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Diffstat (limited to 'expr.c')
| -rw-r--r-- | expr.c | 535 |
1 files changed, 0 insertions, 535 deletions
@@ -1,535 +0,0 @@ -/* 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). */ - -/* no getopt needed */ - -#include <stdio.h> -#include <string.h> -#include <stdlib.h> -#include <regex.h> -#include <sys/types.h> -#include "busybox.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) { - error_msg_and_die("too few arguments"); - } - - args = argv + 1; - - v = eval (); - if (*args) - error_msg_and_die ("syntax error"); - - if (v->type == integer) - printf ("%d\n", v->u.i); - else - puts (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)) \ - error_msg_and_die ("non-numeric argument"); \ - return l->u.i op r->u.i; \ -} - -#define arithdivf(name, op) \ -static int name (l, r) VALUE *l; VALUE *r; \ -{ \ - if (!toarith (l) || !toarith (r)) \ - error_msg_and_die ( "non-numeric argument"); \ - if (r->u.i == 0) \ - error_msg_and_die ( "division by zero"); \ - 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) { - error_msg_and_die("%s", 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) - error_msg_and_die ( "syntax error"); - - if (nextarg ("(")) { - args++; - v = eval (); - if (!nextarg (")")) - error_msg_and_die ( "syntax error"); - args++; - return v; - } - - if (nextarg (")")) - error_msg_and_die ( "syntax error"); - - 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) - error_msg_and_die ( "syntax error"); - 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; -} |