orlp orlp - 1 month ago 19
C Question

splint debugging parse error

This is my first time using splint (from Ubuntu repositories) and I immediately got hit by a WTF. The error message:

nightcracker@nightcracker-pc:~/c/brainfuck$ splint brainfuck.c
Splint 3.1.2 --- 03 May 2009

brainfuck.c:17:6: Parse Error. (For help on parse errors, see splint -help
parseerrors.)
*** Cannot continue.


Now, apparently it sees something wrong on line 16, column 6. Let's check that out (posting full code):

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

enum {
CELL_CHUNK_SIZE = 1024,
};

typedef unsigned char cell;

int main(int argc, char *argv[]) {
if (argc < 1) {
fprintf(stderr, "ERROR: Not enough arguments\n");
return 1;
}

FILE *srcfile; // source file << THIS LINE APPARENTLY IS WRONG
long srclen; // source file size
char *bf; // brainfuck code file in memory

char *ip; // instruction pointer
cell *cells; // brainfuck cells
cell *newcells; // used for creating a new chunk of cells
cell *cp; // cell pointer
unsigned long numcells = CELL_CHUNK_SIZE; // amount of current cells
unsigned nest; // current nesting
int buf; // i/o buffer

srcfile = fopen(argv[1], "rb");
if (srcfile == NULL) {
fprintf(stderr, "ERROR: Couldn't open source file\n");
return 2;
}

// get source file length
fseek(srcfile, 0, SEEK_END);
srclen = ftell(srcfile);
fseek(srcfile, 0, SEEK_SET);

// allocate memory for source file
bf = malloc(srclen);
if (bf == NULL) {
fprintf(stderr, "ERROR: Couldn't allocate memory for source file\n");
return 3;
}

// read source file in memory
if (srclen != fread(bf, sizeof(char), srclen, srcfile)) {
fprintf(stderr, "ERROR: Error while reading source file\n");
free(bf);
return 4;
}

fclose(srcfile);

cells = malloc(CELL_CHUNK_SIZE * sizeof(cell));
memset(cells, 0, CELL_CHUNK_SIZE);

if (cells == NULL) {
fprintf(stderr, "ERROR: Memory allocation failed\n");
free(bf);
free(cells);
return 5;
}

cp = cells; // cell pointer initialized to most-left cell
ip = bf; // instruction pointer initialized to first character
nest = 0;

while (ip >= bf && ip <= (bf + srclen)) {
switch (*ip) {
case '+':
(*cp)++;
break;
case '-':
(*cp)--;
break;
case '>':
cp++;
if ((cp - cells) == numcells) {
newcells = realloc(cells, (numcells + CELL_CHUNK_SIZE) * sizeof(cell)); // allocate memory for new chunk

if (newcells == NULL) {
fprintf(stderr, "ERROR: Memory allocation failed\n");
free(bf);
free(cells);
return 5;
}

cp = newcells + (cp - cells); // point cell pointer to cell in new chunk
cells = newcells; // point cells to new memory location (if altered)
memset(cp, 0, CELL_CHUNK_SIZE); // initialize new chunk
numcells += CELL_CHUNK_SIZE;
}
break;
case '<':
cp--;
break;
case '.':
putchar(*cp);
break;
case ',':
if ((buf = getchar()) != EOF) {
*cp = (unsigned char) buf;
} else *cp = 0;
break;
case '[':
if (!(*cp)) {
ip++; // move past the opening bracket
while (nest > 0 || *ip != ']') { // skip to matching ]
if (*ip == '[') nest++; // enter nest
if (*ip == ']') nest--; // leave nest (or main loop, in which nesting > 0 fails)

ip++; // move right
}

}
break;
case ']':
if (*cp) {
ip--; // move before the closing bracket
while (nest > 0 || *ip != '[') { // rewind to matching [
if (*ip == '[') nest--; // leave nest (or main loop, in which nesting > 0 fails)
if (*ip == ']') nest++; // enter nest

ip--; // move left
}
ip--; // move before the opening bracket
}
break;
}

ip++; // move to next instruction
}


free(cells);
free(bf);
return 0;
}


Note that this program compiles without errors (
gcc -Wall -std=c99 brainfuck.c
) and runtime behaves normal.

Note: if you are offended by the name brainfuck, live with it. It's a programming language that is named that way by the author and I respect and use that name.

pmg pmg
Answer

Is splint C99 aware?

Try /* ... */ instead of // ... and move declarations to before any code