lib/kunit/string-stream.c

Source file repositories/reference/linux-study-clean/lib/kunit/string-stream.c

File Facts

System
Linux kernel
Corpus path
lib/kunit/string-stream.c
Extension
.c
Size
4639 bytes
Lines
208
Domain
Kernel Services
Bucket
lib
Inferred role
Kernel Services: implementation source
Status
source implementation candidate

Why This File Exists

Shared kernel service surface used by multiple subsystems, including helpers, cryptography, virtualization support, and async I/O infrastructure.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * C++ stream style string builder used in KUnit for building messages.
 *
 * Copyright (C) 2019, Google LLC.
 * Author: Brendan Higgins <brendanhiggins@google.com>
 */

#include <kunit/static_stub.h>
#include <kunit/test.h>
#include <linux/list.h>
#include <linux/slab.h>

#include "string-stream.h"


static struct string_stream_fragment *alloc_string_stream_fragment(int len, gfp_t gfp)
{
	struct string_stream_fragment *frag;

	frag = kzalloc_obj(*frag, gfp);
	if (!frag)
		return ERR_PTR(-ENOMEM);

	frag->fragment = kmalloc(len, gfp);
	if (!frag->fragment) {
		kfree(frag);
		return ERR_PTR(-ENOMEM);
	}

	return frag;
}

static void string_stream_fragment_destroy(struct string_stream_fragment *frag)
{
	list_del(&frag->node);
	kfree(frag->fragment);
	kfree(frag);
}

int string_stream_vadd(struct string_stream *stream,
		       const char *fmt,
		       va_list args)
{
	struct string_stream_fragment *frag_container;
	int buf_len, result_len;
	va_list args_for_counting;

	/* Make a copy because `vsnprintf` could change it */
	va_copy(args_for_counting, args);

	/* Evaluate length of formatted string */
	buf_len = vsnprintf(NULL, 0, fmt, args_for_counting);

	va_end(args_for_counting);

	if (buf_len == 0)
		return 0;

	/* Reserve one extra for possible appended newline. */
	if (stream->append_newlines)
		buf_len++;

	/* Need space for null byte. */
	buf_len++;

	frag_container = alloc_string_stream_fragment(buf_len, stream->gfp);
	if (IS_ERR(frag_container))
		return PTR_ERR(frag_container);

	if (stream->append_newlines) {
		/* Don't include reserved newline byte in writeable length. */
		result_len = vsnprintf(frag_container->fragment, buf_len - 1, fmt, args);

		/* Append newline if necessary. */
		if (frag_container->fragment[result_len - 1] != '\n')
			result_len = strlcat(frag_container->fragment, "\n", buf_len);
	} else {
		result_len = vsnprintf(frag_container->fragment, buf_len, fmt, args);
	}

	spin_lock(&stream->lock);
	stream->length += result_len;
	list_add_tail(&frag_container->node, &stream->fragments);
	spin_unlock(&stream->lock);

	return 0;
}

int string_stream_add(struct string_stream *stream, const char *fmt, ...)

Annotation

Implementation Notes