1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <ctype.h>
18 #include <errno.h>
19 #include <getopt.h>
20 #include <limits.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24
25 /*
26 * Append a tag to a property value in a .prop file if it isn't already there.
27 * Normally used to modify build properties to record incremental updates.
28 */
29
30 // Return nonzero if the tag should be added to this line.
should_tag(const char * line,const char * propname)31 int should_tag(const char *line, const char *propname) {
32 const char *prop = strstr(line, propname);
33 if (prop == NULL) return 0;
34
35 // Make sure this is actually the property name (not an accidental hit)
36 const char *ptr;
37 for (ptr = line; ptr < prop && isspace(*ptr); ++ptr) ;
38 if (ptr != prop) return 0; // Must be at the beginning of the line
39
40 for (ptr += strlen(propname); *ptr != '\0' && isspace(*ptr); ++ptr) ;
41 return (*ptr == '='); // Must be followed by a '='
42 }
43
44 // Remove existing tags from the line, return the following number (if any)
remove_tag(char * line,const char * tag)45 int remove_tag(char *line, const char *tag) {
46 char *pos = strstr(line, tag);
47 if (pos == NULL) return 0;
48
49 char *end;
50 int num = strtoul(pos + strlen(tag), &end, 10);
51 strcpy(pos, end);
52 return num;
53 }
54
55 // Write line to output with the tag added, adding a number (if >0)
write_tagged(FILE * out,const char * line,const char * tag,int number)56 void write_tagged(FILE *out, const char *line, const char *tag, int number) {
57 const char *end = line + strlen(line);
58 while (end > line && isspace(end[-1])) --end;
59 if (number > 0) {
60 fprintf(out, "%.*s%s%d%s", end - line, line, tag, number, end);
61 } else {
62 fprintf(out, "%.*s%s%s", end - line, line, tag, end);
63 }
64 }
65
main(int argc,char ** argv)66 int main(int argc, char **argv) {
67 const char *filename = "/system/build.prop";
68 const char *propname = "ro.build.fingerprint";
69 const char *tag = NULL;
70 int do_remove = 0, do_number = 0;
71
72 int opt;
73 while ((opt = getopt(argc, argv, "f:p:rn")) != -1) {
74 switch (opt) {
75 case 'f': filename = optarg; break;
76 case 'p': propname = optarg; break;
77 case 'r': do_remove = 1; break;
78 case 'n': do_number = 1; break;
79 case '?': return 2;
80 }
81 }
82
83 if (argc != optind + 1) {
84 fprintf(stderr,
85 "usage: add-property-tag [flags] tag-to-add\n"
86 "flags: -f /dir/file.prop (default /system/build.prop)\n"
87 " -p prop.name (default ro.build.fingerprint)\n"
88 " -r (if set, remove the tag rather than adding it)\n"
89 " -n (if set, add and increment a number after the tag)\n");
90 return 2;
91 }
92
93 tag = argv[optind];
94 FILE *input = fopen(filename, "r");
95 if (input == NULL) {
96 fprintf(stderr, "can't read %s: %s\n", filename, strerror(errno));
97 return 1;
98 }
99
100 char tmpname[PATH_MAX];
101 snprintf(tmpname, sizeof(tmpname), "%s.tmp", filename);
102 FILE *output = fopen(tmpname, "w");
103 if (output == NULL) {
104 fprintf(stderr, "can't write %s: %s\n", tmpname, strerror(errno));
105 return 1;
106 }
107
108 int found = 0;
109 char line[4096];
110 while (fgets(line, sizeof(line), input)) {
111 if (!should_tag(line, propname)) {
112 fputs(line, output); // Pass through unmodified
113 } else {
114 found = 1;
115 int number = remove_tag(line, tag);
116 if (do_remove) {
117 fputs(line, output); // Remove the tag but don't re-add it
118 } else {
119 write_tagged(output, line, tag, number + do_number);
120 }
121 }
122 }
123
124 fclose(input);
125 fclose(output);
126
127 if (!found) {
128 fprintf(stderr, "property %s not found in %s\n", propname, filename);
129 remove(tmpname);
130 return 1;
131 }
132
133 if (rename(tmpname, filename)) {
134 fprintf(stderr, "can't rename %s to %s: %s\n",
135 tmpname, filename, strerror(errno));
136 remove(tmpname);
137 return 1;
138 }
139
140 return 0;
141 }
142