I am developing a program under Linux.
For debugging purposes I want to trace all calls from my program to a certain (preferably shared) library. (I do not want to trace
The tool you are looking for is called ltrace
. It allows to trace any call from the program to all (or a set of given) libraries.
For example, the following call will list any call to an external function loaded by a shared library:
$> ltrace ls /
__libc_start_main(0x4028c0, 2, 0x7fff1f4e72d8, 0x411e60
strrchr("ls", '/') = nil
setlocale(LC_ALL, "") = "en_US.UTF-8"
bindtextdomain("coreutils", "/usr/share/locale") = "/usr/share/locale"
textdomain("coreutils") = "coreutils"
__cxa_atexit(0x40a200, 0, 0, 0x736c6974756572) = 0
isatty(1) = 0
getenv("QUOTING_STYLE") = nil
getenv("COLUMNS") = nil
ioctl(1, 21523, 0x7fff1f4e6e80) = -1
getenv("TABSIZE") = nil
getopt_long(2, 0x7fff1, "abcdfghiklmnopqrstuvw:xABCDFGHI:"..., 0x413080, -1) = -1
...
+++ exited (status 0) +++
If you want to focus on a particular library, then you should use the --library=pattern
option:
-l, --library library_pattern Display only calls to functions implemented by libraries that match library_pattern. Multiple library patterns can be specified with several instances of this option. Syntax of library_pattern is described in section FILTER EXPRESSIONS. Note that while this option selects calls that might be directed to the selected libraries, there's no actual guarantee that the call won't be directed elsewhere due to e.g. LD_PRELOAD or simply dependency ordering. If you want to make sure that symbols in given library are actually called, use -x @library_pattern instead.
So, for example, getting the list of calls to libselinux.so.1
is done like this:
$ ltrace -l libselinux.so.1 ls /
ls->freecon(0, 0xffffffff, 0x7f78c4eee628, 0) = 0
bin dev media root sbin sys usr boot etc home lib lost+found proc run tmp
+++ exited (status 0) +++
Only one call to the function freecon()
is taken out this run.