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[73.71.40.85]) by smtp.gmail.com with ESMTPSA id o8sm11644059pfa.42.2018.11.29.19.29.25 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 29 Nov 2018 19:29:27 -0800 (PST) Received: by garbanzo.do-not-panic.com (sSMTP sendmail emulation); Thu, 29 Nov 2018 19:29:24 -0800 Date: Thu, 29 Nov 2018 19:29:24 -0800 From: Luis Chamberlain To: Brendan Higgins , Petr Mladek Cc: gregkh@linuxfoundation.org, keescook@google.com, shuah@kernel.org, joel@jms.id.au, mpe@ellerman.id.au, joe@perches.com, brakmo@fb.com, rostedt@goodmis.org, Tim.Bird@sony.com, khilman@baylibre.com, julia.lawall@lip6.fr, linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org, jdike@addtoit.com, richard@nod.at, linux-um@lists.infradead.org, daniel@ffwll.ch, dri-devel@lists.freedesktop.org, robh@kernel.org, dan.j.williams@intel.com, linux-nvdimm@lists.01.org, kieran.bingham@ideasonboard.com, frowand.list@gmail.com, knut.omang@oracle.com Subject: Re: [RFC v3 03/19] kunit: test: add string_stream a std::stream like string builder Message-ID: <20181130032924.GH18410@garbanzo.do-not-panic.com> References: <20181128193636.254378-1-brendanhiggins@google.com> <20181128193636.254378-4-brendanhiggins@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181128193636.254378-4-brendanhiggins@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 28, 2018 at 11:36:20AM -0800, Brendan Higgins wrote: > 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. Hrm, what's the potential for such thing actually being eventually generically useful for printk folks, I wonder? Petr? Luis > > Signed-off-by: Brendan Higgins > --- > include/kunit/string-stream.h | 44 ++++++++++ > kunit/Makefile | 3 +- > kunit/string-stream.c | 149 ++++++++++++++++++++++++++++++++++ > 3 files changed, 195 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..933ed5740cf07 > --- /dev/null > +++ b/include/kunit/string-stream.h > @@ -0,0 +1,44 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * C++ stream style string builder used in KUnit for building messages. > + * > + * Copyright (C) 2018, Google LLC. > + * Author: Brendan Higgins > + */ > + > +#ifndef _KUNIT_STRING_STREAM_H > +#define _KUNIT_STRING_STREAM_H > + > +#include > +#include > +#include > +#include > + > +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; > + int (*add)(struct string_stream *this, const char *fmt, ...); > + int (*vadd)(struct string_stream *this, const char *fmt, va_list args); > + char *(*get_string)(struct string_stream *this); > + void (*clear)(struct string_stream *this); > + bool (*is_empty)(struct string_stream *this); > +}; > + > +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); > + > +#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..1e7efa630cc35 > --- /dev/null > +++ b/kunit/string-stream.c > @@ -0,0 +1,149 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * C++ stream style string builder used in KUnit for building messages. > + * > + * Copyright (C) 2018, Google LLC. > + * Author: Brendan Higgins > + */ > + > +#include > +#include > +#include > + > +static 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; > +} > + > +static 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; > +} > + > +static 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); > +} > + > +static 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; > +} > + > +static 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) > +{ > + 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); > + stream->add = string_stream_add; > + stream->vadd = string_stream_vadd; > + stream->get_string = string_stream_get_string; > + stream->clear = string_stream_clear; > + stream->is_empty = string_stream_is_empty; > + 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); > +} > + > -- > 2.20.0.rc0.387.gc7a69e6b6c-goog >