121 lines
3.1 KiB
C
121 lines
3.1 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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#include <unistd.h>
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#include <string.h>
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#include <err.h>
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/*
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* cat - concatenate and print
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* Usage: cat [files]
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*/
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/* Print a file that's already been opened. */
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static
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void
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docat(const char *name, int fd)
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{
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char buf[1024];
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int len, wr, wrtot;
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/*
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* As long as we get more than zero bytes, we haven't hit EOF.
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* Zero means EOF. Less than zero means an error occurred.
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* We may read less than we asked for, though, in various cases
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* for various reasons.
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*/
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while ((len = read(fd, buf, sizeof(buf)))>0) {
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/*
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* Likewise, we may actually write less than we attempted
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* to. So loop until we're done.
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*/
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wrtot = 0;
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while (wrtot < len) {
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wr = write(STDOUT_FILENO, buf+wrtot, len-wrtot);
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if (wr<0) {
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err(1, "stdout");
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}
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wrtot += wr;
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}
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}
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/*
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* If we got a read error, print it and exit.
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*/
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if (len<0) {
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err(1, "%s", name);
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}
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}
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/* Print a file by name. */
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static
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void
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cat(const char *file)
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{
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int fd;
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/*
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* "-" means print stdin.
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*/
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if (!strcmp(file, "-")) {
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docat("stdin", STDIN_FILENO);
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return;
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}
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/*
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* Open the file, print it, and close it.
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* Bail out if we can't open it.
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*/
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fd = open(file, O_RDONLY);
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if (fd<0) {
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err(1, "%s", file);
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}
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docat(file, fd);
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close(fd);
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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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if (argc==1) {
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/* No args - just do stdin */
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docat("stdin", STDIN_FILENO);
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}
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else {
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/* Print all the files specified on the command line. */
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int i;
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for (i=1; i<argc; i++) {
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cat(argv[i]);
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}
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}
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return 0;
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}
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