Implement patty_kiss_tnc_open_fd()

Implement patty_kiss_tnc_open_fd() to create a TNC object for an
existing Unix file descriptor

include/patty/kiss.h

@@ -29,6 +29,8 @@ enum patty_kiss_command {
 
 typedef struct _patty_kiss_tnc patty_kiss_tnc;
 
+patty_kiss_tnc *patty_kiss_tnc_open_fd(int fd, size_t bufsize);
+
 patty_kiss_tnc *patty_kiss_tnc_open(const char *device, size_t bufsize);
 
 int patty_kiss_tnc_fd_unix(patty_kiss_tnc *tnc);

src/kiss.c

@@ -18,8 +18,6 @@ enum kiss_flags {
 };
 
 struct _patty_kiss_tnc {
-    const char * device;
-
     int fd;
 
     void *buf,
@@ -30,7 +28,7 @@ struct _patty_kiss_tnc {
            dropped;
 };
 
-patty_kiss_tnc *patty_kiss_tnc_open(const char *device, size_t bufsz) {
+patty_kiss_tnc *patty_kiss_tnc_open_fd(int fd, size_t bufsz) {
     patty_kiss_tnc *tnc;
 
     if ((tnc = malloc(sizeof(*tnc))) == NULL) {
@@ -45,20 +43,13 @@ patty_kiss_tnc *patty_kiss_tnc_open(const char *device, size_t bufsz) {
         goto error_malloc_frame;
     }
 
-    if ((tnc->fd = open(device, O_RDWR)) < 0) {
+    tnc->fd      = fd;
-        goto error_open;
-    }
-
-    tnc->device  = device;
     tnc->bufsz   = bufsz;
     tnc->buflen  = 0;
     tnc->dropped = 0;
 
     return tnc;
 
-error_open:
-    free(tnc->frame);
-
 error_malloc_frame:
     free(tnc->buf);
 
@@ -69,6 +60,27 @@ error_malloc_tnc:
     return NULL;
 }
 
+patty_kiss_tnc *patty_kiss_tnc_open(const char *device, size_t bufsz) {
+    patty_kiss_tnc *tnc;
+    int fd;
+
+    if ((fd = open(device, O_RDWR)) < 0) {
+        goto error_open;
+    }
+
+    if ((tnc = patty_kiss_tnc_open_fd(fd, bufsz)) == NULL) {
+        goto error_tnc_open_fd;
+    }
+
+    return tnc;
+
+error_tnc_open_fd:
+    close(fd);
+
+error_open:
+    return NULL;
+}
+
 int patty_kiss_tnc_fd_unix(patty_kiss_tnc *tnc) {
     return tnc->fd;
 }