1/*
2 * Copyright (C) 2007 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#define LOG_TAG "buffer"
18
19#include <assert.h>
20#include <errno.h>
21#include <stdlib.h>
22#include <unistd.h>
23
24#include "buffer.h"
25#include "loghack.h"
26
27Buffer* bufferCreate(size_t capacity) {
28    Buffer* buffer = malloc(sizeof(Buffer));
29    if (buffer == NULL) {
30        return NULL;
31    }
32    buffer->capacity = capacity;
33    buffer->expected = 0;
34    buffer->data = malloc(capacity);
35    if (buffer->data == NULL) {
36        free(buffer);
37        return NULL;
38    }
39    return buffer;
40}
41
42void bufferFree(Buffer* buffer) {
43    free(buffer->data);
44    free(buffer);
45}
46
47Buffer* bufferWrap(char* data, size_t capacity, size_t size) {
48    Buffer* buffer = malloc(sizeof(Buffer));
49    if (buffer == NULL) {
50        return NULL;
51    }
52
53    buffer->data = data;
54    buffer->capacity = capacity;
55    buffer->size = size;
56    buffer->expected = 0;
57    return buffer;
58}
59
60int bufferPrepareForRead(Buffer* buffer, size_t expected) {
61    if (expected > buffer->capacity) {
62        // Expand buffer.
63        char* expanded = realloc(buffer->data, expected);
64        if (expanded == NULL) {
65            errno = ENOMEM;
66            return -1;
67        }
68        buffer->capacity = expected;
69        buffer->data = expanded;
70    }
71
72    buffer->size = 0;
73    buffer->expected = expected;
74    return 0;
75}
76
77ssize_t bufferRead(Buffer* buffer, int fd) {
78    assert(buffer->size < buffer->expected);
79
80    ssize_t bytesRead = read(fd,
81            buffer->data + buffer->size,
82            buffer->expected - buffer->size);
83
84    if (bytesRead > 0) {
85        buffer->size += bytesRead;
86        return buffer->size;
87    }
88
89    return bytesRead;
90}
91
92void bufferPrepareForWrite(Buffer* buffer) {
93    buffer->remaining = buffer->size;
94}
95
96ssize_t bufferWrite(Buffer* buffer, int fd) {
97    assert(buffer->remaining > 0);
98    assert(buffer->remaining <= buffer->size);
99
100    ssize_t bytesWritten = write(fd,
101            buffer->data + buffer->size - buffer->remaining,
102            buffer->remaining);
103
104    if (bytesWritten >= 0) {
105        buffer->remaining -= bytesWritten;
106
107        ALOGD("Buffer bytes written: %d", (int) bytesWritten);
108        ALOGD("Buffer size: %d", (int) buffer->size);
109        ALOGD("Buffer remaining: %d", (int) buffer->remaining);
110
111        return buffer->remaining;
112    }
113
114    return bytesWritten;
115}
116
117