ccache.bbclass: Refactor it to make it more reliable

index 6518dac..1986cf2 100644
@@ -76,9 +76,6 @@ EXTRA_OEMAKE = "${@bb.utils.contains('PACKAGECONFIG', 'manpages', '', 'OE_DISABL
 
 export OE_LDFLAGS = "${LDFLAGS}"
 
-# openssl fails with ccache: https://bugzilla.yoctoproject.org/show_bug.cgi?id=12810
-CCACHE = ""
-
 TERMIO ?= "-DTERMIO"
 TERMIO_libc-musl = "-DTERMIOS"
 

index c2f5900..432e4ed 100644
@@ -37,11 +37,6 @@ CACHED_CONFIGUREVARS += "ac_cv_header_netinet_sctp_h=no ac_cv_header_netinet_sct
 CACHED_CONFIGUREVARS += "ac_cv_sizeof_struct_iovec=yes"
 CACHED_CONFIGUREVARS += "ac_cv_file__dev_zero=yes"
 
-# Otherwise libtool fails to compile apr-utils
-# x86_64-linux-libtool: compile: unable to infer tagged configuration
-# x86_64-linux-libtool:   error: specify a tag with '--tag'
-CCACHE = ""
-
 PACKAGECONFIG ??= "${@bb.utils.filter('DISTRO_FEATURES', 'ipv6', d)}"
 PACKAGECONFIG[ipv6] = "--enable-ipv6,--disable-ipv6,"
 

index b364d2b..12fc452 100644
@@ -4,8 +4,8 @@ OECMAKE_SOURCEPATH ??= "${S}"
 DEPENDS_prepend = "cmake-native "
 B = "${WORKDIR}/build"
 
-# We need to unset CCACHE otherwise cmake gets too confused
-CCACHE = ""
+# We need to disable CCACHE otherwise cmake gets too confused
+CCACHE_DISABLE = "1"
 
 # What CMake generator to use.
 # The supported options are "Unix Makefiles" or "Ninja".

index b2c94fa..1390f31 100644
@@ -42,6 +42,10 @@ TUNE_CCARGS_remove = "-march=mips32r2"
 SECURITY_CFLAGS_mipsarch = "${SECURITY_NOPIE_CFLAGS}"
 SECURITY_NOPIE_CFLAGS ??= ""
 
+# go can't be built with ccache:
+# gcc: fatal error: no input files
+CCACHE_DISABLE = "1"
+
 def go_map_arch(a, d):
     import re
     if re.match('i.86', a):

index 6566328..7f80065 100644
@@ -9,8 +9,19 @@ LICENSE = "GPLv3+"
 
 DEPENDS = "zlib"
 
-SRC_URI = "https://download.samba.org/pub/${BPN}/${BP}.tar.xz"
+SRC_URI = "https://download.samba.org/pub/${BPN}/${BP}.tar.gz"
 
 inherit autotools
 
+# Remove ccache-native's dependencies, so that it can be used widely by
+# other native recipes.
+DEPENDS_class-native = ""
+EXTRA_OECONF_class-native = "--with-bundled-zlib"
+INHIBIT_AUTOTOOLS_DEPS_class-native = "1"
+PATCHTOOL = "patch"
+
 BBCLASSEXTEND = "native"
+
+do_configure_class-native() {
+    oe_runconf
+}

index 7230934..921dc3b 100644
@@ -3,8 +3,8 @@ require ccache.inc
 LICENSE = "GPLv3+"
 LIC_FILES_CHKSUM = "file://LICENSE.adoc;md5=2722abeaf1750dbf175b9491112374e1"
 
-SRC_URI[md5sum] = "9e048f88f3897125864f9a5e1abfb72d"
-SRC_URI[sha256sum] = "18a8b14367d63d3d37fb6c33cba60e1b7fcd7a63d608df97c9771ae0d234fee2"
+SRC_URI[md5sum] = "07d4324efbb3c216bbd1c512f4553480"
+SRC_URI[sha256sum] = "b2264923c63e2b90a17cf56acb1df3f4229c416fb88e476e5ec7e02919d319c3"
 
 SRC_URI += " \
             file://0002-dev.mk.in-fix-file-name-too-long.patch \

index 9609020..59e1022 100644
@@ -1,4 +1,14 @@
-CCACHE = "${@bb.utils.which(d.getVar('PATH'), 'ccache') and 'ccache '}"
+#
+# Usage:
+# - Enable ccache
+#   Add the following line to a conffile such as conf/local.conf:
+#   INHERIT += "ccache"
+#
+# - Disable ccache for a recipe
+#   Add the following line to the recipe if it can't be built with ccache:
+#   CCACHE_DISABLE = '1'
+#
+
 export CCACHE_DIR ?= "${TMPDIR}/ccache/${MULTIMACH_TARGET_SYS}/${PN}"
 
 # We need to stop ccache considering the current directory or the

@@ -7,5 +17,14 @@ export CCACHE_DIR ?= "${TMPDIR}/ccache/${MULTIMACH_TARGET_SYS}/${PN}"
 # ${PV} or ${PR} change.
 export CCACHE_NOHASHDIR ?= "1"
 
-DEPENDS_append_class-target = " ccache-native"
-DEPENDS[vardepvalueexclude] = " ccache-native"
+python() {
+    """
+    Enable ccache for the recipe
+    """
+    pn = d.getVar('PN')
+    # quilt-native doesn't need ccache since no c files
+    if not (pn in ('ccache-native', 'quilt-native') or
+            bb.utils.to_boolean(d.getVar('CCACHE_DISABLE'))):
+        d.appendVar('DEPENDS', ' ccache-native')
+        d.setVar('CCACHE', 'ccache ')
+}

index 6480062..c88d66c 100644
@@ -492,7 +492,7 @@ HOSTTOOLS += " \
 HOSTTOOLS += "${@'ip ping ps scp ssh stty' if (bb.utils.contains_any('IMAGE_CLASSES', 'testimage testsdk', True, False, d) or any(x in (d.getVar("BBINCLUDED") or "") for x in ["testimage.bbclass", "testsdk.bbclass"])) else ''}"
 
 # Link to these if present
-HOSTTOOLS_NONFATAL += "aws ccache gcc-ar gpg ld.bfd ld.gold nc pigz sftp socat ssh sudo"
+HOSTTOOLS_NONFATAL += "aws gcc-ar gpg ld.bfd ld.gold nc pigz sftp socat ssh sudo"
 
 # Temporary add few more detected in bitbake world
 HOSTTOOLS_NONFATAL += "join nl size yes zcat"

@@ -504,10 +504,6 @@ HOSTTOOLS_NONFATAL += "bzr"
 HOSTTOOLS_NONFATAL += "scp"
 
 CCACHE ??= ""
-# ccache < 3.1.10 will create CCACHE_DIR on startup even if disabled, and
-# autogen sets HOME=/dev/null so in certain situations builds can fail.
-# Explicitly export CCACHE_DIR until we can assume ccache >3.1.10 on the host.
-export CCACHE_DIR ??= "${@os.getenv('HOME')}/.ccache"
 
 TOOLCHAIN_OPTIONS = " --sysroot=${STAGING_DIR_TARGET}"
 

index c67dec4..4141d6c 100644
@@ -49,7 +49,6 @@ SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += " \
   *->quilt-native \
   *->subversion-native \
   *->git-native \
-  *->ccache-native \
   *->icecc-create-env-native \
   gcc-cross-${TARGET_ARCH}->virtual/${TARGET_PREFIX}libc-for-gcc \
   gcc-cross-${TARGET_ARCH}->linux-libc-headers \

index 8a584d6..a64f16c 100644
@@ -362,7 +362,8 @@ def host_gcc_version(d, taskcontextonly=False):
     if taskcontextonly and d.getVar('BB_WORKERCONTEXT') != '1':
         return
 
-    compiler = d.getVar("BUILD_CC")
+    # Get rid of ccache since it is not present when parsing.
+    compiler = d.getVar("BUILD_CC").lstrip("ccache-")
     try:
         env = os.environ.copy()
         env["PATH"] = d.getVar("PATH")

index f234bac..181e9a9 100644
@@ -37,13 +37,13 @@ class ImageOptionsTests(OESelftestTestCase):
         p = bb_vars['SYSROOT_DESTDIR'] + bb_vars['bindir'] + "/" + "ccache"
         self.assertTrue(os.path.isfile(p), msg = "No ccache found (%s)" % p)
         self.write_config('INHERIT += "ccache"')
-        self.add_command_to_tearDown('bitbake -c clean m4')
-        bitbake("m4 -c clean")
-        bitbake("m4 -f -c compile")
-        log_compile = os.path.join(get_bb_var("WORKDIR","m4"), "temp/log.do_compile")
+        self.add_command_to_tearDown('bitbake -c clean m4-native')
+        bitbake("m4-native -c clean")
+        bitbake("m4-native -f -c compile")
+        log_compile = os.path.join(get_bb_var("WORKDIR","m4-native"), "temp/log.do_compile")
         with open(log_compile, "r") as f:
             loglines = "".join(f.readlines())
-        self.assertIn("ccache", loglines, msg="No match for ccache in m4 log.do_compile. For further details: %s" % log_compile)
+        self.assertIn("ccache", loglines, msg="No match for ccache in m4-native log.do_compile. For further details: %s" % log_compile)
 
     @OETestID(1435)
     def test_read_only_image(self):

index e715ffa..e6af673 100644
@@ -122,6 +122,10 @@ def setup_hosttools_dir(dest, toolsvar, d, fatal=True):
         desttool = os.path.join(dest, tool)
         if not os.path.exists(desttool):
             srctool = bb.utils.which(path, tool, executable=True)
+            # gcc/g++ may link to ccache on some hosts, e.g.,
+            # /usr/local/bin/ccache/gcc -> /usr/bin/ccache, then which(gcc)
+            # would return /usr/local/bin/ccache/gcc, but what we need is
+            # /usr/bin/gcc, this code can check and fix that.
             if "ccache" in srctool:
                 srctool = bb.utils.which(path, tool, executable=True, direction=1)
             if srctool: