source: trunk/minix/commands/simple/fold.c@ 20

/* fold - folds long lines              Author: Terrence W. Holm */

/*  Usage:  fold  [ -width ]  [ file ... ]  */

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

#define  TAB            8
#define  DEFAULT_WIDTH  80

int column = 0;                 /* Current column, retained between files  */

_PROTOTYPE(int main, (int argc, char **argv));
_PROTOTYPE(void Fold, (FILE *f, int width));

int main(argc, argv)
int argc;
char *argv[];
{
  int width = DEFAULT_WIDTH;
  int i;
  FILE *f;

  if (argc > 1 && argv[1][0] == '-') {
        if ((width = atoi(&argv[1][1])) <= 0) {
                fprintf(stderr, "Bad number for fold\n");
                exit(1);
        }
        --argc;
        ++argv;
  }
  if (argc == 1)
        Fold(stdin, width);
  else {
        for (i = 1; i < argc; ++i) {
                if ((f = fopen(argv[i], "r")) == NULL) {
                        perror(argv[i]);
                        exit(1);
                }
                Fold(f, width);
                fclose(f);
        }
  }
  return(0);
}


void Fold(f, width)
FILE *f;
int width;
{
  int c;

  while ((c = getc(f)) != EOF) {
        if (c == '\t')
                column = (column / TAB + 1) * TAB;
        else if (c == '\b')
                column = column > 0 ? column - 1 : 0;
        else if (c == '\n' || c == '\r')
                column = 0;
        else
                ++column;

        if (column > width) {
                putchar('\n');
                column = c == '\t' ? TAB : 1;
        }
        putchar(c);
  }
}