Aurelien Jarno <[email protected]> writes: > On 2025-02-02 23:52, Bill Allombert wrote: >> On Sun, Feb 02, 2025 at 11:40:45PM +0100, Aurelien Jarno wrote:
>>> The section 8.4, Development files, mentions that the development >>> package should contain a symlink for the associated shared library >>> without a version number. In practice a linker script could be used >>> instead, this is for instance the case of libncurses.so, libncursesw.so, >>> libc.so, and also libm.so for architectures which support the vector >>> math library. >>> Here is a proposal to update the existing paragraph: >>> The development package should contain either a symlink or a linker >>> script for the associated shared library without a version number. For >>> example, the libgdbm-dev package should include a symlink from >>> /usr/lib/libgdbm.so to libgdbm.so.3.0.0, or a linker script that >>> achieves the same effect. This symlink or linker script is needed by >>> the linker (ld) when compiling packages, as it will only look for >>> libgdbm.so when compiling dynamically. >> Maybe a footnote explaining when a linker script could be needed would be >> useful ? > Usually this is decided at the upstream level and not at the debian > level, anyway if you want to add a footnote, here is a proposal: > Linker scripts offer more flexible linking strategies, like > conditionally linking with an additional library, or falling back to a > static library for some symbols. Here is a proposed change incorporating this change and Guillem's feedback. Does this look good to everyone? (I moved one footnote because we now try to keep footnotes immediately after the paragraph they refer to and the added footnote would otherwise be out of order.) -- Russ Allbery ([email protected]) <https://www.eyrie.org/~eagle/>
>From 19414e709a7dd38f35e621474c94a0931c2f6835 Mon Sep 17 00:00:00 2001 From: Russ Allbery <[email protected]> Date: Sat, 7 Feb 2026 16:58:35 -0800 Subject: [PATCH] Allow *.so files to be linker scripts In some cases, *.so files installed by binary development packages for libraries are linker scripts instead of symlinks. Document that, and document the constraints imposed by ldconfig on linker scripts. Based on wording from Aurelien Jarno and feedback from Guillem Jover. Closes: #1095039 --- policy/ch-sharedlibs.rst | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) diff --git a/policy/ch-sharedlibs.rst b/policy/ch-sharedlibs.rst index 69b79d3..cdd2e37 100644 --- a/policy/ch-sharedlibs.rst +++ b/policy/ch-sharedlibs.rst @@ -247,29 +247,39 @@ at a time, librarynameapiversion-dev. Installing the development package must result in installation of all the development files necessary for compiling programs against that shared library. [#]_ +.. [#] This wording allows the development files to be split into several + packages, such as a separate architecture-independent + libraryname-headers, provided that the development package depends + on all the required additional packages. + In case several development versions of a library exist, you may need to use ``dpkg``'s Conflicts mechanism (see :ref:`s-conflicts`) to ensure that the user only installs one development version at a time (as different development versions are likely to have the same header files in them, which would cause a filename clash if both were unpacked). -The development package should contain a symlink for the associated -shared library without a version number. For example, the libgdbm-dev -package should include a symlink from ``/usr/lib/libgdbm.so`` to -``libgdbm.so.3.0.0``. This symlink is needed by the linker (``ld``) when -compiling packages, as it will only look for ``libgdbm.so`` when -compiling dynamically. +The development package should contain either a symlink or a linker script +[#]_ for the associated shared library without a version number. For +example, the ``libgdbm-dev`` package should include a symlink from +:file:`/usr/lib/libgdbm.so` to :file:`libgdbm.so.3.0.0`, or a linker +script that achieves the same effect. This symlink or linker script is +needed by the linker (:command:`ld`) when compiling packages, as it will +only look for :file:`libgdbm.so` when compiling dynamically. + +.. [#] Linker scripts are used when more flexible linking strategies are + desired, such as conditionally linking with an additional library + or falling back to a static library for some symbols. + +If the package installs a linker script, be aware that :command:`ldconfig` +requires the linker script be shorter than 32 bytes, or contain either the +``GROUP`` directive or the string ``GNU ld script`` in a comment in the +first 512 bytes. If the package provides Ada Library Information (``*.ali``) files for use with GNAT, these files must be installed read-only (mode 0444) so that GNAT will not attempt to recompile them. This overrides the normal file mode requirements given in :ref:`s-permissions-owners`. -.. [#] This wording allows the development files to be split into several - packages, such as a separate architecture-independent - libraryname-headers, provided that the development package depends - on all the required additional packages. - .. _s-sharedlibs-intradeps: Dependencies between the packages of the same library -- 2.51.0
