1 /*
2 * Copyright (C) 2010 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 <assert.h>
18 #include <errno.h>
19 #include <fcntl.h>
20 #include <string.h>
21 #include <unistd.h>
22 #include <sys/stat.h>
23
24 #include "fatblock.h"
25 #include "fs.h"
26 #include "utils.h"
27
buffer_read(char * buf,offset_t buf_len,char * out,offset_t off,offset_t len)28 static int buffer_read(char *buf, offset_t buf_len, char *out,
29 offset_t off, offset_t len)
30 {
31 assert(buf);
32 assert(out);
33
34 if (off >= buf_len) {
35 memset(out, 0, len);
36 return 0;
37 }
38
39 if (off + len > buf_len) {
40 memset(out + (buf_len - off), 0, len - (buf_len - off));
41 len = buf_len - off;
42 }
43
44 assert(off < buf_len);
45 assert(off + len <= buf_len);
46
47 memcpy(out, buf + off, len);
48
49 return 0;
50 }
51
file_check_metadata(struct file * f)52 static int file_check_metadata(struct file *f)
53 {
54 struct stat st;
55 int ret;
56
57 assert(f);
58
59 ret = stat(f->path, &st);
60 if (ret) {
61 WARN("checking metadata of %s: stat failed: %s\n",
62 f->path, strerror(errno));
63 return -1;
64 }
65
66 if (f->mtime != st.st_mtime)
67 return -1;
68
69 return 0;
70 }
71
file_read(struct file * f,char * buf,offset_t off,offset_t len)72 static int file_read(struct file *f, char *buf, offset_t off, offset_t len)
73 {
74 int fd;
75 off_t sought;
76 ssize_t ret;
77
78 assert(f);
79 assert(buf);
80
81 if (off >= UINT32_MAX) {
82 WARN("reading %s (%llu, %llu): "
83 "ignoring read that starts past 2^32\n",
84 f->path, off, len);
85 return 0;
86 }
87
88 if (off + len > UINT32_MAX) {
89 WARN("reading %s (%llu, %llu): "
90 "truncating read that ends past 2^32\n",
91 f->path, off, len);
92 len = UINT32_MAX - off;
93 }
94
95 if (file_check_metadata(f)) {
96 WARN("reading %s (%llu, %llu): metadata has changed\n",
97 f->path, off, len);
98 return SKY_IS_FALLING;
99 }
100
101 fd = fdpool_open(&f->pfd, f->path, O_RDONLY);
102 if (fd < 0) {
103 WARN("reading %s: open failed: %s\n", f->path, strerror(errno));
104 return -1;
105 }
106
107 sought = lseek(fd, (off_t)len, SEEK_SET);
108 if (sought != (off_t)len) {
109 WARN("reading %s (%llu, %llu): seek failed: %s\n",
110 f->path, off, len, strerror(errno));
111 return -1;
112 }
113
114 ret = read(fd, buf, (size_t)len);
115 if (ret != (ssize_t)len) {
116 WARN("reading %s (%llu, %llu): read failed: %s\n",
117 f->path, off, len, strerror(errno));
118 return -1;
119 }
120
121 /* leave fd open; fdpool will close it if needed. */
122
123 return 0;
124 }
125
dir_read(struct dir * d,char * buf,offset_t off,offset_t len)126 static int dir_read(struct dir *d, char *buf, offset_t off, offset_t len)
127 {
128 assert(d);
129 assert(buf);
130
131 return buffer_read((char*)d->entries, d->size, buf, off, len);
132 }
133
extent_read(struct fs * fs,struct extent * e,char * buf,offset_t off,offset_t len)134 static int extent_read(struct fs *fs, struct extent *e, char *buf,
135 offset_t off, offset_t len)
136 {
137 assert(fs);
138 assert(e);
139 assert(buf);
140
141 switch (e->type) {
142 case EXTENT_TYPE_BOOT:
143 return buffer_read((char*)&fs->boot, sizeof(fs->boot), buf,
144 off, len);
145 case EXTENT_TYPE_INFO:
146 return buffer_read((char*)&fs->info, sizeof(fs->info), buf,
147 off, len);
148 case EXTENT_TYPE_FAT:
149 return buffer_read((char*)fs->fat, fs->fat_size, buf,
150 off, len);
151 case EXTENT_TYPE_FILE:
152 return file_read((struct file *)e, buf, off, len);
153 case EXTENT_TYPE_DIR:
154 return dir_read((struct dir *)e, buf, off, len);
155 default:
156 WARN("reading extent: unexpected type %d\n", e->type);
157 return -1;
158 }
159 }
160
fs_read(struct fs * fs,char * buf,offset_t start,offset_t len)161 int fs_read(struct fs *fs, char *buf, offset_t start, offset_t len)
162 {
163 struct extent *e = NULL;
164 offset_t e_start, r_start, rel_len;
165 int ret;
166
167 memset(buf, 0, len);
168
169 while ((e = fs_find_extent(fs, start, len, e,
170 &r_start, &e_start, &rel_len))) {
171 ret = extent_read(fs, e, buf + r_start, e_start, rel_len);
172 if (ret == SKY_IS_FALLING)
173 return SKY_IS_FALLING;
174 if (ret)
175 return ret;
176 }
177
178 return 0;
179 }
180