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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 | ||
38 | void usage(void); | |
39 | ||
40 | int 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 | ||
114 | replace: | |
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 | ||
132 | void usage(void) | |
133 | { | |
134 | fprintf(stderr, "Usage: %s <dst> <new> <contents> <...>\n", | |
135 | getprogname()); | |
136 | exit(EX_USAGE); | |
137 | } |