Re: [PATCH glibc] Define __mig_strlen to support dynamically sized strings in hurd RPCs

[Samuel Thibault]

Applied, thanks!

Flavio Cruz via Libc-alpha, le dim. 30 avril 2023 20:09:49 -0400, a ecrit:
> We make lib{mach,hurd}user.so only call __mig_strlen which can be
> relocated before libc.so is relocated, similar to what is done with
> __mig_memcpy.
> ---
>  mach/Makefile                           |  2 +-
>  mach/Versions                           |  1 +
>  mach/mach/mig_support.h                 |  1 +
>  mach/mig_strlen.c                       | 26 +++++++++++++++++++++++++
>  sysdeps/mach/include/mach/mig_support.h |  3 ++-
>  5 files changed, 31 insertions(+), 2 deletions(-)
>  create mode 100644 mach/mig_strlen.c
> 
> diff --git a/mach/Makefile b/mach/Makefile
> index 39358fdb83..a5d1252f95 100644
> --- a/mach/Makefile
> +++ b/mach/Makefile
> @@ -25,7 +25,7 @@ headers = mach_init.h mach.h mach_error.h mach-shortcuts.h 
> mach/mach_traps.h \
>  lock = spin-solid spin-lock mutex-init mutex-solid
>  lock-headers = lock-intern.h spin-lock.h
>  routines = $(mach-syscalls) $(mach-shortcuts) \
> -        mach_init mig_strncpy mig_memcpy msg \
> +        mach_init mig_strncpy mig_strlen mig_memcpy msg \
>          mig-alloc mig-dealloc mig-reply \
>          msg-destroy msgserver \
>          mach_error errstring error_compat errsystems \
> diff --git a/mach/Versions b/mach/Versions
> index b525cfdcf9..72e9d557db 100644
> --- a/mach/Versions
> +++ b/mach/Versions
> @@ -71,5 +71,6 @@ libc {
>    GLIBC_PRIVATE {
>      # functions used by RPC stubs
>      __mig_memcpy;
> +    __mig_strlen;
>    }
>  }
> diff --git a/mach/mach/mig_support.h b/mach/mach/mig_support.h
> index 78d4c4f0e3..c43fa953f8 100644
> --- a/mach/mach/mig_support.h
> +++ b/mach/mach/mig_support.h
> @@ -55,5 +55,6 @@ extern vm_size_t mig_strncpy (char *__dst, const char 
> *__src, vm_size_t __len);
>  extern vm_size_t __mig_strncpy (char *__dst, const char *__src, vm_size_t);
>  
>  extern void *__mig_memcpy (void *__dst, const void *__src, vm_size_t __len);
> +extern vm_size_t __mig_strlen (const char *__src);
>  
>  #endif       /* mach/mig_support.h */
> diff --git a/mach/mig_strlen.c b/mach/mig_strlen.c
> new file mode 100644
> index 0000000000..3c5ef8db15
> --- /dev/null
> +++ b/mach/mig_strlen.c
> @@ -0,0 +1,26 @@
> +/* strlen stub for mig stubs in libmachuser and libhurduser.
> +   Copyright (C) 2023 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <mach.h>
> +#include <string.h>
> +
> +vm_size_t
> +__mig_strlen (const char *src)
> +{
> +  return strlen (src);
> +}
> diff --git a/sysdeps/mach/include/mach/mig_support.h 
> b/sysdeps/mach/include/mach/mig_support.h
> index 1888d481d2..242f310a9c 100644
> --- a/sysdeps/mach/include/mach/mig_support.h
> +++ b/sysdeps/mach/include/mach/mig_support.h
> @@ -9,10 +9,11 @@ libc_hidden_proto (__mig_init)
>  # include <libc-symbols.h>
>  
>  # if defined USE_MULTIARCH && (IS_IN (libmachuser) || IS_IN (libhurduser))
> -/* Avoid directly calling ifunc-enabled memcpy or strpcpy,
> +/* Avoid directly calling ifunc-enabled memcpy or strlen,
>     because they would introduce a relocation loop between lib*user and
>     libc.so.  */
>  #  define memcpy(dest, src, n) __mig_memcpy(dest, src, n)
> +#  define strlen(src) __mig_strlen(src)
>  # endif
>  #endif
>  
> -- 
> 2.39.2
> 

-- 
Samuel
---
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