[hackers] [sbase] expr: improvements || Hiltjo Posthuma

From: <git_AT_suckless.org>
Date: Sun, 16 Nov 2014 15:37:37 +0100

commit b3ae1a7b4b9832d1978fe4676758e53887248c5e
Author: Hiltjo Posthuma <hiltjo_AT_codemadness.org>
Date: Sun Nov 16 15:19:50 2014 +0100

    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.

diff --git a/expr.c b/expr.c
index 679ad38..49fa040 100644
--- a/expr.c
+++ b/expr.c
_AT_@ -2,10 +2,11 @@
 #include <inttypes.h>
 #include <limits.h>
 #include <regex.h>
-#include <stdio.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+
 #include "util.h"
 
 enum {
_AT_@ -13,7 +14,7 @@ enum {
 };
 
 typedef struct {
- char *s;
+ char *s;
         intmax_t n;
 } Val;
 
_AT_@ -21,7 +22,7 @@ static void doop(int*, int**, Val*, Val**);
 static Val match(Val, Val);
 static void num(Val);
 static int valcmp(Val, Val);
-static char *valstr(Val, char*);
+static char *valstr(Val, char*, size_t);
 static int yylex(void);
 static int yyparse(int);
 
_AT_@ -29,6 +30,13 @@ static char **args;
 static size_t intlen;
 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
  * vtop points to one past last val
  * guaranteed otop != ops
_AT_@ -40,43 +48,47 @@ doop(int *ops, int **otop, Val *vals, Val **vtop)
         Val ret, a, b;
         int op;
 
- if((*otop)[-1] == '(')
+ if ((*otop)[-1] == '(')
                 enprintf(2, "syntax error: extra (\n");
- if(*vtop - vals < 2)
+ if (*vtop - vals < 2)
                 enprintf(2, "syntax error: missing expression or extra operator\n");
 
- a = (*vtop)[-2];
- b = (*vtop)[-1];
+ a = (*vtop)[-2];
+ b = (*vtop)[-1];
         op = (*otop)[-1];
 
         switch (op) {
- case '|':
- if ( a.s && *a.s) ret = (Val){ a.s , 0 };
- else if(!a.s && a.n) ret = (Val){ NULL, a.n };
- else if( b.s && *b.s) ret = (Val){ b.s , 0 };
- else ret = (Val){ NULL, b.n };
- break;
-
- case '&':
- if(((a.s && *a.s) || a.n) &&
- ((b.s && *b.s) || b.n)) ret = a;
- else ret = (Val){ NULL, 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 '<': ret = (Val){ NULL, valcmp(a, b) < 0 }; break;
- case LE : ret = (Val){ NULL, valcmp(a, b) <= 0 }; break;
- case NE : ret = (Val){ NULL, valcmp(a, b) != 0 }; 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 ':': ret = match(a, b); break;
+ case '|':
+ if (a.s && *a.s)
+ ret = (Val){ a.s, 0 };
+ else if (!a.s && a.n)
+ ret = (Val){ NULL, a.n };
+ else if (b.s && *b.s)
+ ret = (Val){ b.s, 0 };
+ else
+ ret = (Val){ NULL, b.n };
+ break;
+ case '&':
+ if (((a.s && *a.s) || a.n) &&
+ ((b.s && *b.s) || b.n))
+ ret = a;
+ else
+ ret = (Val){ NULL, 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 '<': ret = (Val){ NULL, valcmp(a, b) < 0 }; break;
+ case LE : ret = (Val){ NULL, valcmp(a, b) <= 0 }; break;
+ case NE : ret = (Val){ NULL, valcmp(a, b) != 0 }; 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); ezero(b.n); ret = (Val){ NULL, a.n % b.n }; break;
+
+ case ':': ret = match(a, b); break;
         }
 
         (*vtop)[-2] = ret;
_AT_@ -87,33 +99,29 @@ doop(int *ops, int **otop, Val *vals, Val **vtop)
 static Val
 match(Val vstr, Val vregx)
 {
- char b1[intlen], *str = valstr(vstr , b1);
- char b2[intlen], *regx = valstr(vregx, b2);
+ intmax_t d;
+ 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;
         regmatch_t matches[2];
         char anchreg[strlen(regx) + 2];
 
- sprintf(anchreg, "^%s", regx);
-
- if(regcomp(&re, anchreg, 0))
- enprintf(3, "regcomp failed\n");
+ snprintf(anchreg, sizeof(anchreg), "^%s", regx);
+ enregcomp(3, &re, anchreg, 0);
 
- if(regexec(&re, str, 2, matches, 0))
+ if (regexec(&re, str, 2, matches, 0))
                 return (Val){ (re.re_nsub ? "" : NULL), 0 };
 
- if(re.re_nsub) {
- intmax_t d;
- char *ret, *p;
- regoff_t len = matches[1].rm_eo - matches[1].rm_so + 1;
-
- if(!(ret = malloc(len))) // FIXME: free
- enprintf(3, "malloc failed\n");
-
+ if (re.re_nsub) {
+ len = matches[1].rm_eo - matches[1].rm_so + 1;
+ ret = emalloc(len); /* TODO: free ret */
                 d = strtoimax(ret, &p, 10);
                 strlcpy(ret, str + matches[1].rm_so, len);
 
- if(*ret && !*p)
+ if (*ret && !*p)
                         return (Val){ NULL, d };
                 return (Val){ ret, 0 };
         }
_AT_@ -123,27 +131,27 @@ match(Val vstr, Val vregx)
 static void
 num(Val v)
 {
- if(v.s)
+ if (v.s)
                 enprintf(2, "syntax error: expected integer got `%s'\n", v.s);
 }
 
 static int
 valcmp(Val a, Val b)
 {
- char b1[intlen], *p = valstr(a, b1);
- char b2[intlen], *q = valstr(b, b2);
+ char b1[intlen], *p = valstr(a, b1, sizeof(b1));
+ 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 strcmp(p, q);
 }
 
 static char *
-valstr(Val val, char *buf)
+valstr(Val val, char *buf, size_t bufsiz)
 {
         char *p = val.s;
- if(!p) {
- sprintf(buf, "%"PRIdMAX, val.n);
+ if (!p) {
+ snprintf(buf, bufsiz, "%"PRIdMAX, val.n);
                 p = buf;
         }
         return p;
_AT_@ -155,21 +163,24 @@ yylex(void)
         intmax_t d;
         char *q, *p, *ops = "|&=><+-*/%():";
 
- if(!(p = *args++))
+ if (!(p = *args++))
                 return 0;
 
         d = strtoimax(p, &q, 10);
- if(*p && !*q) {
+ if (*p && !*q) {
                 yylval = (Val){ NULL, d };
                 return VAL;
         }
 
- if(*p && !p[1] && strchr(ops, *p))
+ if (*p && !p[1] && strchr(ops, *p))
                 return *p;
 
- if(strcmp(p, ">=") == 0) return GE;
- if(strcmp(p, "<=") == 0) return LE;
- if(strcmp(p, "!=") == 0) return NE;
+ if (strcmp(p, ">=") == 0)
+ return GE;
+ if (strcmp(p, "<=") == 0)
+ return LE;
+ if (strcmp(p, "!=") == 0)
+ return NE;
 
         yylval = (Val){ p, 0 };
         return VAL;
_AT_@ -192,38 +203,40 @@ yyparse(int argc)
 
         while((type = yylex())) {
                 switch (type) {
- case VAL: *vtop++ = yylval; break;
- case '(': *otop++ = '(' ; break;
- case ')':
- if(last == '(')
- enprintf(2, "syntax error: empty ( )\n");
- while(otop > ops && otop[-1] != '(')
- doop(ops, &otop, vals, &vtop);
- if(otop == ops)
- enprintf(2, "syntax error: extra )\n");
- otop--;
- break;
- default :
- if(prec[last])
- enprintf(2, "syntax error: extra operator\n");
- while(otop > ops && prec[otop[-1]] >= prec[type])
- doop(ops, &otop, vals, &vtop);
- *otop++ = type;
- break;
+ case VAL: *vtop++ = yylval; break;
+ case '(': *otop++ = '(' ; break;
+ case ')':
+ if (last == '(')
+ enprintf(2, "syntax error: empty ( )\n");
+ while(otop > ops && otop[-1] != '(')
+ doop(ops, &otop, vals, &vtop);
+ if (otop == ops)
+ enprintf(2, "syntax error: extra )\n");
+ otop--;
+ break;
+ default :
+ if (prec[last])
+ enprintf(2, "syntax error: extra operator\n");
+ while (otop > ops && prec[otop[-1]] >= prec[type])
+ doop(ops, &otop, vals, &vtop);
+ *otop++ = type;
+ break;
                 }
                 last = type;
         }
         while(otop > ops)
                 doop(ops, &otop, vals, &vtop);
 
- if(vtop == vals)
+ if (vtop == vals)
                 enprintf(2, "syntax error: missing expression\n");
- if(vtop - vals > 1)
+ if (vtop - vals > 1)
                 enprintf(2, "syntax error: extra expression\n");
 
         vtop--;
- if(vtop->s) printf("%s\n" , vtop->s);
- else printf("%"PRIdMAX"\n", vtop->n);
+ if (vtop->s)
+ printf("%s\n", vtop->s);
+ else
+ printf("%"PRIdMAX"\n", vtop->n);
 
         return (vtop->s && *vtop->s) || vtop->n;
 }
_AT_@ -231,11 +244,11 @@ yyparse(int argc)
 int
 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");
 
         args = argv + 1;
- if(*args && !strcmp("--", *args))
+ if (*args && !strcmp("--", *args))
                 ++args;
 
         return !yyparse(argc);
Received on Sun Nov 16 2014 - 15:37:37 CET