[PATCH v2] curl: enable threaded resolver

["André Draszik" <git@andred.net>]

From: André Draszik <adraszik@tycoint.com>

Multi-threaded applications using libcurl crash
on DNS timeouts when built using OE.

The reason is as follows:
By default, libcurl implements DNS timeouts using a
timer (alarm()) and a pair of setjmp()/longjmp().
This approach is unsafe in multi-threaded applications
for various reasons, as e.g. explained in the relevant
man-pages.

To avoid this, libcurl can be compiled with a built-in
threaded resolver, or against the c-ares asynchronous
resolver library.

To keep extra dependencies to a minimum, and to mimic
other distributions (debian at least), and because
c-ares is not available in OE-core, add a PACKAGECONFIG
to be able to enable use of of the built-in threaded
resolver and enable it by default.

Signed-off-by: André Draszik <adraszik@tycoint.com>

---
v2: rename PACKAGECONFIG option from thres to threaded-resolver
---
 meta/recipes-support/curl/curl_7.54.1.bb | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/meta/recipes-support/curl/curl_7.54.1.bb b/meta/recipes-support/curl/curl_7.54.1.bb
index f42582a9f0..5c8072fc65 100644
--- a/meta/recipes-support/curl/curl_7.54.1.bb
+++ b/meta/recipes-support/curl/curl_7.54.1.bb
@@ -20,9 +20,9 @@ SRC_URI[sha256sum] = "fdfc4df2d001ee0c44ec071186e770046249263c491fcae48df0e1a3ca
 CVE_PRODUCT = "libcurl"
 inherit autotools pkgconfig binconfig multilib_header
 
-PACKAGECONFIG ??= "${@bb.utils.filter('DISTRO_FEATURES', 'ipv6', d)} gnutls proxy zlib"
-PACKAGECONFIG_class-native = "ipv6 proxy ssl zlib"
-PACKAGECONFIG_class-nativesdk = "ipv6 proxy ssl zlib"
+PACKAGECONFIG ??= "${@bb.utils.filter('DISTRO_FEATURES', 'ipv6', d)} gnutls proxy threaded-resolver zlib"
+PACKAGECONFIG_class-native = "ipv6 proxy ssl threaded-resolver zlib"
+PACKAGECONFIG_class-nativesdk = "ipv6 proxy ssl threaded-resolver zlib"
 
 PACKAGECONFIG[dict] = "--enable-dict,--disable-dict,"
 PACKAGECONFIG[gnutls] = "--with-gnutls,--without-gnutls,gnutls"
@@ -42,6 +42,7 @@ PACKAGECONFIG[smtp] = "--enable-smtp,--disable-smtp,"
 PACKAGECONFIG[ssl] = "--with-ssl --with-random=/dev/urandom,--without-ssl,openssl"
 PACKAGECONFIG[telnet] = "--enable-telnet,--disable-telnet,"
 PACKAGECONFIG[tftp] = "--enable-tftp,--disable-tftp,"
+PACKAGECONFIG[threaded-resolver] = "--enable-threaded-resolver,--disable-threaded-resolver"
 PACKAGECONFIG[zlib] = "--with-zlib=${STAGING_LIBDIR}/../,--without-zlib,zlib"
 PACKAGECONFIG[krb5] = "--with-gssapi,--without-gssapi,krb5"
 
-- 
2.14.1