sbase/tail.c
Wolfgang Corcoran-Mathe 438d2542e4 tail: Don't print garbage when input contains no newlines.
getline(3) expects newline-terminated input. While glibc's
implementation seems to catch unterminated input and zero the
buffer, other versions (notably musl's) do not.

This is a workaround. Garbage will still be read, but
not printed.
2015-08-30 18:36:19 +01:00

165 lines
3.2 KiB
C

/* See LICENSE file for copyright and license details. */
#include <sys/stat.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "text.h"
#include "utf.h"
#include "util.h"
static char mode = 'n';
static void
dropinit(FILE *fp, const char *str, size_t n)
{
Rune r;
char *buf = NULL;
size_t size = 0, i = 0;
ssize_t len;
if (mode == 'n') {
while (i < n && (len = getline(&buf, &size, fp)) > 0)
if (len > 0 && buf[len - 1] == '\n')
i++;
} else {
while (i < n && (len = efgetrune(&r, fp, str)))
i++;
}
free(buf);
concat(fp, str, stdout, "<stdout>");
}
static void
taketail(FILE *fp, const char *str, size_t n)
{
Rune *r = NULL;
char **ring = NULL;
size_t i, j, *size = NULL;
int seenln = 0;
if (!n)
return;
if (mode == 'n') {
ring = ecalloc(n, sizeof(*ring));
size = ecalloc(n, sizeof(*size));
for (i = j = 0; getline(ring + i, size + i, fp) > 0; seenln = 1)
i = j = (i + 1) % n;
} else {
r = ecalloc(n, sizeof(*r));
for (i = j = 0; efgetrune(&r[i], fp, str); )
i = j = (i + 1) % n;
}
if (ferror(fp))
eprintf("%s: read error:", str);
do {
if (seenln && ring && ring[j]) {
fputs(ring[j], stdout);
free(ring[j]);
} else if (r) {
efputrune(&r[j], stdout, "<stdout>");
}
} while ((j = (j + 1) % n) != i);
free(ring);
free(size);
free(r);
}
static void
usage(void)
{
eprintf("usage: %s [-f] [-c num | -n num | -num] [file ...]\n", argv0);
}
int
main(int argc, char *argv[])
{
struct stat st1, st2;
FILE *fp;
size_t tmpsize, n = 10;
int fflag = 0, ret = 0, newline = 0, many = 0;
char *numstr, *tmp;
void (*tail)(FILE *, const char *, size_t) = taketail;
ARGBEGIN {
case 'f':
fflag = 1;
break;
case 'c':
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)
tail(stdin, "<stdin>", n);
else {
if ((many = argc > 1) && fflag)
usage();
for (newline = 0; *argv; argc--, argv++) {
if (!strcmp(*argv, "-")) {
*argv = "<stdin>";
fp = stdin;
} else if (!(fp = fopen(*argv, "r"))) {
weprintf("fopen %s:", *argv);
ret = 1;
continue;
}
if (many)
printf("%s==> %s <==\n", newline ? "\n" : "", *argv);
if (stat(*argv, &st1) < 0)
eprintf("stat %s:", *argv);
if (!(S_ISFIFO(st1.st_mode) || S_ISREG(st1.st_mode)))
fflag = 0;
newline = 1;
tail(fp, *argv, n);
if (!fflag) {
if (fp != stdin && fshut(fp, *argv))
ret = 1;
continue;
}
for (tmp = NULL, tmpsize = 0;;) {
while (getline(&tmp, &tmpsize, fp) > 0) {
fputs(tmp, stdout);
fflush(stdout);
}
if (ferror(fp))
eprintf("readline %s:", *argv);
clearerr(fp);
/* ignore error in case file was removed, we continue
* tracking the existing open file descriptor */
if (!stat(*argv, &st2)) {
if (st2.st_size < st1.st_size) {
fprintf(stderr, "%s: file truncated\n", *argv);
rewind(fp);
}
st1 = st2;
}
sleep(1);
}
}
}
ret |= fshut(stdin, "<stdin>") | fshut(stdout, "<stdout>");
return ret;
}