Check for series file consistency

Quilt allows manual changes to the series file to some degree. For
example, adding comments or reordering patches in the unapplied
section of the series file is OK. However, changing the order of
applied patches breaks a number of assumptions and can cause quilt to
produce unexpected or confusing results.

For example, starting from this:

+ patches/01.patch
= patches/02.patch
  patches/03.patch
  patches/04.patch

and moving the last patch at the beginning of the series file,
"quilt series -v" will print:

+ patches/04.patch
+ patches/01.patch
= patches/02.patch
  patches/03.patch

That is, it will claim that 04.patch is applied, while it it not.
Likewise, 04.patch would be listed by neither "quilt applied" nor
"quilt unapplied".

While addressing all such cases would certainly be possible, that
would require a significant amount of work, and would come with
performance penalties. It would also be difficult to be certain that
all issues have been found and addressed. So it seems more reasonable
to simply spot such manual changes to the series file and ask the user
to pop all patches to start from a clean state as needed.

2 files changed, 76 insertions, 3 deletions

diff --git a/quilt/scripts/patchfns.in b/quilt/scripts/patchfns.in
index 91012ec..f3baa29 100644
--- a/quilt/scripts/patchfns.in
+++ b/quilt/scripts/patchfns.in
@@ -953,6 +953,24 @@ version_check()
 	return 1
 }
 
+consistency_check()
+{
+	local top applied patches
+
+	top=$(top_patch)
+	applied=$(applied_before "$top")
+	patches=$(patches_before "$top")
+
+	if [ "$applied" != "$patches" ]
+	then
+		return 1
+	else
+		# Skip check until series file is modified again
+		touch "$DB"
+		return 0
+	fi
+}
+
 print_patch()
 {
 	echo "${QUILT_PATCHES_PREFIX:+$SUBDIR_DOWN$QUILT_PATCHES/}$1"
@@ -1109,10 +1127,21 @@ fi
 
 DB="$QUILT_PC/applied-patches"
 
-if [ -z "$skip_version_check" ] && ! version_check
+if [ -z "$skip_version_check" ]
 then
-	printf $"The working tree was created by an older version of quilt. Please run 'quilt upgrade'.\n" >&2
-	exit 1
+	if ! version_check
+	then
+		printf $"The working tree was created by an older version of quilt. Please run 'quilt upgrade'.\n" >&2
+		exit 1
+	fi
+
+	# Check if series file was modified manually, and if this is the case,
+	# make sure it is still consistent with the applied patches
+	if [ -s "$DB" -a ! "$DB" -nt "$SERIES" ] && [ "$QUILT_COMMAND" != pop ] && ! consistency_check
+	then
+		printf $"The series file no longer matches the applied patches. Please run 'quilt pop -a'.\n" >&2
+		exit 1
+	fi
 fi
 ### Local Variables:
 ### mode: shell-script
diff --git a/test/altered-series.test b/test/altered-series.test
new file mode 100644
index 0000000..5c231f3
--- /dev/null
+++ b/test/altered-series.test
@@ -0,0 +1,44 @@
+# Check that manual changes to the series file are detected
+
+$ mkdir patches
+$ cat > patches/series
+< 01.patch
+< 02.patch
+< 03.patch
+
+$ quilt push -q
+> Applying patch patches/01.patch
+> Patch patches/01.patch does not exist; applied empty patch
+> Now at patch patches/01.patch
+
+$ quilt series -v
+> = patches/01.patch
+>   patches/02.patch
+>   patches/03.patch
+
+# Touch the series file but preserve the order -> OK
+$ touch patches/series
+
+$ quilt series -v
+> = patches/01.patch
+>   patches/02.patch
+>   patches/03.patch
+
+# Change the order of the patch series -> complain
+$ cat > patches/series
+< 03.patch
+< 01.patch
+< 02.patch
+
+$ quilt series -v
+> The series file no longer matches the applied patches. Please run 'quilt pop -a'.
+
+$ quilt pop -a
+> Patch patches/01.patch appears to be empty, removing
+>
+> No patches applied
+
+$ quilt series -v
+>   patches/03.patch
+>   patches/01.patch
+>   patches/02.patch