From: Waldemar Kozaczuk <jwkozac...@gmail.com> Committer: Waldemar Kozaczuk <jwkozac...@gmail.com> Branch: master
iconv: use stubs if iconv functions not used by an app The GCC libstdc++ commit https://github.com/gcc-mirror/gcc/commit/c0ace69ec677d1f85f6a433c8fae2d4df6f75714 which I believe fixes the bug https://gcc.gnu.org/bugzilla/show_bug.cgi?format=multiple&id=64132 makes the C++ standard library depend on libc iconv* functions. The implementation of these functions in musl employs many large arrays used to translate characters from one encoding to another and inflates the kernel by around 156K. After some research to see where exactly the related code - _M_initialize_numpunct() and _M_initialize_moneypunct() is executed it turns out that OSv itself internally does not trigger the code path leading to the execution of iconv functions because it uses a default C locale. This observation in general would be a mute point as by default OSv provides iconv* functions as part of libc anyway so C++ standard library using it does not really change anything. Except when one builds custom kernel to remove all symbols but what application specifically needs like so (for details see d19ccb1cde100ab4a5c8e6db9a0d69560cabbd04): ./scripts/build fs=rofs conf_hide_symbols=1 image=native-example \ conf_version_script=build/last/app_version_script In this case we would like to optimize kernel size and replace real iconv functions which would be referenced by _M_initialize_numpunct and _M_initialize_moneypunct with simple stubs in libc/locale/iconv_stubs.cc. This optimization allows us to reduce kernel size by another 156K. Signed-off-by: Waldemar Kozaczuk <jwkozac...@gmail.com> Message-Id: <20220627185608.37930-1-jwkozac...@gmail.com> --- diff --git a/Makefile b/Makefile --- a/Makefile +++ b/Makefile @@ -1142,8 +1142,6 @@ musl += locale/catgets.o libc += locale/catopen.o libc += locale/duplocale.o libc += locale/freelocale.o -musl += locale/iconv.o -musl += locale/iconv_close.o libc += locale/intl.o libc += locale/langinfo.o musl += locale/localeconv.o @@ -2085,8 +2083,16 @@ endif endif linker_archives_options = --no-whole-archive $(libstdc++.a) $(libgcc.a) $(libgcc_eh.a) $(boost-libs) \ --exclude-libs libstdc++.a --gc-sections +ifneq ($(shell grep -c iconv $(out)/version_script),0) +musl += locale/iconv.o +musl += locale/iconv_close.o +else +libc += locale/iconv_stubs.o +endif else linker_archives_options = --whole-archive $(libstdc++.a) $(libgcc_eh.a) $(boost-libs) --no-whole-archive $(libgcc.a) +musl += locale/iconv.o +musl += locale/iconv_close.o endif $(out)/default_version_script: exported_symbols/*.symbols exported_symbols/$(arch)/*.symbols diff --git a/libc/locale/iconv_stubs.cc b/libc/locale/iconv_stubs.cc --- a/libc/locale/iconv_stubs.cc +++ b/libc/locale/iconv_stubs.cc @@ -0,0 +1,26 @@ +/* + * Copyright (C) 2022 Waldemar Kozaczuk + * + * This work is open source software, licensed under the terms of the + * BSD license as described in the LICENSE file in the top-level directory. + */ + +#include <iconv.h> +#include <errno.h> +#include <osv/stubbing.hh> + +iconv_t iconv_open(const char *to, const char *from) { + WARN_STUBBED(); + errno = EINVAL; + return (iconv_t)-1; +} + +size_t iconv(iconv_t cd, char **in, size_t *inb, char **out, size_t *outb) { + WARN_STUBBED(); + return 0l; +} + +int iconv_close(iconv_t cd) { + WARN_STUBBED(); + return 0l; +} -- You received this message because you are subscribed to the Google Groups "OSv Development" group. To unsubscribe from this group and stop receiving emails from it, send an email to osv-dev+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/osv-dev/000000000000cef62005e3407cbc%40google.com.
