| /* 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 <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 |
| 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)) \ |
| error_msg_and_die ("non-numeric argument"); \ |
| 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)) \ |
| 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; |
| } |