102 lines
3.6 KiB
C
102 lines
3.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/bits/safemacros.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/struct/stat.h"
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#include "libc/macros.h"
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#include "libc/runtime/runtime.h"
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#include "libc/stdio/stdio.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/o.h"
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#include "libc/sysv/consts/sig.h"
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#include "libc/time/time.h"
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#include "libc/x/x.h"
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/**
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* @fileoverview tail -f with lower poll rate
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* @see busybox not having interval flag
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*/
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int fd;
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bool exited;
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struct stat st;
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char buf[FRAMESIZE];
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int WriteString(const char *s) {
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return write(1, s, strlen(s));
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}
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void HideCursor(void) {
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WriteString("\e[?25l");
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}
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void ShowCursor(void) {
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WriteString("\e[?25h");
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}
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void OnInt(void) {
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exited = true;
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}
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void OnExit(void) {
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ShowCursor();
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}
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int main(int argc, char *argv[]) {
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char *p;
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ssize_t n;
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size_t i, j;
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bool chopped;
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if (argc < 2) return 1;
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if ((fd = open(argv[1], O_RDONLY)) == -1) return 2;
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if (fstat(fd, &st) == -1) return 3;
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n = st.st_size - MIN(st.st_size, sizeof(buf));
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if ((n = pread(fd, buf, sizeof(buf), n)) == -1) return 4;
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for (p = buf + n, i = 0; i < 10; ++i) {
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p = firstnonnull(memrchr(buf, '\n', p - buf), buf);
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}
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chopped = false;
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if (buf + n - p) ++p;
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i = st.st_size - (buf + n - p);
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atexit(OnExit);
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HideCursor();
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xsigaction(SIGINT, OnInt, 0, 0, 0);
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xsigaction(SIGTERM, OnInt, 0, 0, 0);
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while (!exited) {
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if (fstat(fd, &st) == -1) return 5;
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if (i > st.st_size) i = 0;
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for (; i < st.st_size; i += n) {
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if ((n = pread(fd, buf, sizeof(buf), i)) == -1) return 6;
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j = n;
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while (j && (buf[j - 1] == '\n' || buf[j - 1] == '\r')) --j;
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if (j) {
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if (chopped) {
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WriteString("\r\n");
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}
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write(1, buf, j);
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}
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chopped = j != n;
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}
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dsleep(.01);
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}
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close(fd);
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WriteString("\r\n");
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return 0;
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}
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