[Question] - Ulfius' linked libraries

[kiranjeet98]

ulfius version used - 2.7.8

I am using ulfius for my rest interface. But i can see that apart from linking with the required libraries my binary is getting linked with additional libraries shown below:

    libsystemd.so.0 => /lib64/libsystemd.so.0 (0x00007f142a1ce000)
    libidn.so.11 => /lib64/libidn.so.11 (0x00007f1429f9b000)
    libssh2.so.1 => /lib64/libssh2.so.1 (0x00007f1429d6e000)
    libssl3.so => /lib64/libssl3.so (0x00007f1429b15000)
    libsmime3.so => /lib64/libsmime3.so (0x00007f14298ed000)
    libnss3.so => /lib64/libnss3.so (0x00007f14295be000)
    libnssutil3.so => /lib64/libnssutil3.so (0x00007f142938e000)
    libplds4.so => /lib64/libplds4.so (0x00007f142918a000)
    libplc4.so => /lib64/libplc4.so (0x00007f1428f85000)
    libnspr4.so => /lib64/libnspr4.so (0x00007f1428d47000)
    libgssapi_krb5.so.2 => /lib64/libgssapi_krb5.so.2 (0x00007f1428afa000)
    libkrb5.so.3 => /lib64/libkrb5.so.3 (0x00007f1428811000)
    libk5crypto.so.3 => /lib64/libk5crypto.so.3 (0x00007f14285de000)
    libcom_err.so.2 => /lib64/libcom_err.so.2 (0x00007f14283da000)
    liblber-2.4.so.2 => /lib64/liblber-2.4.so.2 (0x00007f14281cb000)
    libldap-2.4.so.2 => /lib64/libldap-2.4.so.2 (0x00007f1427f76000)
    libcap.so.2 => /lib64/libcap.so.2 (0x00007f1427d71000)
    librt.so.1 => /lib64/librt.so.1 (0x00007f1427b69000)
    libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f1427942000)
    liblzma.so.5 => /lib64/liblzma.so.5 (0x00007f142771c000)
    liblz4.so.1 => /lib64/liblz4.so.1 (0x00007f1427507000)
    libgcrypt.so.11 => /lib64/libgcrypt.so.11 (0x00007f1427286000)
    libgpg-error.so.0 => /lib64/libgpg-error.so.0 (0x00007f1427081000)
    libresolv.so.2 => /lib64/libresolv.so.2 (0x00007f1426e68000)
    libdw.so.1 => /lib64/libdw.so.1 (0x00007f1426c17000)
    libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f1426a01000)
    libssl.so.10 => /lib64/libssl.so.10 (0x00007f142678f000)
    libcrypto.so.10 => /lib64/libcrypto.so.10 (0x00007f142632c000)
    libkrb5support.so.0 => /lib64/libkrb5support.so.0 (0x00007f142611c000)
    libkeyutils.so.1 => /lib64/libkeyutils.so.1 (0x00007f1425f18000)
    libsasl2.so.3 => /lib64/libsasl2.so.3 (0x00007f1425cfb000)
    libattr.so.1 => /lib64/libattr.so.1 (0x00007f1425af6000)
    libpcre.so.1 => /lib64/libpcre.so.1 (0x00007f1425894000)
    libelf.so.1 => /lib64/libelf.so.1 (0x00007f142567c000)
    libbz2.so.1 => /lib64/libbz2.so.1 (0x00007f142546c000)
    libcrypt.so.1 => /lib64/libcrypt.so.1 (0x00007f1425235000)
    libfreebl3.so => /lib64/libfreebl3.so (0x00007f1425032000)

Could you please explain what is the reason these libraries are getting linked?

[babelouest]

Hello @kiranjeet98 ,

As mentionned in the README.md file, Ulfius, with the default build, requires the following dependencies:

• GNU Libmicrohttpd
• GnuTLS
• Jansson
• Libcurl
• yder

All those libraries are linked to other libraries as well, that's why the ldd output is that long.

The only required dependency is GNU Libmicrohttpd, you can build Ulfius without the other if you want, check the install documentation if you want to disable one or more dependecies.

[kiranjeet98]

But i can see there is a difference in output of ldd command in different OS. I have checked in rocky linux and ubuntu. libidn.so.11 ,libssl3.so ,libsmime3.so,libnss3.so,libnssutil3.so ,libplds4.so , libplc4.so , libnspr4.so => are listed in ouput of ldd command in rocky linux OS but are not listed in ubuntu. What is the reason for this?

[babelouest]

It depends on the distribution's build process with the dependencies.

For example, libcurl is a library with a lot of dependencies, and some dependencies may be replaced by other ones, or skipped by the distribution, that's why you can have differences in ldd commands in different OS or distributions, or even different versions of the same distribution.

[kiranjeet98]

okay Thanks.