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expr: improvements 

- handle divide by zero.
- use eregcomp().
- use emalloc().
- use snprintf() for safety and add a buffer size argument to valstr() just
  to be sure.
- code-style fixes.
This commit is contained in:
Hiltjo Posthuma 2014-11-16 15:19:50 +01:00 committed by sin
parent 1822f70d12
commit b3ae1a7b4b
1 changed files with 98 additions and 85 deletions
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121
expr.c
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@ -2,10 +2,11 @@
#include <inttypes.h> #include <inttypes.h>
#include <limits.h> #include <limits.h>
#include <regex.h> #include <regex.h>
#include <stdio.h>
#include <stdint.h> #include <stdint.h>
#include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
#include <string.h> #include <string.h>
#include "util.h" #include "util.h"
enum { enum {
@ -21,7 +22,7 @@ static void doop(int*, int**, Val*, Val**);
static Val match(Val, Val); static Val match(Val, Val);
static void num(Val); static void num(Val);
static int valcmp(Val, Val); static int valcmp(Val, Val);
static char *valstr(Val, char*); static char *valstr(Val, char*, size_t);
static int yylex(void); static int yylex(void);
static int yyparse(int); static int yyparse(int);
@ -29,6 +30,13 @@ static char **args;
static size_t intlen; static size_t intlen;
static Val yylval; static Val yylval;
static void
ezero(intmax_t n)
{
if(n == 0)
enprintf(2, "division by zero\n");
}
/* otop points to one past last op /* otop points to one past last op
* vtop points to one past last val * vtop points to one past last val
* guaranteed otop != ops * guaranteed otop != ops
@ -40,9 +48,9 @@ doop(int *ops, int **otop, Val *vals, Val **vtop)
Val ret, a, b; Val ret, a, b;
int op; int op;
if((*otop)[-1] == '(') if ((*otop)[-1] == '(')
enprintf(2, "syntax error: extra (\n"); enprintf(2, "syntax error: extra (\n");
if(*vtop - vals < 2) if (*vtop - vals < 2)
enprintf(2, "syntax error: missing expression or extra operator\n"); enprintf(2, "syntax error: missing expression or extra operator\n");
a = (*vtop)[-2]; a = (*vtop)[-2];
@ -51,18 +59,22 @@ doop(int *ops, int **otop, Val *vals, Val **vtop)
switch (op) { switch (op) {
case '|': case '|':
if ( a.s && *a.s) ret = (Val){ a.s , 0 }; if (a.s && *a.s)
else if(!a.s && a.n) ret = (Val){ NULL, a.n }; ret = (Val){ a.s, 0 };
else if( b.s && *b.s) ret = (Val){ b.s , 0 }; else if (!a.s && a.n)
else ret = (Val){ NULL, b.n }; ret = (Val){ NULL, a.n };
else if (b.s && *b.s)
ret = (Val){ b.s, 0 };
else
ret = (Val){ NULL, b.n };
break; break;
case '&': case '&':
if(((a.s && *a.s) || a.n) && if (((a.s && *a.s) || a.n) &&
((b.s && *b.s) || b.n)) ret = a; ((b.s && *b.s) || b.n))
else ret = (Val){ NULL, 0 }; ret = a;
else
ret = (Val){ NULL, 0 };
break; break;
case '=': ret = (Val){ NULL, valcmp(a, b) == 0 }; break; case '=': ret = (Val){ NULL, valcmp(a, b) == 0 }; break;
case '>': ret = (Val){ NULL, valcmp(a, b) > 0 }; break; case '>': ret = (Val){ NULL, valcmp(a, b) > 0 }; break;
case GE : ret = (Val){ NULL, valcmp(a, b) >= 0 }; break; case GE : ret = (Val){ NULL, valcmp(a, b) >= 0 }; break;
@ -73,8 +85,8 @@ doop(int *ops, int **otop, Val *vals, Val **vtop)
case '+': num(a); num(b); ret = (Val){ NULL, a.n + b.n }; break; case '+': num(a); num(b); ret = (Val){ NULL, a.n + b.n }; break;
case '-': num(a); num(b); ret = (Val){ NULL, a.n - b.n }; break; case '-': num(a); num(b); ret = (Val){ NULL, a.n - b.n }; break;
case '*': num(a); num(b); ret = (Val){ NULL, a.n * b.n }; break; case '*': num(a); num(b); ret = (Val){ NULL, a.n * b.n }; break;
case '/': num(a); num(b); ret = (Val){ NULL, a.n / b.n }; break; case '/': num(a); num(b); ezero(b.n); ret = (Val){ NULL, a.n / b.n }; break;
case '%': num(a); num(b); ret = (Val){ NULL, a.n % b.n }; break; case '%': num(a); num(b); ezero(b.n); ret = (Val){ NULL, a.n % b.n }; break;
case ':': ret = match(a, b); break; case ':': ret = match(a, b); break;
} }
@ -87,33 +99,29 @@ doop(int *ops, int **otop, Val *vals, Val **vtop)
static Val static Val
match(Val vstr, Val vregx) match(Val vstr, Val vregx)
{ {
char b1[intlen], *str = valstr(vstr , b1); intmax_t d;
char b2[intlen], *regx = valstr(vregx, b2); char *ret, *p;
regoff_t len;
char b1[intlen], *str = valstr(vstr, b1, sizeof(b1));
char b2[intlen], *regx = valstr(vregx, b2, sizeof(b2));
regex_t re; regex_t re;
regmatch_t matches[2]; regmatch_t matches[2];
char anchreg[strlen(regx) + 2]; char anchreg[strlen(regx) + 2];
sprintf(anchreg, "^%s", regx); snprintf(anchreg, sizeof(anchreg), "^%s", regx);
enregcomp(3, &re, anchreg, 0);
if(regcomp(&re, anchreg, 0)) if (regexec(&re, str, 2, matches, 0))
enprintf(3, "regcomp failed\n");
if(regexec(&re, str, 2, matches, 0))
return (Val){ (re.re_nsub ? "" : NULL), 0 }; return (Val){ (re.re_nsub ? "" : NULL), 0 };
if(re.re_nsub) { if (re.re_nsub) {
intmax_t d; len = matches[1].rm_eo - matches[1].rm_so + 1;
char *ret, *p; ret = emalloc(len); /* TODO: free ret */
regoff_t len = matches[1].rm_eo - matches[1].rm_so + 1;
if(!(ret = malloc(len))) // FIXME: free
enprintf(3, "malloc failed\n");
d = strtoimax(ret, &p, 10); d = strtoimax(ret, &p, 10);
strlcpy(ret, str + matches[1].rm_so, len); strlcpy(ret, str + matches[1].rm_so, len);
if(*ret && !*p) if (*ret && !*p)
return (Val){ NULL, d }; return (Val){ NULL, d };
return (Val){ ret, 0 }; return (Val){ ret, 0 };
} }
@ -123,27 +131,27 @@ match(Val vstr, Val vregx)
static void static void
num(Val v) num(Val v)
{ {
if(v.s) if (v.s)
enprintf(2, "syntax error: expected integer got `%s'\n", v.s); enprintf(2, "syntax error: expected integer got `%s'\n", v.s);
} }
static int static int
valcmp(Val a, Val b) valcmp(Val a, Val b)
{ {
char b1[intlen], *p = valstr(a, b1); char b1[intlen], *p = valstr(a, b1, sizeof(b1));
char b2[intlen], *q = valstr(b, b2); char b2[intlen], *q = valstr(b, b2, sizeof(b2));
if(!a.s && !b.s) if (!a.s && !b.s)
return (a.n > b.n) - (a.n < b.n); return (a.n > b.n) - (a.n < b.n);
return strcmp(p, q); return strcmp(p, q);
} }
static char * static char *
valstr(Val val, char *buf) valstr(Val val, char *buf, size_t bufsiz)
{ {
char *p = val.s; char *p = val.s;
if(!p) { if (!p) {
sprintf(buf, "%"PRIdMAX, val.n); snprintf(buf, bufsiz, "%"PRIdMAX, val.n);
p = buf; p = buf;
} }
return p; return p;
@ -155,21 +163,24 @@ yylex(void)
intmax_t d; intmax_t d;
char *q, *p, *ops = "|&=><+-*/%():"; char *q, *p, *ops = "|&=><+-*/%():";
if(!(p = *args++)) if (!(p = *args++))
return 0; return 0;
d = strtoimax(p, &q, 10); d = strtoimax(p, &q, 10);
if(*p && !*q) { if (*p && !*q) {
yylval = (Val){ NULL, d }; yylval = (Val){ NULL, d };
return VAL; return VAL;
} }
if(*p && !p[1] && strchr(ops, *p)) if (*p && !p[1] && strchr(ops, *p))
return *p; return *p;
if(strcmp(p, ">=") == 0) return GE; if (strcmp(p, ">=") == 0)
if(strcmp(p, "<=") == 0) return LE; return GE;
if(strcmp(p, "!=") == 0) return NE; if (strcmp(p, "<=") == 0)
return LE;
if (strcmp(p, "!=") == 0)
return NE;
yylval = (Val){ p, 0 }; yylval = (Val){ p, 0 };
return VAL; return VAL;
@ -195,18 +206,18 @@ yyparse(int argc)
case VAL: *vtop++ = yylval; break; case VAL: *vtop++ = yylval; break;
case '(': *otop++ = '(' ; break; case '(': *otop++ = '(' ; break;
case ')': case ')':
if(last == '(') if (last == '(')
enprintf(2, "syntax error: empty ( )\n"); enprintf(2, "syntax error: empty ( )\n");
while(otop > ops && otop[-1] != '(') while(otop > ops && otop[-1] != '(')
doop(ops, &otop, vals, &vtop); doop(ops, &otop, vals, &vtop);
if(otop == ops) if (otop == ops)
enprintf(2, "syntax error: extra )\n"); enprintf(2, "syntax error: extra )\n");
otop--; otop--;
break; break;
default : default :
if(prec[last]) if (prec[last])
enprintf(2, "syntax error: extra operator\n"); enprintf(2, "syntax error: extra operator\n");
while(otop > ops && prec[otop[-1]] >= prec[type]) while (otop > ops && prec[otop[-1]] >= prec[type])
doop(ops, &otop, vals, &vtop); doop(ops, &otop, vals, &vtop);
*otop++ = type; *otop++ = type;
break; break;
@ -216,14 +227,16 @@ yyparse(int argc)
while(otop > ops) while(otop > ops)
doop(ops, &otop, vals, &vtop); doop(ops, &otop, vals, &vtop);
if(vtop == vals) if (vtop == vals)
enprintf(2, "syntax error: missing expression\n"); enprintf(2, "syntax error: missing expression\n");
if(vtop - vals > 1) if (vtop - vals > 1)
enprintf(2, "syntax error: extra expression\n"); enprintf(2, "syntax error: extra expression\n");
vtop--; vtop--;
if(vtop->s) printf("%s\n" , vtop->s); if (vtop->s)
else printf("%"PRIdMAX"\n", vtop->n); printf("%s\n", vtop->s);
else
printf("%"PRIdMAX"\n", vtop->n);
return (vtop->s && *vtop->s) || vtop->n; return (vtop->s && *vtop->s) || vtop->n;
} }
@ -231,11 +244,11 @@ yyparse(int argc)
int int
main(int argc, char **argv) main(int argc, char **argv)
{ {
if(!(intlen = snprintf(NULL, 0, "%"PRIdMAX, INTMAX_MIN) + 1)) if (!(intlen = snprintf(NULL, 0, "%"PRIdMAX, INTMAX_MIN) + 1))
enprintf(3, "failed to get max digits\n"); enprintf(3, "failed to get max digits\n");
args = argv + 1; args = argv + 1;
if(*args && !strcmp("--", *args)) if (*args && !strcmp("--", *args))
++args; ++args;
return !yyparse(argc); return !yyparse(argc);