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/* See LICENSE file for copyright and license details. */
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "utf.h"
#include "util.h"
static char mode = 'n';
static int
dropinit(int fd, const char *fname, size_t count)
{
Rune r;
char buf[BUFSIZ], *p;
ssize_t n;
int nr;
if (count < 2)
goto copy;
count--; /* numbering starts at 1 */
while (count && (n = read(fd, buf, sizeof(buf))) > 0) {
switch (mode) {
case 'n': /* lines */
for (p = buf; count && n > 0; p++, n--) {
if (*p == '\n')
count--;
}
break;
case 'c': /* bytes */
if (count > n) {
count -= n;
} else {
p = buf + count;
n -= count;
count = 0;
}
break;
case 'm': /* runes */
for (p = buf; count && n > 0; p += nr, n -= nr, count--) {
nr = charntorune(&r, p, n);
if (!nr) {
/* we don't have a full rune, move
* remaining data to beginning and read
* again */
memmove(buf, p, n);
break;
}
}
break;
}
}
if (count) {
if (n < 0)
weprintf("read %s:", fname);
if (n <= 0)
return n;
}
/* write the rest of the buffer */
if (writeall(1, p, n) < 0)
eprintf("write:");
copy:
switch (concat(fd, fname, 1, "<stdout>")) {
case -1: /* read error */
return -1;
case -2: /* write error */
exit(1);
default:
return 0;
}
}
static int
taketail(int fd, const char *fname, size_t count)
{
static char *buf = NULL;
static size_t size = 0;
char *p;
size_t len = 0, left;
ssize_t n;
if (!count)
return 0;
for (;;) {
if (len + BUFSIZ > size) {
/* make sure we have at least BUFSIZ to read */
size += 2 * BUFSIZ;
buf = erealloc(buf, size);
}
n = read(fd, buf + len, size - len);
if (n < 0) {
weprintf("read %s:", fname);
return -1;
}
if (n == 0)
break;
len += n;
switch (mode) {
case 'n': /* lines */
/* ignore the last character; if it is a newline, it
* ends the last line */
for (p = buf + len - 2, left = count; p >= buf; p--) {
if (*p != '\n')
continue;
left--;
if (!left) {
p++;
break;
}
}
break;
case 'c': /* bytes */
p = count < len ? buf + len - count : buf;
break;
case 'm': /* runes */
for (p = buf + len - 1, left = count; p >= buf; p--) {
/* skip utf-8 continuation bytes */
if ((*p & 0xc0) == 0x80)
continue;
left--;
if (!left)
break;
}
break;
}
if (p > buf) {
len -= p - buf;
memmove(buf, p, len);
}
}
if (writeall(1, buf, len) < 0)
eprintf("write:");
return 0;
}
static void
usage(void)
{
eprintf("usage: %s [-f] [-c num | -m num | -n num | -num] [file ...]\n", argv0);
}
int
main(int argc, char *argv[])
{
struct stat st1, st2;
int fd;
size_t n = 10;
int fflag = 0, ret = 0, newline = 0, many = 0;
char *numstr;
int (*tail)(int, const char *, size_t) = taketail;
ARGBEGIN {
case 'f':
fflag = 1;
break;
case 'c':
case 'm':
case 'n':
mode = ARGC();
numstr = EARGF(usage());
n = MIN(llabs(estrtonum(numstr, LLONG_MIN + 1,
MIN(LLONG_MAX, SIZE_MAX))), SIZE_MAX);
if (strchr(numstr, '+'))
tail = dropinit;
break;
ARGNUM:
n = ARGNUMF();
break;
default:
usage();
} ARGEND
if (!argc) {
if (tail(0, "<stdin>", n) < 0)
ret = 1;
} else {
if ((many = argc > 1) && fflag)
usage();
for (newline = 0; *argv; argc--, argv++) {
if (!strcmp(*argv, "-")) {
*argv = "<stdin>";
fd = 0;
} else if ((fd = open(*argv, O_RDONLY)) < 0) {
weprintf("open %s:", *argv);
ret = 1;
continue;
}
if (many)
printf("%s==> %s <==\n", newline ? "\n" : "", *argv);
if (fstat(fd, &st1) < 0)
eprintf("fstat %s:", *argv);
if (!(S_ISFIFO(st1.st_mode) || S_ISREG(st1.st_mode)))
fflag = 0;
newline = 1;
if (tail(fd, *argv, n) < 0) {
ret = 1;
fflag = 0;
}
if (!fflag) {
if (fd != 0)
close(fd);
continue;
}
for (;;) {
if (concat(fd, *argv, 1, "<stdout>") < 0)
exit(1);
if (fstat(fd, &st2) < 0)
eprintf("fstat %s:", *argv);
if (st2.st_size < st1.st_size) {
fprintf(stderr, "%s: file truncated\n", *argv);
if (lseek(fd, SEEK_SET, 0) < 0)
eprintf("lseek:");
}
st1 = st2;
sleep(1);
}
}
}
return ret;
}