A number of test features need to do pretty complicated string printing where it may not be possible to rely on a single preallocated string with parameters.
So provide a library for constructing the string as you go similar to C++'s std::string.
Signed-off-by: Brendan Higgins brendanhiggins@google.com --- include/kunit/string-stream.h | 51 ++++++++++++ kunit/Makefile | 3 +- kunit/string-stream.c | 144 ++++++++++++++++++++++++++++++++++ 3 files changed, 197 insertions(+), 1 deletion(-) create mode 100644 include/kunit/string-stream.h create mode 100644 kunit/string-stream.c
diff --git a/include/kunit/string-stream.h b/include/kunit/string-stream.h new file mode 100644 index 0000000000000..567a4629406da --- /dev/null +++ b/include/kunit/string-stream.h @@ -0,0 +1,51 @@ +/* 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 + */ + +#ifndef _KUNIT_STRING_STREAM_H +#define _KUNIT_STRING_STREAM_H + +#include <linux/types.h> +#include <linux/spinlock.h> +#include <linux/kref.h> +#include <stdarg.h> + +struct string_stream_fragment { + struct list_head node; + char *fragment; +}; + +struct string_stream { + size_t length; + struct list_head fragments; + + /* length and fragments are protected by this lock */ + spinlock_t lock; + struct kref refcount; +}; + +struct string_stream *new_string_stream(void); + +void destroy_string_stream(struct string_stream *stream); + +void string_stream_get(struct string_stream *stream); + +int string_stream_put(struct string_stream *stream); + +int string_stream_add(struct string_stream *this, const char *fmt, ...); + +int string_stream_vadd(struct string_stream *this, + const char *fmt, + va_list args); + +char *string_stream_get_string(struct string_stream *this); + +void string_stream_clear(struct string_stream *this); + +bool string_stream_is_empty(struct string_stream *this); + +#endif /* _KUNIT_STRING_STREAM_H */ diff --git a/kunit/Makefile b/kunit/Makefile index 5efdc4dea2c08..275b565a0e81f 100644 --- a/kunit/Makefile +++ b/kunit/Makefile @@ -1 +1,2 @@ -obj-$(CONFIG_KUNIT) += test.o +obj-$(CONFIG_KUNIT) += test.o \ + string-stream.o diff --git a/kunit/string-stream.c b/kunit/string-stream.c new file mode 100644 index 0000000000000..7018194ecf2fa --- /dev/null +++ b/kunit/string-stream.c @@ -0,0 +1,144 @@ +// 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 <linux/list.h> +#include <linux/slab.h> +#include <kunit/string-stream.h> + +int string_stream_vadd(struct string_stream *this, + const char *fmt, + va_list args) +{ + struct string_stream_fragment *fragment; + int len; + va_list args_for_counting; + unsigned long flags; + + /* Make a copy because `vsnprintf` could change it */ + va_copy(args_for_counting, args); + + /* Need space for null byte. */ + len = vsnprintf(NULL, 0, fmt, args_for_counting) + 1; + + va_end(args_for_counting); + + fragment = kmalloc(sizeof(*fragment), GFP_KERNEL); + if (!fragment) + return -ENOMEM; + + fragment->fragment = kmalloc(len, GFP_KERNEL); + if (!fragment->fragment) { + kfree(fragment); + return -ENOMEM; + } + + len = vsnprintf(fragment->fragment, len, fmt, args); + spin_lock_irqsave(&this->lock, flags); + this->length += len; + list_add_tail(&fragment->node, &this->fragments); + spin_unlock_irqrestore(&this->lock, flags); + return 0; +} + +int string_stream_add(struct string_stream *this, const char *fmt, ...) +{ + va_list args; + int result; + + va_start(args, fmt); + result = string_stream_vadd(this, fmt, args); + va_end(args); + return result; +} + +void string_stream_clear(struct string_stream *this) +{ + struct string_stream_fragment *fragment, *fragment_safe; + unsigned long flags; + + spin_lock_irqsave(&this->lock, flags); + list_for_each_entry_safe(fragment, + fragment_safe, + &this->fragments, + node) { + list_del(&fragment->node); + kfree(fragment->fragment); + kfree(fragment); + } + this->length = 0; + spin_unlock_irqrestore(&this->lock, flags); +} + +char *string_stream_get_string(struct string_stream *this) +{ + struct string_stream_fragment *fragment; + size_t buf_len = this->length + 1; /* +1 for null byte. */ + char *buf; + unsigned long flags; + + buf = kzalloc(buf_len, GFP_KERNEL); + if (!buf) + return NULL; + + spin_lock_irqsave(&this->lock, flags); + list_for_each_entry(fragment, &this->fragments, node) + strlcat(buf, fragment->fragment, buf_len); + spin_unlock_irqrestore(&this->lock, flags); + + return buf; +} + +bool string_stream_is_empty(struct string_stream *this) +{ + bool is_empty; + unsigned long flags; + + spin_lock_irqsave(&this->lock, flags); + is_empty = list_empty(&this->fragments); + spin_unlock_irqrestore(&this->lock, flags); + + return is_empty; +} + +void destroy_string_stream(struct string_stream *stream) +{ + string_stream_clear(stream); + kfree(stream); +} + +static void string_stream_destroy(struct kref *kref) +{ + struct string_stream *stream = container_of(kref, + struct string_stream, + refcount); + destroy_string_stream(stream); +} + +struct string_stream *new_string_stream(void) +{ + struct string_stream *stream = kzalloc(sizeof(*stream), GFP_KERNEL); + + if (!stream) + return NULL; + + INIT_LIST_HEAD(&stream->fragments); + spin_lock_init(&stream->lock); + kref_init(&stream->refcount); + return stream; +} + +void string_stream_get(struct string_stream *stream) +{ + kref_get(&stream->refcount); +} + +int string_stream_put(struct string_stream *stream) +{ + return kref_put(&stream->refcount, &string_stream_destroy); +} +