From d33b221e17252362a9e93c35517529f6db0f0383 Mon Sep 17 00:00:00 2001
From: TD-er <gijs.noorlander@gmail.com>
Date: Thu, 6 Feb 2025 11:43:33 +0100
Subject: [PATCH 1/3] Fix crash when using String::move on empty string
 (#10938)

Fixes: #10938
---
 cores/esp32/WString.cpp | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/cores/esp32/WString.cpp b/cores/esp32/WString.cpp
index 71183213ac2..151880a0a21 100644
--- a/cores/esp32/WString.cpp
+++ b/cores/esp32/WString.cpp
@@ -238,16 +238,15 @@ String &String::copy(const char *cstr, unsigned int length) {
 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 void String::move(String &rhs) {
   if (buffer()) {
-    if (capacity() >= rhs.len()) {
+    if (capacity() >= rhs.len() && rhs.len() && rhs.buffer()) {
       memmove(wbuffer(), rhs.buffer(), rhs.length() + 1);
       setLen(rhs.len());
       rhs.invalidate();
       return;
-    } else {
-      if (!isSSO()) {
-        free(wbuffer());
-        setBuffer(nullptr);
-      }
+    }
+    if (!isSSO()) {
+      free(wbuffer());
+      setBuffer(nullptr);
     }
   }
   if (rhs.isSSO()) {
@@ -259,10 +258,7 @@ void String::move(String &rhs) {
   }
   setCapacity(rhs.capacity());
   setLen(rhs.len());
-  rhs.setSSO(false);
-  rhs.setCapacity(0);
-  rhs.setBuffer(nullptr);
-  rhs.setLen(0);
+  rhs.init();
 }
 #endif
 

From 7948954cbc88829141b409e4825150d5ddc4b320 Mon Sep 17 00:00:00 2001
From: TD-er <gijs.noorlander@gmail.com>
Date: Thu, 6 Feb 2025 12:00:56 +0100
Subject: [PATCH 2/3] Keep allocated memory when rhs fits

Use case: Appending to a String with pre-allocated memory (e.g. from `reserve()`)
---
 cores/esp32/WString.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/cores/esp32/WString.cpp b/cores/esp32/WString.cpp
index 151880a0a21..a31cff5cf03 100644
--- a/cores/esp32/WString.cpp
+++ b/cores/esp32/WString.cpp
@@ -238,8 +238,12 @@ String &String::copy(const char *cstr, unsigned int length) {
 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 void String::move(String &rhs) {
   if (buffer()) {
-    if (capacity() >= rhs.len() && rhs.len() && rhs.buffer()) {
-      memmove(wbuffer(), rhs.buffer(), rhs.length() + 1);
+    if (capacity() >= rhs.len()) {
+      // Use case: When 'reserve()' was called and the first
+      // assignment/append is the return value of a function.
+      if (rhs.len() && rhs.buffer()) {
+        memmove(wbuffer(), rhs.buffer(), rhs.length() + 1);
+      }
       setLen(rhs.len());
       rhs.invalidate();
       return;

From d024beab6412cfd78d0063f746d2c1ec70100a6c Mon Sep 17 00:00:00 2001
From: TD-er <gijs.noorlander@gmail.com>
Date: Thu, 6 Feb 2025 14:02:58 +0100
Subject: [PATCH 3/3] No need to move 0-termination char in String::move

---
 cores/esp32/WString.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cores/esp32/WString.cpp b/cores/esp32/WString.cpp
index a31cff5cf03..14b40e3ae34 100644
--- a/cores/esp32/WString.cpp
+++ b/cores/esp32/WString.cpp
@@ -242,7 +242,7 @@ void String::move(String &rhs) {
       // Use case: When 'reserve()' was called and the first
       // assignment/append is the return value of a function.
       if (rhs.len() && rhs.buffer()) {
-        memmove(wbuffer(), rhs.buffer(), rhs.length() + 1);
+        memmove(wbuffer(), rhs.buffer(), rhs.length());
       }
       setLen(rhs.len());
       rhs.invalidate();