120 lines
3.4 KiB
C
120 lines
3.4 KiB
C
/* tailf.c -- tail a log file and then follow it
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* Created: Tue Jan 9 15:49:21 1996 by faith@acm.org
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* Copyright 1996, 2003 Rickard E. Faith (faith@acm.org)
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*
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* less -F and tail -f cause a disk access every five seconds. This
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* program avoids this problem by waiting for the file size to change.
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* Hence, the file is not accessed, and the access time does not need to be
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* flushed back to disk. This is sort of a "stealth" tail.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <malloc.h>
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#include <sys/stat.h>
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#include "nls.h"
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static size_t filesize(const char *filename)
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{
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struct stat sb;
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if (!stat(filename, &sb)) return sb.st_size;
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return 0;
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}
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static void tailf(const char *filename, int lines)
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{
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char **buffer;
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int head = 0;
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int tail = 0;
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FILE *str;
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int i;
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if (!(str = fopen(filename, "r"))) {
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fprintf(stderr, _("Cannot open \"%s\" for read\n"), filename);
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perror("");
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exit(1);
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}
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buffer = malloc(lines * sizeof(*buffer));
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for (i = 0; i < lines; i++) buffer[i] = malloc(BUFSIZ + 1);
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while (fgets(buffer[tail], BUFSIZ, str)) {
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if (++tail >= lines) {
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tail = 0;
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head = 1;
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}
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}
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if (head) {
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for (i = tail; i < lines; i++) fputs(buffer[i], stdout);
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for (i = 0; i < tail; i++) fputs(buffer[i], stdout);
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} else {
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for (i = head; i < tail; i++) fputs(buffer[i], stdout);
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}
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fflush(stdout);
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for (i = 0; i < lines; i++) free(buffer[i]);
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free(buffer);
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}
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int main(int argc, char **argv)
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{
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char buffer[BUFSIZ];
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size_t osize, nsize;
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FILE *str;
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const char *filename;
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int count;
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setlocale(LC_ALL, "");
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bindtextdomain(PACKAGE, LOCALEDIR);
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textdomain(PACKAGE);
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if (argc != 2) {
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fprintf(stderr, _("Usage: tailf logfile\n"));
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exit(1);
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}
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filename = argv[1];
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tailf(filename, 10);
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for (osize = filesize(filename);;) {
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nsize = filesize(filename);
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if (nsize != osize) {
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if (!(str = fopen(filename, "r"))) {
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fprintf(stderr, _("Cannot open \"%s\" for read\n"), filename);
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perror(argv[0]);
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exit(1);
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}
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if (!fseek(str, osize, SEEK_SET))
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while ((count = fread(buffer, 1, sizeof(buffer), str)) > 0)
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fwrite(buffer, 1, count, stdout);
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fflush(stdout);
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fclose(str);
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osize = nsize;
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}
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usleep(250000); /* 250mS */
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}
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return 0;
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}
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