toolchain: make paranoid check of library/header paths unconditional

When we introduced support for the paranoid check of unsafe libraries
and headers path with commit 4ac8f78d3771 (Add option for paranoid
unsafe path checking) back in 2014, we made it optional, as we expected
that would break quite a few packages.

Now, almost 8 years later, we only have three packages that explicitly
reference the option (dillo, gnuradio, and libtalloc), either in a patch
or in their .mk.

The option has been enabled by default since 2016, with 61c8854cef2a
(toolchain: enable paranoid unsafe path check by default), and that has
not triggered many build failures in a while.

The minimal defconfig used by test-pkg has also had it enabled as of
b6c98b3549d8 (minimal.config: add BR2_COMPILER_PARANOID_UNSAFE_PATH=y)
in 2017.

It is time to make that globally unconditional now.

There is still a remnant, in our binutils patches. As our toolchain may
get used outside of Buildroot, people may got the expectation that path
poisoning is only a warning, so we keep the current behaviour.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Romain Naour <romain.naour@gmail.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

Config.in

@@ -685,24 +685,6 @@ config BR2_GLOBAL_PATCH_DIR
 
 menu "Advanced"
 
-config BR2_COMPILER_PARANOID_UNSAFE_PATH
-	bool "paranoid check of library/header paths"
-	default y
-	help
-	  By default, when this option is disabled, when the Buildroot
-	  cross-compiler will encounter an unsafe library or header path
-	  (such as /usr/include, or /usr/lib), the compiler will display
-	  a warning.
-
-	  By enabling this option, this warning is turned into an error,
-	  which will completely abort the build when such unsafe paths
-	  are encountered.
-
-	  Note that this mechanism is available for both the internal
-	  toolchain (through the toolchain wrapper and binutils patches)
-	  and external toolchain backends (through the toolchain
-	  wrapper).
-
 config BR2_FORCE_HOST_BUILD
 	bool "Force the building of host dependencies"
 	help

package/Makefile.in

@@ -426,9 +426,8 @@ else ifeq ($(BR2_SHARED_STATIC_LIBS),y)
 SHARED_STATIC_LIBS_OPTS = --enable-static --enable-shared
 endif
 
-ifeq ($(BR2_COMPILER_PARANOID_UNSAFE_PATH),y)
+# Used by our binutils patches.
 export BR_COMPILER_PARANOID_UNSAFE_PATH=enabled
-endif
 
 include package/pkg-download.mk
 include package/pkg-autotools.mk

support/config-fragments/minimal.config

@@ -4,5 +4,4 @@ BR2_INIT_NONE=y
 BR2_SYSTEM_BIN_SH_NONE=y
 # BR2_PACKAGE_BUSYBOX is not set
 # BR2_TARGET_ROOTFS_TAR is not set
-BR2_COMPILER_PARANOID_UNSAFE_PATH=y
 BR2_PACKAGE_BUSYBOX_SHOW_OTHERS=y

toolchain/toolchain-wrapper.c

@@ -154,12 +154,9 @@ static const struct str_len_s unsafe_opts[] = {
  * or separated (e.g. -I /foo/bar). In the first case, we need only print
  * the argument as it already contains the path (arg_has_path), while in
  * the second case we need to print both (!arg_has_path).
- *
- * If paranoid, exit in error instead of just printing a warning.
  */
 static void check_unsafe_path(const char *arg,
 			      const char *path,
-			      int paranoid,
 			      int arg_has_path)
 {
 	const struct str_len_s *p;
@@ -168,14 +165,12 @@ static void check_unsafe_path(const char *arg,
 		if (strncmp(path, p->str, p->len))
 			continue;
 		fprintf(stderr,
-			"%s: %s: unsafe header/library path used in cross-compilation: '%s%s%s'\n",
+			"%s: ERROR: unsafe header/library path used in cross-compilation: '%s%s%s'\n",
 			program_invocation_short_name,
-			paranoid ? "ERROR" : "WARNING",
 			arg,
 			arg_has_path ? "" : "' '", /* close single-quote, space, open single-quote */
 			arg_has_path ? "" : path); /* so that arg and path are properly quoted. */
-		if (paranoid)
-			exit(1);
+		exit(1);
 	}
 }
 
@@ -250,8 +245,6 @@ int main(int argc, char **argv)
 	char *progpath = argv[0];
 	char *basename;
 	char *env_debug;
-	char *paranoid_wrapper;
-	int paranoid;
 	int ret, i, count = 0, debug = 0, found_shared = 0;
 
 	/* Debug the wrapper to see arguments it was called with.
@@ -470,12 +463,6 @@ int main(int argc, char **argv)
 #endif
 	}
 
-	paranoid_wrapper = getenv("BR_COMPILER_PARANOID_UNSAFE_PATH");
-	if (paranoid_wrapper && strlen(paranoid_wrapper) > 0)
-		paranoid = 1;
-	else
-		paranoid = 0;
-
 	/* Check for unsafe library and header paths */
 	for (i = 1; i < argc; i++) {
 		const struct str_len_s *opt;
@@ -492,9 +479,9 @@ int main(int argc, char **argv)
 				i++;
 				if (i == argc)
 					break;
-				check_unsafe_path(argv[i-1], argv[i], paranoid, 0);
+				check_unsafe_path(argv[i-1], argv[i], 0);
 			} else
-				check_unsafe_path(argv[i], argv[i] + opt->len, paranoid, 1);
+				check_unsafe_path(argv[i], argv[i] + opt->len, 1);
 		}
 	}