push: Check for duplicate patch in series

In the case of a generated or manually tweaked series file, it can
happen that the same patch shows up twice in the series file. Check
for this before pushing any patch, otherwise we would corrupt quilt's
internal database.

This fixes bug #20628:
https://savannah.nongnu.org/bugs/?20628

2 files changed, 61 insertions, 0 deletions

diff --git a/quilt/push.in b/quilt/push.in
index fde9472..e00573d 100644
--- a/quilt/push.in
+++ b/quilt/push.in
@@ -276,6 +276,24 @@ list_patches()
 	fi
 }
 
+check_duplicate_patches()
+{
+	local IFS=$'\n'
+	local -a duplicates
+	local patch
+
+	duplicates=($((applied_patches ; printf $'%s\n' "${patches[@]}") \
+		      | awk '{ if (lines[$0]++ == 1) print }'))
+	[ ${#duplicates[@]} -ge 1 ] || return 0
+
+	for patch in "${duplicates[@]}"
+	do
+		printf $"Patch %s is already applied; check your series file\n" \
+		       "$(print_patch "$patch")"
+	done
+	return 1
+}
+
 options=`getopt -o fqvam::h --long fuzz:,merge::,leave-rejects,color:: -- "$@"`
 
 if [ $? -ne 0 ]
@@ -381,6 +399,12 @@ then
 fi
 
 patches=$(list_patches)
+
+# In theory, these patches can't be already applied. However in the case
+# of a generated or manually tweaked series file, this could happen and
+# cause havoc, so play it safe and check.
+check_duplicate_patches || exit 1
+
 create_db
 for patch in $patches
 do
diff --git a/test/duplicate-patch-in-series.test b/test/duplicate-patch-in-series.test
new file mode 100644
index 0000000..98591b2
--- /dev/null
+++ b/test/duplicate-patch-in-series.test
@@ -0,0 +1,37 @@
+# Check that duplicate patches in generated series files won't cause havoc
+# See bug #20628 at https://savannah.nongnu.org/bugs/?20628
+
+$ mkdir patches
+$ echo "old line" > file.txt
+
+$ cat > patches/first.patch
+< --- file.txt
+< +++ file.txt
+< @@ -1 +1 @@
+< -old line
+< +new line
+
+$ cat > patches/series
+< first.patch -p0
+< first.patch -p0
+
+$ quilt push
+> Applying patch %{P}first.patch
+> patching file file.txt
+>
+> Now at patch %{P}first.patch
+
+$ quilt push
+> Patch %{P}first.patch is already applied; check your series file
+
+$ quilt pop
+> Removing patch %{P}first.patch
+> Restoring file.txt
+>
+> No patches applied
+
+$ quilt push -qa
+> Patch %{P}first.patch is already applied; check your series file
+
+$ quilt pop -q
+> No patch removed