Introduce a way to override dependencies for all pkgs thru a file.

The `etc/defaults.virtual` file contains the default replacement
for our use cases; at this moment we only use it to use `eudev`
rather than `systemd` for udev.

If `etc/virtual` exists it overrides the settings of `etc/defaults.virtual`.

README.md

@@ -12,13 +12,15 @@ To start using it first you'll need some external dependencies:
 Make sure your user is added to the `xbuilder` group to be able to use `xbps-uchroot(8)`,
 otherwise `xbps-src` won't work correctly.
 
-The `xbps-src` utility will allow you to generate XBPS binary packages, type
+Type:
 
      $ ./xbps-src -h
 
 to see all available targets/options and start building any available package
 in the `srcpkgs` directory.
 
+### Configuration
+
 The `etc/defaults.conf` file contains the possible settings that can be overrided
 through the `etc/conf` configuration file for the `xbps-src` utility; if that file
 does not exist, will try to read configuration settings from `~/.xbps-src.conf`.
@@ -29,5 +31,15 @@ those defined in `etc/defaults.conf`, append to them instead via `etc/conf` i.e:
     $ echo 'XBPS_CFLAGS+=" your flags here "' >> etc/conf
     $ echo 'XBPS_LDFLAGS+=" your flags here "' >> etc/conf
 
+#### Virtual packages
+
+The `etc/defaults.virtual` file contains the default replacements for virtual packages,
+used as dependencies in the source packages tree.
+
+If you want to customize those replacements, copy `etc/defaults.virtual` to `etc/virtual`
+and edit it accordingly to your needs.
+
+### Contributing
+
 See [Manual](https://github.com/voidlinux/xbps-packages/blob/master/Manual.md)
 for documentation to create and learn about the source packages.

common/xbps-src/shutils/build_dependencies.sh

@@ -1,7 +1,7 @@
 # vim: set ts=4 sw=4 et:
 #
 setup_pkg_depends() {
-    local pkg="$1" j _pkgdepname _pkgdep _rpkgname _depname
+    local pkg="$1" j _pkgdepname _pkgdep _rpkgname _depname _replacement
 
     if [ -n "$pkg" ]; then
         # subpkg
@@ -17,7 +17,17 @@ setup_pkg_depends() {
         if [ -z "${_pkgdepname}" ]; then
             _pkgdepname="$($XBPS_UHELPER_CMD getpkgname ${_depname} 2>/dev/null)"
         fi
-
+        if [ -s ${XBPS_DISTDIR}/etc/virtual ]; then
+            _replacement=$(egrep "^${_pkgdepname:-${_depname}}[[:blank:]]" ${XBPS_DISTDIR}/etc/virtual|cut -d ' ' -f2)
+            if [ -n "${_replacement}" ]; then
+                _depname="${_depname/${_pkgdepname:-${_depname}}/${_replacement}}"
+            fi
+        elif [ -s ${XBPS_DISTDIR}/etc/defaults.virtual ]; then
+            _replacement=$(egrep "^${_pkgdepname:-${_depname}}[[:blank:]]" ${XBPS_DISTDIR}/etc/defaults.virtual|cut -d ' ' -f2)
+            if [ -n "${_replacement}" ]; then
+                _depname="${_depname/${_pkgdepname:-${_depname}}/${_replacement}}"
+            fi
+        fi
         if [ -z "${_pkgdepname}" ]; then
             _pkgdep="${_depname}>=0"
         else
@@ -35,6 +45,17 @@ setup_pkg_depends() {
         if [ -z "${_pkgdepname}" ]; then
             _pkgdepname="$($XBPS_UHELPER_CMD getpkgname ${_depname} 2>/dev/null)"
         fi
+        if [ -s ${XBPS_DISTDIR}/etc/virtual ]; then
+            _replacement=$(egrep "^${_pkgdepname:-${_depname}}[[:blank:]]" ${XBPS_DISTDIR}/etc/virtual|cut -d ' ' -f2)
+            if [ -n "${_replacement}" ]; then
+                _depname="${_depname/${_pkgdepname:-${_depname}}/${_replacement}}"
+            fi
+        elif [ -s ${XBPS_DISTDIR}/etc/defaults.virtual ]; then
+            _replacement=$(egrep "^${_pkgdepname:-${_depname}}[[:blank:]]" ${XBPS_DISTDIR}/etc/defaults.virtual|cut -d ' ' -f2)
+            if [ -n "${_replacement}" ]; then
+                _depname="${_depname/${_pkgdepname:-${_depname}}/${_replacement}}"
+            fi
+        fi
         if [ -z "${_pkgdepname}" ]; then
             _pkgdep="${_depname}>=0"
         else
@@ -48,6 +69,17 @@ setup_pkg_depends() {
         if [ -z "${_pkgdepname}" ]; then
             _pkgdepname="$($XBPS_UHELPER_CMD getpkgname ${_depname} 2>/dev/null)"
         fi
+        if [ -s ${XBPS_DISTDIR}/etc/virtual ]; then
+            _replacement=$(egrep "^${_pkgdepname:-${_depname}}[[:blank:]]" ${XBPS_DISTDIR}/etc/virtual|cut -d ' ' -f2)
+            if [ -n "${_replacement}" ]; then
+                _depname="${_depname/${_pkgdepname:-${_depname}}/${_replacement}}"
+            fi
+        elif [ -s ${XBPS_DISTDIR}/etc/defaults.virtual ]; then
+            _replacement=$(egrep "^${_pkgdepname:-${_depname}}[[:blank:]]" ${XBPS_DISTDIR}/etc/defaults.virtual|cut -d ' ' -f2)
+            if [ -n "${_replacement}" ]; then
+                _depname="${_depname/${_pkgdepname:-${_depname}}/${_replacement}}"
+            fi
+        fi
         if [ -z "${_pkgdepname}" ]; then
             _pkgdep="${_depname}>=0"
         else

etc/defaults.virtual

@@ -0,0 +1,22 @@
+# --*-- shell --*--
+#
+# etc/defaults.virtual
+#	default configuration of etc/virtual
+#
+# DO NOT EDIT THIS FILE DIRECTLY; IT MAY BE REPLACED DURING UPDATES,
+# EDIT etc/virtual INSTEAD.
+#
+# This file specifies a mapping between virtual packages and real packages
+# available in the source packages collection (srcpkgs).
+#
+# The format uses 2 arguments delimited by a blank: <vpkgname> <realpkgname>
+#
+# If a source package depends on a virtual package (<vpkgname>) and there's
+# a replacement defined in that file, <realpkgname> will be used to resolve
+# the dependency instead.
+#
+# - Please add entries sorted alphabetically on its first argument.
+# - Create your own etc/virtual file to override these defaults.
+#
+libgudev-devel eudev-libgudev-devel
+libudev-devel eudev-libudev-devel