mirror of
https://github.com/openssl/openssl.git
synced 2024-12-11 11:04:03 +08:00
2c879241ba
... and mention more runtime search path flags. Reviewed-by: Rich Salz <rsalz@openssl.org> Reviewed-by: Richard Levitte <levitte@openssl.org> (Merged from https://github.com/openssl/openssl/pull/6587)
118 lines
5.4 KiB
Plaintext
118 lines
5.4 KiB
Plaintext
|
|
NOTES FOR UNIX LIKE PLATFORMS
|
|
=============================
|
|
|
|
For Unix/POSIX runtime systems on Windows, please see NOTES.WIN.
|
|
|
|
|
|
OpenSSL uses the compiler to link programs and shared libraries
|
|
---------------------------------------------------------------
|
|
|
|
OpenSSL's generated Makefile uses the C compiler command line to
|
|
link programs, shared libraries and dynamically loadable shared
|
|
objects. Because of this, any linking option that's given to the
|
|
configuration scripts MUST be in a form that the compiler can accept.
|
|
This varies between systems, where some have compilers that accept
|
|
linker flags directly, while others take them in '-Wl,' form. You need
|
|
to read your compiler documentation to figure out what is acceptable,
|
|
and ld(1) to figure out what linker options are available.
|
|
|
|
|
|
Shared libraries and installation in non-default locations
|
|
----------------------------------------------------------
|
|
|
|
Every Unix system has its own set of default locations for shared
|
|
libraries, such as /lib, /usr/lib or possibly /usr/local/lib. If
|
|
libraries are installed in non-default locations, dynamically linked
|
|
binaries will not find them and therefore fail to run, unless they get
|
|
a bit of help from a defined runtime shared library search path.
|
|
|
|
For OpenSSL's application (the 'openssl' command), our configuration
|
|
scripts do NOT generally set the runtime shared library search path for
|
|
you. It's therefore advisable to set it explicitly when configuring,
|
|
unless the libraries are to be installed in directories that you know
|
|
to be in the default list.
|
|
|
|
Runtime shared library search paths are specified with different
|
|
linking options depending on operating system and versions thereof, and
|
|
are talked about differently in their respective documentation;
|
|
variations of RPATH are the most usual (note: ELF systems have two such
|
|
tags, more on that below).
|
|
|
|
Possible options to set the runtime shared library search path include
|
|
the following:
|
|
|
|
-Wl,-rpath,/whatever/path # Linux, *BSD, etc.
|
|
-R /whatever/path # Solaris
|
|
-Wl,-R,/whatever/path # AIX (-bsvr4 is passed internally)
|
|
-Wl,+b,/whatever/path # HP-UX
|
|
-rpath /whatever/path # Tru64, IRIX
|
|
|
|
OpenSSL's configuration scripts recognise all these options and pass
|
|
them to the Makefile that they build. (In fact, all arguments starting
|
|
with '-Wl,' are recognised as linker options.)
|
|
|
|
Please do not use verbatim directories in your runtime shared library
|
|
search path! Some OpenSSL config targets add an extra directory level
|
|
for multilib installations. To help with that, the produced Makefile
|
|
includes the variable LIBRPATH, which is a convenience variable to be
|
|
used with the runtime shared library search path options, as shown in
|
|
this example:
|
|
|
|
$ ./config --prefix=/usr/local/ssl --openssldir=/usr/local/ssl \
|
|
'-Wl,-rpath,$(LIBRPATH)'
|
|
|
|
On modern ELF based systems, there are two runtime search paths tags to
|
|
consider, DT_RPATH and DT_RUNPATH. Shared objects are searched for in
|
|
this order:
|
|
|
|
1. Using directories specified in DT_RPATH, unless DT_RUNPATH is
|
|
also set.
|
|
2. Using the environment variable LD_LIBRARY_PATH
|
|
3. Using directories specified in DT_RUNPATH.
|
|
4. Using system shared object caches and default directories.
|
|
|
|
This means that the values in the environment variable LD_LIBRARY_PATH
|
|
won't matter if the library is found in the paths given by DT_RPATH
|
|
(and DT_RUNPATH isn't set).
|
|
|
|
Exactly which of DT_RPATH or DT_RUNPATH is set by default appears to
|
|
depend on the system. For example, according to documentation,
|
|
DT_RPATH appears to be deprecated on Solaris in favor of DT_RUNPATH,
|
|
while on Debian GNU/Linux, either can be set, and DT_RPATH is the
|
|
default at the time of writing.
|
|
|
|
How to choose which runtime search path tag is to be set depends on
|
|
your system, please refer to ld(1) for the exact information on your
|
|
system. As an example, the way to ensure the DT_RUNPATH is set on
|
|
Debian GNU/Linux systems rather than DT_RPATH is to tell the linker to
|
|
set new dtags, like this:
|
|
|
|
$ ./config --prefix=/usr/local/ssl --openssldir=/usr/local/ssl \
|
|
'-Wl,--enable-new-dtags,-rpath,$(LIBRPATH)'
|
|
|
|
It might be worth noting that some/most ELF systems implement support
|
|
for runtime search path relative to the directory containing current
|
|
executable, by interpreting $ORIGIN along with some other internal
|
|
variables. Consult your system documentation.
|
|
|
|
Linking your application
|
|
------------------------
|
|
|
|
Third-party applications dynamically linked with OpenSSL (or any other)
|
|
shared library face exactly the same problem with non-default locations.
|
|
The OpenSSL config options mentioned above might or might not have bearing
|
|
on linking of the target application. "Might" means that under some
|
|
circumstances it would be sufficient to link with OpenSSL shared library
|
|
"naturally", i.e. with -L/whatever/path -lssl -lcrypto. But there are
|
|
also cases when you'd have to explicitly specify runtime search path
|
|
when linking your application. Consult your system documentation and use
|
|
above section as inspiration...
|
|
|
|
Shared OpenSSL builds also install static libraries. Linking with the
|
|
latter is likely to require special care, because linkers usually look
|
|
for shared libraries first and tend to remain "blind" to static OpenSSL
|
|
libraries. Referring to system documentation would suffice, if not for
|
|
a corner case. On AIX static libraries (in shared build) are named
|
|
differently, add _a suffix to link with them, e.g. -lcrypto_a.
|