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/* Copyright (c) 2023-2026 Markus Uhlin <markus.uhlin@icloud.com>
All rights reserved.
Permission to use, copy, modify, and distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE. */
#include <sys/stat.h>
#include <sys/types.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
//lint -sem(err, r_no)
//lint -sem(errx, r_no)
static const off_t one_megabyte = 1048576;
static void
usage(const char *exe)
{
(void) fprintf(stderr, "usage: %s <filename> <megabytes>\n", exe);
exit(1);
}
int
main(int argc, char *argv[])
{
FILE *fp = NULL;
char *ep = NULL;
const int maxchars = 1024;
int c, i;
long int lval = 0;
off_t maxfile = 0;
struct stat sb = { 0 };
if (argc != 3)
usage(argv[0]);
else if (geteuid() == 0)
errx(1, "running the program as root is forbidden");
errno = 0;
lval = strtol(argv[2], &ep, 10);
if (argv[2][0] == '\0' || *ep != '\0')
errx(1, "argument 2 not a number");
else if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN))
errx(1, "megabytes out of range");
else if (lval < 1 || lval > 300)
errx(1, "megabytes out of range");
maxfile = (lval * one_megabyte);
if ((fp = fopen(argv[1], "a")) == NULL) {
err(1, "fopen");
} else if (stat(argv[1], &sb) == -1) {
warn("stat");
(void) fclose(fp);
return 1;
} else if (sb.st_size >= maxfile) {
warnx("file too large");
(void) fclose(fp);
return 1;
}
i = 0;
while ((c = fgetc(stdin)) != EOF && i++ < maxchars) {
if (fputc(c, fp) == EOF)
break;
}
return (fclose(fp) != 0 ? 1 : 0);
}
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