[Mesa-dev] [PATCH] util: Add a string buffer implementation
Thomas Helland
thomashelland90 at gmail.com
Thu Sep 14 20:42:32 UTC 2017
Based on Vladislav Egorovs 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.
Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>
V2: Address review feedback from Timothy and Grazvydas
- Fix MINGW preprocessor check
- Changed len from uint to int
- Make string argument const in append function
- Move to header and inline append function
- Add crimp_to_fit function for resizing buffer
V3: Move include of ralloc to string_buffer.h
V4: Use u_string.h for a cross-platform working vsnprintf
V5: Remember to cast to char * in crimp function
V6: Address review feedback from Nicolai
- Handle !str->buf in buffer_create
- Ensure va_end is always called in buffer_append_all
- Add overflow check in buffer_append_len
- Do not expose buffer_space_left, just remove it
- Clarify why a loop is used in vprintf, change to for-loop
- Add a va_copy to buffer_vprintf to fix failure to append arguments
when having to resize the buffer for vsnprintf.
V7: Address more review feedback from Nicolai
- Add missing va_end corresponding to va_copy
- Error check failure to allocate in crimp_to_fit
---
src/util/Makefile.sources | 2 +
src/util/string_buffer.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++
src/util/string_buffer.h | 104 ++++++++++++++++++++++++++++++++
3 files changed, 254 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 4ed4e39f03..c7f6516a99 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 \
strndup.h \
strtod.c \
strtod.h \
diff --git a/src/util/string_buffer.c b/src/util/string_buffer.c
new file mode 100644
index 0000000000..c33173bfa0
--- /dev/null
+++ b/src/util/string_buffer.c
@@ -0,0 +1,148 @@
+/*
+ * 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 "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, 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 : 32;
+ str->buf = ralloc_array(str, char, str->capacity);
+
+ if (!str->buf) {
+ ralloc_free(str);
+ return NULL;
+ }
+
+ str->length = 0;
+ str->buf[str->length] = '\0';
+ return str;
+}
+
+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))) {
+ va_end(args);
+ return false;
+ }
+ }
+ va_end(args);
+ return true;
+}
+
+bool
+_mesa_string_buffer_append_len(struct _mesa_string_buffer *str,
+ const char *c, uint32_t len)
+{
+ uint32_t needed_length = str->length + len + 1;
+
+ /* Check if we're overflowing uint32_t */
+ if (needed_length < str->length)
+ return false;
+
+ 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;
+}
+
+bool
+_mesa_string_buffer_vprintf(struct _mesa_string_buffer *str,
+ const char *format, va_list args)
+{
+ /* We're looping two times to avoid duplicating code */
+ for (uint32_t i = 0; i < 2; i++) {
+ va_list arg_copy;
+ va_copy(arg_copy, args);
+ uint32_t space_left = str->capacity - str->length;
+
+ int32_t len = util_vsnprintf(str->buf + str->length,
+ space_left, format, arg_copy);
+ va_end(arg_copy);
+
+ /* Error in vsnprintf() or measured len overflows size_t */
+ if (unlikely(len < 0 || str->length + len + 1 < str->length))
+ return false;
+
+ /* There was enough space for the string; we're done */
+ if (len < space_left) {
+ str->length += len;
+ return true;
+ }
+
+ /* Not enough space, resize and retry */
+ ensure_capacity(str, str->length + len + 1);
+ }
+
+ return false;
+}
+
+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..eaaf5f33df
--- /dev/null
+++ b/src/util/string_buffer.h
@@ -0,0 +1,104 @@
+/*
+ * 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 "ralloc.h"
+#include "u_string.h"
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+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);
+
+static inline void
+_mesa_string_buffer_destroy(struct _mesa_string_buffer *str)
+{
+ ralloc_free(str);
+}
+
+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,
+ const char *c, uint32_t len);
+
+static inline bool
+_mesa_string_buffer_append_char(struct _mesa_string_buffer *str, char c)
+{
+ return _mesa_string_buffer_append_len(str, &c, 1);
+}
+
+static inline bool
+_mesa_string_buffer_append(struct _mesa_string_buffer *str, const char *c)
+{
+ return _mesa_string_buffer_append_len(str, c, strlen(c));
+}
+
+static inline void
+_mesa_string_buffer_clear(struct _mesa_string_buffer *str)
+{
+ str->length = 0;
+ str->buf[str->length] = '\0';
+}
+
+static inline void
+_mesa_string_buffer_crimp_to_fit(struct _mesa_string_buffer *str)
+{
+ char *crimped =
+ (char *) reralloc_array_size(str, str->buf, sizeof(char),
+ str->capacity);
+ if (!crimped)
+ return;
+
+ str->capacity = str->length + 1;
+ str->buf = crimped;
+}
+
+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, ...);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* _STRING_BUFFER_H */
--
2.13.3
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