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3020f72618
Instead of using a special ELF section along with a linker script directive to put the IO vtables within the RELRO section, the libio vtables are all moved to an array marked as data.relro (so linker will place in the RELRO segment without the need of extra directives). To avoid static linking namespace issues and including all vtable referenced objects, all required function pointers are set to weak alias. Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
125 lines
4.0 KiB
C
125 lines
4.0 KiB
C
/* FILE * interface to a struct __printf_buffer. Multibyte version.
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Copyright (C) 2022-2023 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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#include <printf_buffer_as_file.h>
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#include <assert.h>
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#include <printf_buffer.h>
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/* Commit the data directly written through the stdio stream. */
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static void
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__printf_buffer_as_file_commit (struct __printf_buffer_as_file *file)
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{
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/* Check that the write pointers in the file stream are consistent
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with the next buffer. */
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assert (file->stream._IO_write_ptr >= file->next->write_ptr);
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assert (file->stream._IO_write_ptr <= file->next->write_end);
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assert (file->stream._IO_write_base == file->next->write_base);
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assert (file->stream._IO_write_end == file->next->write_end);
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file->next->write_ptr = file->stream._IO_write_ptr;
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}
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/* Pointer the FILE * write buffer into the active printf_buffer
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area. */
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static void
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__printf_buffer_as_file_switch_to_buffer (struct __printf_buffer_as_file *file)
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{
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file->stream._IO_write_base = file->next->write_base;
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file->stream._IO_write_ptr = file->next->write_ptr;
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file->stream._IO_write_end = file->next->write_end;
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}
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/* Only a small subset of the vtable functions is implemented here,
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following _IO_obstack_jumps. */
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int
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__printf_buffer_as_file_overflow (FILE *fp, int ch)
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{
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struct __printf_buffer_as_file *file = (struct __printf_buffer_as_file *) fp;
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__printf_buffer_as_file_commit (file);
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/* EOF means only a flush is requested. */
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if (ch != EOF)
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__printf_buffer_putc (file->next, ch);
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/* Ensure that flushing actually produces room. */
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if (!__printf_buffer_has_failed (file->next)
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&& file->next->write_ptr == file->next->write_end)
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__printf_buffer_flush (file->next);
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__printf_buffer_as_file_switch_to_buffer (file);
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if (!__printf_buffer_has_failed (file->next))
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return (unsigned char) ch;
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else
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return EOF;
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}
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size_t
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__printf_buffer_as_file_xsputn (FILE *fp, const void *buf, size_t len)
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{
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struct __printf_buffer_as_file *file = (struct __printf_buffer_as_file *) fp;
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__printf_buffer_as_file_commit (file);
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/* Copy the data. */
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__printf_buffer_write (file->next, buf, len);
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__printf_buffer_as_file_switch_to_buffer (file);
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if (!__printf_buffer_has_failed (file->next))
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return len;
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else
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/* We may actually have written something. But the stream is
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corrupted in this case anyway, so try not to divine the write
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count here. */
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return 0;
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}
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void
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__printf_buffer_as_file_init (struct __printf_buffer_as_file *file,
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struct __printf_buffer *next)
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{
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file->stream._lock = NULL;
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_IO_no_init (&file->stream, _IO_USER_LOCK, -1, NULL, NULL);
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file->vtable = &_IO_printf_buffer_as_file_jumps;
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/* Set up the write buffer from the next buffer. */
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file->next = next;
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__printf_buffer_as_file_switch_to_buffer (file);
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/* Mark the read area as inactive, by making all pointers equal. */
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file->stream._IO_read_base = file->stream._IO_write_base;
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file->stream._IO_read_ptr = file->stream._IO_write_base;
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file->stream._IO_read_end = file->stream._IO_write_base;
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}
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bool
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__printf_buffer_as_file_terminate (struct __printf_buffer_as_file *file)
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{
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if (file->stream._flags & _IO_ERR_SEEN)
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return false;
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else
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{
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__printf_buffer_as_file_commit (file);
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return true;
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}
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}
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