growing_fifo: new utility library for growing fifo_buffer

2 files changed, 163 insertions, 0 deletions

diff --git a/src/growing_fifo.c b/src/growing_fifo.c
new file mode 100644
index 000000000..88431f60e
--- /dev/null
+++ b/src/growing_fifo.c
@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "growing_fifo.h"
+#include "fifo_buffer.h"
+
+#include <assert.h>
+#include <string.h>
+
+/**
+ * Align buffer sizes at 8 kB boundaries.  Must be a power of two.
+ */
+static const size_t GROWING_FIFO_ALIGN = 8192;
+
+/**
+ * Align the specified size to the next #GROWING_FIFO_ALIGN boundary.
+ */
+static size_t
+align(size_t size)
+{
+	return ((size - 1) | (GROWING_FIFO_ALIGN - 1)) + 1;
+}
+
+struct fifo_buffer *
+growing_fifo_new(void)
+{
+	return fifo_buffer_new(GROWING_FIFO_ALIGN);
+}
+
+void *
+growing_fifo_write(struct fifo_buffer **buffer_p, size_t length)
+{
+	assert(buffer_p != NULL);
+
+	struct fifo_buffer *buffer = *buffer_p;
+	assert(buffer != NULL);
+
+	size_t max_length;
+	void *p = fifo_buffer_write(buffer, &max_length);
+	if (p != NULL && max_length >= length)
+		return p;
+
+	/* grow */
+	size_t new_size = fifo_buffer_available(buffer) + length;
+	assert(new_size > fifo_buffer_capacity(buffer));
+	*buffer_p = buffer = fifo_buffer_realloc(buffer, align(new_size));
+
+	/* try again */
+	p = fifo_buffer_write(buffer, &max_length);
+	assert(p != NULL);
+	assert(max_length >= length);
+
+	return p;
+}
+
+void
+growing_fifo_append(struct fifo_buffer **buffer_p,
+		    const void *data, size_t length)
+{
+	void *p = growing_fifo_write(buffer_p, length);
+	memcpy(p, data, length);
+	fifo_buffer_append(*buffer_p, length);
+}
diff --git a/src/growing_fifo.h b/src/growing_fifo.h
new file mode 100644
index 000000000..723c3b3ff
--- /dev/null
+++ b/src/growing_fifo.h
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** \file
+ *
+ * Helper functions for our FIFO buffer library (fifo_buffer.h) that
+ * allows growing the buffer on demand.
+ *
+ * This library is not thread safe.
+ */
+
+#ifndef MPD_GROWING_FIFO_H
+#define MPD_GROWING_FIFO_H
+
+#include <stddef.h>
+
+struct fifo_buffer;
+
+/**
+ * Allocate a new #fifo_buffer with the default size.
+ */
+struct fifo_buffer *
+growing_fifo_new(void);
+
+/**
+ * Prepares writing to the buffer, see fifo_buffer_write() for
+ * details.  The difference is that this function will automatically
+ * grow the buffer if it is too small.
+ *
+ * The caller is responsible for limiting the capacity of the buffer.
+ *
+ * @param length the number of bytes that will be written
+ * @return a pointer to the end of the buffer (will not be NULL)
+ */
+void *
+growing_fifo_write(struct fifo_buffer **buffer_p, size_t length);
+
+/**
+ * A helper function that combines growing_fifo_write(), memcpy(),
+ * fifo_buffer_append().
+ */
+void
+growing_fifo_append(struct fifo_buffer **buffer_p,
+		    const void *data, size_t length);
+
+#endif