How can I log
a string passed to a library function like strdup() where there's no
debug information ?
In the absence of debug information all parameters would be assumed
to be of type 'int' and only positional ($1, $2, etc.) references will
If you know the type of such parameter you could cast it to the right
type. The strdup() function doesn't have debug information, but you
could still compile and use the following apc file:
probe extern:"strdup()" in "libc.so"
Note that ap_StringValue is a macro which among other things casts
the argument to a string.
For a complete list of subprograms that you can probe in shared
apinfo -sa <your_executable_here>
It is best not to mix apc code that relies on debug information with
the apc code that should compile without it. This way when you compile
the apc code that doesn't require debug info you may omit the -x option
altogether, and you would not have any warnings from the apc compiler.