This is a simple, early-stage project that explores cross-references of dynamic symbols in dynamic link libraries (DSOs, DLLs). It downloads binary Debian packages and searches all contained ELF binaries for definitions of or references to dynamic symbols. The data is stored in an SQLite database.
My initial motivation was to get some insights into which open-source projects happen to use symbols from libxml2, a very popular library I currently maintain. Since libxml2 suffers from over-exporting many internals, I was especially interested in symbols that none of the 600+ reverse dependencies use.
While Debian Linux was chosen for its vast number of packages, this is intended to be cross-platform code. I actually started most of the development on my MacBook.
- POSIX shell
- C compiler
- libelf
- sqlite3
index.sh updates the database with the contents of a package or all
its reverse dependencies.
sh index.sh package <PACKAGE>
sh index.sh rdeps <PACKAGE>
The symbls C program does most of the work extracting dynamic symbols
from the .dynsym section and gathering additional data.
query.sh queries the database.
sh query.sh package <PACKAGE> # Show package
sh query.sh symbol <SYMBOL> # Show symbol
sh query.sh defs <BINARY-PATH> # Show definitions of a binary
sh query.sh refs <BINARY-PATH> # Show references of a binary
Create or update the database. This will take a while.
$ sh index.sh rdeps libxslt1.1
Show information about the package.
$ sh query.sh package libxslt1.1
/usr/lib/x86_64-linux-gnu/libxslt.so.1.1.34|libxslt.so.1
/usr/lib/x86_64-linux-gnu/libexslt.so.0.8.20|libexslt.so.0
Show exported symbols.
$ sh query.sh defs /usr/lib/x86_64-linux-gnu/libxslt.so.1.1.34
F|xslAddCall|0
F|xslDropCall|0
F|xslHandleDebugger|0
F|xsltAddKey|0
F|xsltAddStackElemList|0
F|xsltAddTemplate|0
F|xsltAllocateExtra|0
F|xsltAllocateExtraCtxt|0
F|xsltApplyAttributeSet|0
F|xsltApplyImports|0
F|xsltApplyOneTemplate|4
F|xsltApplyStripSpaces|0
F|xsltApplyStylesheet|51
F|xsltApplyStylesheetUser|24
F|xsltApplyTemplates|0
...
Show information about a symbol.
$ sh query.sh symbol xsltApplyStylesheetUser
Definitions:
libxslt1.1|/usr/lib/x86_64-linux-gnu/libxslt.so.1.1.34
References:
chromium|/usr/lib/chromium/chromium
chromium-shell|/usr/lib/chromium/chromium-shell
libapache2-mod-parser3|/usr/lib/apache2/modules/mod_parser3.so
libnetcf1|/usr/lib/x86_64-linux-gnu/libnetcf.so.1.4.0
libnginx-mod-http-xslt-filter|/usr/lib/nginx/modules/ngx_http_xslt_filter_module.so
libosinfo-1.0-0|/usr/lib/x86_64-linux-gnu/libosinfo-1.0.so.0.1008.0
libqt5webenginecore5|/usr/lib/x86_64-linux-gnu/libQt5WebEngineCore.so.5.15.2
libqt5webkit5|/usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5.212.0
libraptor2-0|/usr/lib/x86_64-linux-gnu/libraptor2.so.0.0.0
libreoffice-core|/usr/lib/libreoffice/program/libucpchelp1.so
libreoffice-core|/usr/lib/libreoffice/program/libxsltfilterlo.so
libreoffice-core-nogui|/usr/lib/libreoffice/program/libucpchelp1.so
libreoffice-core-nogui|/usr/lib/libreoffice/program/libxsltfilterlo.so
libwebkit2gtk-4.0-37|/usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37.55.4
libwpewebkit-1.0-3|/usr/lib/x86_64-linux-gnu/libWPEWebKit-1.0.so.3.16.3
libxml-libxslt-perl|/usr/lib/x86_64-linux-gnu/perl5/5.32/auto/XML/LibXSLT/LibXSLT.so
libxmlsec1|/usr/lib/x86_64-linux-gnu/libxmlsec1.so.1.2.31
libyelp0|/usr/lib/x86_64-linux-gnu/libyelp.so.0.0.0
parser3-cgi|/usr/bin/parser3
php7.4-xml|/usr/lib/php/20190902/xsl.so
postgresql-13|/usr/lib/postgresql/13/lib/pgxml.so
python3-lxml|/usr/lib/python3/dist-packages/lxml/etree.cpython-39-x86_64-linux-gnu.so
python3-lxml-dbg|/usr/lib/python3/dist-packages/lxml/etree.cpython-39d-x86_64-linux-gnu.so
tclxml|/usr/lib/tcltk/x86_64-linux-gnu/tclxml3.2/libtclxml3.2.so
xmlstarlet|/usr/bin/xmlstarlet
xsltproc|/usr/bin/xsltproc
This could be made into a useful web database, offering a cross-reference of dynamic symbols in OSS C libraries.