Generate soname dependency metadata (bug 282639)

Generate soname dependency metadata for binary and installed packages,
in the form of PROVIDES and REQUIRES metadata. It is useful to generate
PROVIDES and REQUIRES metadata now, so that it will be available
when dependency resolver support is added in the future. Note that
slot-operator dependencies will not be able to serve as a substitute
for soname dependencies for the forseeable future, because system
dependencies are frequently unspecified (according to Gentoo policy).

The PROVIDES/REQUIRES system is very similar to the automatic Requires
and Provides system which is supported by RPM. The PROVIDES/REQUIRES
metadata is generated automatically from the ELF files that are
installed by a package. The PROVIDES/REQUIRES syntax is described in
the /var/db/pkg section of the portage(5) man page. REQUIRES_EXCLUDE
and PROVIDES_EXCLUDE ebuild variables allow for filtering of the
sonames that are saved in REQUIRES and PROVIDES (see the ebuild(5) man
page for details).

The /var/db/pkg NEEDED.ELF.2 format now includes an additional field
which indicates the multilib category, as discussed in bug #534206. The
multilib category is used to categorize the sonames that are listed in
PROVIDES/REQUIRES metadata, since sonames need to be resolved
separately for each multilib category. The complete list of supported
multilib categories is documented in the comments of the
portage.dep.soname.multilib_category module.

X-Gentoo-Bug: 282639
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=282639
Acked-by: Brian Dolbec <dolsen@gentoo.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/man/portage.5 b/man/portage.5
index 8bebd3290..cec4e2fe3 100644
--- a/man/portage.5
+++ b/man/portage.5
@@ -1479,6 +1479,31 @@ can be changed quickly.  Generally though there is one file per environment
 variable that "matters" (like CFLAGS) with the contents stored inside of it.
 Another common file is the CONTENTS file which lists the path and hashes of
 all objects that the package installed onto your system.
+.TP
+.BR PROVIDES
+Contains information about the sonames that a package provides, which is
+automatically generated from the files that it installs. The sonames
+may have been filtered by the \fBPROVIDES_EXCLUDE\fR \fBebuild\fR(5)
+variable. A multilib category, followed by a colon, always preceeds a
+list of one or more sonames.
+
+.I Example:
+.nf
+x86_32: libcom_err.so.2 libss.so.2 x86_64: libcom_err.so.2 libss.so.2
+.fi
+.TP
+.BR REQUIRES
+Contains information about the sonames that a package requires, which is
+automatically generated from the files that it installs. The sonames
+may have been filtered by the \fBREQUIRES_EXCLUDE\fR \fBebuild\fR(5)
+variable. Any sonames that a package provides are automatically excluded
+from \fBREQUIRES\fR. A multilib category, followed by a colon, always
+preceeds a list of one or more sonames.
+
+.I Example:
+.nf
+x86_32: ld-linux.so.2 libc.so.6 x86_64: ld-linux-x86-64.so.2 libc.so.6
+.fi
 .RE
 .TP
 .BR /var/lib/portage/