From 659fe9fdd14b0772f4e9722b751b9b010665e053 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Mon, 19 Dec 2022 18:56:54 +0100 Subject: stdio-common: Introduce buffers for implementing printf 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 --- stdio-common/wprintf_buffer_to_file.c | 55 +++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 stdio-common/wprintf_buffer_to_file.c (limited to 'stdio-common/wprintf_buffer_to_file.c') diff --git a/stdio-common/wprintf_buffer_to_file.c b/stdio-common/wprintf_buffer_to_file.c new file mode 100644 index 0000000000..ac936fab6c --- /dev/null +++ b/stdio-common/wprintf_buffer_to_file.c @@ -0,0 +1,55 @@ +/* Wide printf buffers writing data to a FILE *. + Copyright (C) 2022 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +/* This implementation is not optimized (unlikely the multibyte + implementation) and always writes to the temporary buffer first. */ + +#include + +#include +#include + +void +__wprintf_buffer_flush_to_file (struct __wprintf_buffer_to_file *buf) +{ + size_t count = buf->base.write_ptr - buf->stage; + if ((size_t) _IO_sputn (buf->fp, buf->stage, count) != count) + { + __wprintf_buffer_mark_failed (&buf->base); + return; + } + buf->base.written += count; + buf->base.write_ptr = buf->stage; +} + +void +__wprintf_buffer_to_file_init (struct __wprintf_buffer_to_file *buf, FILE *fp) +{ + __wprintf_buffer_init (&buf->base, buf->stage, array_length (buf->stage), + __wprintf_buffer_mode_to_file); + buf->fp = fp; +} + +int +__wprintf_buffer_to_file_done (struct __wprintf_buffer_to_file *buf) +{ + if (__wprintf_buffer_has_failed (&buf->base)) + return -1; + __wprintf_buffer_flush_to_file (buf); + return __wprintf_buffer_done (&buf->base); +} -- cgit v1.2.3