gh-151126: Fix missing PyErr_NoMemory in fileutils.c

Misc/NEWS.d/next/Core_and_Builtins/2026-06-17-14-39-04.gh-issue-151126.xpOZrp.rst

@@ -0,0 +1,3 @@
+Avoid possible crash in ``fileutils.c`` where a device has no memory left.
+Now it properly raises a :exc:`MemoryError`.
+Patch by Ivy Xu.

Python/fileutils.c

@@ -351,6 +351,7 @@ encode_ascii(const wchar_t *text, char **str,
  result = PyMem_Malloc(len + 1);
  }
  if (result == NULL) {
+ PyErr_NoMemory();
  return -1;
  }
 
@@ -421,6 +422,7 @@ decode_ascii(const char *arg, wchar_t **wstr, size_t *wlen,
  }
  res = PyMem_RawMalloc(argsize * sizeof(wchar_t));
  if (!res) {
+ PyErr_NoMemory();
  return -1;
  }
 
@@ -487,6 +489,7 @@ decode_current_locale(const char* arg, wchar_t **wstr, size_t *wlen,
  }
  res = (wchar_t *)PyMem_RawMalloc((argsize + 1) * sizeof(wchar_t));
  if (!res) {
+ PyErr_NoMemory();
  return -1;
  }
 
@@ -513,6 +516,7 @@ decode_current_locale(const char* arg, wchar_t **wstr, size_t *wlen,
  }
  res = (wchar_t*)PyMem_RawMalloc(argsize * sizeof(wchar_t));
  if (!res) {
+ PyErr_NoMemory();
  return -1;
  }
 
@@ -743,6 +747,7 @@ encode_current_locale(const wchar_t *text, char **str,
  result = PyMem_Malloc(size);
  }
  if (result == NULL) {
+ PyErr_NoMemory();
  return -1;
  }
  bytes = result;
@@ -2448,6 +2453,7 @@ _Py_join_relfile(const wchar_t *dirname, const wchar_t *relfile)
  size_t bufsize = maxlen + 1;
  wchar_t *filename = PyMem_RawMalloc(bufsize * sizeof(wchar_t));
  if (filename == NULL) {
+ PyErr_NoMemory();
  return NULL;
  }
  assert(wcslen(dirname) < MAXPATHLEN);