83 lines
1.4 KiB
C
83 lines
1.4 KiB
C
/* See LICENSE file for copyright and license details. */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "text.h"
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#include "util.h"
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static void dropinit(FILE *, const char *, long);
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static void taketail(FILE *, const char *, long);
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static void
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usage(void)
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{
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eprintf("usage: %s [-n lines] [file]\n", argv0);
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}
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int
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main(int argc, char *argv[])
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{
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long n = 10;
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FILE *fp;
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void (*tail)(FILE *, const char *, long) = taketail;
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ARGBEGIN {
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case 'n':
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n = abs(estrtol(EARGF(usage()), 0));
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if(optarg[0] == '+')
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tail = dropinit;
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break;
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default:
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usage();
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} ARGEND;
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if(argc == 0) {
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tail(stdin, "<stdin>", n);
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} else if(argc == 1) {
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if(!(fp = fopen(argv[0], "r")))
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eprintf("fopen %s:", argv[0]);
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tail(fp, argv[0], n);
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fclose(fp);
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} else
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usage();
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return 0;
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}
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void
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dropinit(FILE *fp, const char *str, long n)
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{
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char buf[BUFSIZ];
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long i = 0;
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while(i < n && fgets(buf, sizeof buf, fp))
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if(buf[strlen(buf)-1] == '\n')
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i++;
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concat(fp, str, stdout, "<stdout>");
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}
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void
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taketail(FILE *fp, const char *str, long n)
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{
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char **ring;
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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)))
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eprintf("calloc:");
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for(i = j = 0; afgets(&ring[i], &size[i], fp); i = j = (i+1)%n)
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;
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if(ferror(fp))
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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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}
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} while((j = (j+1)%n) != i);
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free(ring);
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free(size);
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}
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