82 lines
2.5 KiB
C
82 lines
2.5 KiB
C
/*
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* Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
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* The President and Fellows of Harvard College.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* tail.c
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*
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* Outputs a file beginning at a specific location.
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* Usage: tail <file> <location>
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*
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* This may be useful for testing during the file system assignment.
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*/
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#include <unistd.h>
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#include <stdlib.h>
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#include <err.h>
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#define BUFSIZE 1000
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/* Put buffer in data space. We know that the program should allocate as */
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/* much data space as required, but stack space is tight. */
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char buffer[BUFSIZE];
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static
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void
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tail(int file, off_t where, const char *filename)
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{
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int len;
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if (lseek(file, where, SEEK_SET)<0) {
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err(1, "%s", filename);
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}
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while ((len = read(file, buffer, sizeof(buffer))) > 0) {
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write(STDOUT_FILENO, buffer, len);
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}
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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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int file;
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if (argc < 3) {
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errx(1, "Usage: tail <file> <location>");
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}
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file = open(argv[1], O_RDONLY);
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if (file < 0) {
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err(1, "%s", argv[1]);
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}
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tail(file, atoi(argv[2]), argv[1]);
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close(file);
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return 0;
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}
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