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1/*
2 * Copyright (c) 2013 Apple Inc. All rights reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. Please obtain a copy of the License at
10 * http://www.opensource.apple.com/apsl/ and read it before using this
11 * file.
12 *
13 * The Original Code and all software distributed under the License are
14 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
15 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
16 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
18 * Please see the License for the specific language governing rights and
19 * limitations under the License.
20 *
21 * @APPLE_LICENSE_HEADER_END@
22 */
23
24#include <stdio.h>
25#include <stdlib.h>
26#include <unistd.h>
27#include <string.h>
28#include <stdbool.h>
29#include <errno.h>
30#include <err.h>
31#include <sysexits.h>
32
33#include <sys/stat.h>
34#include <sys/fcntl.h>
35#include <sys/param.h>
36#include <sys/time.h>
37
38void usage(void);
39
40int main(int argc, char * argv[])
41{
42 struct stat sb;
43 char *newcontent = NULL;
44 size_t newcontentlength = 0;
45 char *oldcontent = NULL;
46 int ret;
47 int dstfd;
48 const char *dst = NULL;
49 ssize_t readsize, writesize;
50 int i;
51
52 if (argc < 2) {
53 usage();
54 }
55
56 dst = argv[1];
57
58 for (i=2; i < argc; i++) {
59 newcontentlength += strlen(argv[i]) + 1 /* space or newline */;
60 }
61 newcontentlength += 1; /* NUL */
62
63 newcontent = malloc(newcontentlength);
64 if (newcontent == NULL)
65 err(EX_UNAVAILABLE, "malloc() failed");
66
67 newcontent[0] = '\0';
68
69 for (i=2; i < argc; i++) {
70 strlcat(newcontent, argv[i], newcontentlength);
71 if (i < argc - 1) {
72 strlcat(newcontent, " ", newcontentlength);
73 } else {
74 strlcat(newcontent, "\n", newcontentlength);
75 }
76 }
77
78 dstfd = open(dst, O_RDWR | O_CREAT | O_APPEND, DEFFILEMODE);
79 if (dstfd < 0)
80 err(EX_NOINPUT, "open(%s)", dst);
81
82 ret = fstat(dstfd, &sb);
83 if (ret < 0)
84 err(EX_NOINPUT, "fstat(%s)", dst);
85
86 if (!S_ISREG(sb.st_mode))
87 err(EX_USAGE, "%s is not a regular file", dst);
88
89 if (sb.st_size != newcontentlength) {
90 /* obvious new content must be different than old */
91 goto replace;
92 }
93
94 oldcontent = malloc(newcontentlength);
95 if (oldcontent == NULL)
96 err(EX_UNAVAILABLE, "malloc(%lu) failed", newcontentlength);
97
98 readsize = read(dstfd, oldcontent, newcontentlength);
99 if (readsize == -1)
100 err(EX_UNAVAILABLE, "read() failed");
101 else if (readsize != newcontentlength)
102 errx(EX_UNAVAILABLE, "short read of file");
103
104 if (0 == memcmp(oldcontent, newcontent, newcontentlength)) {
105 /* binary comparison succeeded, just exit */
106 free(oldcontent);
107 ret = close(dstfd);
108 if (ret < 0)
109 err(EX_UNAVAILABLE, "close() failed");
110
111 exit(0);
112 }
113
114replace:
115 ret = ftruncate(dstfd, 0);
116 if (ret < 0)
117 err(EX_UNAVAILABLE, "ftruncate() failed");
118
119 writesize = write(dstfd, newcontent, newcontentlength);
120 if (writesize == -1)
121 err(EX_UNAVAILABLE, "write() failed");
122 else if (writesize != newcontentlength)
123 errx(EX_UNAVAILABLE, "short write of file");
124
125 ret = close(dstfd);
126 if (ret < 0)
127 err(EX_NOINPUT, "close(dst)");
128
129 return 0;
130}
131
132void usage(void)
133{
134 fprintf(stderr, "Usage: %s <dst> <new> <contents> <...>\n",
135 getprogname());
136 exit(EX_USAGE);
137}