[Mesa-dev] [PATCH 1/9] util: Add a string buffer implementation
Timothy Arceri
tarceri at itsqueeze.com
Sun May 21 22:28:21 UTC 2017
On 22/05/17 06:49, Thomas Helland wrote:
> Based on Vladislav Egorov's work on the preprocessor, but split
> out to a util functionality that should be universal. Setup, teardown,
> memory handling and general layout is modeled around the hash_table
> and the set, to make it familiar for everyone.
>
> A notable change is that this implementation is always null terminated.
> The rationale is that it will be less error-prone, as one might
> access the buffer directly, thereby reading a non-terminated string.
> Also, vsnprintf and friends prints the null-terminator.
> ---
> src/util/Makefile.sources | 2 +
> src/util/string_buffer.c | 180 ++++++++++++++++++++++++++++++++++++++++++++++
> src/util/string_buffer.h | 75 +++++++++++++++++++
> 3 files changed, 257 insertions(+)
> create mode 100644 src/util/string_buffer.c
> create mode 100644 src/util/string_buffer.h
>
> diff --git a/src/util/Makefile.sources b/src/util/Makefile.sources
> index e9057343dc..cb46639c87 100644
> --- a/src/util/Makefile.sources
> +++ b/src/util/Makefile.sources
> @@ -37,6 +37,8 @@ MESA_UTIL_FILES := \
> simple_list.h \
> slab.c \
> slab.h \
> + string_buffer.c \
> + string_buffer.h \
> string_to_uint_map.cpp \
> string_to_uint_map.h \
> strndup.h \
> diff --git a/src/util/string_buffer.c b/src/util/string_buffer.c
> new file mode 100644
> index 0000000000..a500ffd389
> --- /dev/null
> +++ b/src/util/string_buffer.c
> @@ -0,0 +1,180 @@
> +/*
> + * Copyright © 2017 Thomas Helland
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + *
> + */
> +#include "ralloc.h"
> +#include "string_buffer.h"
> +
> +static bool
> +ensure_capacity(struct _mesa_string_buffer *str, uint32_t needed_capacity)
> +{
> + if (needed_capacity <= str->capacity)
> + return true;
> +
> + /* Too small, we have to resize our buffer.
> + * Double until we can fit the new string.
> + */
> + uint32_t new_capacity = str->capacity * 2;
> + while (needed_capacity > new_capacity)
> + new_capacity *= 2;
> +
> + str->buf = reralloc_array_size(str, str->buf, sizeof(char), new_capacity);
> + if (str->buf == NULL)
> + return false;
> +
> + str->capacity = new_capacity;
> + return true;
> +}
> +
> +struct _mesa_string_buffer *
> +_mesa_string_buffer_create(void *mem_ctx, uint32_t initial_capacity)
> +{
> + struct _mesa_string_buffer *str;
> + str = ralloc(mem_ctx, struct _mesa_string_buffer);
> +
> + if (str == NULL)
> + return NULL;
> +
> + /* If no initial capacity is set then set it to something */
> + str->capacity = initial_capacity ? initial_capacity : 8;
> + str->buf = ralloc_array(str, char, str->capacity);
> + str->length = 0;
> + str->buf[str->length] = '\0';
> + return str;
> +}
> +
> +void
> +_mesa_string_buffer_destroy(struct _mesa_string_buffer *str)
> +{
> + ralloc_free(str);
Using ralloc doesn't really gain us much in this util. Since the goal is
performance it would probably make sense to avoid the extra overhead and
just use regular memory functions.
> +}
> +
> +bool
> +_mesa_string_buffer_append(struct _mesa_string_buffer *str, char *c)
> +{
> + return _mesa_string_buffer_append_len(str, c, strlen(c));
> +}
I'd move this to the header as an inlined function.
> +
> +bool
> +_mesa_string_buffer_append_all(struct _mesa_string_buffer *str,
> + uint32_t num_args, ...)
> +{
> + int i;
> + char* s;
> + va_list args;
> + va_start(args, num_args);
> + for (i = 0; i < num_args; i++) {
> + s = va_arg(args, char*);
> + if (!_mesa_string_buffer_append_len(str, s, strlen(s)))
> + return false;
> + }
> + va_end(args);
> + return true;
> +}
> +
> +bool
> +_mesa_string_buffer_append_len(struct _mesa_string_buffer *str,
> + char *c, uint32_t len)
> +{
> + uint32_t needed_length = str->length + len + 1;
> + if (!ensure_capacity(str, needed_length))
> + return false;
> +
> + memcpy(str->buf + str->length, c, len);
> + str->length += len;
> + str->buf[str->length] = '\0';
> + return true;
> +}
> +
> +void
> +_mesa_string_buffer_clear(struct _mesa_string_buffer *str)
> +{
> + str->length = 0;
> + str->buf[str->length] = '\0';
> +}
> +
> +uint32_t
> +_mesa_string_buffer_space_left(struct _mesa_string_buffer *str)
> +{
> + return str->capacity - str->length - 1;
> +}
> +
> +bool
> +_mesa_string_buffer_vprintf(struct _mesa_string_buffer *str,
> + const char *format, va_list args)
> +{
> + uint32_t len;
> + uint32_t end = str->length;
> +
> +#if (defined(_MSC_VER) && _MSC_VER < 1900) || __MINGW32__
> + /* MSVC up to 2013 used non-standard vsnprintf() that returned -1
> + * if the buffer wasn't large enough. Another non-standard function
> + * _vscprintf() should be used to measure length of printf() output.
> + */
> + len = _vscprintf(format, args);
> +
> + /* Fail if an error happened in vscprintf() */
> + if (unlikely(len < 0))
> + return false;
> +
> + len = vsprintf(str->buf + end, format, args);
> + str->length += len;
> + return len >= 0;
> +
> +#else
> + uint32_t size = MAX2(100, _mesa_string_buffer_space_left(str));
> + while (1) {
> + ensure_capacity(str, end + size + 1);
> + len = vsnprintf(str->buf + end, size, format, args);
> +
> + /* Fail if an error happened in vsnprintf()
> + * or if measured len overflows size_t
> + */
> + if (unlikely(len < 0 || str->length + len + 1 < str->length))
> + return false;
> +
> + /* There was enough room for the string, so we're done */
> + if (len < size) {
> + str->length += len;
> + return true;
> + }
> +
> + /* Formatted string is too large for the buffer.
> + * Increase the size and print again.
> + */
> + size = MAX2(size * 2, str->length + len);
> + }
> +#endif
> +
> +}
> +
> +bool
> +_mesa_string_buffer_printf(struct _mesa_string_buffer *str,
> + const char *format, ...)
> +{
> + bool res;
> + va_list args;
> + va_start(args, format);
> + res = _mesa_string_buffer_vprintf(str, format, args);
> + va_end(args);
> + return res;
> +}
> diff --git a/src/util/string_buffer.h b/src/util/string_buffer.h
> new file mode 100644
> index 0000000000..f03e7841f3
> --- /dev/null
> +++ b/src/util/string_buffer.h
> @@ -0,0 +1,75 @@
> +/*
> + * Copyright © 2017 Thomas Helland
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + *
> + */
> +#ifndef _STRING_BUFFER_H
> +#define _STRING_BUFFER_H
> +
> +#include <stdbool.h>
> +#include <stdint.h>
> +#include <stdio.h>
> +#include <string.h>
> +
> +struct _mesa_string_buffer {
> + char *buf;
> + uint32_t length;
> + uint32_t capacity;
> +};
> +
> +struct _mesa_string_buffer *
> +_mesa_string_buffer_create(void *mem_ctx, uint32_t initial_capacity);
> +
> +void
> +_mesa_string_buffer_destroy(struct _mesa_string_buffer *str);
> +
> +bool
> +_mesa_string_buffer_append(struct _mesa_string_buffer *str, char *c);
> +
> +bool
> +_mesa_string_buffer_append_all(struct _mesa_string_buffer *str,
> + uint32_t num_args, ...);
> +bool
> +_mesa_string_buffer_append_len(struct _mesa_string_buffer *str,
> + char *c, uint32_t len);
> +
> +static inline bool
> +_mesa_string_buffer_append_char(struct _mesa_string_buffer *str, char c)
> +{
> + assert(str->capacity > 0 && ch != '\0');
> + return _mesa_string_buffer_append_len(str, &c, 1);
> +}
> +
> +void
> +_mesa_string_buffer_clear(struct _mesa_string_buffer *str);
> +
> +uint32_t
> +_mesa_string_buffer_space_left(struct _mesa_string_buffer *str);
> +
> +bool
> +_mesa_string_buffer_vprintf(struct _mesa_string_buffer *str,
> + const char *format, va_list args);
> +
> +bool
> +_mesa_string_buffer_printf(struct _mesa_string_buffer *str,
> + const char *format, ...);
> +
> +#endif /* _STRING_BUFFER_H */
>
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