I am having issues with outputting a string correctly that is coming from a 4K read buffer. Here is the code I have currently:

read_4K.c (cannot be modified)

c Syntax (Toggle Plain Text)

int read_4K(char *b)
{
  return read(0, b, 4096);
}

int read_4K(char *b) { return read(0, b, 4096); }

reader.c

c Syntax (Toggle Plain Text)

static char Buffer[4096];
static int Bend = 0;
static int Bptr = 0;
 
int read_string(char *s,int size){
 
	if(Bptr >= Bend){
		Bend = read_4K(Buffer);
		if(!Bend){
			return 0;
		}
		Bptr = 0;
	}
 
	strncpy(s, &Buffer[Bptr], size);
	Bptr += size;
 
}

static char Buffer[4096]; static int Bend = 0; static int Bptr = 0; int read_string(char *s,int size){ if(Bptr >= Bend){ Bend = read_4K(Buffer); if(!Bend){ return 0; } Bptr = 0; } strncpy(s, &Buffer[Bptr], size); Bptr += size; }

bcat.c

c Syntax (Toggle Plain Text)

main(int argc, char **argv)
{
  int i;
  char *str;
  int bsize;
 
  if (argc != 2 || sscanf(argv[1], "%d", &bsize) == 0 || bsize <= 0) {
    fprintf(stderr, "usage: bcat strsize\n");
  }
 
  str = (char *) malloc(sizeof(char)*bsize);
  if (str == NULL) { perror("malloc str"); exit(1); }
 
  while (1) {
    i = read_string(str, bsize);
    if (i == 0) exit(0);
    fwrite(str, 1, i, stdout);
  }
}

main(int argc, char **argv) { int i; char *str; int bsize; if (argc != 2 || sscanf(argv[1], "%d", &bsize) == 0 || bsize <= 0) { fprintf(stderr, "usage: bcat strsize\n"); } str = (char *) malloc(sizeof(char)*bsize); if (str == NULL) { perror("malloc str"); exit(1); } while (1) { i = read_string(str, bsize); if (i == 0) exit(0); fwrite(str, 1, i, stdout); } }

When I execute this I get the following output

> ./bcat2 10 < input1.txt
Up and down the puppñies' hair ñ
Fleas andñ ticks jumñp everywheñre
'Causeñ of originñal sin

input1.txt:
Up and down the puppies' hair
Fleas and ticks jump everywhere
'Cause of original sin


I can't figure out why I am getting these garbage characters after the first read from the buffer... Can anyone help?

Try to use fflush(stdin) before reading. It will flush the standard input(keyboard)

Are you guys on autopilot again? Beg to explain how null termination is related to the OP problem.

When I execute this I get the following output

> ./bcat2 10 < input1.txt
Up and down the puppñies' hair ñ
Fleas andñ ticks jumñp everywheñre
'Causeñ of originñal sin

input1.txt:
Up and down the puppies' hair
Fleas and ticks jump everywhere
'Cause of original sin


I can't figure out why I am getting these garbage characters after the first read from the buffer...

The real problem is that read_string doesn't return anything when it should.

See that garbage character every 10? Which coincides with the size limit with the call to strncpy? Which doesn't automatically null terminate?

I sure do. I also see that the output is produced with fwrite(str, 1, i, stdout) , which cares not of null termination. I am absolutely sure that the counter i is plain wrong.