toolchain/toolchain-wrapper.c: set CCACHE env variables only when ccache is enabled

This commit modifies the toolchain-wrapper to make sure that the
CCACHE_COMPILERCHECK and CCACHE_BASEDIR are only set if ccache support
is enabled. Indeed, when BR2_USE_CCACHE is not set (or to a value
different than 1), we don't call the compiler with ccache, so there is
no reason to set those ccache environment variables, and they could
potentially conflict with a separate usage of ccache, outside of
Buildroot, for example when using the Buildroot SDK.

In particular, the value of CCACHE_BASEDIR doesn't not make any sense
when the Buildroot toolchain is not used during the Buildroot build,
as it points to the output directory $(BASE_DIR).

We pay attention to also not show those variables as being set in the
BR2_DEBUG_WRAPPER dump.

To help a little bit with this, a ccache_enabled boolean is introduced
to indicate when ccache is being used.

There is still quite a bit of #ifdef-ery involved, but it's not easy
to find a simpler way to organize the code.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Tested-By: Vincent Fazio <vfazio@xes-inc.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

toolchain/toolchain-wrapper.c

@@ -494,10 +494,28 @@ int main(int argc, char **argv)
 
 	exec_args = args;
 #ifdef BR_CCACHE
-	/* If BR2_USE_CCACHE is not defined, or its value is not 1,
-	 * skip the ccache call */
+	/* If BR2_USE_CCACHE is set and its value is 1, enable ccache
+	 * usage */
 	char *br_use_ccache = getenv("BR2_USE_CCACHE");
-	if (!br_use_ccache || strncmp(br_use_ccache, "1", strlen("1")))
+	bool ccache_enabled = br_use_ccache && !strncmp(br_use_ccache, "1", strlen("1"));
+
+	if (ccache_enabled) {
+#ifdef BR_CCACHE_HASH
+		/* Allow compilercheck to be overridden through the environment */
+		if (setenv("CCACHE_COMPILERCHECK", "string:" BR_CCACHE_HASH, 0)) {
+			perror(__FILE__ ": Failed to set CCACHE_COMPILERCHECK");
+			return 3;
+		}
+#endif
+#ifdef BR_CCACHE_BASEDIR
+		/* Allow compilercheck to be overridden through the environment */
+		if (setenv("CCACHE_BASEDIR", BR_CCACHE_BASEDIR, 0)) {
+			perror(__FILE__ ": Failed to set CCACHE_BASEDIR");
+			return 3;
+		}
+#endif
+	} else
+		/* ccache is disabled, skip it */
 		exec_args++;
 #endif
 
@@ -505,12 +523,14 @@ int main(int argc, char **argv)
 	if (debug > 0) {
 		fprintf(stderr, "Toolchain wrapper executing:");
 #ifdef BR_CCACHE_HASH
-		fprintf(stderr, "%sCCACHE_COMPILERCHECK='string:" BR_CCACHE_HASH "'",
-			(debug == 2) ? "\n    " : " ");
+		if (ccache_enabled)
+			fprintf(stderr, "%sCCACHE_COMPILERCHECK='string:" BR_CCACHE_HASH "'",
+				(debug == 2) ? "\n    " : " ");
 #endif
 #ifdef BR_CCACHE_BASEDIR
-		fprintf(stderr, "%sCCACHE_BASEDIR='" BR_CCACHE_BASEDIR "'",
-			(debug == 2) ? "\n    " : " ");
+		if (ccache_enabled)
+			fprintf(stderr, "%sCCACHE_BASEDIR='" BR_CCACHE_BASEDIR "'",
+				(debug == 2) ? "\n    " : " ");
 #endif
 		for (i = 0; exec_args[i]; i++)
 			fprintf(stderr, "%s'%s'",
@@ -518,21 +538,6 @@ int main(int argc, char **argv)
 		fprintf(stderr, "\n");
 	}
 
-#ifdef BR_CCACHE_HASH
-	/* Allow compilercheck to be overridden through the environment */
-	if (setenv("CCACHE_COMPILERCHECK", "string:" BR_CCACHE_HASH, 0)) {
-		perror(__FILE__ ": Failed to set CCACHE_COMPILERCHECK");
-		return 3;
-	}
-#endif
-#ifdef BR_CCACHE_BASEDIR
-	/* Allow compilercheck to be overridden through the environment */
-	if (setenv("CCACHE_BASEDIR", BR_CCACHE_BASEDIR, 0)) {
-		perror(__FILE__ ": Failed to set CCACHE_BASEDIR");
-		return 3;
-	}
-#endif
-
 	if (execv(exec_args[0], exec_args))
 		perror(path);