From a215ab6de0ae34db7311136404d0f9feab34ef04 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Wed, 5 Jul 2023 10:45:56 -0400
Subject: Use strcmp() instead of fnmatch() if possible

---
 src/eval.c  | 21 +++++++++++++++++----
 src/expr.h  | 10 ++++++++++
 src/parse.c | 17 ++++++++++++-----
 3 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/src/eval.c b/src/eval.c
index 5f27681..56753af 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -547,6 +547,20 @@ bool eval_links(const struct bfs_expr *expr, struct bfs_eval *state) {
 	return bfs_expr_cmp(expr, statbuf->nlink);
 }
 
+/** Common code for fnmatch() tests. */
+static bool eval_fnmatch(const struct bfs_expr *expr, const char *str) {
+	if (expr->literal) {
+#ifdef FNM_CASEFOLD
+		if (expr->fnm_flags & FNM_CASEFOLD) {
+			return strcasecmp(expr->pattern, str) == 0;
+		}
+#endif
+		return strcmp(expr->pattern, str) == 0;
+	} else {
+		return fnmatch(expr->pattern, str, expr->fnm_flags) == 0;
+	}
+}
+
 /**
  * -i?lname test.
  */
@@ -568,7 +582,7 @@ bool eval_lname(const struct bfs_expr *expr, struct bfs_eval *state) {
 		goto done;
 	}
 
-	ret = fnmatch(expr->argv[1], name, expr->num) == 0;
+	ret = eval_fnmatch(expr, name);
 
 done:
 	free(name);
@@ -589,7 +603,7 @@ bool eval_name(const struct bfs_expr *expr, struct bfs_eval *state) {
 		name = copy = xbasename(name);
 	}
 
-	bool ret = fnmatch(expr->argv[1], name, expr->num) == 0;
+	bool ret = eval_fnmatch(expr, name);
 	free(copy);
 	return ret;
 }
@@ -598,8 +612,7 @@ bool eval_name(const struct bfs_expr *expr, struct bfs_eval *state) {
  * -i?path test.
  */
 bool eval_path(const struct bfs_expr *expr, struct bfs_eval *state) {
-	const struct BFTW *ftwbuf = state->ftwbuf;
-	return fnmatch(expr->argv[1], ftwbuf->path, expr->num) == 0;
+	return eval_fnmatch(expr, state->ftwbuf->path);
 }
 
 /**
diff --git a/src/expr.h b/src/expr.h
index 356689d..95118b9 100644
--- a/src/expr.h
+++ b/src/expr.h
@@ -143,6 +143,16 @@ struct bfs_expr {
 			};
 		};
 
+		/** String comparisons. */
+		struct {
+			/** String pattern. */
+			const char *pattern;
+			/** fnmatch() flags. */
+			int fnm_flags;
+			/** Whether strcmp() can be used instead of fnmatch(). */
+			bool literal;
+		};
+
 		/** Printing actions. */
 		struct {
 			/** The output stream. */
diff --git a/src/parse.c b/src/parse.c
index 623a528..c225a5b 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -1676,16 +1676,18 @@ static struct bfs_expr *parse_fnmatch(const struct parser_state *state, struct b
 		return NULL;
 	}
 
+	expr->pattern = expr->argv[1];
+
 	if (casefold) {
 #ifdef FNM_CASEFOLD
-		expr->num = FNM_CASEFOLD;
+		expr->fnm_flags = FNM_CASEFOLD;
 #else
 		parse_expr_error(state, expr, "Missing platform support.\n");
 		bfs_expr_free(expr);
 		return NULL;
 #endif
 	} else {
-		expr->num = 0;
+		expr->fnm_flags = 0;
 	}
 
 	// POSIX says, about fnmatch():
@@ -1694,10 +1696,9 @@ static struct bfs_expr *parse_fnmatch(const struct parser_state *state, struct b
 	//     return a non-zero value (indicating either no match or an error).
 	//
 	// But not all implementations obey this, so check for it ourselves.
-	const char *pattern = expr->argv[1];
-	size_t i, len = strlen(pattern);
+	size_t i, len = strlen(expr->pattern);
 	for (i = 0; i < len; ++i) {
-		if (pattern[len - i - 1] != '\\') {
+		if (expr->pattern[len - i - 1] != '\\') {
 			break;
 		}
 	}
@@ -1707,6 +1708,12 @@ static struct bfs_expr *parse_fnmatch(const struct parser_state *state, struct b
 		return expr;
 	}
 
+	// strcmp() can be much faster than fnmatch() since it doesn't have to
+	// parse the pattern, so special-case patterns with no wildcards.
+	//
+	//     https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_13_01
+	expr->literal = strcspn(expr->pattern, "?*\\[") == len;
+
 	return expr;
 }
 
-- 
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