+/* vi: set sw=4 ts=4: */
+/*
+ * Mini expr implementation for busybox
+ *
+ * based on GNU expr Mike Parker.
+ * Copyright (C) 86, 1991-1997, 1999 Free Software Foundation, Inc.
+ *
+ * Busybox modifications
+ * Copyright (c) 2000 Edward Betts <edward@debian.org>.
+ *
+ * this program is free software; you can redistribute it and/or modify
+ * it under the terms of the gnu general public license as published by
+ * the free software foundation; either version 2 of the license, or
+ * (at your option) any later version.
+ *
+ * this program is distributed in the hope that it will be useful,
+ * but without any warranty; without even the implied warranty of
+ * merchantability or fitness for a particular purpose. see the gnu
+ * general public license for more details.
+ *
+ * you should have received a copy of the gnu general public license
+ * along with this program; if not, write to the free software
+ * foundation, inc., 59 temple place, suite 330, boston, ma 02111-1307 usa
+ *
+ */
+
+/* This program evaluates expressions. Each token (operator, operand,
+ * parenthesis) of the expression must be a seperate argument. The
+ * parser used is a reasonably general one, though any incarnation of
+ * it is language-specific. It is especially nice for expressions.
+ *
+ * No parse tree is needed; a new node is evaluated immediately.
+ * One function can handle multiple operators all of equal precedence,
+ * provided they all associate ((x op x) op x). */
+
+#include "internal.h"
+#include <stdio.h>
+#include <sys/types.h>
+
+#include <regex.h>
+
+/* The kinds of value we can have. */
+enum valtype {
+ integer,
+ string
+};
+typedef enum valtype TYPE;
+
+/* A value is.... */
+struct valinfo {
+ TYPE type; /* Which kind. */
+ union { /* The value itself. */
+ int i;
+ char *s;
+ } u;
+};
+typedef struct valinfo VALUE;
+
+/* The arguments given to the program, minus the program name. */
+static char **args;
+
+static VALUE *docolon (VALUE *sv, VALUE *pv);
+static VALUE *eval (void);
+static VALUE *int_value (int i);
+static VALUE *str_value (char *s);
+static int nextarg (char *str);
+static int null (VALUE *v);
+static int toarith (VALUE *v);
+static void freev (VALUE *v);
+static void tostring (VALUE *v);
+
+int expr_main (int argc, char **argv)
+{
+ VALUE *v;
+
+ if (argc == 1) {
+ fatalError("too few arguments\n");
+ }
+
+ args = argv + 1;
+
+ v = eval ();
+ if (*args)
+ fatalError ("syntax error\n");
+
+ if (v->type == integer)
+ printf ("%d\n", v->u.i);
+ else
+ printf ("%s\n", v->u.s);
+
+ exit (null (v));
+}
+
+/* Return a VALUE for I. */
+
+static VALUE *int_value (int i)
+{
+ VALUE *v;
+
+ v = xmalloc (sizeof(VALUE));
+ v->type = integer;
+ v->u.i = i;
+ return v;
+}
+
+/* Return a VALUE for S. */
+
+static VALUE *str_value (char *s)
+{
+ VALUE *v;
+
+ v = xmalloc (sizeof(VALUE));
+ v->type = string;
+ v->u.s = strdup (s);
+ return v;
+}
+
+/* Free VALUE V, including structure components. */
+
+static void freev (VALUE *v)
+{
+ if (v->type == string)
+ free (v->u.s);
+ free (v);
+}
+
+/* Return nonzero if V is a null-string or zero-number. */
+
+static int null (VALUE *v)
+{
+ switch (v->type) {
+ case integer:
+ return v->u.i == 0;
+ case string:
+ return v->u.s[0] == '\0' || strcmp (v->u.s, "0") == 0;
+ default:
+ abort ();
+ }
+}
+
+/* Coerce V to a string value (can't fail). */
+
+static void tostring (VALUE *v)
+{
+ char *temp;
+
+ if (v->type == integer) {
+ temp = xmalloc (4 * (sizeof (int) / sizeof (char)));
+ sprintf (temp, "%d", v->u.i);
+ v->u.s = temp;
+ v->type = string;
+ }
+}
+
+/* Coerce V to an integer value. Return 1 on success, 0 on failure. */
+
+static int toarith (VALUE *v)
+{
+ int i;
+
+ switch (v->type) {
+ case integer:
+ return 1;
+ case string:
+ i = 0;
+ /* Don't interpret the empty string as an integer. */
+ if (v->u.s == 0)
+ return 0;
+ i = atoi(v->u.s);
+ free (v->u.s);
+ v->u.i = i;
+ v->type = integer;
+ return 1;
+ default:
+ abort ();
+ }
+}
+
+/* Return nonzero if the next token matches STR exactly.
+ STR must not be NULL. */
+
+static int
+nextarg (char *str)
+{
+ if (*args == NULL)
+ return 0;
+ return strcmp (*args, str) == 0;
+}
+
+/* The comparison operator handling functions. */
+
+#define cmpf(name, rel) \
+static int name (l, r) VALUE *l; VALUE *r; \
+{ \
+ if (l->type == string || r->type == string) { \
+ tostring (l); \
+ tostring (r); \
+ return strcmp (l->u.s, r->u.s) rel 0; \
+ } \
+ else \
+ return l->u.i rel r->u.i; \
+}
+ cmpf (less_than, <)
+ cmpf (less_equal, <=)
+ cmpf (equal, ==)
+ cmpf (not_equal, !=)
+ cmpf (greater_equal, >=)
+ cmpf (greater_than, >)
+
+#undef cmpf
+
+/* The arithmetic operator handling functions. */
+
+#define arithf(name, op) \
+static \
+int name (l, r) VALUE *l; VALUE *r; \
+{ \
+ if (!toarith (l) || !toarith (r)) \
+ fatalError ("non-numeric argument\n"); \
+ return l->u.i op r->u.i; \
+}
+
+#define arithdivf(name, op) \
+int name (l, r) VALUE *l; VALUE *r; \
+{ \
+ if (!toarith (l) || !toarith (r)) \
+ fatalError ( "non-numeric argument\n"); \
+ if (r->u.i == 0) \
+ fatalError ( "division by zero\n"); \
+ return l->u.i op r->u.i; \
+}
+
+ arithf (plus, +)
+ arithf (minus, -)
+ arithf (multiply, *)
+ arithdivf (divide, /)
+ arithdivf (mod, %)
+
+#undef arithf
+#undef arithdivf
+
+/* Do the : operator.
+ SV is the VALUE for the lhs (the string),
+ PV is the VALUE for the rhs (the pattern). */
+
+static VALUE *docolon (VALUE *sv, VALUE *pv)
+{
+ VALUE *v;
+ const char *errmsg;
+ struct re_pattern_buffer re_buffer;
+ struct re_registers re_regs;
+ int len;
+
+ tostring (sv);
+ tostring (pv);
+
+ if (pv->u.s[0] == '^') {
+ fprintf (stderr, "\
+warning: unportable BRE: `%s': using `^' as the first character\n\
+of a basic regular expression is not portable; it is being ignored",
+ pv->u.s);
+ }
+
+ len = strlen (pv->u.s);
+ memset (&re_buffer, 0, sizeof (re_buffer));
+ memset (&re_regs, 0, sizeof (re_regs));
+ re_buffer.allocated = 2 * len;
+ re_buffer.buffer = (unsigned char *) xmalloc (re_buffer.allocated);
+ re_buffer.translate = 0;
+ re_syntax_options = RE_SYNTAX_POSIX_BASIC;
+ errmsg = re_compile_pattern (pv->u.s, len, &re_buffer);
+ if (errmsg) {
+ fatalError("%s\n", errmsg);
+ }
+
+ len = re_match (&re_buffer, sv->u.s, strlen (sv->u.s), 0, &re_regs);
+ if (len >= 0) {
+ /* Were \(...\) used? */
+ if (re_buffer.re_nsub > 0) { /* was (re_regs.start[1] >= 0) */
+ sv->u.s[re_regs.end[1]] = '\0';
+ v = str_value (sv->u.s + re_regs.start[1]);
+ }
+ else
+ v = int_value (len);
+ }
+ else {
+ /* Match failed -- return the right kind of null. */
+ if (re_buffer.re_nsub > 0)
+ v = str_value ("");
+ else
+ v = int_value (0);
+ }
+ free (re_buffer.buffer);
+ return v;
+}
+
+/* Handle bare operands and ( expr ) syntax. */
+
+static VALUE *eval7 (void)
+{
+ VALUE *v;
+
+ if (!*args)
+ fatalError ( "syntax error\n");
+
+ if (nextarg ("(")) {
+ args++;
+ v = eval ();
+ if (!nextarg (")"))
+ fatalError ( "syntax error\n");
+ args++;
+ return v;
+ }
+
+ if (nextarg (")"))
+ fatalError ( "syntax error\n");
+
+ return str_value (*args++);
+}
+
+/* Handle match, substr, index, length, and quote keywords. */
+
+static VALUE *eval6 (void)
+{
+ VALUE *l, *r, *v, *i1, *i2;
+
+ if (nextarg ("quote")) {
+ args++;
+ if (!*args)
+ fatalError ( "syntax error\n");
+ return str_value (*args++);
+ }
+ else if (nextarg ("length")) {
+ args++;
+ r = eval6 ();
+ tostring (r);
+ v = int_value (strlen (r->u.s));
+ freev (r);
+ return v;
+ }
+ else if (nextarg ("match")) {
+ args++;
+ l = eval6 ();
+ r = eval6 ();
+ v = docolon (l, r);
+ freev (l);
+ freev (r);
+ return v;
+ }
+ else if (nextarg ("index")) {
+ args++;
+ l = eval6 ();
+ r = eval6 ();
+ tostring (l);
+ tostring (r);
+ v = int_value (strcspn (l->u.s, r->u.s) + 1);
+ if (v->u.i == (int) strlen (l->u.s) + 1)
+ v->u.i = 0;
+ freev (l);
+ freev (r);
+ return v;
+ }
+ else if (nextarg ("substr")) {
+ args++;
+ l = eval6 ();
+ i1 = eval6 ();
+ i2 = eval6 ();
+ tostring (l);
+ if (!toarith (i1) || !toarith (i2)
+ || i1->u.i > (int) strlen (l->u.s)
+ || i1->u.i <= 0 || i2->u.i <= 0)
+ v = str_value ("");
+ else {
+ v = xmalloc (sizeof(VALUE));
+ v->type = string;
+ v->u.s = strncpy ((char *) xmalloc (i2->u.i + 1),
+ l->u.s + i1->u.i - 1, i2->u.i);
+ v->u.s[i2->u.i] = 0;
+ }
+ freev (l);
+ freev (i1);
+ freev (i2);
+ return v;
+ }
+ else
+ return eval7 ();
+}
+
+/* Handle : operator (pattern matching).
+ Calls docolon to do the real work. */
+
+static VALUE *eval5 (void)
+{
+ VALUE *l, *r, *v;
+
+ l = eval6 ();
+ while (nextarg (":")) {
+ args++;
+ r = eval6 ();
+ v = docolon (l, r);
+ freev (l);
+ freev (r);
+ l = v;
+ }
+ return l;
+}
+
+/* Handle *, /, % operators. */
+
+static VALUE *eval4 (void)
+{
+ VALUE *l, *r;
+ int (*fxn) (), val;
+
+ l = eval5 ();
+ while (1) {
+ if (nextarg ("*"))
+ fxn = multiply;
+ else if (nextarg ("/"))
+ fxn = divide;
+ else if (nextarg ("%"))
+ fxn = mod;
+ else
+ return l;
+ args++;
+ r = eval5 ();
+ val = (*fxn) (l, r);
+ freev (l);
+ freev (r);
+ l = int_value (val);
+ }
+}
+
+/* Handle +, - operators. */
+
+static VALUE *eval3 (void)
+{
+ VALUE *l, *r;
+ int (*fxn) (), val;
+
+ l = eval4 ();
+ while (1) {
+ if (nextarg ("+"))
+ fxn = plus;
+ else if (nextarg ("-"))
+ fxn = minus;
+ else
+ return l;
+ args++;
+ r = eval4 ();
+ val = (*fxn) (l, r);
+ freev (l);
+ freev (r);
+ l = int_value (val);
+ }
+}
+
+/* Handle comparisons. */
+
+static VALUE *eval2 (void)
+{
+ VALUE *l, *r;
+ int (*fxn) (), val;
+
+ l = eval3 ();
+ while (1) {
+ if (nextarg ("<"))
+ fxn = less_than;
+ else if (nextarg ("<="))
+ fxn = less_equal;
+ else if (nextarg ("=") || nextarg ("=="))
+ fxn = equal;
+ else if (nextarg ("!="))
+ fxn = not_equal;
+ else if (nextarg (">="))
+ fxn = greater_equal;
+ else if (nextarg (">"))
+ fxn = greater_than;
+ else
+ return l;
+ args++;
+ r = eval3 ();
+ toarith (l);
+ toarith (r);
+ val = (*fxn) (l, r);
+ freev (l);
+ freev (r);
+ l = int_value (val);
+ }
+}
+
+/* Handle &. */
+
+static VALUE *eval1 (void)
+{
+ VALUE *l, *r;
+
+ l = eval2 ();
+ while (nextarg ("&")) {
+ args++;
+ r = eval2 ();
+ if (null (l) || null (r)) {
+ freev (l);
+ freev (r);
+ l = int_value (0);
+ }
+ else
+ freev (r);
+ }
+ return l;
+}
+
+/* Handle |. */
+
+static VALUE *eval (void)
+{
+ VALUE *l, *r;
+
+ l = eval1 ();
+ while (nextarg ("|")) {
+ args++;
+ r = eval1 ();
+ if (null (l)) {
+ freev (l);
+ l = r;
+ }
+ else
+ freev (r);
+ }
+ return l;
+}
projects / platform / upstream / busybox.git / commitdiff