3 files changed, 42 insertions, 0 deletions
diff --git a/CCache/ccache.c b/CCache/ccache.c
index 3a4e8c7b2..222fbe70f 100644
--- a/CCache/ccache.c
+++ b/CCache/ccache.c
@@ -1128,6 +1128,14 @@ int main(int argc, char *argv[])
 		exit(1);
 	}
 
+	if (!getenv("CCACHE_READONLY")) {
+		if (create_cachedirtag(cache_dir) != 0) {
+			fprintf(stderr,"ccache: failed to create %s/CACHEDIR.TAG (%s)\n",
+				cache_dir, strerror(errno));
+			exit(1);
+		}
+	}
+
 	ccache(argc, argv);
 	return 1;
 }
diff --git a/CCache/ccache.h b/CCache/ccache.h
index 67904cdf7..71b03ffe9 100644
--- a/CCache/ccache.h
+++ b/CCache/ccache.h
@@ -94,6 +94,7 @@ int move_file(const char *src, const char *dest);
 int test_if_compressed(const char *filename);
 
 int create_dir(const char *dir);
+int create_cachedirtag(const char *dir);
 void x_asprintf(char **ptr, const char *format, ...);
 char *x_strdup(const char *s);
 void *x_realloc(void *ptr, size_t size);
diff --git a/CCache/util.c b/CCache/util.c
index 70d7ea7d4..6056d36f7 100644
--- a/CCache/util.c
+++ b/CCache/util.c
@@ -329,6 +329,39 @@ int create_dir(const char *dir)
 	return 0;
 }
 
+char const CACHEDIR_TAG[] =
+	"Signature: 8a477f597d28d172789f06886806bc55\n"
+	"# This file is a cache directory tag created by ccache.\n"
+	"# For information about cache directory tags, see:\n"
+	"#	http://www.brynosaurus.com/cachedir/\n";
+
+int create_cachedirtag(const char *dir)
+{
+	char *filename;
+	struct stat st;
+	FILE *f;
+	x_asprintf(&filename, "%s/CACHEDIR.TAG", dir);
+	if (stat(filename, &st) == 0) {
+		if (S_ISREG(st.st_mode)) {
+			goto success;
+		}
+		errno = EEXIST;
+		goto error;
+	}
+	f = fopen(filename, "w");
+	if (!f) goto error;
+	if (fwrite(CACHEDIR_TAG, sizeof(CACHEDIR_TAG)-1, 1, f) != 1) {
+		goto error;
+	}
+	if (fclose(f)) goto error;
+success:
+	free(filename);
+	return 0;
+error:
+	free(filename);
+	return 1;
+}
+
 /*
   this is like asprintf() but dies if the malloc fails
   note that we use vsnprintf in a rather poor way to make this more portable