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 --- elf/Makefile | 2 ++ 1 file changed, 2 insertions(+) (limited to 'elf') diff --git a/elf/Makefile b/elf/Makefile index eca7b28..0bfaffb 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -602,6 +602,7 @@ $(objpfx)tst-relro-libc.out: tst-relro-symbols.py $(..)/scripts/glibcelf.py \ --required=_IO_helper_jumps \ --required=_IO_mem_jumps \ --required=_IO_obstack_jumps \ + --required=_IO_printf_buffer_as_file_jumps \ --required=_IO_proc_jumps \ --required=_IO_str_chk_jumps \ --required=_IO_str_jumps \ @@ -610,6 +611,7 @@ $(objpfx)tst-relro-libc.out: tst-relro-symbols.py $(..)/scripts/glibcelf.py \ --required=_IO_wfile_jumps_maybe_mmap \ --required=_IO_wfile_jumps_mmap \ --required=_IO_wmem_jumps \ + --required=_IO_wprintf_buffer_as_file_jumps \ --required=_IO_wstr_jumps \ --required=_IO_wstrn_jumps \ --optional=_IO_old_cookie_jumps \ -- cgit v1.1