[hackers] [sbase] bc: Don't reuse ids from functions || Roberto E. Vargas Caballero

From: <git_AT_suckless.org>
Date: Thu, 27 Nov 2025 19:34:22 +0100 (CET)

commit 6edcf9948848793f67f04458a72c7825fe9e4138
Author: Roberto E. Vargas Caballero <k0ga_AT_shike2.net>
AuthorDate: Thu Nov 27 19:02:33 2025 +0100
Commit: Roberto E. Vargas Caballero <k0ga_AT_shike2.net>
CommitDate: Thu Nov 27 19:02:33 2025 +0100

    bc: Don't reuse ids from functions
    
    When a function has control flow structures they live forever
    because the function can be called at any moment. But when
    they are in the top level context (in home) then we can reuse
    the ids because they cannot be used after being added to the
    system.

diff --git a/bc.y b/bc.y
index eb98463..e3e0f4d 100644
--- a/bc.y
+++ b/bc.y
_AT_@ -42,7 +42,7 @@ static char *funcode(Macro *, char *, char *, char *);
 static Macro *define(char *, char *);
 static char *retcode(char *);
 static char *brkcode(void);
-static Macro *macro(int, int);
+static Macro *macro(int);
 
 static char *ftn(char *);
 static char *var(char *);
_AT_@ -52,9 +52,9 @@ static void writeout(char *);
 static char *yytext, *buff;
 static char *filename;
 static FILE *filep;
-static int lineno, nerr;
+static int lineno, nerr, flowid;
 static jmp_buf recover;
-static int nested;
+static int nested, inhome;
 static Macro macros[NESTED_MAX];
 int cflag, dflag, lflag, sflag;
 
_AT_@ -146,16 +146,16 @@ stat : exprstat
         | for '(' expr ';' rel ';' expr ')' stat {$$ = forcode($1, $3, $5, $7, $9);}
         ;
 
-while : WHILE {$$ = macro(LOOP, 0);}
+while : WHILE {$$ = macro(LOOP);}
         ;
 
-if : IF {$$ = macro(IF, 0);}
+if : IF {$$ = macro(IF);}
         ;
 
-for : FOR {$$ = macro(LOOP, 0);}
+for : FOR {$$ = macro(LOOP);}
         ;
 
-def : DEF ID {$$ = macro(DEF, funid($2));}
+def : DEF ID {$$ = macro(DEF);}
         ;
 
 parlst : '(' ')' {$$ = code("%%s");}
_AT_@ -333,19 +333,48 @@ err:
 }
 
 static Macro *
-macro(int op, int id)
+macro(int op)
 {
- Macro *d;
+ int preop;
+ Macro *d, *p;
 
         if (nested == NESTED_MAX)
                 yyerror("too much nesting");
 
         d = &macros[nested];
- d->flowid = (op == HOME) ? '0' - 1: d[-1].flowid + 1;
- d->id = (id != 0) ? id : d->flowid;
         d->op = op;
         d->nested = nested++;
 
+ switch (op) {
+ case HOME:
+ d->id = 0;
+ d->flowid = flowid;
+ inhome = 1;
+ break;
+ case DEF:
+ inhome = 0;
+ d->id = funid(yytext);
+ d->flowid = macros[0].flowid;
+ break;
+ default:
+ assert(nested > 1);
+ preop = d[-1].op;
+ d->flowid = d[-1].flowid;
+ if (preop != HOME && preop != DEF) {
+ if (d->flowid == 255)
+ eprintf("too many control flow structures");
+ d->flowid++;
+ }
+ d->id = d->flowid;
+ if (!inhome) {
+ /* populate reserved id */
+ flowid = d->flowid;
+ for (p = d; p != macros; --p)
+ p[-1].flowid++;
+ }
+ break;
+ }
+
         return d;
 }
 
_AT_@ -358,6 +387,7 @@ funcode(Macro *d, char *params, char *vars, char *body)
         t2 = code(t1, body);
 
         nested--;
+ inhome = 0;
         free(vars);
         free(t1);
 
_AT_@ -385,10 +415,10 @@ forcode(Macro *d, char *init, char *cmp, char *inc, char *body)
                  body,
                  inc,
                  estrdup(cmp),
- d->flowid, d->flowid);
+ d->flowid, d->id);
         writeout(s);
 
- s = code("%ss.%s%c", init, cmp, d->flowid);
+ s = code("%ss.%s%c", init, cmp, d->id);
         nested--;
 
         return s;
_AT_@ -402,10 +432,10 @@ whilecode(Macro *d, char *cmp, char *body)
         s = code("[%ss.%s%c]s%c",
                  body,
                  estrdup(cmp),
- d->flowid, d->flowid);
+ d->flowid, d->id);
         writeout(s);
 
- s = code("%s%c", cmp, d->flowid);
+ s = code("%s%c", cmp, d->id);
         nested--;
 
         return s;
_AT_@ -416,10 +446,10 @@ ifcode(Macro *d, char *cmp, char *body)
 {
         char *s;
 
- s = code("[%s]s%c", body, d->flowid);
+ s = code("[%s]s%c", body, d->id);
         writeout(s);
 
- s = code("%s%c", cmp, d->flowid);
+ s = code("%s%c", cmp, d->id);
         nested--;
 
         return s;
_AT_@ -761,7 +791,7 @@ bc(char *fname)
         lineno = 1;
         nested = 0;
 
- macro(HOME, 0);
+ macro(HOME);
         if (!fname) {
                 filename = "<stdin>";
                 filep = stdin;
_AT_@ -841,6 +871,7 @@ main(int argc, char *argv[])
         buff = malloc(BUFSIZ);
         if (!yytext || !buff)
                 eprintf("out of memory\n");
+ flowid = 128;
 
         if (!cflag)
                 spawn();
Received on Thu Nov 27 2025 - 19:34:22 CET