From 02fe51719751e14dcd711e9e9055d141f0d3f0d1 Mon Sep 17 00:00:00 2001
From: alrvid <126816223+alrvid@users.noreply.github.com>
Date: Thu, 31 Aug 2023 15:17:56 +0200
Subject: [PATCH 1/3] Fix that malloc() doesn't return a null pointer for too
 large allocations

The _sbrk() function wasn't implemented. It's used by malloc() to request more heap memory. This function must be defined and correctly implemented if we want malloc() to return a null pointer if more space is requested than is available. It already works that way for the Mbed Core (although with a different implementation), but doesn't for the Renesas Core before this addition.
---
 cores/arduino/main.cpp | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/cores/arduino/main.cpp b/cores/arduino/main.cpp
index b13d1a22e..ee5d06678 100644
--- a/cores/arduino/main.cpp
+++ b/cores/arduino/main.cpp
@@ -145,4 +145,36 @@ extern "C" __attribute__((weak)) void __cxa_pure_virtual(void);
 extern "C" __attribute__((weak)) void __cxa_pure_virtual(void)
 {
    exit(1);
-}
\ No newline at end of file
+}
+
+// Used by malloc() to request more heap memory. This function
+// must be defined if we want malloc() to return a null pointer
+// if more space is requested than is available. Notice that
+// there's no support for decrement as the very first action,
+// because the result of that is unspecified by the standard,
+// so we can do whatever we want in that case.
+extern "C" void * _sbrk(ptrdiff_t change)
+{
+  extern char __HeapBase;   // From the linker script
+  extern char __HeapLimit;  // From the linker script
+  static char *programBreak = nullptr;
+
+  // If malloc() hasn't been called before, then set the program break
+  // to __HeapBase from the linker script
+  if (nullptr == programBreak)
+  {
+    programBreak = &__HeapBase;
+  }
+  // We must return the old program break if everything is ok, so save it
+  char * const oldProgramBreak = programBreak;
+  // Check that the new program break doesn't pass __HeapLimit from the
+  // linker script
+  if ((programBreak + change) > &__HeapLimit)
+  {
+    return (void *) -1;
+  }
+  // Update the program break according to the requested amount of heap
+  // memory
+  programBreak += change;
+  return oldProgramBreak;
+}

From 13a97354c38fc851871b664c6f25e7b6e0dba623 Mon Sep 17 00:00:00 2001
From: alrvid <126816223+alrvid@users.noreply.github.com>
Date: Sat, 2 Sep 2023 12:48:32 +0200
Subject: [PATCH 2/3] Remove _sbrk() function definition

This function isn't necessary when the root cause is fixed in the next commit.
---
 cores/arduino/main.cpp | 32 --------------------------------
 1 file changed, 32 deletions(-)

diff --git a/cores/arduino/main.cpp b/cores/arduino/main.cpp
index ee5d06678..85e228081 100644
--- a/cores/arduino/main.cpp
+++ b/cores/arduino/main.cpp
@@ -146,35 +146,3 @@ extern "C" __attribute__((weak)) void __cxa_pure_virtual(void)
 {
    exit(1);
 }
-
-// Used by malloc() to request more heap memory. This function
-// must be defined if we want malloc() to return a null pointer
-// if more space is requested than is available. Notice that
-// there's no support for decrement as the very first action,
-// because the result of that is unspecified by the standard,
-// so we can do whatever we want in that case.
-extern "C" void * _sbrk(ptrdiff_t change)
-{
-  extern char __HeapBase;   // From the linker script
-  extern char __HeapLimit;  // From the linker script
-  static char *programBreak = nullptr;
-
-  // If malloc() hasn't been called before, then set the program break
-  // to __HeapBase from the linker script
-  if (nullptr == programBreak)
-  {
-    programBreak = &__HeapBase;
-  }
-  // We must return the old program break if everything is ok, so save it
-  char * const oldProgramBreak = programBreak;
-  // Check that the new program break doesn't pass __HeapLimit from the
-  // linker script
-  if ((programBreak + change) > &__HeapLimit)
-  {
-    return (void *) -1;
-  }
-  // Update the program break according to the requested amount of heap
-  // memory
-  programBreak += change;
-  return oldProgramBreak;
-}

From b42b234cbe08e92359876f4d4faa12777a2e20cc Mon Sep 17 00:00:00 2001
From: alrvid <126816223+alrvid@users.noreply.github.com>
Date: Sat, 2 Sep 2023 12:52:58 +0200
Subject: [PATCH 3/3] Fix bug where malloc() doesn't return a null pointer

The malloc() function doesn't return a null pointer for too large requests. The cause is that the _sbrk() function isn't linked from the Renesas FSP as it should be, but instead from the Arm toolchain. This fix makes sure that the correct version of _sbrk() is linked.
---
 platform.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/platform.txt b/platform.txt
index 0d82f606a..5152ab5dd 100644
--- a/platform.txt
+++ b/platform.txt
@@ -76,7 +76,7 @@ recipe.S.o.pattern="{compiler.path}{compiler.S.cmd}" {compiler.S.flags} -DARDUIN
 recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}"
 
 ## Combine gc-sections, archives, and objects
-recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.flags} {build.extra_flags} -o "{build.path}/{build.project_name}.elf" "-L{build.path}" "-L{build.variant.path}" "-T{build.variant.path}/fsp.ld" {object_files} -Wl,--start-group {compiler.fsp} "{build.path}/{archive_file}" {compiler.fsp.extra_ldflags} {compiler.libraries.ldflags} -Wl,--end-group "-Wl,-Map,{build.path}/{build.project_name}.map"
+recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.flags} {build.extra_flags} -o "{build.path}/{build.project_name}.elf" "-L{build.path}" "-L{build.variant.path}" "-T{build.variant.path}/fsp.ld" {object_files} -Wl,--whole-archive -Wl,--start-group {compiler.fsp} "{build.path}/{archive_file}" -Wl,--no-whole-archive {compiler.fsp.extra_ldflags} {compiler.libraries.ldflags} -Wl,--end-group "-Wl,-Map,{build.path}/{build.project_name}.map"
 
 ## Create output (bin file)
 recipe.objcopy.bin.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf2hex.bin.flags} {compiler.elf2hex.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.bin"