Coverity: Dereference before null check

1. When cleaning the path, check that the path pointer is not null
   before using it.
2. Move the strlen of path.
3. Remove the second check of path, and just loop over it.

Fixed CID: 572847

Author: ejohnstown

examples/sftpclient/sftpclient.c

@@ -249,9 +249,15 @@ static void sig_handler(const int sig)
 static void clean_path(char* path)
 {
     int  i;
-    long sz = (long)WSTRLEN(path);
+    long sz;
     byte found;
 
+    if (path == NULL) {
+        return;
+    }
+
+    sz = (long)WSTRLEN(path);
+
     /* remove any double '/' chars */
     for (i = 0; i < sz; i++) {
         if (path[i] == '/' && path[i+1] == '/') {
@@ -272,51 +278,49 @@ static void clean_path(char* path)
         }
     }
 
-    if (path != NULL) {
-        /* go through path until no cases are found */
-        do {
-            int prIdx = 0; /* begin of cut */
-            int enIdx = 0; /* end of cut */
-            sz = (long)WSTRLEN(path);
-
-            found = 0;
-            for (i = 0; i < sz; i++) {
-                if (path[i] == '/') {
-                    int z;
-
-                    /* if next two chars are .. then delete */
-                    if (path[i+1] == '.' && path[i+2] == '.') {
-                        enIdx = i + 3;
-
-                        /* start at one char before / and retrace path */
-                        for (z = i - 1; z > 0; z--) {
-                            if (path[z] == '/') {
-                                prIdx = z;
-                                break;
-                            }
+    /* go through path until no cases are found */
+    do {
+        int prIdx = 0; /* begin of cut */
+        int enIdx = 0; /* end of cut */
+        sz = (long)WSTRLEN(path);
+
+        found = 0;
+        for (i = 0; i < sz; i++) {
+            if (path[i] == '/') {
+                int z;
+
+                /* if next two chars are .. then delete */
+                if (path[i+1] == '.' && path[i+2] == '.') {
+                    enIdx = i + 3;
+
+                    /* start at one char before / and retrace path */
+                    for (z = i - 1; z > 0; z--) {
+                        if (path[z] == '/') {
+                            prIdx = z;
+                            break;
                         }
+                    }
 
-                        /* cut out .. and previous */
-                        WMEMMOVE(path + prIdx, path + enIdx, sz - enIdx);
-                        path[sz - (enIdx - prIdx)] = '\0';
-
-                        if (enIdx == sz) {
-                            path[prIdx] = '\0';
-                        }
+                    /* cut out .. and previous */
+                    WMEMMOVE(path + prIdx, path + enIdx, sz - enIdx);
+                    path[sz - (enIdx - prIdx)] = '\0';
 
-                        /* case of at / */
-                        if (WSTRLEN(path) == 0) {
-                           path[0] = '/';
-                           path[1] = '\0';
-                        }
+                    if (enIdx == sz) {
+                        path[prIdx] = '\0';
+                    }
 
-                        found = 1;
-                        break;
+                    /* case of at / */
+                    if (WSTRLEN(path) == 0) {
+                       path[0] = '/';
+                       path[1] = '\0';
                     }
+
+                    found = 1;
+                    break;
                 }
             }
-        } while (found);
-    }
+        }
+    } while (found);
 }
 
 #define WS_MAX_EXAMPLE_RW 1024