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DEFINITIONS
This source file includes following definitions.
- docat
- cat
- main
1 /*
2 * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
3 * The President and Fellows of Harvard College.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #include <unistd.h>
31 #include <string.h>
32 #include <err.h>
33
34 /*
35 * cat - concatenate and print
36 * Usage: cat [files]
37 */
38
39
40
41 /* Print a file that's already been opened. */
42 static
43 void
44 docat(const char *name, int fd)
45 {
46 char buf[1024];
47 int len, wr, wrtot;
48
49 /*
50 * As long as we get more than zero bytes, we haven't hit EOF.
51 * Zero means EOF. Less than zero means an error occurred.
52 * We may read less than we asked for, though, in various cases
53 * for various reasons.
54 */
55 while ((len = read(fd, buf, sizeof(buf)))>0) {
56 /*
57 * Likewise, we may actually write less than we attempted
58 * to. So loop until we're done.
59 */
60 wrtot = 0;
61 while (wrtot < len) {
62 wr = write(STDOUT_FILENO, buf+wrtot, len-wrtot);
63 if (wr<0) {
64 err(1, "stdout");
65 }
66 wrtot += wr;
67 }
68 }
69 /*
70 * If we got a read error, print it and exit.
71 */
72 if (len<0) {
73 err(1, "%s", name);
74 }
75 }
76
77 /* Print a file by name. */
78 static
79 void
80 cat(const char *file)
81 {
82 int fd;
83
84 /*
85 * "-" means print stdin.
86 */
87 if (!strcmp(file, "-")) {
88 docat("stdin", STDIN_FILENO);
89 return;
90 }
91
92 /*
93 * Open the file, print it, and close it.
94 * Bail out if we can't open it.
95 */
96 fd = open(file, O_RDONLY);
97 if (fd<0) {
98 err(1, "%s", file);
99 }
100 docat(file, fd);
101 close(fd);
102 }
103
104
105 int
106 main(int argc, char *argv[])
107 {
108 if (argc==1) {
109 /* No args - just do stdin */
110 docat("stdin", STDIN_FILENO);
111 }
112 else {
113 /* Print all the files specified on the command line. */
114 int i;
115 for (i=1; i<argc; i++) {
116 cat(argv[i]);
117 }
118 }
119 return 0;
120 }