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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>
56 lines
1.8 KiB
C
56 lines
1.8 KiB
C
/* Wide printf buffers writing data to a FILE *.
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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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/* This implementation is not optimized (unlikely the multibyte
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implementation) and always writes to the temporary buffer first. */
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#include <printf_buffer_to_file.h>
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#include <array_length.h>
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#include <libio/libioP.h>
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void
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__wprintf_buffer_flush_to_file (struct __wprintf_buffer_to_file *buf)
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{
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size_t count = buf->base.write_ptr - buf->stage;
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if ((size_t) _IO_sputn (buf->fp, buf->stage, count) != count)
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{
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__wprintf_buffer_mark_failed (&buf->base);
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return;
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}
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buf->base.written += count;
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buf->base.write_ptr = buf->stage;
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}
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void
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__wprintf_buffer_to_file_init (struct __wprintf_buffer_to_file *buf, FILE *fp)
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{
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__wprintf_buffer_init (&buf->base, buf->stage, array_length (buf->stage),
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__wprintf_buffer_mode_to_file);
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buf->fp = fp;
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}
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int
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__wprintf_buffer_to_file_done (struct __wprintf_buffer_to_file *buf)
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{
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if (__wprintf_buffer_has_failed (&buf->base))
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return -1;
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__wprintf_buffer_flush_to_file (buf);
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return __wprintf_buffer_done (&buf->base);
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}
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