/* cat.c -- provides a routine to output the contents of the named files in either a buffered or unbuffered fashion. */
/* Accepts the following parameters:                                                                                 */
/*     -u: Output should be unbuffered.                                                                              */

/* Returns the following values: */
/*     0: All files were printed successfully. */
/*     1: One or more files could not be opened. */
   

#include "common.h"

/* If mode is set to zero, return a null pointer and print characters directly. Otherwise, return a pointer to a buffer containing */
/* the contents of the file pointed to by fp. The size of the new buffer is stored in the int pointed to by bufsize.               */
char *cat(FILE *fp, const int mode, long unsigned *bufsize)
    {
    char c;
    
    if(!mode)
	{
	static long unsigned int i, finalbuflen, tmpbuflen;
	tmpbuflen = 4096;
	char *arr = malloc(tmpbuflen);
	char *tmparr = 0;
	char *finalarr = 0;
	
	for(i = 0, finalbuflen = 0; (c = fgetc(fp)) != EOF; i++, finalbuflen++)
	    {
	    if(i >= tmpbuflen)
		{
		tmpbuflen *= 2;
		tmparr = malloc(tmpbuflen);
		memcpy(tmparr, arr, tmpbuflen/2);
		free(arr);
		arr = tmparr;
		}
	    
	    arr[i] = c;
	    }

	finalarr = malloc(finalbuflen);
	memcpy(finalarr, arr, finalbuflen);
	free(arr);
	arr = finalarr;
	*bufsize = finalbuflen;
	return arr;
	}
    else
	{
	for(;(c = fgetc(fp)) != EOF;)
	    {
	    putchar(c);
	    }
	}
    
    return NULL;
    }

int main(int argc, char **argv)
    {
    char *buf, *newbuf, *tmpbuf;
    long unsigned int i, upresence, fppresence;
    i = upresence = fppresence = 0;
    long unsigned int buflen, newbuflen;
    buflen = newbuflen = 0;
    FILE *fp;
    fp = 0;
    buf = newbuf = tmpbuf = 0;
    
    if((upresence = (getopt(argc, argv, ":u") == 'u')))
	{
	i++;
	}
    
    for(i++;argv[i] != NULL; i++)
	{
	if(!strcmp(argv[i], "-"))
	    {
	    fppresence++;
	    newbuf = cat(fopen("/dev/stdin", "r"), upresence, &newbuflen);
	    }
	else if((fp = fopen(argv[i], "r")) != NULL)
	    {
	    fppresence++;
	    newbuf = cat(fp, upresence, &newbuflen);
	    fclose(fp);
	    }
	else
	    {
	    fprintf(stderr, "%s: failed to open %s. Aborting.\n", argv[0], argv[i]);
	    exit(1);
	    }

	/* This is where the actual magic happens. */
	if(!upresence)
	    {
	    /* Here, we copy buf and newbuf end-to-end into a new buffer of size buflen+newbuflen, then store that in buflen and */
	    /* return a pointer to the new buffer. */
	    tmpbuf = arrccat(buf, newbuf, &buflen, newbuflen);
	    free(buf);
	    buf = tmpbuf;
	    }

	}

    if(!fppresence)
	{
	buf = cat(fopen("/dev/stdin", "r"), upresence, &buflen);
	}

    if(!upresence)
	{
	for(i = 0; i < buflen; i++)
	    {
	    putchar(buf[i]);
	    }
	}

    exit(0);
    }