Re: [pushed] Block signals during the initial part of dlopen

[Joseph Myers <joseph@codesourcery.com>]

On Wed, 27 Nov 2019, Sourceware to Gerrit sync (Code Review) wrote:

> Block signals during the initial part of dlopen
> 
> Lazy binding in a signal handler that interrupts a dlopen sees
> intermediate dynamic linker state.  This has likely been always
> unsafe, but with the new pending NODELETE state, this is clearly
> incorrect.  Other threads are excluded via the loader lock, but the
> current thread is not.  Blocking signals until right before ELF
> constructors run is the safe thing to do.

This change (commit a2e8aa0d9ea648068d8be52dd7b15f1b6a008e23) breaks the 
build for i686-gnu (unfortunately this was after a syntax error was 
introduced in build-many-glibcs.py so my bots quietly died on re-execing 
with the syntax error, and so didn't get to find this build failure).

There are a series of errors linking ld.so starting with:

/scratch/jmyers/glibc/many9/install/compilers/i686-gnu/lib/gcc/i686-glibc-gnu/9.2.1/../../../../i686-glibc-gnu/bin/ld: /scratch/jmyers/glibc/many9/build/glibcs/i686-gnu/glibc/libc_pic.a(libc_fatal.os): in function `__GI___libc_fatal':
/scratch/jmyers/glibc/many9/src/glibc/libio/../sysdeps/posix/libc_fatal.c:161: multiple definition of `__libc_fatal'; /scratch/jmyers/glibc/many9/build/glibcs/i686-gnu/glibc/elf/dl-allobjs.os:/scratch/jmyers/glibc/many9/src/glibc/elf/dl-minimal.c:188: first defined here

and leading up to:

make[3]: *** [/scratch/jmyers/glibc/many9/build/glibcs/i686-gnu/glibc/elf/librtld.map] Error 1

-- 
Joseph S. Myers
joseph@codesourcery.com