The Android Open Source Project | dd7bc33 | 2009-03-03 19:32:55 -0800 | [diff] [blame] | 1 | /* libs/cutils/record_stream.c |
| 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 <cutils/record_stream.h> |
| 23 | #include <string.h> |
| 24 | #include <stdint.h> |
| 25 | #ifdef HAVE_WINSOCK |
| 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 | |
| 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 | |
| 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 */ |
| 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 | |
| 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 | */ |
| 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 |
Steve Block | 01dda20 | 2012-01-06 14:13:42 +0000 | [diff] [blame] | 147 | //ALOGE("max record length exceeded\n"); |
The Android Open Source Project | dd7bc33 | 2009-03-03 19:32:55 -0800 | [diff] [blame] | 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 | } |