sbase/tail.c

93 lines
1.7 KiB
C
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/* See LICENSE file for copyright and license details. */
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "text.h"
#include "util.h"
static void dropinit(FILE *, const char *, long);
static void taketail(FILE *, const char *, long);
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static void
usage(void)
{
eprintf("usage: %s [-n lines] [file]\n", argv0);
}
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int
main(int argc, char *argv[])
{
long n = 10;
FILE *fp;
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void (*tail)(FILE *, const char *, long) = taketail;
char *lines;
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ARGBEGIN {
case 'n':
lines = EARGF(usage());
n = abs(estrtol(lines, 0));
if(lines[0] == '+')
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tail = dropinit;
break;
ARGNUM:
n = ARGNUMF(0);
break;
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default:
usage();
} ARGEND;
if(argc == 0) {
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tail(stdin, "<stdin>", n);
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} else {
for (; argc > 0; argc--, argv++) {
if(!(fp = fopen(argv[0], "r"))) {
weprintf("fopen %s:", argv[0]);
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continue;
}
tail(fp, argv[0], n);
fclose(fp);
}
}
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return EXIT_SUCCESS;
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}
static void
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dropinit(FILE *fp, const char *str, long n)
{
char *buf = NULL;
size_t size = 0;
ssize_t len;
unsigned long i = 0;
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while(i < n && ((len = agetline(&buf, &size, fp) != -1)))
if(len && buf[len - 1] == '\n')
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i++;
free(buf);
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concat(fp, str, stdout, "<stdout>");
}
static void
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taketail(FILE *fp, const char *str, long n)
{
char **ring = NULL;
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long i, j;
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size_t *size = NULL;
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if(!(ring = calloc(n, sizeof *ring)) || !(size = calloc(n, sizeof *size)))
eprintf("calloc:");
for(i = j = 0; agetline(&ring[i], &size[i], fp) != -1; i = j = (i + 1) % n)
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;
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if(ferror(fp))
eprintf("%s: read error:", str);
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do {
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if(ring[j]) {
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fputs(ring[j], stdout);
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free(ring[j]);
}
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} while((j = (j+1)%n) != i);
free(ring);
free(size);
}