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From: Andrea Claudi <aclaudi@redhat.com>
Date: Wed, 20 Oct 2021 12:32:38 +0200
Subject: [PATCH] configure: fix parsing issue on libbpf_dir option

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1999860
Upstream Status: iproute2-next.git commit 48c379bc

commit 48c379bc2afd43b3246f68ed46475f5318b1218f
Author: Andrea Claudi <aclaudi@redhat.com>
Date:   Thu Oct 14 10:50:50 2021 +0200

    configure: fix parsing issue on libbpf_dir option

    configure is stuck in an endless loop if '--libbpf_dir' option is used
    without a value:

    $ ./configure --libbpf_dir
    ./configure: line 515: shift: 2: shift count out of range
    ./configure: line 515: shift: 2: shift count out of range
    [...]

    Fix it splitting 'shift 2' into two consecutive shifts, and making the
    second one conditional to the number of remaining arguments.

    A check is also provided after the while loop to verify the libbpf dir
    exists; also, as LIBBPF_DIR does not have a default value, configure bails
    out if the user does not specify a value after --libbpf_dir, thus avoiding
    to produce an erroneous configuration.

    Fixes: 7ae2585b865a ("configure: convert LIBBPF environment variables to command-line options")
    Signed-off-by: Andrea Claudi <aclaudi@redhat.com>
    Acked-by: Phil Sutter <phil@nwl.cc>
    Signed-off-by: David Ahern <dsahern@kernel.org>
---
 configure | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/configure b/configure
index ea9051ab..0f304206 100755
--- a/configure
+++ b/configure
@@ -486,7 +486,7 @@ usage()
 	cat <<EOF
 Usage: $0 [OPTIONS]
 	--include_dir <dir>	Path to iproute2 include dir
-	--libbpf_dir		Path to libbpf DESTDIR
+	--libbpf_dir <dir>	Path to libbpf DESTDIR
 	--libbpf_force		Enable/disable libbpf by force. Available options:
 				  on: require link against libbpf, quit config if no libbpf support
 				  off: disable libbpf probing
@@ -506,8 +506,9 @@ else
 				INCLUDE="$1"
 				[ "$#" -gt 0 ] && shift ;;
 			--libbpf_dir)
-				LIBBPF_DIR="$2"
-				shift 2 ;;
+				shift
+				LIBBPF_DIR="$1"
+				[ "$#" -gt 0 ] && shift ;;
 			--libbpf_force)
 				if [ "$2" != 'on' ] && [ "$2" != 'off' ]; then
 					usage 1
@@ -525,6 +526,9 @@ else
 fi
 
 [ -d "$INCLUDE" ] || usage 1
+if [ "${LIBBPF_DIR-unused}" != "unused" ]; then
+	[ -d "$LIBBPF_DIR" ] || usage 1
+fi
 
 echo "# Generated config based on" $INCLUDE >$CONFIG
 quiet_config >> $CONFIG
-- 
2.31.1