OpenPGP: refactor do_dump_do()

- limit length of data to write even in raw mode to the real length
- cluster variuable definitions
- restrict scope of variables
- introduce a variable length to make the purpose more obious
- start preprocessor directives at column one
- add comments where needed
- harmonize coding style: space after "if" and casts

src/tools/openpgp-tool.c

@@ -391,11 +391,10 @@ static int do_userinfo(sc_card_t *card)
 
 static int do_dump_do(sc_card_t *card, unsigned int tag)
 {
-	int r, tmp;
+	int r;
-	FILE *fp;
+	size_t length;
+	unsigned char buffer[254];	// Private DO are specified up to 254 bytes
 
-	// Private DO are specified up to 254 bytes
-	unsigned char buffer[254];
 	memset(buffer, '\0', sizeof(buffer));
 
 	if (tag < 0x101 || tag > 0x104) {
@@ -411,9 +410,12 @@ static int do_dump_do(sc_card_t *card, unsigned int tag)
 		}
 		return r;
 	}
+	length = (size_t) r;	/* r is guaranteed to be non-negative */
 
 	if (opt_raw) {
-		r = 0;
+		int tmp;
+		FILE *fp;
+
 #ifndef _WIN32
 		tmp = dup(fileno(stdout));
 #else
@@ -423,7 +425,7 @@ static int do_dump_do(sc_card_t *card, unsigned int tag)
 			return EXIT_FAILURE;
 		fp = freopen(NULL, "wb", stdout);
 		if (fp) {
-			r = (int)fwrite(buffer, sizeof(char), sizeof(buffer), fp);
+			r = (int) fwrite(buffer, sizeof(char), length, fp);
 		}
 #ifndef _WIN32
 		dup2(tmp, fileno(stdout));
@@ -432,10 +434,11 @@ static int do_dump_do(sc_card_t *card, unsigned int tag)
 #endif
 		clearerr(stdout);
 		close(tmp);
-		if (sizeof(buffer) != r)
+
+		if (length != r)	/* fail on write errors */
 			return EXIT_FAILURE;
 	} else {
-		util_hex_dump_asc(stdout, buffer, r, -1);
+		util_hex_dump_asc(stdout, buffer, length, -1);
 	}
 
 	return EXIT_SUCCESS;