Add compilation of c files

asyncio_mongo/_bson/buffer.c

@@ -0,0 +1,146 @@
+/*
+ * Copyright 2009-2012 10gen, Inc.
+ *
+ * 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 <string.h>
+
+#include "buffer.h"
+
+#define INITIAL_BUFFER_SIZE 256
+
+struct buffer {
+    char* buffer;
+    int size;
+    int position;
+};
+
+/* Allocate and return a new buffer.
+ * Return NULL on allocation failure. */
+buffer_t buffer_new(void) {
+    buffer_t buffer;
+    buffer = (buffer_t)malloc(sizeof(struct buffer));
+    if (buffer == NULL) {
+        return NULL;
+    }
+
+    buffer->size = INITIAL_BUFFER_SIZE;
+    buffer->position = 0;
+    buffer->buffer = (char*)malloc(sizeof(char) * INITIAL_BUFFER_SIZE);
+    if (buffer->buffer == NULL) {
+        free(buffer);
+        return NULL;
+    }
+
+    return buffer;
+}
+
+/* Free the memory allocated for `buffer`.
+ * Return non-zero on failure. */
+int buffer_free(buffer_t buffer) {
+    if (buffer == NULL) {
+        return 1;
+    }
+    free(buffer->buffer);
+    free(buffer);
+    return 0;
+}
+
+/* Grow `buffer` to at least `min_length`.
+ * Return non-zero on allocation failure. */
+static int buffer_grow(buffer_t buffer, int min_length) {
+    int old_size = 0;
+    int size = buffer->size;
+    char* old_buffer = buffer->buffer;
+    if (size >= min_length) {
+        return 0;
+    }
+    while (size < min_length) {
+        old_size = size;
+        size *= 2;
+        if (size <= old_size) {
+           /* Size did not increase. Could be an overflow
+            * or size < 1. Just go with min_length. */
+           size = min_length;
+        }
+    }
+    buffer->buffer = (char*)realloc(buffer->buffer, sizeof(char) * size);
+    if (buffer->buffer == NULL) {
+        free(old_buffer);
+        free(buffer);
+        return 1;
+    }
+    buffer->size = size;
+    return 0;
+}
+
+/* Assure that `buffer` has at least `size` free bytes (and grow if needed).
+ * Return non-zero on allocation failure. */
+static int buffer_assure_space(buffer_t buffer, int size) {
+    if (buffer->position + size <= buffer->size) {
+        return 0;
+    }
+    return buffer_grow(buffer, buffer->position + size);
+}
+
+/* Save `size` bytes from the current position in `buffer` (and grow if needed).
+ * Return offset for writing, or -1 on allocation failure. */
+buffer_position buffer_save_space(buffer_t buffer, int size) {
+    int position = buffer->position;
+    if (buffer_assure_space(buffer, size) != 0) {
+        return -1;
+    }
+    buffer->position += size;
+    return position;
+}
+
+/* Write `size` bytes from `data` to `buffer` (and grow if needed).
+ * Return non-zero on allocation failure. */
+int buffer_write(buffer_t buffer, const char* data, int size) {
+    if (buffer_assure_space(buffer, size) != 0) {
+        return 1;
+    }
+
+    memcpy(buffer->buffer + buffer->position, data, size);
+    buffer->position += size;
+    return 0;
+}
+
+/* Write `size` bytes from `data` to `buffer` at position `position`.
+ * Does not change the internal position of `buffer`.
+ * Return non-zero if buffer isn't large enough for write. */
+int buffer_write_at_position(buffer_t buffer, buffer_position position,
+                             const char* data, int size) {
+    if (position + size > buffer->size) {
+        buffer_free(buffer);
+        return 1;
+    }
+
+    memcpy(buffer->buffer + position, data, size);
+    return 0;
+}
+
+
+int buffer_get_position(buffer_t buffer) {
+    return buffer->position;
+}
+
+char* buffer_get_buffer(buffer_t buffer) {
+    return buffer->buffer;
+}
+
+void buffer_update_position(buffer_t buffer, buffer_position new_position) {
+    buffer->position = new_position;
+}