HACK: cutils: restore record_stream temporarily

Restore the record_stream code in cutils that was removed
in e00a12bf8a as part of cutils
cleanup.

Unfortunately, there are some prebuilt vendor libs that rely on
this functionality that we cannot currently rebuild.

Remove at the earliest possible convenience once the vendor libs
have been fixed.

Bug: 9189218
Change-Id: I5d44126756f1e3ed194d1b5873d64d9154183199
Signed-off-by: Dima Zavin <dima@android.com>

include/cutils/record_stream.h

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 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.
+ */
+
+/*
+ * A simple utility for reading fixed records out of a stream fd
+ */
+
+#ifndef _CUTILS_RECORD_STREAM_H
+#define _CUTILS_RECORD_STREAM_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+typedef struct RecordStream RecordStream;
+
+extern RecordStream *record_stream_new(int fd, size_t maxRecordLen);
+extern void record_stream_free(RecordStream *p_rs);
+
+extern int record_stream_get_next (RecordStream *p_rs, void ** p_outRecord, 
+                                    size_t *p_outRecordLen);
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif /*_CUTILS_RECORD_STREAM_H*/
+

libcutils/Android.mk

@@ -41,6 +41,7 @@ commonSources := \
 	open_memstream.c \
 	strdup16to8.c \
 	strdup8to16.c \
+	record_stream.c \
 	process_name.c \
 	threads.c \
 	sched_policy.c \

libcutils/record_stream.c

@@ -0,0 +1,186 @@
+/* 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 <stdlib.h>
+#include <unistd.h>
+#include <assert.h>
+#include <errno.h>
+#include <cutils/record_stream.h>
+#include <string.h>
+#include <stdint.h>
+#ifdef HAVE_WINSOCK
+#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;
+}