Date: Sat, 18 May 2013 11:18:20 +0200 From: Szabolcs Nagy <nsz@...t70.net> To: musl@...ts.openwall.com Subject: Re: Broken silent glibc-specific assumptions uncovered by musl * Rich Felker <dalias@...ifal.cx> [2013-05-17 13:37:10 -0400]: > Making wrong assumptions about fsync and fdatasync. (I'm not familiar > with this issue so somebody else will have to fill it in.) apparently i didn't remember this correctly it's just an old-linux vs new-linux break: linux used to implement fsync,O_SYNC with the same guarantees as fdatasync,O_DSYNC, so many applications use fsync when they actually mean fdatasync (faster, no mtime sync) then some filesystems started to support O_SYNC properly with a new flag, but it took some time to trickle down as distros often use older libc (where the O_DSYNC and O_SYNC definition was the same so even on new kernel the applications kept getting the old flag, hence i remembered it as a libc issue: when i first tried musl on some storage application it was significantly slower due to this difference) other runtime differences: - "%Ld" instead of "%lld" as mentioned by sh4rm4 on irc - lfs64 problems: eg printing off_t with "%d" - serializing abi incompatible structures with (char*) cast - relying on some locale specific behaviour (LC_NUMERIC) - /proc fs issue with writev in musl stdio - relying on LD_* or other env vars for glibc or the loader - relying on /etc/* files used by glibc or the loader - dlopen with RTLD_LAZY - timezone files are not yet supported in musl - crypt sha2 with long key input - using constructors with priority gcc extension - relying on the random generator algorithm to be the same - musl's err does not print __progname, it might annoy one - musl have some stubs - ppc double-double long double
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