Brian Dessent wrote:
Ray Hurst wrote:
Thanks for the info. How do I display the contents of libc.a.
I tried ar -t libc.a and malloc did not show up.
However, if I open lib.c with a hex editor I can see that the symbol
__malloc exitst is libc.a
ar -t isn't ever going to give you useful information, as that only
lists the filenames of object files in the archive. It would be only by
coincidence that a function was implemented in an object file by the
same name.
For static archives you can use nm to list symbols, but this is like
drinking from a firehose as it shows all references to all symbols from
every object file, where you probably just want the 'T' ones, e.g.
nm -P libc.a | egrep "^[^ ]+ T" | sort -u
But since almost nothing is linked statically it would probably be
better to look at the shared library. For this you need to use objdump
-T or readelf -s, and note that "libc.so" is not actually a shared
object but a linker script, so you'll need to use the actual filename of
the shared object, e.g. libc-x.y.z.so (or the symlink libc.so.x). And
also note that the shared version of the library uses symbol versioning,
which allows one .so file to be backwards compatible with many other
past versions, an essential requirement without which it would be very
difficult to have binary distributions.
But more importantly, all of the above should be an absolute last
resort. glibc has great documentation that covers every function and
interface, e.g.
<http://www.gnu.org/software/libc/manual/html_node/Function-Index.html>.
This should be considered the definitive reference to how to use the
library and what it provides, not hex dumps of library files and things
like objdump.
Brian
Thanks. This does the job.
Ray
