[LibOS] Get rid of qstrtostr()

Used in one place. Needed to remove non-standard use of alloca.

LibOS/shim/include/shim_utils.h

@@ -145,19 +145,6 @@ void* malloc(size_t size);
 void free(void* mem);
 void* malloc_copy(const void* mem, size_t size);
 
-static inline __attribute__((always_inline)) char* qstrtostr(struct shim_qstr* qstr, bool on_stack) {
-    int len   = qstr->len;
-    char* buf = on_stack ? __alloca(len + 1) : malloc(len + 1);
-
-    if (!buf)
-        return NULL;
-
-    memcpy(buf, qstrgetstr(qstr), len);
-
-    buf[len] = 0;
-    return buf;
-}
-
 /* typedef a 32 bit type */
 #ifndef UINT4
 #define UINT4 uint32_t

LibOS/shim/src/ipc/shim_ipc_ranges.c

@@ -1504,8 +1504,13 @@ retry:
         if (!p->port) {
             IDTYPE type                = IPC_PORT_OWNER | IPC_PORT_LISTEN;
             IDTYPE owner               = p->vmid;
-            char* uri                  = qstrtostr(&p->uri, true);
             struct shim_ipc_port* port = NULL;
+            size_t uri_len             = p->uri.len;
+            char uri[uri_len + 1];
+
+            memcpy(&uri, qstrgetstr(&p->uri), uri_len);
+            uri[uri_len] = 0;
+
             unlock(&range_map_lock);
 
             PAL_HANDLE pal_handle = DkStreamOpen(uri, 0, 0, 0, 0);