aboutsummaryrefslogtreecommitdiff
path: root/coreutils/expr.c
diff options
context:
space:
mode:
Diffstat (limited to 'coreutils/expr.c')
-rw-r--r--coreutils/expr.c504
1 files changed, 504 insertions, 0 deletions
diff --git a/coreutils/expr.c b/coreutils/expr.c
new file mode 100644
index 0000000..2f9c5c1
--- /dev/null
+++ b/coreutils/expr.c
@@ -0,0 +1,504 @@
+/* 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>.
+ * Copyright (C) 2003-2005 Vladimir Oleynik <dzo@simtreas.ru>
+ * - reduced 464 bytes.
+ * - 64 math support
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
+/* This program evaluates expressions. Each token (operator, operand,
+ * parenthesis) of the expression must be a separate 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). */
+
+/* no getopt needed */
+
+#include "libbb.h"
+#include "xregex.h"
+
+#if ENABLE_EXPR_MATH_SUPPORT_64
+typedef int64_t arith_t;
+
+#define PF_REZ "ll"
+#define PF_REZ_TYPE (long long)
+#define STRTOL(s, e, b) strtoll(s, e, b)
+#else
+typedef long arith_t;
+
+#define PF_REZ "l"
+#define PF_REZ_TYPE (long)
+#define STRTOL(s, e, b) strtol(s, e, b)
+#endif
+
+/* TODO: use bb_strtol[l]? It's easier to check for errors... */
+
+/* The kinds of value we can have. */
+enum {
+ INTEGER,
+ STRING
+};
+
+/* A value is.... */
+struct valinfo {
+ smallint type; /* Which kind. */
+ union { /* The value itself. */
+ arith_t i;
+ char *s;
+ } u;
+};
+typedef struct valinfo VALUE;
+
+/* The arguments given to the program, minus the program name. */
+struct globals {
+ char **args;
+};
+#define G (*(struct globals*)&bb_common_bufsiz1)
+
+/* forward declarations */
+static VALUE *eval(void);
+
+
+/* Return a VALUE for I. */
+
+static VALUE *int_value(arith_t i)
+{
+ VALUE *v;
+
+ v = xzalloc(sizeof(VALUE));
+ if (INTEGER) /* otherwise xzaaloc did it already */
+ v->type = INTEGER;
+ v->u.i = i;
+ return v;
+}
+
+/* Return a VALUE for S. */
+
+static VALUE *str_value(const char *s)
+{
+ VALUE *v;
+
+ v = xzalloc(sizeof(VALUE));
+ if (STRING) /* otherwise xzaaloc did it already */
+ v->type = STRING;
+ v->u.s = xstrdup(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)
+{
+ if (v->type == INTEGER)
+ return v->u.i == 0;
+ /* STRING: */
+ return v->u.s[0] == '\0' || LONE_CHAR(v->u.s, '0');
+}
+
+/* Coerce V to a STRING value (can't fail). */
+
+static void tostring(VALUE *v)
+{
+ if (v->type == INTEGER) {
+ v->u.s = xasprintf("%" PF_REZ "d", PF_REZ_TYPE v->u.i);
+ v->type = STRING;
+ }
+}
+
+/* Coerce V to an INTEGER value. Return 1 on success, 0 on failure. */
+
+static bool toarith(VALUE *v)
+{
+ if (v->type == STRING) {
+ arith_t i;
+ char *e;
+
+ /* Don't interpret the empty string as an integer. */
+ /* Currently does not worry about overflow or int/long differences. */
+ i = STRTOL(v->u.s, &e, 10);
+ if ((v->u.s == e) || *e)
+ return 0;
+ free(v->u.s);
+ v->u.i = i;
+ v->type = INTEGER;
+ }
+ return 1;
+}
+
+/* Return str[0]+str[1] if the next token matches STR exactly.
+ STR must not be NULL. */
+
+static int nextarg(const char *str)
+{
+ if (*G.args == NULL || strcmp(*G.args, str) != 0)
+ return 0;
+ return (unsigned char)str[0] + (unsigned char)str[1];
+}
+
+/* The comparison operator handling functions. */
+
+static int cmp_common(VALUE *l, VALUE *r, int op)
+{
+ arith_t ll, rr;
+
+ ll = l->u.i;
+ rr = r->u.i;
+ if (l->type == STRING || r->type == STRING) {
+ tostring(l);
+ tostring(r);
+ ll = strcmp(l->u.s, r->u.s);
+ rr = 0;
+ }
+ /* calculating ll - rr and checking the result is prone to overflows.
+ * We'll do it differently: */
+ if (op == '<')
+ return ll < rr;
+ if (op == ('<' + '='))
+ return ll <= rr;
+ if (op == '=' || (op == '=' + '='))
+ return ll == rr;
+ if (op == '!' + '=')
+ return ll != rr;
+ if (op == '>')
+ return ll > rr;
+ /* >= */
+ return ll >= rr;
+}
+
+/* The arithmetic operator handling functions. */
+
+static arith_t arithmetic_common(VALUE *l, VALUE *r, int op)
+{
+ arith_t li, ri;
+
+ if (!toarith(l) || !toarith(r))
+ bb_error_msg_and_die("non-numeric argument");
+ li = l->u.i;
+ ri = r->u.i;
+ if (op == '+')
+ return li + ri;
+ if (op == '-')
+ return li - ri;
+ if (op == '*')
+ return li * ri;
+ if (ri == 0)
+ bb_error_msg_and_die("division by zero");
+ if (op == '/')
+ return li / ri;
+ return li % ri;
+}
+
+/* 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;
+ regex_t re_buffer;
+ const int NMATCH = 2;
+ regmatch_t re_regs[NMATCH];
+
+ tostring(sv);
+ tostring(pv);
+
+ if (pv->u.s[0] == '^') {
+ bb_error_msg("\
+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);
+ }
+
+ memset(&re_buffer, 0, sizeof(re_buffer));
+ memset(re_regs, 0, sizeof(*re_regs));
+ xregcomp(&re_buffer, pv->u.s, 0);
+
+ /* expr uses an anchored pattern match, so check that there was a
+ * match and that the match starts at offset 0. */
+ if (regexec(&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH
+ && re_regs[0].rm_so == 0
+ ) {
+ /* Were \(...\) used? */
+ if (re_buffer.re_nsub > 0) {
+ sv->u.s[re_regs[1].rm_eo] = '\0';
+ v = str_value(sv->u.s + re_regs[1].rm_so);
+ } else {
+ v = int_value(re_regs[0].rm_eo);
+ }
+ } else {
+ /* Match failed -- return the right kind of null. */
+ if (re_buffer.re_nsub > 0)
+ v = str_value("");
+ else
+ v = int_value(0);
+ }
+//FIXME: sounds like here is a bit missing: regfree(&re_buffer);
+ return v;
+}
+
+/* Handle bare operands and ( expr ) syntax. */
+
+static VALUE *eval7(void)
+{
+ VALUE *v;
+
+ if (!*G.args)
+ bb_error_msg_and_die("syntax error");
+
+ if (nextarg("(")) {
+ G.args++;
+ v = eval();
+ if (!nextarg(")"))
+ bb_error_msg_and_die("syntax error");
+ G.args++;
+ return v;
+ }
+
+ if (nextarg(")"))
+ bb_error_msg_and_die("syntax error");
+
+ return str_value(*G.args++);
+}
+
+/* Handle match, substr, index, length, and quote keywords. */
+
+static VALUE *eval6(void)
+{
+ static const char keywords[] ALIGN1 =
+ "quote\0""length\0""match\0""index\0""substr\0";
+
+ VALUE *r, *i1, *i2;
+ VALUE *l = l; /* silence gcc */
+ VALUE *v = v; /* silence gcc */
+ int key = *G.args ? index_in_strings(keywords, *G.args) + 1 : 0;
+
+ if (key == 0) /* not a keyword */
+ return eval7();
+ G.args++; /* We have a valid token, so get the next argument. */
+ if (key == 1) { /* quote */
+ if (!*G.args)
+ bb_error_msg_and_die("syntax error");
+ return str_value(*G.args++);
+ }
+ if (key == 2) { /* length */
+ r = eval6();
+ tostring(r);
+ v = int_value(strlen(r->u.s));
+ freev(r);
+ } else
+ l = eval6();
+
+ if (key == 3) { /* match */
+ r = eval6();
+ v = docolon(l, r);
+ freev(l);
+ freev(r);
+ }
+ if (key == 4) { /* index */
+ r = eval6();
+ tostring(l);
+ tostring(r);
+ v = int_value(strcspn(l->u.s, r->u.s) + 1);
+ if (v->u.i == (arith_t) strlen(l->u.s) + 1)
+ v->u.i = 0;
+ freev(l);
+ freev(r);
+ }
+ if (key == 5) { /* substr */
+ i1 = eval6();
+ i2 = eval6();
+ tostring(l);
+ if (!toarith(i1) || !toarith(i2)
+ || i1->u.i > (arith_t) 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 = xstrndup(l->u.s + i1->u.i - 1, i2->u.i);
+ }
+ freev(l);
+ freev(i1);
+ freev(i2);
+ }
+ return v;
+
+}
+
+/* Handle : operator (pattern matching).
+ Calls docolon to do the real work. */
+
+static VALUE *eval5(void)
+{
+ VALUE *l, *r, *v;
+
+ l = eval6();
+ while (nextarg(":")) {
+ G.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 op;
+ arith_t val;
+
+ l = eval5();
+ while (1) {
+ op = nextarg("*");
+ if (!op) { op = nextarg("/");
+ if (!op) { op = nextarg("%");
+ if (!op) return l;
+ }}
+ G.args++;
+ r = eval5();
+ val = arithmetic_common(l, r, op);
+ freev(l);
+ freev(r);
+ l = int_value(val);
+ }
+}
+
+/* Handle +, - operators. */
+
+static VALUE *eval3(void)
+{
+ VALUE *l, *r;
+ int op;
+ arith_t val;
+
+ l = eval4();
+ while (1) {
+ op = nextarg("+");
+ if (!op) {
+ op = nextarg("-");
+ if (!op) return l;
+ }
+ G.args++;
+ r = eval4();
+ val = arithmetic_common(l, r, op);
+ freev(l);
+ freev(r);
+ l = int_value(val);
+ }
+}
+
+/* Handle comparisons. */
+
+static VALUE *eval2(void)
+{
+ VALUE *l, *r;
+ int op;
+ arith_t val;
+
+ l = eval3();
+ while (1) {
+ op = nextarg("<");
+ if (!op) { op = nextarg("<=");
+ if (!op) { op = nextarg("=");
+ if (!op) { op = nextarg("==");
+ if (!op) { op = nextarg("!=");
+ if (!op) { op = nextarg(">=");
+ if (!op) { op = nextarg(">");
+ if (!op) return l;
+ }}}}}}
+ G.args++;
+ r = eval3();
+ toarith(l);
+ toarith(r);
+ val = cmp_common(l, r, op);
+ freev(l);
+ freev(r);
+ l = int_value(val);
+ }
+}
+
+/* Handle &. */
+
+static VALUE *eval1(void)
+{
+ VALUE *l, *r;
+
+ l = eval2();
+ while (nextarg("&")) {
+ G.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("|")) {
+ G.args++;
+ r = eval1();
+ if (null(l)) {
+ freev(l);
+ l = r;
+ } else
+ freev(r);
+ }
+ return l;
+}
+
+int expr_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int expr_main(int argc, char **argv)
+{
+ VALUE *v;
+
+ if (argc == 1) {
+ bb_error_msg_and_die("too few arguments");
+ }
+
+ G.args = argv + 1;
+
+ v = eval();
+ if (*G.args)
+ bb_error_msg_and_die("syntax error");
+
+ if (v->type == INTEGER)
+ printf("%" PF_REZ "d\n", PF_REZ_TYPE v->u.i);
+ else
+ puts(v->u.s);
+
+ fflush_stdout_and_exit(null(v));
+}