[v5,2/2] package/libssh2: Add selectable crypto libraries

Add functionality to allow crypto libraries for libssh2 to be selectable
by a choice instead of a fallback that may not work in all cases.
Previous fallback is maintained from within the "defaults" of the choice
menu, but can be overridden by making a choice.

This fixes issues where two crypto libraries are present on the system,
but the fallback order picks the wrong one.

Signed-off-by: Sam Voss <sam.voss@rockwellcollins.com>

--

[v2->v3]
 - Fix comment about favoring mbedtls

[v1->v2]
 - Do not have comments when crypo is not selected, select it instead.
 - Do not select OpenSSL by default when libssh2 is selected if no
   others are chosen
---
 package/libssh2/Config.in  | 24 +++++++++++++++++++++++-
 package/libssh2/libssh2.mk |  8 ++++----
 2 files changed, 27 insertions(+), 5 deletions(-)

Sam, All,

On 2017-10-31 12:56 -0500, Sam Voss spake thusly:
> Add functionality to allow crypto libraries for libssh2 to be selectable
> by a choice instead of a fallback that may not work in all cases.
> Previous fallback is maintained from within the "defaults" of the choice
> menu, but can be overridden by making a choice.
> 
> This fixes issues where two crypto libraries are present on the system,
> but the fallback order picks the wrong one.

As seen on IRC, you have to explain a bit more why one would want to
select a specific backend rather than the "priority" choice we have now.

> Signed-off-by: Sam Voss <sam.voss@rockwellcollins.com>
[--SNIP--]
> diff --git a/package/libssh2/Config.in b/package/libssh2/Config.in
> index 9b60823..fcdbbf3 100644
> --- a/package/libssh2/Config.in
> +++ b/package/libssh2/Config.in
> @@ -1,6 +1,5 @@
>  config BR2_PACKAGE_LIBSSH2
>  	bool "libssh2"
> -	select BR2_PACKAGE_OPENSSL if !(BR2_PACKAGE_MBEDTLS || BR2_PACKAGE_LIBGCRYPT)
>  	help
>  	  libssh2 is a client-side C library implementing the SSH2
>  	  protocol as defined by Internet Drafts: SECSH-TRANS(22),
> @@ -8,3 +7,26 @@ config BR2_PACKAGE_LIBSSH2
>  	  SECSH-FILEXFER(06)*, SECSH-DHGEX(04), and SECSH-NUMBERS(10)
>  
>  	  http://www.libssh2.org/
> +
> +if BR2_PACKAGE_LIBSSH2
> +
> +choice
> +	prompt "Crypto Backend"
> +	help
> +	  Select crypto library to be used in libssh2.
> +
> +config BR2_PACKAGE_LIBSSH2_MBEDTLS
> +	select BR2_PACKAGE_MBEDTLS
> +	bool "mbedtls"

Ordering of options is type, depends, then select:

    config BR2_PACKAGE_LIBSSH2_MBEDTLS
        bool "mbedtls"
        select BR2_PACKAGE_MBEDTLS

> +config BR2_PACKAGE_LIBSSH2_LIBGCRYPT
> +	select BR2_PACKAGE_LIBGCRYPT
> +	depends on BR2_PACKAGE_LIBGPG_ERROR_ARCH_SUPPORTS # libgcrypt -> libgpg-error
> +	bool "gcrypt"

And here:

    config BR2_PACKAGE_LIBSSH2_LIBGCRYPT
        bool "gcrypt"
        depends on BR2_PACKAGE_LIBGPG_ERROR_ARCH_SUPPORTS # libgcrypt -> libgpg-error
        select BR2_PACKAGE_LIBGCRYPT

Regards,
Yann E. MORIN.

> +config BR2_PACKAGE_LIBSSH2_OPENSSL
> +	select BR2_PACKAGE_OPENSSL
> +	bool "openssl"
> +
> +endchoice
> +endif
> diff --git a/package/libssh2/libssh2.mk b/package/libssh2/libssh2.mk
> index d40e844..befac92 100644
> --- a/package/libssh2/libssh2.mk
> +++ b/package/libssh2/libssh2.mk
> @@ -15,19 +15,19 @@ LIBSSH2_CONF_OPTS = --disable-examples-build
>  LIBSSH2_AUTORECONF = YES
>  
>  # Dependency is one of mbedtls, libgcrypt or openssl, guaranteed in
> -# Config.in. Favour mbedtls.
> -ifeq ($(BR2_PACKAGE_MBEDTLS),y)
> +# Config.in.
> +ifeq ($(BR2_PACKAGE_LIBSSH2_MBEDTLS),y)
>  LIBSSH2_DEPENDENCIES += mbedtls
>  LIBSSH2_CONF_OPTS += --with-libmbedcrypto-prefix=$(STAGING_DIR)/usr \
>  	--with-crypto=mbedtls
> -else ifeq ($(BR2_PACKAGE_LIBGCRYPT),y)
> +else ifeq ($(BR2_PACKAGE_LIBSSH2_LIBGCRYPT),y)
>  LIBSSH2_DEPENDENCIES += libgcrypt
>  LIBSSH2_CONF_OPTS += --with-libgcrypt-prefix=$(STAGING_DIR)/usr \
>  	--with-crypto=libgcrypt
>  # configure.ac forgets to link to dependent libraries of gcrypt breaking static
>  # linking
>  LIBSSH2_CONF_ENV += LIBS="`$(STAGING_DIR)/usr/bin/libgcrypt-config --libs`"
> -else
> +else ifeq ($(BR2_PACKAGE_LIBSSH2_OPENSSL),y)
>  LIBSSH2_DEPENDENCIES += openssl
>  LIBSSH2_CONF_OPTS += --with-libssl-prefix=$(STAGING_DIR)/usr \
>  	--with-crypto=openssl
> -- 
> 1.9.1
> 
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