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linux/gcc: ldd functionality from inside a C/C++ program

Is there a simple and efficient way to know that a given dynamically linked ELF is missing a required .so for it to run, all from the inside of a C/C++ program?

I need a program with somewhat similar functionality as ldd, without trying to execute the ELF to find out the (met/unmet) dependencies in the system. Perhaps asking the ld-linux.so utility via some library? (I'm a newbie in this part of linux =)

NOTE: reading the source code of ldd was not very helpful for my intentions: it seems that ldd is in fact forking another process and executing the program.

If it's not possible to know that a program has unmet dependencies without executing it, is there some way to, at least, quickly list the .so's required for that ELF all from within my program?

Thanks in advance =)

Solution

  • As per ld.so(8), setting the environment variable LD_TRACE_LOADED_OBJECTS to a non-empty string will give ldd-like results (instead of executing the binary or library normally).

    setenv("LD_TRACE_LOADED_OBJECTS", "1", 1);
FILE *ldd = popen("/lib/libz.so");