regression_8100: use null terminated strings with file_to_c

GCC 9 is more strict with string manipulation, causing the build to
fail as the string data converted via file_to_c is not null terminated,
as described by the following build error:

regression_8100.c:100:29: error: '%*s' directive argument is not a
nul-terminated string [-Werror=format-overflow=]
tlen = myasprintf(&trust, "%*s", (int)sizeof(regression_8100_ca_crt),
                           ^~~
      regression_8100_ca_crt);
      ~~~~~~~~~~~~~~~~~~~~~~

Change file_to_c to terminate the string after conversion and update the
string size to remove the null terminated byte. Also update
regression_8100 to use the size variable defined via file_to_c instead
of manually calling sizeof.

Signed-off-by: Ricardo Salveti <ricardo@foundries.io>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/host/xtest/regression_8100.c b/host/xtest/regression_8100.c
index 0e865be..a1f8d0d 100644
--- a/host/xtest/regression_8100.c
+++ b/host/xtest/regression_8100.c
@@ -91,13 +91,13 @@
 		return;
 
 	clen = myasprintf(&chain, "%*s\n%*s",
-			  (int)sizeof(regression_8100_my_crt),
+			  (int)regression_8100_my_crt_size,
 			  regression_8100_my_crt,
-			  (int)sizeof(regression_8100_mid_crt),
+			  (int)regression_8100_mid_crt_size,
 			   regression_8100_mid_crt);
 	if (!ADBG_EXPECT_COMPARE_SIGNED(c, clen, !=, -1))
 		goto out;
-	tlen = myasprintf(&trust, "%*s", (int)sizeof(regression_8100_ca_crt),
+	tlen = myasprintf(&trust, "%*s", (int)regression_8100_ca_crt_size,
 			  regression_8100_ca_crt);
 	if (!ADBG_EXPECT_COMPARE_SIGNED(c, tlen, !=, -1))
 		goto out;
@@ -282,7 +282,7 @@
 					      NULL, &ret_orig)))
 		return;
 
-	clen = myasprintf(&csr, "%*s", (int)sizeof(regression_8100_my_csr),
+	clen = myasprintf(&csr, "%*s", (int)regression_8100_my_csr_size,
 			  regression_8100_my_csr);
 	if (!ADBG_EXPECT_COMPARE_SIGNED(c, clen, >=, 0))
 		goto out;
@@ -300,7 +300,7 @@
 	if (!ADBG_EXPECT_TEEC_SUCCESS(c, res))
 		goto out;
 
-	myasprintf(&ca, "%*s", (int)sizeof(regression_8100_ca_crt),
+	myasprintf(&ca, "%*s", (int)regression_8100_ca_crt_size,
 		   regression_8100_ca_crt);
 	if (!ADBG_EXPECT_NOT_NULL(c, ca))
 		goto out;
diff --git a/scripts/file_to_c.py b/scripts/file_to_c.py
index 83a9832..ae16f52 100755
--- a/scripts/file_to_c.py
+++ b/scripts/file_to_c.py
@@ -37,9 +37,9 @@
         else:
             f.write(" ")
 
-    f.write("};\n")
+    f.write("'\\0'};\n")
     f.write("const size_t " + args.name + "_size = sizeof(" + 
-            args.name + ");\n")
+            args.name + ") - 1;\n")
 
     f.close()
     inf.close()