gh-106084: Remove _PySequence_BytesToCharpArray() function (#106088)

Remove private _PySequence_BytesToCharpArray() and
_Py_FreeCharPArray() functions from the public C API: move these
functions from Objects/abstract.c to Modules/_posixsubprocess.c.

1 files changed, 82 insertions, 0 deletions

diff --git a/Modules/_posixsubprocess.c b/Modules/_posixsubprocess.c
index 2d88f5e..52e1d2f 100644
--- a/Modules/_posixsubprocess.c
+++ b/Modules/_posixsubprocess.c
@@ -182,6 +182,88 @@ _is_fd_in_sorted_fd_sequence(int fd, int *fd_sequence,
     return 0;
 }
 
+
+// Forward declaration
+static void _Py_FreeCharPArray(char *const array[]);
+
+/*
+ * Flatten a sequence of bytes() objects into a C array of
+ * NULL terminated string pointers with a NULL char* terminating the array.
+ * (ie: an argv or env list)
+ *
+ * Memory allocated for the returned list is allocated using PyMem_Malloc()
+ * and MUST be freed by _Py_FreeCharPArray().
+ */
+static char *const *
+_PySequence_BytesToCharpArray(PyObject* self)
+{
+    char **array;
+    Py_ssize_t i, argc;
+    PyObject *item = NULL;
+    Py_ssize_t size;
+
+    argc = PySequence_Size(self);
+    if (argc == -1)
+        return NULL;
+
+    assert(argc >= 0);
+
+    if ((size_t)argc > (PY_SSIZE_T_MAX-sizeof(char *)) / sizeof(char *)) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+
+    array = PyMem_Malloc((argc + 1) * sizeof(char *));
+    if (array == NULL) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+    for (i = 0; i < argc; ++i) {
+        char *data;
+        item = PySequence_GetItem(self, i);
+        if (item == NULL) {
+            /* NULL terminate before freeing. */
+            array[i] = NULL;
+            goto fail;
+        }
+        /* check for embedded null bytes */
+        if (PyBytes_AsStringAndSize(item, &data, NULL) < 0) {
+            /* NULL terminate before freeing. */
+            array[i] = NULL;
+            goto fail;
+        }
+        size = PyBytes_GET_SIZE(item) + 1;
+        array[i] = PyMem_Malloc(size);
+        if (!array[i]) {
+            PyErr_NoMemory();
+            goto fail;
+        }
+        memcpy(array[i], data, size);
+        Py_DECREF(item);
+    }
+    array[argc] = NULL;
+
+    return array;
+
+fail:
+    Py_XDECREF(item);
+    _Py_FreeCharPArray(array);
+    return NULL;
+}
+
+
+/* Free's a NULL terminated char** array of C strings. */
+static void
+_Py_FreeCharPArray(char *const array[])
+{
+    Py_ssize_t i;
+    for (i = 0; array[i] != NULL; ++i) {
+        PyMem_Free(array[i]);
+    }
+    PyMem_Free((void*)array);
+}
+
+
 /*
  * Do all the Python C API calls in the parent process to turn the pass_fds
  * "py_fds_to_keep" tuple into a C array.  The caller owns allocation and