1 /*
2 **
3 ** Copyright 2006, The Android Open Source Project
4 **
5 ** Licensed under the Apache License, Version 2.0 (the "License");
6 ** you may not use this file except in compliance with the License.
7 ** You may obtain a copy of the License at
8 **
9 ** http://www.apache.org/licenses/LICENSE-2.0
10 **
11 ** Unless required by applicable law or agreed to in writing, software
12 ** distributed under the License is distributed on an "AS IS" BASIS,
13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 ** See the License for the specific language governing permissions and
15 ** limitations under the License.
16 */
17
18 #include <stdlib.h>
19 #include <unistd.h>
20 #include <assert.h>
21 #include <errno.h>
22 #include <telephony/record_stream.h>
23 #include <string.h>
24 #include <stdint.h>
25 #if defined(_WIN32)
26 #include <winsock2.h> /* for ntohl */
27 #else
28 #include <netinet/in.h>
29 #endif
30
31 #define HEADER_SIZE 4
32
33 struct RecordStream {
34 int fd;
35 size_t maxRecordLen;
36
37 unsigned char *buffer;
38
39 unsigned char *unconsumed;
40 unsigned char *read_end;
41 unsigned char *buffer_end;
42 };
43
44
record_stream_new(int fd,size_t maxRecordLen)45 extern RecordStream *record_stream_new(int fd, size_t maxRecordLen)
46 {
47 RecordStream *ret;
48
49 assert (maxRecordLen <= 0xffff);
50
51 ret = (RecordStream *)calloc(1, sizeof(RecordStream));
52
53 ret->fd = fd;
54 ret->maxRecordLen = maxRecordLen;
55 ret->buffer = (unsigned char *)malloc (maxRecordLen + HEADER_SIZE);
56
57 ret->unconsumed = ret->buffer;
58 ret->read_end = ret->buffer;
59 ret->buffer_end = ret->buffer + maxRecordLen + HEADER_SIZE;
60
61 return ret;
62 }
63
64
record_stream_free(RecordStream * rs)65 extern void record_stream_free(RecordStream *rs)
66 {
67 free(rs->buffer);
68 free(rs);
69 }
70
71
72 /* returns NULL; if there isn't a full record in the buffer */
getEndOfRecord(unsigned char * p_begin,unsigned char * p_end)73 static unsigned char * getEndOfRecord (unsigned char *p_begin,
74 unsigned char *p_end)
75 {
76 size_t len;
77 unsigned char * p_ret;
78
79 if (p_end < p_begin + HEADER_SIZE) {
80 return NULL;
81 }
82
83 //First four bytes are length
84 len = ntohl(*((uint32_t *)p_begin));
85
86 p_ret = p_begin + HEADER_SIZE + len;
87
88 if (p_end < p_ret) {
89 return NULL;
90 }
91
92 return p_ret;
93 }
94
getNextRecord(RecordStream * p_rs,size_t * p_outRecordLen)95 static void *getNextRecord (RecordStream *p_rs, size_t *p_outRecordLen)
96 {
97 unsigned char *record_start, *record_end;
98
99 record_end = getEndOfRecord (p_rs->unconsumed, p_rs->read_end);
100
101 if (record_end != NULL) {
102 /* one full line in the buffer */
103 record_start = p_rs->unconsumed + HEADER_SIZE;
104 p_rs->unconsumed = record_end;
105
106 *p_outRecordLen = record_end - record_start;
107
108 return record_start;
109 }
110
111 return NULL;
112 }
113
114 /**
115 * Reads the next record from stream fd
116 * Records are prefixed by a 16-bit big endian length value
117 * Records may not be larger than maxRecordLen
118 *
119 * Doesn't guard against EINTR
120 *
121 * p_outRecord and p_outRecordLen may not be NULL
122 *
123 * Return 0 on success, -1 on fail
124 * Returns 0 with *p_outRecord set to NULL on end of stream
125 * Returns -1 / errno = EAGAIN if it needs to read again
126 */
record_stream_get_next(RecordStream * p_rs,void ** p_outRecord,size_t * p_outRecordLen)127 int record_stream_get_next (RecordStream *p_rs, void ** p_outRecord,
128 size_t *p_outRecordLen)
129 {
130 void *ret;
131
132 ssize_t countRead;
133
134 /* is there one record already in the buffer? */
135 ret = getNextRecord (p_rs, p_outRecordLen);
136
137 if (ret != NULL) {
138 *p_outRecord = ret;
139 return 0;
140 }
141
142 // if the buffer is full and we don't have a full record
143 if (p_rs->unconsumed == p_rs->buffer
144 && p_rs->read_end == p_rs->buffer_end
145 ) {
146 // this should never happen
147 //ALOGE("max record length exceeded\n");
148 assert (0);
149 errno = EFBIG;
150 return -1;
151 }
152
153 if (p_rs->unconsumed != p_rs->buffer) {
154 // move remainder to the beginning of the buffer
155 size_t toMove;
156
157 toMove = p_rs->read_end - p_rs->unconsumed;
158 if (toMove) {
159 memmove(p_rs->buffer, p_rs->unconsumed, toMove);
160 }
161
162 p_rs->read_end = p_rs->buffer + toMove;
163 p_rs->unconsumed = p_rs->buffer;
164 }
165
166 countRead = read (p_rs->fd, p_rs->read_end, p_rs->buffer_end - p_rs->read_end);
167
168 if (countRead <= 0) {
169 /* note: end-of-stream drops through here too */
170 *p_outRecord = NULL;
171 return countRead;
172 }
173
174 p_rs->read_end += countRead;
175
176 ret = getNextRecord (p_rs, p_outRecordLen);
177
178 if (ret == NULL) {
179 /* not enough of a buffer to for a whole command */
180 errno = EAGAIN;
181 return -1;
182 }
183
184 *p_outRecord = ret;
185 return 0;
186 }
187