Re: [Minios-devel] [UNIKRAFT PATCH RFC] build: isolate symbols inside libraries

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Hey,

I am fine with this, this is actually a good idea. It is a good practice 
to enforce this. However, we would need to adopt also the documentation. 
People should know that they have to provide an `export.syms` file 
together with their library.
Thanks,

Simon

On 05.06.2018 22:26, Yuri Volchkov wrote:
> The aim is to avoid symbol name conflicts between different
> libraries.
>
> Every lib have to have a file 'export.syms', which is simply a flat
> file, with one symbol name per line. All symbols not listed there will
> become local to the library.
>
> This patch is RFC, and covers only symbols needed to build a
> hello-world application for xen platform.
>
> Signed-off-by: Yuri Volchkov <yuri.volchkov@xxxxxxxxx>
> ---
>   lib/nolibc/export.syms        | 12 ++++++++++++
>   lib/ukalloc/export.syms       |  8 ++++++++
>   lib/ukallocbbuddy/export.syms |  1 +
>   lib/ukargparse/export.syms    |  1 +
>   lib/ukboot/export.syms        |  2 ++
>   lib/ukdebug/export.syms       |  3 +++
>   plat/xen/export.syms          | 11 +++++++++++
>   support/build/Makefile.rules  |  7 +++++--
>   8 files changed, 43 insertions(+), 2 deletions(-)
>   create mode 100644 lib/nolibc/export.syms
>   create mode 100644 lib/ukalloc/export.syms
>   create mode 100644 lib/ukallocbbuddy/export.syms
>   create mode 100644 lib/ukargparse/export.syms
>   create mode 100644 lib/ukboot/export.syms
>   create mode 100644 lib/ukdebug/export.syms
>   create mode 100644 plat/xen/export.syms
>
> diff --git a/lib/nolibc/export.syms b/lib/nolibc/export.syms
> new file mode 100644
> index 0000000..53816e0
> --- /dev/null
> +++ b/lib/nolibc/export.syms
> @@ -0,0 +1,12 @@
> +strncpy
> +strlen
> +strnlen
> +printf
> +vsnprintf
> +vfprintf
> +snprintf
> +memchr
> +memcmp
> +memcpy
> +memset
> +_nolibc_errno
> diff --git a/lib/ukalloc/export.syms b/lib/ukalloc/export.syms
> new file mode 100644
> index 0000000..66a9948
> --- /dev/null
> +++ b/lib/ukalloc/export.syms
> @@ -0,0 +1,8 @@
> +uk_alloc_get_default
> +uk_malloc_ifpages
> +uk_calloc_compat
> +uk_realloc_ifpages
> +uk_posix_memalign_ifpages
> +uk_memalign_compat
> +uk_free_ifpages
> +uk_alloc_register
> diff --git a/lib/ukallocbbuddy/export.syms b/lib/ukallocbbuddy/export.syms
> new file mode 100644
> index 0000000..6c871e3
> --- /dev/null
> +++ b/lib/ukallocbbuddy/export.syms
> @@ -0,0 +1 @@
> +uk_allocbbuddy_init
> diff --git a/lib/ukargparse/export.syms b/lib/ukargparse/export.syms
> new file mode 100644
> index 0000000..8995cb1
> --- /dev/null
> +++ b/lib/ukargparse/export.syms
> @@ -0,0 +1 @@
> +uk_argnparse
> diff --git a/lib/ukboot/export.syms b/lib/ukboot/export.syms
> new file mode 100644
> index 0000000..08b8999
> --- /dev/null
> +++ b/lib/ukboot/export.syms
> @@ -0,0 +1,2 @@
> +ukplat_entry_argp
> +main
> diff --git a/lib/ukdebug/export.syms b/lib/ukdebug/export.syms
> new file mode 100644
> index 0000000..4f8faba
> --- /dev/null
> +++ b/lib/ukdebug/export.syms
> @@ -0,0 +1,3 @@
> +_uk_printd
> +_uk_printk
> +uk_printk
> diff --git a/plat/xen/export.syms b/plat/xen/export.syms
> new file mode 100644
> index 0000000..7da37fd
> --- /dev/null
> +++ b/plat/xen/export.syms
> @@ -0,0 +1,11 @@
> +_libxenplat_start
> +_libxenplat_x86entry
> +ukplat_coutk
> +ukplat_coutd
> +ukplat_time_init
> +ukplat_memregion_count
> +ukplat_memregion_get
> +ukplat_irq_init
> +ukplat_terminate
> +ukplat_lcpu_enable_irq
> +ukplat_monotonic_clock
> diff --git a/support/build/Makefile.rules b/support/build/Makefile.rules
> index feb1455..7e2f7bd 100644
> --- a/support/build/Makefile.rules
> +++ b/support/build/Makefile.rules
> @@ -49,6 +49,8 @@ libname2olib = $(addprefix $(BUILD_DIR)/,$(addsuffix .o,$(1)))
>   
>   libname2preolib = $(addprefix $(BUILD_DIR)/,$(addsuffix .ld.o,$(1)))
>   
> +libname2exports = $($(call vprefix_lib,$1,BASE))/export.syms
> +
>   # converts a list of sources to paths pointing to their corresponding object 
> file
>   # src2obj $libname,$source(s),$variant(optional)
>   define src2obj =
> @@ -411,11 +413,12 @@ $(call libname2preolib,$(1)): $($(call 
> vprefix_lib,$(1),OBJS)) $($(call vprefix_
>                       $($(call vprefix_lib,$(1),OBJS)) $($(call 
> vprefix_lib,$(1),OBJS-y)) \
>                       -o $(call libname2preolib,$(1)))
>   
> -$(call libname2olib,$(1)): $(call libname2preolib,$(1))
> +$(call libname2olib,$(1)): $(call libname2preolib,$(1)) $(call 
> libname2exports,$1)
>         $(call build_cmd,OBJCOPY,,$(call libname2olib,$(1)),\
>                 $(OBJCOPY) $(OBJCFLAGS) $(OBJCFLAGS-y) \
>                            $($(call vprefix_lib,$(1),OBJCFLAGS)) $($(call 
> vprefix_lib,$(1),OBJCFLAGS-y)) \
> -                          $(call libname2preolib,$(1)) $(call 
> libname2olib,$(1)))
> +                          $(call libname2preolib,$(1)) $(call 
> libname2olib,$(1))) \
> +                          --keep-global-symbols=$(call libname2exports,$1)
>   
>   $(eval $(call vprefix_lib,$(1),CLEAN-y) += $(call build_clean,$(call libname2preolib,$(1))))
>   $(eval $(call vprefix_lib,$(1),CLEAN-y) += $(call build_clean,$(call 
> libname2olib,$(1))))
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