sbase/tail.c

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