Re: [PATCH v3] manual: Document the dlinfo function

[Carlos O'Donell <carlos@redhat.com>]

On 4/29/22 10:31, Florian Weimer wrote:
> ---
> v3: Add safety information.  Mention this is a GNU extension.
>  manual/dynlink.texi | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 70 insertions(+), 1 deletion(-)

PDF manual looks good. Safety markup looks good.

LGTM.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
 
> diff --git a/manual/dynlink.texi b/manual/dynlink.texi
> index 54091be18e..bc3b779b69 100644
> --- a/manual/dynlink.texi
> +++ b/manual/dynlink.texi
> @@ -22,6 +22,76 @@ Dynamic linkers are sometimes called @dfn{dynamic loaders}.
>  @Theglibc{} provides various functions for querying information from the
>  dynamic linker.
>  
> +@deftypefun {int} dlinfo (void *@var{handle}, int @var{request}, void *@var{arg})
> +@safety{@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
> +@standards{GNU, dlfcn.h}
> +This function returns information about @var{handle} in the memory
> +location @var{arg}, based on @var{request}.  The @var{handle} argument
> +must be a pointer returned by @code{dlopen} or @code{dlmopen}; it must
> +not have been closed by @code{dlclose}.
> +
> +On success, @code{dlinfo} returns 0.  If there is an error, the function
> +returns @math{-1}, and @code{dlerror} can be used to obtain a
> +corresponding error message.
> +
> +The following operations are defined for use with @var{request}:
> +
> +@vtable @code
> +@item RTLD_DI_LINKMAP
> +The corresponding @code{struct link_map} pointer for @var{handle} is
> +written to @code{*@var{arg}}.  The @var{arg} argument must be the
> +address of an object of type @code{struct link_map *}.
> +
> +@item RTLD_DI_LMID
> +The namespace identifier of @var{handle} is written to
> +@code{*@var{arg}}.  The @var{arg} argument must be the address of an
> +object of type @code{Lmid_t}.
> +
> +@item RTLD_DI_ORIGIN
> +The value of the @code{$ORIGIN} dynamic string token for @var{handle} is
> +written to the character array starting at @var{arg} as a
> +null-terminated string.
> +
> +This request type should not be used because it is prone to buffer
> +overflows.
> +
> +@item RTLD_DI_SERINFO
> +@itemx RTLD_DI_SERINFOSIZE
> +These requests can be used to obtain search path information for
> +@var{handle}.  For both requests, @var{arg} must point to a
> +@code{Dl_serinfo} object.  The @code{RTLD_DI_SERINFOSIZE} request must
> +be made first; it updates the @code{dls_size} and @code{dls_cnt} members
> +of the @code{Dl_serinfo} object.  The caller should then allocate memory
> +to store at least @code{dls_size} bytes and pass that buffer to a
> +@code{RTLD_DI_SERINFO} request.  This second request fills the
> +@code{dls_serpath} array.  The number of array elements was returned in
> +the @code{dls_cnt} member in the initial @code{RTLD_DI_SERINFOSIZE}
> +request.  The caller is responsible for freeing the allocated buffer.
> +
> +This interface is prone to buffer overflows in multi-threaded processes
> +because the required size can change between the
> +@code{RTLD_DI_SERINFOSIZE} and @code{RTLD_DI_SERINFO} requests.
> +
> +@item RTLD_DI_TLS_DATA
> +This request writes the address of the TLS block (in the current thread)
> +for the shared object identified by @var{handle} to @code{*@var{arg}}.
> +The argument @var{arg} must be the address of an object of type
> +@code{void *}.  A null pointer is written if the object does not have
> +any associated TLS block.
> +
> +@item RTLD_DI_TLS_MODID
> +This request writes the TLS module ID for the shared object @var{handle}
> +to @code{*@var{arg}}.  The argument @var{arg} must be the address of an
> +object of type @code{size_t}.  The module ID is zero if the object
> +does not have an associated TLS block.
> +@end vtable
> +
> +The @code{dlinfo} function is a GNU extension.
> +@end deftypefun
> +
> +The remainder of this section documents the @code{_dl_find_object}
> +function and supporting types and constants.
> +
>  @deftp {Data Type} {struct dl_find_object}
>  @standards{GNU, dlfcn.h}
>  This structure contains information about a main program or loaded
> @@ -130,7 +200,6 @@ This function is a GNU extension.
>  @c dladdr1
>  @c dlclose
>  @c dlerror
> -@c dlinfo
>  @c dlmopen
>  @c dlopen
>  @c dlsym
> 


-- 
Cheers,
Carlos.