1 /*
2 * Copyright (C) 2007-2016 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 "pmsg_writer.h"
18
19 #include <errno.h>
20 #include <fcntl.h>
21 #include <stdlib.h>
22 #include <string.h>
23 #include <sys/types.h>
24 #include <time.h>
25
26 #include <log/log_properties.h>
27 #include <private/android_logger.h>
28
29 #include "logger.h"
30 #include "uio.h"
31
32 static atomic_int pmsg_fd;
33
34 // pmsg_fd should only beopened once. If we see that pmsg_fd is uninitialized, we open "/dev/pmsg0"
35 // then attempt to compare/exchange it into pmsg_fd. If the compare/exchange was successful, then
36 // that will be the fd used for the duration of the program, otherwise a different thread has
37 // already opened and written the fd to the atomic, so close the new fd and return.
GetPmsgFd()38 static void GetPmsgFd() {
39 if (pmsg_fd != 0) {
40 return;
41 }
42
43 int new_fd = TEMP_FAILURE_RETRY(open("/dev/pmsg0", O_WRONLY | O_CLOEXEC));
44 if (new_fd <= 0) {
45 return;
46 }
47
48 int uninitialized_value = 0;
49 if (!pmsg_fd.compare_exchange_strong(uninitialized_value, new_fd)) {
50 close(new_fd);
51 return;
52 }
53 }
54
PmsgClose()55 void PmsgClose() {
56 if (pmsg_fd > 0) {
57 close(pmsg_fd);
58 }
59 pmsg_fd = 0;
60 }
61
PmsgWrite(log_id_t logId,struct timespec * ts,struct iovec * vec,size_t nr)62 int PmsgWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr) {
63 static const unsigned headerLength = 2;
64 struct iovec newVec[nr + headerLength];
65 android_log_header_t header;
66 android_pmsg_log_header_t pmsgHeader;
67 size_t i, payloadSize;
68 ssize_t ret;
69
70 if (!__android_log_is_debuggable()) {
71 if (logId != LOG_ID_EVENTS && logId != LOG_ID_SECURITY) {
72 return -1;
73 }
74
75 if (logId == LOG_ID_EVENTS) {
76 if (vec[0].iov_len < 4) {
77 return -EINVAL;
78 }
79
80 if (SNET_EVENT_LOG_TAG != *static_cast<uint32_t*>(vec[0].iov_base)) {
81 return -EPERM;
82 }
83 }
84 }
85
86 GetPmsgFd();
87
88 if (pmsg_fd <= 0) {
89 return -EBADF;
90 }
91
92 /*
93 * struct {
94 * // what we provide to pstore
95 * android_pmsg_log_header_t pmsgHeader;
96 * // what we provide to file
97 * android_log_header_t header;
98 * // caller provides
99 * union {
100 * struct {
101 * char prio;
102 * char payload[];
103 * } string;
104 * struct {
105 * uint32_t tag
106 * char payload[];
107 * } binary;
108 * };
109 * };
110 */
111
112 pmsgHeader.magic = LOGGER_MAGIC;
113 pmsgHeader.len = sizeof(pmsgHeader) + sizeof(header);
114 pmsgHeader.uid = getuid();
115 pmsgHeader.pid = getpid();
116
117 header.id = logId;
118 header.tid = gettid();
119 header.realtime.tv_sec = ts->tv_sec;
120 header.realtime.tv_nsec = ts->tv_nsec;
121
122 newVec[0].iov_base = (unsigned char*)&pmsgHeader;
123 newVec[0].iov_len = sizeof(pmsgHeader);
124 newVec[1].iov_base = (unsigned char*)&header;
125 newVec[1].iov_len = sizeof(header);
126
127 for (payloadSize = 0, i = headerLength; i < nr + headerLength; i++) {
128 newVec[i].iov_base = vec[i - headerLength].iov_base;
129 payloadSize += newVec[i].iov_len = vec[i - headerLength].iov_len;
130
131 if (payloadSize > LOGGER_ENTRY_MAX_PAYLOAD) {
132 newVec[i].iov_len -= payloadSize - LOGGER_ENTRY_MAX_PAYLOAD;
133 if (newVec[i].iov_len) {
134 ++i;
135 }
136 payloadSize = LOGGER_ENTRY_MAX_PAYLOAD;
137 break;
138 }
139 }
140 pmsgHeader.len += payloadSize;
141
142 ret = TEMP_FAILURE_RETRY(writev(pmsg_fd, newVec, i));
143 if (ret < 0) {
144 ret = errno ? -errno : -ENOTCONN;
145 }
146
147 if (ret > (ssize_t)(sizeof(header) + sizeof(pmsgHeader))) {
148 ret -= sizeof(header) - sizeof(pmsgHeader);
149 }
150
151 return ret;
152 }
153
154 /*
155 * Virtual pmsg filesystem
156 *
157 * Payload will comprise the string "<basedir>:<basefile>\0<content>" to a
158 * maximum of LOGGER_ENTRY_MAX_PAYLOAD, but scaled to the last newline in the
159 * file.
160 *
161 * Will hijack the header.realtime.tv_nsec field for a sequence number in usec.
162 */
163
strnrchr(const char * buf,size_t len,char c)164 static inline const char* strnrchr(const char* buf, size_t len, char c) {
165 const char* cp = buf + len;
166 while ((--cp > buf) && (*cp != c))
167 ;
168 if (cp <= buf) {
169 return buf + len;
170 }
171 return cp;
172 }
173
174 /* Write a buffer as filename references (tag = <basedir>:<basename>) */
__android_log_pmsg_file_write(log_id_t logId,char prio,const char * filename,const char * buf,size_t len)175 ssize_t __android_log_pmsg_file_write(log_id_t logId, char prio, const char* filename,
176 const char* buf, size_t len) {
177 size_t length, packet_len;
178 const char* tag;
179 char *cp, *slash;
180 struct timespec ts;
181 struct iovec vec[3];
182
183 /* Make sure the logId value is not a bad idea */
184 if ((logId == LOG_ID_KERNEL) || /* Verbotten */
185 (logId == LOG_ID_EVENTS) || /* Do not support binary content */
186 (logId == LOG_ID_SECURITY) || /* Bad idea to allow */
187 ((unsigned)logId >= 32)) { /* fit within logMask on arch32 */
188 return -EINVAL;
189 }
190
191 clock_gettime(CLOCK_REALTIME, &ts);
192
193 cp = strdup(filename);
194 if (!cp) {
195 return -ENOMEM;
196 }
197
198 tag = cp;
199 slash = strrchr(cp, '/');
200 if (slash) {
201 *slash = ':';
202 slash = strrchr(cp, '/');
203 if (slash) {
204 tag = slash + 1;
205 }
206 }
207
208 length = strlen(tag) + 1;
209 packet_len = LOGGER_ENTRY_MAX_PAYLOAD - sizeof(char) - length;
210
211 vec[0].iov_base = &prio;
212 vec[0].iov_len = sizeof(char);
213 vec[1].iov_base = (unsigned char*)tag;
214 vec[1].iov_len = length;
215
216 for (ts.tv_nsec = 0, length = len; length; ts.tv_nsec += ANDROID_LOG_PMSG_FILE_SEQUENCE) {
217 ssize_t ret;
218 size_t transfer;
219
220 if ((ts.tv_nsec / ANDROID_LOG_PMSG_FILE_SEQUENCE) >= ANDROID_LOG_PMSG_FILE_MAX_SEQUENCE) {
221 len -= length;
222 break;
223 }
224
225 transfer = length;
226 if (transfer > packet_len) {
227 transfer = strnrchr(buf, packet_len - 1, '\n') - buf;
228 if ((transfer < length) && (buf[transfer] == '\n')) {
229 ++transfer;
230 }
231 }
232
233 vec[2].iov_base = (unsigned char*)buf;
234 vec[2].iov_len = transfer;
235
236 ret = PmsgWrite(logId, &ts, vec, sizeof(vec) / sizeof(vec[0]));
237
238 if (ret <= 0) {
239 free(cp);
240 return ret ? ret : (len - length);
241 }
242 length -= transfer;
243 buf += transfer;
244 }
245 free(cp);
246 return len;
247 }
248