Merge branch 'nd/attr-match-optim-more'

Start laying the foundation to build the "wildmatch" after we can
agree on its desired semantics.

* nd/attr-match-optim-more:
  attr: more matching optimizations from .gitignore
  gitignore: make pattern parsing code a separate function
  exclude: split pathname matching code into a separate function
  exclude: fix a bug in prefix compare optimization
  exclude: split basename matching code into a separate function
  exclude: stricten a length check in EXC_FLAG_ENDSWITH case

Author: peff

Documentation/gitattributes.txt

@@ -56,6 +56,7 @@ When more than one pattern matches the path, a later line
 overrides an earlier line.  This overriding is done per
 attribute.  The rules how the pattern matches paths are the
 same as in `.gitignore` files; see linkgit:gitignore[5].
+Unlike `.gitignore`, negative patterns are forbidden.
 
 When deciding what attributes are assigned to a path, git
 consults `$GIT_DIR/info/attributes` file (which has the highest

attr.c

@@ -115,6 +115,13 @@ struct attr_state {
 	const char *setto;
 };
 
+struct pattern {
+	const char *pattern;
+	int patternlen;
+	int nowildcardlen;
+	int flags;		/* EXC_FLAG_* */
+};
+
 /*
  * One rule, as from a .gitattributes file.
  *
@@ -131,7 +138,7 @@ struct attr_state {
  */
 struct match_attr {
 	union {
-		char *pattern;
+		struct pattern pat;
 		struct git_attr *attr;
 	} u;
 	char is_macro;
@@ -241,9 +248,16 @@ static struct match_attr *parse_attr_line(const char *line, const char *src,
 	if (is_macro)
 		res->u.attr = git_attr_internal(name, namelen);
 	else {
-		res->u.pattern = (char *)&(res->state[num_attr]);
-		memcpy(res->u.pattern, name, namelen);
-		res->u.pattern[namelen] = 0;
+		char *p = (char *)&(res->state[num_attr]);
+		memcpy(p, name, namelen);
+		res->u.pat.pattern = p;
+		parse_exclude_pattern(&res->u.pat.pattern,
+				      &res->u.pat.patternlen,
+				      &res->u.pat.flags,
+				      &res->u.pat.nowildcardlen);
+		if (res->u.pat.flags & EXC_FLAG_NEGATIVE)
+			die(_("Negative patterns are forbidden in git attributes\n"
+			      "Use '\\!' for literal leading exclamation."));
 	}
 	res->is_macro = is_macro;
 	res->num_attr = num_attr;
@@ -648,25 +662,21 @@ static void prepare_attr_stack(const char *path)
 
 static int path_matches(const char *pathname, int pathlen,
 			const char *basename,
-			const char *pattern,
+			const struct pattern *pat,
 			const char *base, int baselen)
 {
-	if (!strchr(pattern, '/')) {
-		return (fnmatch_icase(pattern, basename, 0) == 0);
+	const char *pattern = pat->pattern;
+	int prefix = pat->nowildcardlen;
+
+	if (pat->flags & EXC_FLAG_NODIR) {
+		return match_basename(basename,
+				      pathlen - (basename - pathname),
+				      pattern, prefix,
+				      pat->patternlen, pat->flags);
 	}
-	/*
-	 * match with FNM_PATHNAME; the pattern has base implicitly
-	 * in front of it.
-	 */
-	if (*pattern == '/')
-		pattern++;
-	if (pathlen < baselen ||
-	    (baselen && pathname[baselen] != '/') ||
-	    strncmp(pathname, base, baselen))
-		return 0;
-	if (baselen != 0)
-		baselen++;
-	return fnmatch_icase(pattern, pathname + baselen, FNM_PATHNAME) == 0;
+	return match_pathname(pathname, pathlen,
+			      base, baselen,
+			      pattern, prefix, pat->patternlen, pat->flags);
 }
 
 static int macroexpand_one(int attr_nr, int rem);
@@ -704,7 +714,7 @@ static int fill(const char *path, int pathlen, const char *basename,
 		if (a->is_macro)
 			continue;
 		if (path_matches(path, pathlen, basename,
-				 a->u.pattern, base, stk->originlen))
+				 &a->u.pat, base, stk->originlen))
 			rem = fill_one("fill", a, rem);
 	}
 	return rem;

dir.c

@@ -308,42 +308,69 @@ static int no_wildcard(const char *string)
 	return string[simple_length(string)] == '\0';
 }
 
+void parse_exclude_pattern(const char **pattern,
+			   int *patternlen,
+			   int *flags,
+			   int *nowildcardlen)
+{
+	const char *p = *pattern;
+	size_t i, len;
+
+	*flags = 0;
+	if (*p == '!') {
+		*flags |= EXC_FLAG_NEGATIVE;
+		p++;
+	}
+	len = strlen(p);
+	if (len && p[len - 1] == '/') {
+		len--;
+		*flags |= EXC_FLAG_MUSTBEDIR;
+	}
+	for (i = 0; i < len; i++) {
+		if (p[i] == '/')
+			break;
+	}
+	if (i == len)
+		*flags |= EXC_FLAG_NODIR;
+	*nowildcardlen = simple_length(p);
+	/*
+	 * we should have excluded the trailing slash from 'p' too,
+	 * but that's one more allocation. Instead just make sure
+	 * nowildcardlen does not exceed real patternlen
+	 */
+	if (*nowildcardlen > len)
+		*nowildcardlen = len;
+	if (*p == '*' && no_wildcard(p + 1))
+		*flags |= EXC_FLAG_ENDSWITH;
+	*pattern = p;
+	*patternlen = len;
+}
+
 void add_exclude(const char *string, const char *base,
 		 int baselen, struct exclude_list *which)
 {
 	struct exclude *x;
-	size_t len;
-	int to_exclude = 1;
-	int flags = 0;
+	int patternlen;
+	int flags;
+	int nowildcardlen;
 
-	if (*string == '!') {
-		to_exclude = 0;
-		string++;
-	}
-	len = strlen(string);
-	if (len && string[len - 1] == '/') {
+	parse_exclude_pattern(&string, &patternlen, &flags, &nowildcardlen);
+	if (flags & EXC_FLAG_MUSTBEDIR) {
 		char *s;
-		x = xmalloc(sizeof(*x) + len);
+		x = xmalloc(sizeof(*x) + patternlen + 1);
 		s = (char *)(x+1);
-		memcpy(s, string, len - 1);
-		s[len - 1] = '\0';
-		string = s;
+		memcpy(s, string, patternlen);
+		s[patternlen] = '\0';
 		x->pattern = s;
-		flags = EXC_FLAG_MUSTBEDIR;
 	} else {
 		x = xmalloc(sizeof(*x));
 		x->pattern = string;
 	}
-	x->to_exclude = to_exclude;
-	x->patternlen = strlen(string);
+	x->patternlen = patternlen;
+	x->nowildcardlen = nowildcardlen;
 	x->base = base;
 	x->baselen = baselen;
 	x->flags = flags;
-	if (!strchr(string, '/'))
-		x->flags |= EXC_FLAG_NODIR;
-	x->nowildcardlen = simple_length(string);
-	if (*string == '*' && no_wildcard(string+1))
-		x->flags |= EXC_FLAG_ENDSWITH;
 	ALLOC_GROW(which->excludes, which->nr + 1, which->alloc);
 	which->excludes[which->nr++] = x;
 }
@@ -505,6 +532,72 @@ static void prep_exclude(struct dir_struct *dir, const char *base, int baselen)
 	dir->basebuf[baselen] = '\0';
 }
 
+int match_basename(const char *basename, int basenamelen,
+		   const char *pattern, int prefix, int patternlen,
+		   int flags)
+{
+	if (prefix == patternlen) {
+		if (!strcmp_icase(pattern, basename))
+			return 1;
+	} else if (flags & EXC_FLAG_ENDSWITH) {
+		if (patternlen - 1 <= basenamelen &&
+		    !strcmp_icase(pattern + 1,
+				  basename + basenamelen - patternlen + 1))
+			return 1;
+	} else {
+		if (fnmatch_icase(pattern, basename, 0) == 0)
+			return 1;
+	}
+	return 0;
+}
+
+int match_pathname(const char *pathname, int pathlen,
+		   const char *base, int baselen,
+		   const char *pattern, int prefix, int patternlen,
+		   int flags)
+{
+	const char *name;
+	int namelen;
+
+	/*
+	 * match with FNM_PATHNAME; the pattern has base implicitly
+	 * in front of it.
+	 */
+	if (*pattern == '/') {
+		pattern++;
+		prefix--;
+	}
+
+	/*
+	 * baselen does not count the trailing slash. base[] may or
+	 * may not end with a trailing slash though.
+	 */
+	if (pathlen < baselen + 1 ||
+	    (baselen && pathname[baselen] != '/') ||
+	    strncmp_icase(pathname, base, baselen))
+		return 0;
+
+	namelen = baselen ? pathlen - baselen - 1 : pathlen;
+	name = pathname + pathlen - namelen;
+
+	if (prefix) {
+		/*
+		 * if the non-wildcard part is longer than the
+		 * remaining pathname, surely it cannot match.
+		 */
+		if (prefix > namelen)
+			return 0;
+
+		if (strncmp_icase(pattern, name, prefix))
+			return 0;
+		pattern += prefix;
+		name    += prefix;
+		namelen -= prefix;
+	}
+
+	return fnmatch_icase(pattern, name, FNM_PATHNAME) == 0;
+}
+
 /* Scan the list and let the last match determine the fate.
  * Return 1 for exclude, 0 for include and -1 for undecided.
  */
@@ -519,9 +612,9 @@ int excluded_from_list(const char *pathname,
 
 	for (i = el->nr - 1; 0 <= i; i--) {
 		struct exclude *x = el->excludes[i];
-		const char *name, *exclude = x->pattern;
-		int to_exclude = x->to_exclude;
-		int namelen, prefix = x->nowildcardlen;
+		const char *exclude = x->pattern;
+		int to_exclude = x->flags & EXC_FLAG_NEGATIVE ? 0 : 1;
+		int prefix = x->nowildcardlen;
 
 		if (x->flags & EXC_FLAG_MUSTBEDIR) {
 			if (*dtype == DT_UNKNOWN)
@@ -531,51 +624,18 @@ int excluded_from_list(const char *pathname,
 		}
 
 		if (x->flags & EXC_FLAG_NODIR) {
-			/* match basename */
-			if (prefix == x->patternlen) {
-				if (!strcmp_icase(exclude, basename))
-					return to_exclude;
-			} else if (x->flags & EXC_FLAG_ENDSWITH) {
-				if (x->patternlen - 1 <= pathlen &&
-				    !strcmp_icase(exclude + 1, pathname + pathlen - x->patternlen + 1))
-					return to_exclude;
-			} else {
-				if (fnmatch_icase(exclude, basename, 0) == 0)
-					return to_exclude;
-			}
-			continue;
-		}
-
-		/* match with FNM_PATHNAME:
-		 * exclude has base (baselen long) implicitly in front of it.
-		 */
-		if (*exclude == '/') {
-			exclude++;
-			prefix--;
-		}
-
-		if (pathlen < x->baselen ||
-		    (x->baselen && pathname[x->baselen-1] != '/') ||
-		    strncmp_icase(pathname, x->base, x->baselen))
+			if (match_basename(basename,
+					   pathlen - (basename - pathname),
+					   exclude, prefix, x->patternlen,
+					   x->flags))
+				return to_exclude;
 			continue;
-
-		namelen = x->baselen ? pathlen - x->baselen : pathlen;
-		name = pathname + pathlen  - namelen;
-
-		/* if the non-wildcard part is longer than the
-		   remaining pathname, surely it cannot match */
-		if (prefix > namelen)
-			continue;
-
-		if (prefix) {
-			if (strncmp_icase(exclude, name, prefix))
-				continue;
-			exclude += prefix;
-			name    += prefix;
-			namelen -= prefix;
 		}
 
-		if (!namelen || !fnmatch_icase(exclude, name, FNM_PATHNAME))
+		assert(x->baselen == 0 || x->base[x->baselen - 1] == '/');
+		if (match_pathname(pathname, pathlen,
+				   x->base, x->baselen ? x->baselen - 1 : 0,
+				   exclude, prefix, x->patternlen, x->flags))
 			return to_exclude;
 	}
 	return -1; /* undecided */

dir.h

@@ -11,6 +11,7 @@ struct dir_entry {
 #define EXC_FLAG_NODIR 1
 #define EXC_FLAG_ENDSWITH 4
 #define EXC_FLAG_MUSTBEDIR 8
+#define EXC_FLAG_NEGATIVE 16
 
 struct exclude_list {
 	int nr;
@@ -21,7 +22,6 @@ struct exclude_list {
 		int nowildcardlen;
 		const char *base;
 		int baselen;
-		int to_exclude;
 		int flags;
 	} **excludes;
 };
@@ -80,6 +80,16 @@ extern int excluded_from_list(const char *pathname, int pathlen, const char *bas
 			      int *dtype, struct exclude_list *el);
 struct dir_entry *dir_add_ignored(struct dir_struct *dir, const char *pathname, int len);
 
+/*
+ * these implement the matching logic for dir.c:excluded_from_list and
+ * attr.c:path_matches()
+ */
+extern int match_basename(const char *, int,
+			  const char *, int, int, int);
+extern int match_pathname(const char *, int,
+			  const char *, int,
+			  const char *, int, int, int);
+
 /*
  * The excluded() API is meant for callers that check each level of leading
  * directory hierarchies with excluded() to avoid recursing into excluded
@@ -97,6 +107,7 @@ extern int path_excluded(struct path_exclude_check *, const char *, int namelen,
 extern int add_excludes_from_file_to_list(const char *fname, const char *base, int baselen,
 					  char **buf_p, struct exclude_list *which, int check_index);
 extern void add_excludes_from_file(struct dir_struct *, const char *fname);
+extern void parse_exclude_pattern(const char **string, int *patternlen, int *flags, int *nowildcardlen);
 extern void add_exclude(const char *string, const char *base,
 			int baselen, struct exclude_list *which);
 extern void free_excludes(struct exclude_list *el);

t/t0003-attributes.sh

@@ -196,6 +196,16 @@ test_expect_success 'root subdir attribute test' '
 	attr_check subdir/a/i unspecified
 '
 
+test_expect_success 'negative patterns' '
+	echo "!f test=bar" >.gitattributes &&
+	test_must_fail git check-attr test -- f
+'
+
+test_expect_success 'patterns starting with exclamation' '
+	echo "\!f test=foo" >.gitattributes &&
+	attr_check "!f" foo
+'
+
 test_expect_success 'setup bare' '
 	git clone --bare . bare.git &&
 	cd bare.git