Paul Romero wrote:
> I looked at the examples and they are quite good. Also,
> I performed some experiments and concluded libssh2
> is well suited to my application.
Great!
> I suppose the size of the library can be reduced by
> disabling libz compression.
I actually doubt that, since zlib is an external dependency. The code
in libssh2 that would call into zlib is very small, so the space
saving in libssh2 would be minimal. But if no other package in your
target system depends on zlib then you can obviously save the space
needed for that, by disabling compression.
> I noticed PIC in the configuration options. What is it and is it
> important ?
Short for Position Independent Code, and yes, all shared libraries
must be compiled PIC or the machine code will make assumptions on
which address in memory they will be running at, which can usually
not be predicted at build time.
> Finally, any hints about how to minimize the library size would be
> appreciated.
I'm sure you can get size down by removing everything from the
library that is not absolutely neccessary. If you do a good job at
that and come up with a clean patch against the current master
codebase which introduces some configure options for the minimal
behavior I would welcome that contribution into the official code.
Another option is of course for you to locally maintain a more brutal
modification of the code where you simply rip out things that you
know you will never use. Then you'll have to do more work to re-do
those changes if at some point you wish to use a newer version of
libssh2.
I just ran strip on the plain Linux objects built here:
/tmp/.libs $ ls -l
total 456
-rw-r--r-- 1 stuge stuge 3460 Jul 10 22:36 agent.o
-rw-r--r-- 1 stuge stuge 16512 Jul 10 22:36 channel.o
-rw-r--r-- 1 stuge stuge 2820 Jul 10 22:36 comp.o
-rw-r--r-- 1 stuge stuge 2396 Jul 10 22:36 crypt.o
-rw-r--r-- 1 stuge stuge 812 Jul 10 22:36 global.o
-rw-r--r-- 1 stuge stuge 2988 Jul 10 22:36 hostkey.o
-rw-r--r-- 1 stuge stuge 1084 Jul 10 22:36 keepalive.o
-rw-r--r-- 1 stuge stuge 15216 Jul 10 22:36 kex.o
-rw-r--r-- 1 stuge stuge 7988 Jul 10 22:36 knownhost.o
-rw-r--r-- 1 stuge stuge 432 Jul 10 22:36 libgcrypt.o
-rw-r--r-- 1 stuge stuge 123148 Jul 10 22:36 libssh2.a
-rw-r--r-- 1 stuge stuge 2817 May 3 15:26 libssh2.exp
lrwxrwxrwx 1 stuge stuge 13 Jul 10 22:33 libssh2.la -> ../libssh2.la
-rw-r--r-- 1 stuge stuge 938 May 3 15:26 libssh2.lai
lrwxrwxrwx 1 stuge stuge 16 Jul 10 22:33 libssh2.so -> libssh2.so.1.0.1
lrwxrwxrwx 1 stuge stuge 16 Jul 10 22:33 libssh2.so.1 -> libssh2.so.1.0.1
-rwxr-xr-x 1 stuge stuge 134128 Jul 10 22:36 libssh2.so.1.0.1
-rw-r--r-- 1 stuge stuge 2953 May 3 15:26 libssh2.ver
-rw-r--r-- 1 stuge stuge 2080 Jul 10 22:36 mac.o
-rw-r--r-- 1 stuge stuge 3056 Jul 10 22:36 misc.o
-rw-r--r-- 1 stuge stuge 3572 Jul 10 22:36 openssl.o
-rw-r--r-- 1 stuge stuge 7696 Jul 10 22:36 packet.o
-rw-r--r-- 1 stuge stuge 432 Jul 10 22:36 pem.o
-rw-r--r-- 1 stuge stuge 8352 Jul 10 22:36 publickey.o
-rw-r--r-- 1 stuge stuge 7996 Jul 10 22:36 scp.o
-rw-r--r-- 1 stuge stuge 8032 Jul 10 22:36 session.o
-rw-r--r-- 1 stuge stuge 18408 Jul 10 22:36 sftp.o
-rw-r--r-- 1 stuge stuge 4272 Jul 10 22:36 transport.o
-rw-r--r-- 1 stuge stuge 13284 Jul 10 22:36 userauth.o
-rw-r--r-- 1 stuge stuge 664 Jul 10 22:36 version.o
The largest offenders are SFTP, channel and userauth, all of which
you need. I guess you can strip userauth down selectively. Maybe you
can remove stuff like knownhost.o and scp.o and save a few kb..
But I have to say that if the system is so size constrained that you
need to hunt kilobytes then you will face severe problems quite soon
anyway, so in that case I'd work on increasing storage as soon as
possible instead.
//Peter
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Received on 2010-07-10