canned_fs_config.c

   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 <stdio.h>
  18 #include <string.h>
  19 #include <errno.h>
  20 #include <limits.h>
  21 #include <stdlib.h>
  22
  23 #include "canned_fs_config.h"
  24
  25 typedef struct {
  26         const char* path;
  27         unsigned uid;
  28         unsigned gid;
  29         unsigned mode;
  30         uint64_t capabilities;
  31 } Path;
  32
  33 static Path* canned_data = NULL;
  34 static int canned_alloc = 0;
  35 static int canned_used = 0;
  36
  37 static int path_compare(const void* a, const void* b) {
  38         return strcmp(((Path*)a)->path, ((Path*)b)->path);
  39 }
  40
  41 int load_canned_fs_config(const char* fn) {
  42         FILE* f = fopen(fn, "r");
  43         if (f == NULL) {
  44                 fprintf(stderr, "failed to open %s: %s\n", fn, strerror(errno));
  45                 return -1;
  46         }
  47
  48         char line[PATH_MAX + 200];
  49         while (fgets(line, sizeof(line), f)) {
  50                 while (canned_used >= canned_alloc) {
  51                         canned_alloc = (canned_alloc+1) * 2;
  52                         canned_data = (Path*) realloc(canned_data, canned_alloc * sizeof(Path));
  53                 }
  54                 Path* p = canned_data + canned_used;
  55                 p->path = strdup(strtok(line, " \t"));
  56
  57                 if (!p->path || !*p->path || *p->path == '#')
  58                         continue;
  59
  60                 p->uid = atoi(strtok(NULL, " \t"));
  61                 p->gid = atoi(strtok(NULL, " \t"));
  62                 p->mode = strtol(strtok(NULL, " \t"), NULL, 8);   // mode is in octal
  63                 p->capabilities = 0;
  64
  65                 char* token = NULL;
  66                 do {
  67                         token = strtok(NULL, " \t");
  68                         if (token && strncmp(token, "capabilities=", 13) == 0) {
  69                                 p->capabilities = strtoll(token+13, NULL, 0);
  70                                 break;
  71                         }
  72                 } while (token);
  73
  74                 canned_used++;
  75         }
  76
  77         fclose(f);
  78
  79         qsort(canned_data, canned_used, sizeof(Path), path_compare);
  80         printf("loaded %d fs_config entries\n", canned_used);
  81
  82         return 0;
  83 }
  84
  85 int canned_fs_config(const char* path, int dir,
  86                                           unsigned* uid, unsigned* gid, unsigned* mode, uint64_t* capabilities) {
  87         Path key;
  88         key.path = path;
  89         Path* p = (Path*) bsearch(&key, canned_data, canned_used, sizeof(Path), path_compare);
  90         if (p == NULL) {
  91                 return 0;
  92         }
  93         *uid = p->uid;
  94         *gid = p->gid;
  95         *mode = p->mode;
  96         *capabilities = p->capabilities;
  97
  98 #if 0
  99         // for debugging, run the built-in fs_config and compare the results.
 100
 101         unsigned c_uid, c_gid, c_mode;
 102         uint64_t c_capabilities;
 103         fs_config(path, dir, &c_uid, &c_gid, &c_mode, &c_capabilities);
 104
 105         if (c_uid != *uid) printf("%s uid %d %d\n", path, *uid, c_uid);
 106         if (c_gid != *gid) printf("%s gid %d %d\n", path, *gid, c_gid);
 107         if (c_mode != *mode) printf("%s mode 0%o 0%o\n", path, *mode, c_mode);
 108         if (c_capabilities != *capabilities) printf("%s capabilities %llx %llx\n", path, *capabilities, c_capabilities);
 109 #endif
 110
 111         return 1;
 112 }