New commandline/script parser, supports backslash quoting and environment

variable substitution.

Submitted by:	Jordan Hubbard <jkh@freebsd.org>

1 files changed, 190 insertions, 0 deletions

diff --git a/sys/boot/common/interp_parse.c b/sys/boot/common/interp_parse.c
new file mode 100644
index 0000000..ff5c274
--- /dev/null
+++ b/sys/boot/common/interp_parse.c
@@ -0,0 +1,190 @@
+/*
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 
+ * Jordan K. Hubbard
+ * 29 August 1998
+ *
+ *	$Id$
+ * 
+ * The meat of the simple parser.
+ */
+
+#include <stand.h>
+#include <string.h>
+
+/* Forward decls */
+extern char *backslash(char *str);
+
+static void init(int *argcp, char ***argvp);
+static void clean(void);
+static int insert(int *argcp, char *buf);
+static char *variable_lookup(char *name);
+
+#define PARSE_BUFSIZE	1024	/* maximum size of one element */
+#define MAXARGS		20	/* maximum number of elements */
+static char		*args[MAXARGS];
+
+/*
+ * parse: accept a string of input and "parse" it for backslash
+ * substitutions and environment variable expansions (${var}),
+ * returning an argc/argv style vector of whitespace separated
+ * arguments.  Returns 0 on success, 1 on failure (ok, ok, so I
+ * wimped-out on the error codes! :).
+ *
+ * Note that the argv array returned must be freed by the caller, but
+ * we own the space allocated for arguments and will free that on next
+ * invocation.  This allows argv consumers to modify the array if
+ * required.
+ *
+ * NB: environment variables that expand to more than one whitespace
+ * separated token will be returned as a single argv[] element, not
+ * split in turn.  Expanded text is also immune to further backslash
+ * elimination or expansion since this is a one-pass, non-recursive
+ * parser.  You didn't specify more than this so if you want more, ask
+ * me. - jkh
+ */
+
+#define PARSE_FAIL(expr) \
+if (expr) { \
+    printf("fail at line %d\n", __LINE__); \
+    clean(); \
+    free(copy); \
+    free(buf); \
+    return 1; \
+}
+
+/* Accept the usual delimiters for a variable, returning counterpart */
+static char
+isdelim(char ch)
+{
+    if (ch == '{')
+	return '}';
+    else if (ch == '(')
+	return ')';
+    return '\0';
+}
+
+int
+parse(int *argc, char ***argv, char *str)
+{
+    int ac;
+    char *val, *p, *q, *copy = NULL;
+    int i = 0;
+    char token, tmp, *buf;
+    enum { STR, VAR, WHITE } state;
+
+    ac = *argc = 0;
+    if (!str || (p = copy = backslash(str)) == NULL)
+	return 1;
+
+    /* Initialize vector and state */
+    clean();
+    state = STR;
+    buf = malloc(PARSE_BUFSIZE);
+    token = 0;
+
+    /* And awaaaaaaaaay we go! */
+    while (*p) {
+	switch (state) {
+	case STR:
+	    if (isspace(*p)) {
+		state = WHITE;
+		if (i) {
+		    buf[i] = '\0';
+		    PARSE_FAIL(insert(&ac, buf));
+		    i = 0;
+		}
+		++p;
+	    } else if (*p == '$') {
+		token = isdelim(*(p + 1));
+		if (token)
+		    p += 2;
+		else
+		    ++p;
+		state = VAR;
+	    } else {
+		PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
+		buf[i++] = *p++;
+	    }
+	    break;
+
+	case WHITE:
+	    if (isspace(*p))
+		++p;
+	    else
+		state = STR;
+	    break;
+
+	case VAR:
+	    if (token) {
+		PARSE_FAIL((q = index(p, token)) == NULL);
+	    } else {
+		q = p;
+		while (*q && !isspace(*q))
+		    ++q;
+	    }
+	    tmp = *q;
+	    *q = '\0';
+	    if ((val = variable_lookup(p)) != NULL) {
+		int len = strlen(val);
+
+		strncpy(buf + i, val, PARSE_BUFSIZE - (i + 1));
+		i += min(len, sizeof(buf) - 1);
+	    }
+	    *q = tmp;	/* restore value */
+	    p = q + (token ? 1 : 0);
+	    state = STR;
+	    break;
+	}
+    }
+    /* If at end of token, add it */
+    if (i && state == STR) {
+	buf[i] = '\0';
+	PARSE_FAIL(insert(&ac, buf));
+    }
+    args[ac] = NULL;
+    *argc = ac;
+    *argv = malloc((sizeof(char *) * ac + 1));
+    bcopy(args, *argv, sizeof(char *) * ac + 1);
+    free(copy);
+    return 0;
+}
+
+#define MAXARGS	20
+
+/* Clean vector space */
+static void
+clean(void)
+{
+    int		i;
+
+    for (i = 0; i < MAXARGS; i++) {
+	if (args[i] != NULL) {
+	    free(args[i]);
+	    args[i] = NULL;
+	}
+    }
+}
+
+static int
+insert(int *argcp, char *buf)
+{
+    if (*argcp >= MAXARGS)
+	return 1;
+    args[(*argcp)++] = strdup(buf);
+    return 0;
+}
+
+static char *
+variable_lookup(char *name)
+{
+    /* XXX search "special variable" space first? */
+    return (char *)getenv(name);
+}