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

char *progname;
char *word = NULL;
int xflag = 0;

void
usage(void)
{
	fprintf(stderr, "Usage: %s [-c WORD [-x]] [FILE...]\n", progname);
	exit(1);
}

char *
readlongline(FILE *fp)
{
	static char *bufp;
	static int size = 8;  /* a realistic value would be 80+2 (LF & NUL) */
	char *cp;
	int offset = 0;

	if (!bufp) {
		if (!(bufp = malloc(size))) {
			fprintf(stderr, "Out of mem\n");
			exit(1);
		}
	}
	*bufp = '\0';
	cp = bufp;
	while (fgets(cp, size-offset, fp)) {
		cp += strlen(cp) - 1;
		if (*cp == '\n') {
			*cp = '\0';
			return bufp;
		}
		size *= 2;
		if (!(bufp = realloc(bufp, size))) {
			fprintf(stderr, "Out of mem\n");
			exit(1);
		}
		offset = strlen(bufp);
		cp = bufp + offset;
	}
	return (*bufp) ? bufp : NULL;  /* possibly incomplete last line */
}

void
rev_line(char *line)
{
	char *cp = line;
	char *ep = line + strlen(line) - 1;
	char tmp;

	while (cp < ep) {
		tmp = *cp; *cp = *ep; *ep = tmp;
		cp++; ep--;
	}
}

void
processfile(FILE *fp)
{
	char *line;

	while ((line = readlongline(fp))) {
		if (!word || (xflag != (strstr(line, word)!=NULL))) {
			rev_line(line);
		}
		printf("%s\n", line);
	}
}

int
main(int argc, char *argv[])
{
	char *cp;
	FILE *fp;

	progname = argv[0];
	argc--; argv++;  /* remove program name */

	for (; *argv && **argv=='-'; argc--,argv++) {
		cp = *argv + 1;
		if (!*cp) {
			/* ``-'' is no option but use stdin as first file */
			break;
		}
		switch (*cp) {
		case 'x':
			if (cp[1]) {
				fprintf(stderr, "Unknown option `-%s'\n", cp);
				usage();
			}
			xflag = 1;
			break;
		case 'c':
			if (cp[1]) {
				word = cp + 1;
			} else if (*++argv) {
				word = *argv;
				argc--;
			} else {
				usage();
			}
			break;
		default:
			usage();
		}
	}

	if (!*argv) {
		processfile(stdin);
		return 0;
	}
	for (; *argv; argv++,argc--) {
		if (strcmp(*argv, "-") == 0) {
			processfile(stdin);
		} else {
			if (!(fp = fopen(*argv, "r"))) {
				fprintf(stderr,"Could not open `%s'\n", *argv);
				continue;
			}
			processfile(fp);
			fclose(fp);
		}
	}

	return 0;
}