/* * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009 * The President and Fellows of Harvard College. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <unistd.h> #include <string.h> #include <err.h> /* * cat - concatenate and print * Usage: cat [files] */ /* Print a file that's already been opened. */ static void docat(const char *name, int fd) { char buf[1024]; int len, wr, wrtot; /* * As long as we get more than zero bytes, we haven't hit EOF. * Zero means EOF. Less than zero means an error occurred. * We may read less than we asked for, though, in various cases * for various reasons. */ while ((len = read(fd, buf, sizeof(buf)))>0) { /* * Likewise, we may actually write less than we attempted * to. So loop until we're done. */ wrtot = 0; while (wrtot < len) { wr = write(STDOUT_FILENO, buf+wrtot, len-wrtot); if (wr<0) { err(1, "stdout"); } wrtot += wr; } } /* * If we got a read error, print it and exit. */ if (len<0) { err(1, "%s", name); } } /* Print a file by name. */ static void cat(const char *file) { int fd; /* * "-" means print stdin. */ if (!strcmp(file, "-")) { docat("stdin", STDIN_FILENO); return; } /* * Open the file, print it, and close it. * Bail out if we can't open it. */ fd = open(file, O_RDONLY); if (fd<0) { err(1, "%s", file); } docat(file, fd); close(fd); } int main(int argc, char *argv[]) { if (argc==1) { /* No args - just do stdin */ docat("stdin", STDIN_FILENO); } else { /* Print all the files specified on the command line. */ int i; for (i=1; i<argc; i++) { cat(argv[i]); } } return 0; }