support/download: add support to exclude svn externals

Like git which can have submodules, subversion can have externals. The
default behaviour for subversion is to retrieve all the externals,
unless told otherwise.

For some repositories, the externals may be huge (e.g. a dataset or some
assets) and may not be required for building the package. In such a
case, retrieving the externals is both a waste of network bandwitdh and
time, and a waste of disk storage.

Like for git submodules and git lfs, add an option that packages can set
to specify whether they want externals or not.

Since we've so far been retrieving externals, we keep that the default,
and packages can opt-out (rather than the opt-in for git submodules or
git lfs).

We must only set it when the package is actually hosted on svn, to avoid
passing -r when the package is not hosted by svn; otherwise, -r would
also be passed e.g. to a git-hosted package, triggering the download of
git submodules even when they are not requested. We need to do so,
because we have a default value, which we usually do not have in other
download options.

Signed-off-by: Yann E. MORIN <yann.morin@orange.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

docs/manual/adding-packages-generic.txt

@@ -347,6 +347,12 @@ not and can not work as people would expect it should:
   Git LFS to store large files out of band.  This is only available for
   packages downloaded with git (i.e. when +LIBFOO_SITE_METHOD=git+).
 
++ +LIBFOO_SVN_EXTERNAL+ can be set to +YES+ (the default) to specify
+  whether to retrieve the svn external references, or to +NO+ to avoid
+  retrieving those externals. Note that, contrary to other similar
+  options like +LIBFOO_GIT_SUBMODULES+ or +LIBFOO_GIT_LFS+, the default
+  here is to actually retrieve the externals; this is a legacy heritage.
+
 * +LIBFOO_STRIP_COMPONENTS+ is the number of leading components
   (directories) that tar must strip from file names on extraction.
   The tarball for most packages has one leading component named

package/pkg-download.mk

@@ -119,6 +119,7 @@ define DOWNLOAD
 		-n '$($(2)_BASENAME_RAW)' \
 		-N '$($(2)_RAWNAME)' \
 		-o '$($(2)_DL_DIR)/$(notdir $(1))' \
+		$(if $(filter YES,$($(2)_SVN_EXTERNALS)),-r) \
 		$(if $($(2)_GIT_SUBMODULES),-r) \
 		$(if $($(2)_GIT_LFS),-l) \
 		$(foreach uri,$(call DOWNLOAD_URIS,$(1),$(2)),-u $(uri)) \

package/pkg-generic.mk

@@ -643,6 +643,16 @@ ifndef $(2)_GIT_SUBMODULES
  endif
 endif
 
+ifndef $(2)_SVN_EXTERNALS
+ ifdef $(3)_SVN_EXTERNALS
+  $(2)_SVN_EXTERNALS = $$($(3)_SVN_EXTERNALS)
+ else
+  # Legacy: we used to always use externals by default
+  # Only set it when the package is actually hosted on svn
+  $(2)_SVN_EXTERNALS = $$(if $$(filter svn,$$($(2)_SITE_METHOD)),YES)
+ endif
+endif
+
 # Do not accept to download git submodule if not using the git method
 ifneq ($$($(2)_GIT_SUBMODULES),)
  ifneq ($$($(2)_SITE_METHOD),git)

support/download/svn

@@ -16,6 +16,7 @@ set -e
 #   -u URI      Checkout from repository at URI.
 #   -c REV      Use revision REV.
 #   -n NAME     Use basename NAME.
+#   -r          Recursive, i.e. use externals
 #
 # Environment:
 #   SVN      : the svn command to call
@@ -24,6 +25,7 @@ set -e
 . "${0%/*}/helpers"
 
 quiet=
+externals=--ignore-externals
 while getopts "${BR_BACKEND_DL_GETOPTS}" OPT; do
     case "${OPT}" in
     q)  quiet=-q;;
@@ -31,6 +33,7 @@ while getopts "${BR_BACKEND_DL_GETOPTS}" OPT; do
     u)  uri="${OPTARG}";;
     c)  rev="${OPTARG}";;
     n)  basename="${OPTARG}";;
+    r)  externals=;;
     :)  printf "option '%s' expects a mandatory argument\n" "${OPTARG}"; exit 1;;
     \?) printf "unknown option '%s'\n" "${OPTARG}" >&2; exit 1;;
     esac
@@ -52,7 +55,8 @@ _plain_svn() {
     eval ${SVN} "${@}"
 }
 
-_svn export --ignore-keywords ${quiet} "${@}" "'${uri}@${rev}'" "'${basename}'"
+# shellcheck disable=SC2086 # externals and quiet may be empty
+_svn export --ignore-keywords ${quiet} ${externals} "${@}" "'${uri}@${rev}'" "'${basename}'"
 
 # For 'svn info', we only need the credentials, if any; other options
 # would be invalid, as they are intended for 'svn export'.