implement support for parameter substitution via #/% operators

shell/match.c

@@ -0,0 +1,141 @@
+/*
+ * ##/%% variable matching code ripped out of ash shell for code sharing
+ *
+ * Copyright (c) 1989, 1991, 1993, 1994
+ *      The Regents of the University of California.  All rights reserved.
+ *
+ * Copyright (c) 1997-2005 Herbert Xu <herbert@gondor.apana.org.au>
+ * was re-ported from NetBSD and debianized.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Kenneth Almquist.
+ *
+ * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
+ *
+ * Original BSD copyright notice is retained at the end of this file.
+ */
+
+#ifdef STANDALONE
+# include <stdbool.h>
+# include <stdio.h>
+# include <stdlib.h>
+# include <string.h>
+# include <unistd.h>
+#else
+# include "busybox.h"
+#endif
+#include <fnmatch.h>
+#include "match.h"
+
+#define pmatch(a, b) !fnmatch((a), (b), 0)
+
+char *scanleft(char *string, char *pattern, bool zero)
+{
+	char c;
+	char *loc = string;
+
+	do {
+		int match;
+		const char *s;
+
+		c = *loc;
+		if (zero) {
+			*loc = '\0';
+			s = string;
+		} else
+			s = loc;
+		match = pmatch(pattern, s);
+		*loc = c;
+
+		if (match)
+			return loc;
+
+		loc++;
+	} while (c);
+
+	return NULL;
+}
+
+char *scanright(char *string, char *pattern, bool zero)
+{
+	char c;
+	char *loc = string + strlen(string);
+
+	while (loc >= string) {
+		int match;
+		const char *s;
+
+		c = *loc;
+		if (zero) {
+			*loc = '\0';
+			s = string;
+		} else
+			s = loc;
+		match = pmatch(pattern, s);
+		*loc = c;
+
+		if (match)
+			return loc;
+
+		loc--;
+	}
+
+	return NULL;
+}
+
+#ifdef STANDALONE
+int main(int argc, char *argv[])
+{
+	char *string;
+	char *op;
+	char *pattern;
+	bool zero;
+	char *loc;
+
+	int i;
+
+	if (argc == 1) {
+		puts(
+			"Usage: match <test> [test...]\n\n"
+			"Where a <test> is the form: <string><op><match>\n"
+			"This is to test the shell ${var#val} expression type.\n\n"
+			"e.g. `match 'abc#a*'` -> bc"
+		);
+		return 1;
+	}
+
+	for (i = 1; i < argc; ++i) {
+		size_t off;
+		scan_t scan;
+
+		printf("'%s': ", argv[i]);
+
+		string = strdup(argv[i]);
+		off = strcspn(string, "#%");
+		if (!off) {
+			printf("invalid format\n");
+			free(string);
+			continue;
+		}
+		op = string + off;
+		scan = pick_scan(op[0], op[1], &zero);
+		pattern = op + 1;
+		if (op[0] == op[1])
+			op[1] = '\0', ++pattern;
+		op[0] = '\0';
+
+		loc = scan(string, pattern, zero);
+
+		if (zero) {
+			printf("'%s'\n", loc);
+		} else {
+			*loc = '\0';
+			printf("'%s'\n", string);
+		}
+
+		free(string);
+	}
+
+	return 0;
+}
+#endif