From 4e25298fb87b68641b77a12e921773cfbb18ea16 Mon Sep 17 00:00:00 2001
From: Satoru Takagi <satakagi@users.noreply.github.com>
Date: Fri, 3 Sep 2021 15:46:55 +0900
Subject: [PATCH] Fix issue #30 (#31)
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EACCES: permission deniedエラーが出る問題の解決
Fix #30
---
 index.ts | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/index.ts b/index.ts
index f3b2755..5ab3818 100644
--- a/index.ts
+++ b/index.ts
@@ -81,6 +81,7 @@ export class GPIOPort extends EventEmitter {
   private readonly _pollingInterval: number;
   private _direction: DirectionMode | OperationError;
   private _exported: boolean | OperationError;
+  private _exportRetry: number;
   private _value: GPIOValue | undefined;
   private _timeout: ReturnType<typeof setInterval> | undefined;
   onchange: GPIOChangeEventHandler | undefined;
@@ -92,6 +93,7 @@ export class GPIOPort extends EventEmitter {
     this._pollingInterval = PollingInterval;
     this._direction = new OperationError("Unknown direction.");
     this._exported = new OperationError("Unknown export.");
+    this._exportRetry = 0;
 
     this.on("change", (event: GPIOChangeEvent): void => {
       if (this.onchange !== undefined) this.onchange(event);
@@ -153,7 +155,14 @@ export class GPIOPort extends EventEmitter {
         );
       }
     } catch (error) {
-      throw new OperationError(error);
+      if ( this._exportRetry == 0 ){
+        await sleep(100);
+        console.warn("May be the first time port access. Retry..");
+        ++ this._exportRetry;
+        await this.export(direction);
+      } else {
+        throw new OperationError(error);
+      }
     }
 
     this._direction = direction;
@@ -244,3 +253,9 @@ export async function requestGPIOAccess(): Promise<GPIOAccess> {
 
   return new GPIOAccess(ports);
 }
+
+function sleep(ms: number) {
+  return new Promise((resolve) => {
+    return setTimeout(resolve, ms);
+  });
+}
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