tools/env: Remove unneeded complexity

The length included the name length, and then it was subtracted back
out on each use.  Now we don't include it in the first place.  Also
realloc as we process arguments and eliminate memset.  Use memcpy
instead of manually copying each byte.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

tools/env/fw_env.c

@@ -478,7 +478,6 @@ int fw_setenv(int argc, char *argv[])
 	int i, len;
 	char *name;
 	char *value = NULL;
-	char *tmpval = NULL;
 
 	if (argc < 2) {
 		errno = EINVAL;
@@ -492,34 +491,28 @@ int fw_setenv(int argc, char *argv[])
 
 	name = argv[1];
 
-	len = strlen(name) + 2;
-	for (i = 2; i < argc; ++i)
-		len += strlen(argv[i]) + 1;
-
-	/* Allocate enough place to the data string */
+	len = 0;
 	for (i = 2; i < argc; ++i) {
 		char *val = argv[i];
+		size_t val_len = strlen(val);
+
+		value = realloc(value, len + val_len + 1);
 		if (!value) {
-			value = (char *)malloc(len - strlen(name));
-			if (!value) {
-				fprintf(stderr,
+			fprintf(stderr,
 				"Cannot malloc %zu bytes: %s\n",
-				len - strlen(name), strerror(errno));
-				return -1;
-			}
-			memset(value, 0, len - strlen(name));
-			tmpval = value;
+				len, strerror(errno));
+			return -1;
 		}
-		if (i != 2)
-			*tmpval++ = ' ';
-		while (*val != '\0')
-			*tmpval++ = *val++;
+
+		memcpy(value + len, val, val_len);
+		len += val_len;
+		value[len++] = ' ';
 	}
+	value[len - 1] = '\0';
 
 	fw_env_write(name, value);
 
-	if (value)
-		free(value);
+	free(value);
 
 	return fw_env_close();
 }