Progress bar test segfaults

Ok, so this is supposed to display a wget-style progress bar. It segfaults and I don't know where. Any help finding it is appreciated. Thanks!

Code:

---

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

inline int getpercent(int a, int b) {
  return (int)((a / b) * 100);
}

/*Dest should be the length of the progress bar*/
/*Returns 0 on error, 1 on success*/
int pbar(const int percent, char *dest) {
  int cur, size, tostop, destlen = strlen(dest);
  size = destlen - 3;
  dest[0] = '|';
  dest[destlen - 2] = '|';
  dest[destlen - 1] = '\0';
  tostop = ((int)((percent / size) * 100));
 
  for (cur = 1; cur <= size; cur++) {
    if (cur <= tostop) dest[cur] = '=';
    else dest[cur] = ' ';
  }
  return 1;
}

void progbar(const int amount) {
  int current, cols = atoi(getenv("COLUMNS"));
  char *bstr = malloc(cols + 1);
  for (current = 0; current < cols; current++) bstr[current] = ' ';
  bstr[cols] = '\0';
  for (current = 0; current < amount; current++) {
    printf("\r%s", pbar(getpercent(current, amount), bstr));
    usleep(500000);
  }
  free(bstr);
  return;
} 

int main(int argc, char **argv) {
  int total;
  scanf("%d", &total);
  progbar(total);
  return 0;
}

---

Are you sure the environment variable COLUMNS is defined?

EDIT: Also, pbar() returns an int, but you're trying to print its return value as a string. That could also cause a segfault.

yeah, apparently that's it.

Code:

---

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

int main() {
        printf("%d\n", atoi(getenv("COLUMNS")));
        return 0;
}

---

that segfaults.

any idea how to do a wget-style progress bar then?

Set the columns in the environment?

Code:

---

itsme@itsme:~/C$ COLUMNS=80
itsme@itsme:~/C$ set | grep COLUMNS
COLUMNS=80
itsme@itsme:~/C$

---

But you're also going to have to the fix the printf() where you call pbar(). You can't print an int as a string.

Another option would be to check if COLUMNS exists and if it doesn't, choose a default value. Something like:

Code:

---

{
  char *colstr = getenv("COLUMNS");

  if(colstr)
    cols = atoi(colstr);
  else
    cols = 40;
}

---

oops yeah lol pbar originally returned a char*
still.... how do i manage to do it without setting them in advance?

> how do i manage to do it without setting them in advance?
Probably with great difficulty.
I mean, what it stdout is redirected to another file (or another program). There is no longer the concept of a terminal with a width.

If there is no COLUMNS, then perhaps look to see if there is a TERM and use that to look up information in the termcap database.

yeah that's what i tried to do the other day (using termcap)
i'm just using this in case my program is run with -v... thought progress bars would be cool :-D

anybody know a really good termcap tutorial? all I need is to get term width.