From 6ce663784d431f293fde39cded0e7fa9d4e5dcc0 Mon Sep 17 00:00:00 2001
From: Frank <91616163+softhack007@users.noreply.github.com>
Date: Fri, 24 Oct 2025 16:24:33 +0200
Subject: [PATCH] bugfix to prevent random corruption of presets.json

accroding to the docs of setBufferSize() and svbuf():
> setBufferSize() has to be called right after opening file before any other operation!

so changing buffer sizes on an already opened and partially read file can cause file corruption as the internal buffer is exchanged "mid-flight".

Fix: move all f.setBufferSize() so they appear directly after f.open().
---
 wled00/file.cpp | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/wled00/file.cpp b/wled00/file.cpp
index 39813ba0..43458a6b 100644
--- a/wled00/file.cpp
+++ b/wled00/file.cpp
@@ -18,7 +18,7 @@
  * 1. File must be a string representation of a valid JSON object
  * 2. File must have '{' as first character
  * 3. There must not be any additional characters between a root-level key and its value object (e.g. space, tab, newline)
- * 4. There must not be any characters between an root object-separating ',' and the next object key string
+ * 4. There must not be any characters between a root object-separating ',' and the next object key string
  * 5. There may be any number of spaces, tabs, and/or newlines before such object-separating ','
  * 6. There must not be more than 5 consecutive spaces at any point except for those permitted in condition 5
  * 7. If it is desired to delete the first usable object (e.g. preset file), a dummy object '"0":{}' is inserted at the beginning.
@@ -66,9 +66,6 @@ static bool bufferedFind(const char *target, bool fromStart = true) {
 
   size_t index = 0;
   byte buf[FS_BUFSIZE];
-  #if ESP_IDF_VERSION_MAJOR >= 4
-  f.setBufferSize(FS_BUFSIZE);
-  #endif
   if (fromStart) f.seek(0);
 
   while (f.position() < f.size() -1) {
@@ -110,9 +107,6 @@ static bool bufferedFindSpace(size_t targetLen, bool fromStart = true) {
 
   size_t index = 0; // better to use size_t instead if uint16_t
   byte buf[FS_BUFSIZE];
-  #if ESP_IDF_VERSION_MAJOR >= 4
-  f.setBufferSize(FS_BUFSIZE);
-  #endif
   if (fromStart) f.seek(0);
 
   while (f.position() < f.size() -1) {
@@ -156,9 +150,6 @@ static bool bufferedFindObjectEnd() {
   uint16_t objDepth = 0; //num of '{' minus num of '}'. return once 0
   //size_t start = f.position();
   byte buf[FS_BUFSIZE];
-  #if ESP_IDF_VERSION_MAJOR >= 4
-  f.setBufferSize(FS_BUFSIZE);
-  #endif
   while (f.position() < f.size() -1) {
     size_t bufsize = f.read(buf, FS_BUFSIZE); // better to use size_t instead of uint16_t
     size_t count = 0;
@@ -183,9 +174,6 @@ static void writeSpace(size_t l)
 {
   byte buf[FS_BUFSIZE];
   memset(buf, ' ', FS_BUFSIZE);
-  #if ESP_IDF_VERSION_MAJOR >= 4
-  f.setBufferSize(FS_BUFSIZE);
-  #endif
   while (l > 0) {
     size_t block = (l>FS_BUFSIZE) ? FS_BUFSIZE : l;
     f.write(buf, block);
@@ -299,6 +287,9 @@ bool writeObjectToFile(const char* file, const char* key, JsonDocument* content)
     DEBUGFS_PRINTLN(F("Failed to open!"));
     return false;
   }
+  #if ESP_IDF_VERSION_MAJOR >= 4
+  f.setBufferSize(FS_BUFSIZE);        // reduced internal buffer leads to shorter blocking delay, and might prevent LED glitches
+  #endif
 
   if (!bufferedFind(key)) //key does not exist in file
   {
@@ -366,6 +357,10 @@ bool readObjectFromFile(const char* file, const char* key, JsonDocument* dest)
   if (!f) return false;
   else { DEBUG_PRINTF(PSTR("FILE '%s' open to read, size %d bytes\n"), file, (int)f.size());} // WLEDMM additional debug message
 
+  #if ESP_IDF_VERSION_MAJOR >= 4
+  f.setBufferSize(FS_BUFSIZE*2);        // reduced internal buffer leads to shorter blocking delay, and might prevent LED glitches
+  #endif
+
   if (key != nullptr && !bufferedFind(key)) //key does not exist in file
   {
     f.close();
@@ -444,6 +439,10 @@ static const uint8_t *getPresetCache(size_t &size) {
 
   if (!presetsCached) {
     File file = WLED_FS.open("/presets.json", "r");
+
+  #if ESP_IDF_VERSION_MAJOR >= 4
+    if (file) f.setBufferSize(FS_BUFSIZE*2);        // reduced internal buffer leads to shorter blocking delay, and might prevent LED glitches
+  #endif
     if (file) {
       presetsCachedTime = presetsModifiedTime;
       presetsCachedValidate = cacheInvalidate;