The open source OpenXR runtime
u/truncate_printf: Add truncating helpers
authored by
Jakob Bornecrantz
and committed by
Ryan Pavlik
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299471f2
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src/xrt/auxiliary/util/u_truncate_printf.h
+88
src/xrt/auxiliary/util/u_truncate_printf.h
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// Copyright 2023, Collabora, Ltd.
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// SPDX-License-Identifier: BSL-1.0
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/*!
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* @file
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* @brief Truncating versions of string printing functions.
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* @author Jakob Bornecrantz <jakob@collabora.com>
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* @ingroup aux_util
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*/
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#pragma once
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#include "xrt/xrt_compiler.h"
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#include <stdio.h>
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#include <stdarg.h>
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#include <limits.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*!
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* We want to truncate the value, not get the possible written.
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*
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* There are no version of the *many* Windows versions of this functions that
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* truncates and returns the number of bytes written (not including null). Also
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* need to have the same behaviour on Linux.
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*
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* @ingroup @aux_util
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*/
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static inline int
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u_truncate_vsnprintf(char *chars, size_t char_count, const char *fmt, va_list args)
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{
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/*
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* We always want to be able to write null terminator, and
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* something propbly went wrong if char_count larger then INT_MAX.
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*/
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if (char_count == 0 || char_count > INT_MAX) {
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return -1;
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}
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// Will always be able to write null terminator.
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int ret = vsnprintf(chars, char_count, fmt, args);
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if (ret < 0) {
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return ret;
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}
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// Safe, ret is checked for negative above.
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if ((size_t)ret > char_count - 1) {
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return (int)char_count - 1;
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}
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return ret;
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}
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/*!
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* We want to truncate the value, not get the possible written, and error when
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* we can not write out anything.
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*
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* See @ref u_truncate_vsnprintf for more info.
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*
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* @ingroup @aux_util
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*/
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static inline int
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u_truncate_snprintf(char *chars, size_t char_count, const char *fmt, ...)
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{
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/*
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* We always want to be able to write null terminator, and
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* something propbly went wrong if char_count larger then INT_MAX.
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*/
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if (char_count == 0 || char_count > INT_MAX) {
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return -1;
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}
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va_list args;
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va_start(args, fmt);
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int ret = u_truncate_vsnprintf(chars, char_count, fmt, args);
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va_end(args);
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return ret;
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}
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#ifdef __cplusplus
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}
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#endif