Fix warnings about missing return value checks.

In some harmless places, checks for the return value of ECDSA and RSA
key generation and verification was omitted. Add them to keep the
compiler happy and to warn end users in case something is wrong.

src/invitation.c

@@ -335,7 +335,11 @@ int cmd_invite(int argc, char *argv[]) {
 			return 1;
 		}
 		chmod(filename, 0600);
-		ecdsa_write_pem_private_key(key, f);
+		if(!ecdsa_write_pem_private_key(key, f)) {
+			fprintf(stderr, "Could not write ECDSA private key\n");
+			fclose(f);
+			return 1;
+		}
 		fclose(f);
 
 		if(connect_tincd(false))
@@ -704,6 +708,8 @@ make_names:
 
 	snprintf(filename, sizeof filename, "%s" SLASH "ed25519_key.priv", confbase);
 	f = fopenmask(filename, "w", 0600);
+	if(!f)
+		return false;
 
 	if(!ecdsa_write_pem_private_key(key, f)) {
 		fprintf(stderr, "Error writing private key!\n");
@@ -725,10 +731,14 @@ make_names:
 	snprintf(filename, sizeof filename, "%s" SLASH "rsa_key.priv", confbase);
 	f = fopenmask(filename, "w", 0600);
 
-	rsa_write_pem_private_key(rsa, f);
+	if(!f || !rsa_write_pem_private_key(rsa, f)) {
+		fprintf(stderr, "Could not write private RSA key\n");
+	} else if(!rsa_write_pem_public_key(rsa, fh)) {
+		fprintf(stderr, "Could not write public RSA key\n");
+	}
+
 	fclose(f);
 
-	rsa_write_pem_public_key(rsa, fh);
 	fclose(fh);
 
 	rsa_free(rsa);

src/sptps_keypair.c

@@ -88,7 +88,10 @@ int main(int argc, char *argv[]) {
 	
 	FILE *fp = fopen(argv[1], "w");
 	if(fp) {
-		ecdsa_write_pem_private_key(key, fp);
+		if(!ecdsa_write_pem_private_key(key, fp)) {
+			fprintf(stderr, "Could not write ECDSA private key\n");
+			return 1;
+		}
 		fclose(fp);
 	} else {
 		fprintf(stderr, "Could not open '%s' for writing: %s\n", argv[1], strerror(errno));
@@ -97,7 +100,8 @@ int main(int argc, char *argv[]) {
 
 	fp = fopen(argv[2], "w");
 	if(fp) {
-		ecdsa_write_pem_public_key(key, fp);
+		if(!ecdsa_write_pem_public_key(key, fp))
+			fprintf(stderr, "Could not write ECDSA public key\n");
 		fclose(fp);
 	} else {
 		fprintf(stderr, "Could not open '%s' for writing: %s\n", argv[2], strerror(errno));

src/sptps_speed.c

@@ -102,19 +102,26 @@ int main(int argc, char *argv[]) {
 
 	fprintf(stderr, "Ed25519 sign for %lg seconds: ", duration);
 	for(clock_start(); clock_countto(duration);)
-		ecdsa_sign(key1, buf1, 256, buf2);
+		if(!ecdsa_sign(key1, buf1, 256, buf2))
+			return 1;
 	fprintf(stderr, "%22.2lf op/s\n", rate);
 
 	fprintf(stderr, "Ed25519 verify for %lg seconds: ", duration);
 	for(clock_start(); clock_countto(duration);)
-		ecdsa_verify(key1, buf1, 256, buf2);
+		if(!ecdsa_verify(key1, buf1, 256, buf2)) {
+			fprintf(stderr, "Signature verification failed\n");
+			return 1;
+		}
 	fprintf(stderr, "%20.2lf op/s\n", rate);
 
 	ecdh1 = ecdh_generate_public(buf1);
 	fprintf(stderr, "ECDH for %lg seconds: ", duration);
 	for(clock_start(); clock_countto(duration);) {
 		ecdh2 = ecdh_generate_public(buf2);
-		ecdh_compute_shared(ecdh2, buf1, buf3);
+		if(!ecdh2)
+			return 1;
+		if(!ecdh_compute_shared(ecdh2, buf1, buf3))
+			return 1;
 	}
 	fprintf(stderr, "%28.2lf op/s\n", rate);
 	ecdh_free(ecdh1);

src/tincctl.c

@@ -233,6 +233,12 @@ FILE *fopenmask(const char *filename, const char *mode, mode_t perms) {
 	perms &= ~mask;
 	umask(~perms);
 	FILE *f = fopen(filename, mode);
+
+	if(!f) {
+		fprintf(stderr, "Could not open %s: %s\n", filename, strerror(errno));
+		return NULL;
+	}
+
 #ifdef HAVE_FCHMOD
 	if((perms & 0444) && f)
 		fchmod(fileno(f), perms);