1 files changed, 187 insertions, 0 deletions

diff --git a/libcutils/record_stream.cpp b/libcutils/record_stream.cpp
new file mode 100644
index 000000000..5a86b8393
--- /dev/null
+++ b/libcutils/record_stream.cpp
@@ -0,0 +1,187 @@
+/* libs/cutils/record_stream.c
+**
+** Copyright 2006, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License"); 
+** you may not use this file except in compliance with the License. 
+** You may obtain a copy of the License at 
+**
+**     http://www.apache.org/licenses/LICENSE-2.0 
+**
+** Unless required by applicable law or agreed to in writing, software 
+** distributed under the License is distributed on an "AS IS" BASIS, 
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
+** See the License for the specific language governing permissions and 
+** limitations under the License.
+*/
+
+#include <cutils/record_stream.h>
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+#include <stdint.h>
+#if defined(_WIN32)
+#include <winsock2.h>   /* for ntohl */
+#else
+#include <netinet/in.h>
+#endif
+
+#define HEADER_SIZE 4
+
+struct RecordStream {
+    int fd;
+    size_t maxRecordLen;
+
+    unsigned char *buffer;
+
+    unsigned char *unconsumed;
+    unsigned char *read_end;
+    unsigned char *buffer_end;
+};
+
+
+extern RecordStream *record_stream_new(int fd, size_t maxRecordLen)
+{
+    RecordStream *ret;
+
+    assert (maxRecordLen <= 0xffff);
+
+    ret = (RecordStream *)calloc(1, sizeof(RecordStream));
+
+    ret->fd = fd;
+    ret->maxRecordLen = maxRecordLen;
+    ret->buffer = (unsigned char *)malloc (maxRecordLen + HEADER_SIZE);
+    
+    ret->unconsumed = ret->buffer;
+    ret->read_end = ret->buffer;
+    ret->buffer_end = ret->buffer + maxRecordLen + HEADER_SIZE;
+
+    return ret;
+}
+
+
+extern void record_stream_free(RecordStream *rs)
+{
+    free(rs->buffer);
+    free(rs);
+}
+
+
+/* returns NULL; if there isn't a full record in the buffer */
+static unsigned char * getEndOfRecord (unsigned char *p_begin,
+                                            unsigned char *p_end)
+{
+    size_t len;
+    unsigned char * p_ret;
+
+    if (p_end < p_begin + HEADER_SIZE) {
+        return NULL;
+    }
+
+    //First four bytes are length
+    len = ntohl(*((uint32_t *)p_begin));
+
+    p_ret = p_begin + HEADER_SIZE + len;
+
+    if (p_end < p_ret) {
+        return NULL;
+    }
+
+    return p_ret;
+}
+
+static void *getNextRecord (RecordStream *p_rs, size_t *p_outRecordLen)
+{
+    unsigned char *record_start, *record_end;
+
+    record_end = getEndOfRecord (p_rs->unconsumed, p_rs->read_end);
+
+    if (record_end != NULL) {
+        /* one full line in the buffer */
+        record_start = p_rs->unconsumed + HEADER_SIZE;
+        p_rs->unconsumed = record_end;
+
+        *p_outRecordLen = record_end - record_start;
+
+        return record_start;
+    }
+
+    return NULL;
+}
+
+/**
+ * Reads the next record from stream fd
+ * Records are prefixed by a 16-bit big endian length value
+ * Records may not be larger than maxRecordLen
+ *
+ * Doesn't guard against EINTR
+ *
+ * p_outRecord and p_outRecordLen may not be NULL
+ *
+ * Return 0 on success, -1 on fail
+ * Returns 0 with *p_outRecord set to NULL on end of stream
+ * Returns -1 / errno = EAGAIN if it needs to read again
+ */
+int record_stream_get_next (RecordStream *p_rs, void ** p_outRecord, 
+                                    size_t *p_outRecordLen)
+{
+    void *ret;
+
+    ssize_t countRead;
+
+    /* is there one record already in the buffer? */
+    ret = getNextRecord (p_rs, p_outRecordLen);
+
+    if (ret != NULL) {
+        *p_outRecord = ret;
+        return 0;
+    }
+
+    // if the buffer is full and we don't have a full record
+    if (p_rs->unconsumed == p_rs->buffer 
+        && p_rs->read_end == p_rs->buffer_end
+    ) {
+        // this should never happen
+        //ALOGE("max record length exceeded\n");
+        assert (0);
+        errno = EFBIG;
+        return -1;
+    }
+
+    if (p_rs->unconsumed != p_rs->buffer) {
+        // move remainder to the beginning of the buffer
+        size_t toMove;
+
+        toMove = p_rs->read_end - p_rs->unconsumed;
+        if (toMove) {
+            memmove(p_rs->buffer, p_rs->unconsumed, toMove);
+        }
+
+        p_rs->read_end = p_rs->buffer + toMove;
+        p_rs->unconsumed = p_rs->buffer;
+    }
+
+    countRead = read (p_rs->fd, p_rs->read_end, p_rs->buffer_end - p_rs->read_end);
+
+    if (countRead <= 0) {
+        /* note: end-of-stream drops through here too */
+        *p_outRecord = NULL;
+        return countRead;
+    }
+
+    p_rs->read_end += countRead;
+
+    ret = getNextRecord (p_rs, p_outRecordLen);
+
+    if (ret == NULL) {
+        /* not enough of a buffer to for a whole command */
+        errno = EAGAIN;
+        return -1;
+    }
+
+    *p_outRecord = ret;        
+    return 0;
+}