commit 974179ce006d118086cb91a4c3176d05a60daa60
parent c759756d2e47cf2737949d0007937e467a4825eb
Author: Roberto E. Vargas Caballero <k0ga@shike2.net>
Date: Tue, 25 Nov 2025 16:08:58 +0100
bc: Don't use freopen()
If we use freopen() in bc() then after loading the math library
we cannot recover the original stdin because it previously closed.
While we can still use fdopen(), it is better to just don't close
stdin and use a variable to change the input stream.
Diffstat:
| M | bc.y | | | 62 | ++++++++++++++++++++++++++++++++++++-------------------------- |
1 file changed, 36 insertions(+), 26 deletions(-)
diff --git a/bc.y b/bc.y
@@ -51,7 +51,8 @@ static void writeout(char *);
static size_t used;
static char *yytext, *buff;
-static char *filename = "<stdin>";
+static char *filename;
+static FILE *filep;
static int lineno, nerr;
static jmp_buf recover;
static int nested;
@@ -421,13 +422,13 @@ skipspaces(void)
{
int ch;
- while (isspace(ch = getchar())) {
+ while (isspace(ch = getc(filep))) {
if (ch == '\n') {
lineno++;
break;
}
}
- ungetc(ch, stdin);
+ ungetc(ch, filep);
}
static int
@@ -456,9 +457,9 @@ iden(int ch)
struct keyword *p;
char *bp;
- ungetc(ch, stdin);
+ ungetc(ch, filep);
for (bp = yytext; bp < &yytext[BUFSIZ]; ++bp) {
- ch = getchar();
+ ch = getc(filep);
if (!islower(ch))
break;
*bp = ch;
@@ -467,7 +468,7 @@ iden(int ch)
if (bp == &yytext[BUFSIZ])
yyerror("too long token");
*bp = '\0';
- ungetc(ch, stdin);
+ ungetc(ch, filep);
if (strlen(yytext) == 1) {
strcpy(yylval.id, yytext);
@@ -490,7 +491,7 @@ digits(char *bp)
char *digits = DIGITS, *p;
while (bp < &yytext[BUFSIZ]) {
- ch = getchar();
+ ch = getc(filep);
p = strchr(digits, ch);
if (!p)
break;
@@ -499,7 +500,7 @@ digits(char *bp)
if (bp == &yytext[BUFSIZ])
return NULL;
- ungetc(ch, stdin);
+ ungetc(ch, filep);
return bp;
}
@@ -510,12 +511,12 @@ number(int ch)
int d;
char *bp;
- ungetc(ch, stdin);
+ ungetc(ch, filep);
if ((bp = digits(yytext)) == NULL)
goto toolong;
- if ((ch = getchar()) != '.') {
- ungetc(ch, stdin);
+ if ((ch = getc(filep)) != '.') {
+ ungetc(ch, filep);
goto end;
}
*bp++ = '.';
@@ -541,7 +542,7 @@ string(int ch)
char *bp;
for (bp = yytext; bp < &yytext[BUFSIZ]; ++bp) {
- if ((ch = getchar()) == '"')
+ if ((ch = getc(filep)) == '"')
break;
*bp = ch;
}
@@ -559,10 +560,10 @@ follow(int next, int yes, int no)
{
int ch;
- ch = getchar();
+ ch = getc(filep);
if (ch == next)
return yes;
- ungetc(ch, stdin);
+ ungetc(ch, filep);
return no;
}
@@ -583,7 +584,7 @@ operand(int ch)
case ';':
return ch;
case '.':
- peekc = ungetc(getchar(), stdin);
+ peekc = ungetc(getc(filep), filep);
if (strchr(DIGITS, peekc))
return number(ch);
yylval.str = ".";
@@ -615,7 +616,7 @@ operand(int ch)
case '>':
return follow('=', GE, '>');
case '!':
- if (getchar() == '=')
+ if (getc(filep) == '=')
return NE;
default:
yyerror("invalid operand");
@@ -628,13 +629,13 @@ comment(void)
int c;
for (;;) {
- while ((c = getchar()) != '*') {
+ while ((c = getc(filep)) != '*') {
if (c == '\n')
lineno++;
}
- if ((c = getchar()) == '/')
+ if ((c = getc(filep)) == '/')
break;
- ungetc(c, stdin);
+ ungetc(c, filep);
}
}
@@ -646,7 +647,7 @@ yylex(void)
repeat:
skipspaces();
- ch = getchar();
+ ch = getc(filep);
if (ch == EOF) {
return EOF;
} else if (!isascii(ch)) {
@@ -657,12 +658,12 @@ repeat:
return number(ch);
} else {
if (ch == '/') {
- peekc = getchar();
+ peekc = getc(filep);
if (peekc == '*') {
comment();
goto repeat;
}
- ungetc(peekc, stdin);
+ ungetc(peekc, filep);
}
return operand(ch);
}
@@ -699,10 +700,15 @@ spawn(void)
}
}
-static int
+static void
run(void)
{
- setjmp(recover);
+ if (setjmp(recover)) {
+ if (ferror(filep))
+ eprintf("%s:", filename);
+ if (feof(filep))
+ return;
+ }
yyparse();
}
@@ -715,13 +721,17 @@ bc(char *fname)
used = nested = 0;
macro(HOME, 0);
- if (fname) {
+ if (!fname) {
+ filename = "<stdin>";
+ filep = stdin;
+ } else {
filename = fname;
- if (!freopen(fname, "r", stdin))
+ if ((filep = fopen(fname, "r")) == NULL)
eprintf("%s:", fname);
}
run();
+ fclose(filep);
}
static void
