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659fe9fdd1
These buffers will eventually be used instead of FILE * objects to implement printf functions. The multibyte buffer is struct __printf_buffer, the wide buffer is struct __wprintf_buffer. To enable writing type-generic code, the header files printf_buffer-char.h and printf_buffer-wchar_t.h define the Xprintf macro differently, enabling Xprintf (buffer) to stand for __printf_buffer and __wprintf_buffer as appropriate. For common cases, macros like Xprintf_buffer are provided as a more syntactically convenient shortcut. Buffer-specific flush callbacks are implemented with a switch statement instead of a function pointer, to avoid hardening issues similar to those of libio vtables. struct __printf_buffer_as_file is needed to support custom printf specifiers because the public interface for that requires passing a FILE *, which is why there is a trapdoor back from these buffers to FILE * streams. Since the immediate user of these interfaces knows when processing has finished, there is no flush callback for the end of processing, only a flush callback for the intermediate buffer flush. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
58 lines
2.0 KiB
C
58 lines
2.0 KiB
C
/* Multibyte and wide printf buffers writing data to a FILE * stream.
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Copyright (C) 2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef PRINTF_BUFFER_TO_FILE_H
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#define PRINTF_BUFFER_TO_FILE_H
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#include <bits/types/FILE.h>
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#include <printf_buffer.h>
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struct __printf_buffer_to_file
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{
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struct __printf_buffer base;
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FILE *fp;
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/* Staging buffer. Used if fp does not have any available buffer
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space. */
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char stage[PRINTF_BUFFER_SIZE_TO_FILE_STAGE];
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};
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/* Initializes *BUF to write data to FP. */
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void __printf_buffer_to_file_init (struct __printf_buffer_to_file *buf,
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FILE *fp) attribute_hidden;
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/* Transfers any pending data in BUF to BUF->FP. The return value
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follows the printf convention (number bytes written; or -1 for error). */
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int __printf_buffer_to_file_done (struct __printf_buffer_to_file *buf)
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attribute_hidden;
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/* Wide version below. */
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struct __wprintf_buffer_to_file
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{
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struct __wprintf_buffer base;
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FILE *fp;
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wchar_t stage[PRINTF_BUFFER_SIZE_TO_FILE_STAGE];
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};
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void __wprintf_buffer_to_file_init (struct __wprintf_buffer_to_file *buf,
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FILE *fp) attribute_hidden;
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int __wprintf_buffer_to_file_done (struct __wprintf_buffer_to_file *buf)
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attribute_hidden;
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#endif /* PRINTF_BUFFER_TO_FILE_H */
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