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/* rnl - remove final newlines */
#include <sys/stat.h>
#include <sys/types.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int
main(int argc, char *argv[])
{
int c;
int i;
int mode = -1;
char nl = '\n';
while ((c = getopt(argc, argv, "0aso")) != -1)
switch (c) {
case '0': nl = '\0'; break;
case 'a': mode = 0; break;
case 's': mode = -1; break;
case 'o': mode = 1; break;
default:
fprintf(stderr,
"Usage: %s [-0aso] < INPUT writes to stdout\n"
" %s [-0aso] INPUT... modifies files in-place!\n"
" -0 strip NUL bytes instead of newlines\n"
" -a strip all newlines at end\n"
" -s default: strip all but one newline at end\n"
" -o strip one newline at end\n",
argv[0], argv[0]);
exit(1);
}
if (optind == argc) {
/* pipe mode stdin -> stdout */
off_t n = 0;
while ((c = getchar()) != EOF) {
if (c == nl) {
n++;
continue;
}
for (i = 0; i < n; i++)
putchar(nl);
n = 0;
putchar(c);
}
if (mode == 1)
for (i = 0; i < n - 1; i++)
putchar(nl);
else if (mode == -1 && n > 0)
putchar(nl);
/* else (mode == 0) ; noop */
return 0;
}
/* in-place mode */
for (i = optind; i < argc; i++) {
int fd = open(argv[i], O_RDWR);
if (fd < 0)
perror("rnl: open");
off_t pos = lseek(fd, 0, SEEK_END);
if (mode == 1) {
if (pos > 0) {
char buf;
if (pread(fd, &buf, 1, pos - 1) != 1)
perror("rnl: pread");
if (buf == nl)
if (ftruncate(fd, pos - 1) < 0)
perror("rnl: ftruncate");
}
} else {
char buf[1024];
off_t n = 0;
off_t endpos = pos;
ssize_t rd;
do {
off_t l = sizeof buf;
if (pos > l)
pos -= l;
else {
l = pos;
pos = 0;
}
rd = pread(fd, buf, l, pos);
while (rd > 0 && buf[--rd] == nl)
n++;
} while (rd == 0 && n > 0 && pos > 0);
if (rd < 0)
perror("rnl: pread");
if (mode == -1 && n > 0)
n--;
if (n > 0)
if (ftruncate(fd, endpos - n) < 0)
perror("rnl: ftruncate");
}
close(fd);
}
return 0;
}
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