[PATCH] pathspec: stop --*-pathspecs impact on internal parse_pathspec() uses

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Normally parse_pathspec() is used on command line arguments where it
can do fancy thing like parsing magic on each argument or adding magic
for all pathspecs based on --*-pathspecs options.

There's another use of parse_pathspec(), where pathspec is needed, but
the input is known to be pure paths. In this case we usually don't
want --*-pathspecs to interfere. And we definitely do not want to
parse magic in these paths, regardless of --literal-pathspecs.

Add new flag PATHSPEC_LITERAL_PATH for this purpose. When it's set,
--*-pathspecs are ignored, no magic is parsed. And if the caller
allows PATHSPEC_LITERAL (i.e. the next calls can take literal magic),
then PATHSPEC_LITERAL will be set.

This fixes cases where git chokes when GIT_*_PATHSPECS are set because
parse_pathspec() indicates it won't take any magic. But
GIT_*_PATHSPECS add them anyway. These are

   export GIT_LITERAL_PATHSPECS=1
   git blame -- something
   git log --follow something
   git log --merge

"git ls-files --with-tree=path" (aka parse_pathspec() in
overlay_tree_on_cache()) is safe because the input is empty, and
producing one pathspec due to PATHSPEC_PREFER_CWD does not take any
magic into account.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Jeff, how about this?
 
 It's similar to your last suggestion (i.e.  relaxing the magic mask
 about literal magic). In addition, it forces literal magic
 unconditionally in this case, which I think is the right thing to do.
 And it will fix other --*-pathspecs as well.

 builtin/blame.c            | 4 +++-
 pathspec.c                 | 9 ++++++++-
 pathspec.h                 | 7 +++++++
 revision.c                 | 3 ++-
 t/t6130-pathspec-noglob.sh | 7 +++++++
 tree-diff.c                | 4 +++-
 6 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/builtin/blame.c b/builtin/blame.c
index 6da7233..1407ae7 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -409,7 +409,9 @@ static struct origin *find_origin(struct scoreboard *sb,
 	paths[0] = origin->path;
 	paths[1] = NULL;
 
-	parse_pathspec(&diff_opts.pathspec, PATHSPEC_ALL_MAGIC, 0, "", paths);
+	parse_pathspec(&diff_opts.pathspec,
+		       PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
+		       PATHSPEC_LITERAL_PATH, "", paths);
 	diff_setup_done(&diff_opts);
 
 	if (is_null_sha1(origin->commit->object.sha1))
diff --git a/pathspec.c b/pathspec.c
index ad1a9f5..4cf2bd3 100644
--- a/pathspec.c
+++ b/pathspec.c
@@ -128,7 +128,11 @@ static unsigned prefix_pathspec(struct pathspec_item *item,
 		die(_("global 'literal' pathspec setting is incompatible "
 		      "with all other global pathspec settings"));
 
-	if (elt[0] != ':' || literal_global) {
+	if (flags & PATHSPEC_LITERAL_PATH)
+		global_magic = 0;
+
+	if (elt[0] != ':' || literal_global ||
+	    (flags & PATHSPEC_LITERAL_PATH)) {
 		; /* nothing to do */
 	} else if (elt[1] == '(') {
 		/* longhand */
@@ -405,6 +409,9 @@ void parse_pathspec(struct pathspec *pathspec,
 		item[i].magic = prefix_pathspec(item + i, &short_magic,
 						argv + i, flags,
 						prefix, prefixlen, entry);
+		if ((flags & PATHSPEC_LITERAL_PATH) &&
+		    !(magic_mask & PATHSPEC_LITERAL))
+			item[i].magic |= PATHSPEC_LITERAL;
 		if (item[i].magic & magic_mask)
 			unsupported_magic(entry,
 					  item[i].magic & magic_mask,
diff --git a/pathspec.h b/pathspec.h
index 944baeb..a75e924 100644
--- a/pathspec.h
+++ b/pathspec.h
@@ -58,6 +58,13 @@ struct pathspec {
 #define PATHSPEC_STRIP_SUBMODULE_SLASH_EXPENSIVE (1<<5)
 #define PATHSPEC_PREFIX_ORIGIN (1<<6)
 #define PATHSPEC_KEEP_ORDER (1<<7)
+/*
+ * For the callers that just need pure paths from somewhere else, not
+ * from command line. Global --*-pathspecs options are ignored. No
+ * magic is parsed in each pathspec either. If PATHSPEC_LITERAL is
+ * allowed, then it will automatically set for every pathspec.
+ */
+#define PATHSPEC_LITERAL_PATH (1<<8)
 
 extern void parse_pathspec(struct pathspec *pathspec,
 			   unsigned magic_mask,
diff --git a/revision.c b/revision.c
index 0173e01..9b9e22e 100644
--- a/revision.c
+++ b/revision.c
@@ -1372,7 +1372,8 @@ static void prepare_show_merge(struct rev_info *revs)
 			i++;
 	}
 	free_pathspec(&revs->prune_data);
-	parse_pathspec(&revs->prune_data, PATHSPEC_ALL_MAGIC, 0, "", prune);
+	parse_pathspec(&revs->prune_data, PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
+		       PATHSPEC_LITERAL_PATH, "", prune);
 	revs->limited = 1;
 }
 
diff --git a/t/t6130-pathspec-noglob.sh b/t/t6130-pathspec-noglob.sh
index ea00d71..6583532 100755
--- a/t/t6130-pathspec-noglob.sh
+++ b/t/t6130-pathspec-noglob.sh
@@ -108,6 +108,13 @@ test_expect_success 'no-glob environment variable works' '
 	test_cmp expect actual
 '
 
+test_expect_success 'blame takes global pathspec flags' '
+	git --literal-pathspecs blame -- foo &&
+	git --icase-pathspecs   blame -- foo &&
+	git --glob-pathspecs    blame -- foo &&
+	git --noglob-pathspecs  blame -- foo
+'
+
 test_expect_success 'setup xxx/bar' '
 	mkdir xxx &&
 	test_commit xxx xxx/bar
diff --git a/tree-diff.c b/tree-diff.c
index ccf9d7c..456660c 100644
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -254,7 +254,9 @@ static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, co
 			path[0] = p->one->path;
 			path[1] = NULL;
 			free_pathspec(&opt->pathspec);
-			parse_pathspec(&opt->pathspec, PATHSPEC_ALL_MAGIC, 0, "", path);
+			parse_pathspec(&opt->pathspec,
+				       PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
+				       PATHSPEC_LITERAL_PATH, "", path);
 
 			/*
 			 * The caller expects us to return a set of vanilla
-- 
1.8.2.83.gc99314b