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1 /*
2  * Copyright (C) 2014 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 <private/android_filesystem_config.h>
18 #include <private/canned_fs_config.h>
19 #include <private/fs_config.h>
20 
21 #include <errno.h>
22 #include <inttypes.h>
23 #include <limits.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <string.h>
27 
28 typedef struct {
29     const char* path;
30     unsigned uid;
31     unsigned gid;
32     unsigned mode;
33     uint64_t capabilities;
34 } Path;
35 
36 static Path* canned_data = NULL;
37 static int canned_alloc = 0;
38 static int canned_used = 0;
39 
path_compare(const void * a,const void * b)40 static int path_compare(const void* a, const void* b) {
41     return strcmp(((Path*)a)->path, ((Path*)b)->path);
42 }
43 
load_canned_fs_config(const char * fn)44 int load_canned_fs_config(const char* fn) {
45     char buf[PATH_MAX + 200];
46     FILE* f;
47 
48     f = fopen(fn, "r");
49     if (f == NULL) {
50         fprintf(stderr, "failed to open %s: %s\n", fn, strerror(errno));
51         return -1;
52     }
53 
54     while (fgets(buf, sizeof(buf), f)) {
55         Path* p;
56         char* token;
57         char* line = buf;
58         bool rootdir;
59 
60         while (canned_used >= canned_alloc) {
61             canned_alloc = (canned_alloc+1) * 2;
62             canned_data = (Path*) realloc(canned_data, canned_alloc * sizeof(Path));
63         }
64         p = canned_data + canned_used;
65         if (line[0] == '/') line++;
66         rootdir = line[0] == ' ';
67         p->path = strdup(rootdir ? "" : strtok(line, " "));
68         p->uid = atoi(strtok(rootdir ? line : NULL, " "));
69         p->gid = atoi(strtok(NULL, " "));
70         p->mode = strtol(strtok(NULL, " "), NULL, 8);   // mode is in octal
71         p->capabilities = 0;
72 
73         do {
74             token = strtok(NULL, " ");
75             if (token && strncmp(token, "capabilities=", 13) == 0) {
76                 p->capabilities = strtoll(token+13, NULL, 0);
77                 break;
78             }
79         } while (token);
80 
81         canned_used++;
82     }
83 
84     fclose(f);
85 
86     qsort(canned_data, canned_used, sizeof(Path), path_compare);
87     printf("loaded %d fs_config entries\n", canned_used);
88 
89     return 0;
90 }
91 
92 static const int kDebugCannedFsConfig = 0;
93 
canned_fs_config(const char * path,int dir,const char * target_out_path,unsigned * uid,unsigned * gid,unsigned * mode,uint64_t * capabilities)94 void canned_fs_config(const char* path, int dir, const char* target_out_path,
95                       unsigned* uid, unsigned* gid, unsigned* mode, uint64_t* capabilities) {
96     Path key, *p;
97 
98     key.path = path;
99     if (path[0] == '/') key.path++; // canned paths lack the leading '/'
100     p = (Path*) bsearch(&key, canned_data, canned_used, sizeof(Path), path_compare);
101     if (p == NULL) {
102         fprintf(stderr, "failed to find [%s] in canned fs_config\n", path);
103         exit(1);
104     }
105     *uid = p->uid;
106     *gid = p->gid;
107     *mode = p->mode;
108     *capabilities = p->capabilities;
109 
110     if (kDebugCannedFsConfig) {
111         // for debugging, run the built-in fs_config and compare the results.
112 
113         unsigned c_uid, c_gid, c_mode;
114         uint64_t c_capabilities;
115 
116         fs_config(path, dir, target_out_path, &c_uid, &c_gid, &c_mode, &c_capabilities);
117 
118         if (c_uid != *uid) printf("%s uid %d %d\n", path, *uid, c_uid);
119         if (c_gid != *gid) printf("%s gid %d %d\n", path, *gid, c_gid);
120         if (c_mode != *mode) printf("%s mode 0%o 0%o\n", path, *mode, c_mode);
121         if (c_capabilities != *capabilities) {
122             printf("%s capabilities %" PRIx64 " %" PRIx64 "\n",
123                 path,
124                 *capabilities,
125                 c_capabilities);
126         }
127     }
128 }
129