/upstream/bin/clang++ -target wasm32-unknown-emscripten -DEMSCRIPTEN -fignore-exceptions -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -D__EMSCRIPTEN_major__=2 -D__EMSCRIPTEN_minor__=0 -D__EMSCRIPTEN_tiny__=25 -D_LIBCPP_ABI_VERSION=2 -Dunix -D__unix -D__unix__ -Werror=implicit-function-declaration -Xclang -iwithsysroot/include/SDL --sysroot=/home/user/Tesi/extensions/manualBuild/emsdk/upstream/emscripten/cache/sysroot -Xclang -iwithsysroot/include/compat -DHAVE_CONFIG_H -I. -std=c++11 -I.. -g -I../others -fPIC -O3 -I../headers -DWITH_CURL_SSLVERSION_TLSv1_2 -DWITH_CURL -DWITH_GEOIP -I/usr/include -I/usr/include/libxml2 -DWITH_LIBXML2 -g -O2 -MT parser/libmodsecurity_la-seclang-parser.lo -MD -MP -MF parser/.deps/libmodsecurity_la-seclang-parser.Tpo -c -fPIC -DPIC parser/seclang-parser.cc -o parser/.libs/libmodsecurity_la-seclang-parser.o' failed (returned 1)
make[3]: *** [Makefile:2072: parser/libmodsecurity_la-seclang-parser.lo] Error 1
make[3]: Leaving directory '/home/user/Tesi/extensions/manualBuild/ModSecurity/src'
make[2]: *** [Makefile:3479: all-recursive] Error 1
make[2]: Leaving directory '/home/user/Tesi/extensions/manualBuild/ModSecurity/src'
make[1]: *** [Makefile:1224: all] Error 2
make[1]: Leaving directory '/home/user/Tesi/extensions/manualBuild/ModSecurity/src'
make: *** [Makefile:1035: all-recursive] Error 1
emmake: error: 'make' failed (returned 2)

It may be quite similar to this issue, but I don't get:

1. How to remove the inclusions from the wasm file
2. Even removing the inclusions, how can the compiler satisfy all the dependencies? Is it capable of automatically build them for WASM?

Thanks for any support in helping me understand what is wrong in my porting phase.

[sbc100]

The problem is that -I/usr/include -I/usr/include/libxml2 are being added to your command line. The headers in those directories won't work with emscripten.

[M4tteoP]

hi @sbc100, thanks a lot for the reply. I was trying to follow your idea based on this other reply, but still,l I can't succeed. I suppose that I have to try harder to modify in the correct way the Makefile.
I still don't get the conceptual question about all the dependencies that this library carries on. Where is the "magic" behind being able to link the wasm compiled binary (If I will ever succeed to remove the headers) with libraries like libGeoIP.so that are in the system, but compiled not for the wasm architecture?
Thanks for any clarification!

[sbc100]

There is no way to link against pre-compiled libraries that are not compiled for wasm. All libraries need to be re-built/re-compiled for wasm in order to use them.

[stale]

This issue has been automatically marked as stale because there has been no activity in the past year. It will be closed automatically if no further activity occurs in the next 30 days. Feel free to re-open at any time if this issue is still relevant.