bpo-26826: Expose copy_file_range in the os module (GH-7255)

1 files changed, 71 insertions, 0 deletions

diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 77a3700..8f6cfff 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -117,6 +117,10 @@ corresponding Unix manual entries for more information on calls.");
 #include <sched.h>
 #endif
 
+#ifdef HAVE_COPY_FILE_RANGE
+#include <unistd.h>
+#endif
+
 #if !defined(CPU_ALLOC) && defined(HAVE_SCHED_SETAFFINITY)
 #undef HAVE_SCHED_SETAFFINITY
 #endif
@@ -9455,8 +9459,74 @@ os_pwritev_impl(PyObject *module, int fd, PyObject *buffers, Py_off_t offset,
 }
 #endif /* HAVE_PWRITEV */
 
+#ifdef HAVE_COPY_FILE_RANGE
+/*[clinic input]
+
+os.copy_file_range
+    src: int
+        Source file descriptor.
+    dst: int
+        Destination file descriptor.
+    count: Py_ssize_t
+        Number of bytes to copy.
+    offset_src: object = None
+        Starting offset in src.
+    offset_dst: object = None
+        Starting offset in dst.
+
+Copy count bytes from one file descriptor to another.
+
+If offset_src is None, then src is read from the current position;
+respectively for offset_dst.
+[clinic start generated code]*/
+
+static PyObject *
+os_copy_file_range_impl(PyObject *module, int src, int dst, Py_ssize_t count,
+                        PyObject *offset_src, PyObject *offset_dst)
+/*[clinic end generated code: output=1a91713a1d99fc7a input=42fdce72681b25a9]*/
+{
+    off_t offset_src_val, offset_dst_val;
+    off_t *p_offset_src = NULL;
+    off_t *p_offset_dst = NULL;
+    Py_ssize_t ret;
+    int async_err = 0;
+    /* The flags argument is provided to allow
+     * for future extensions and currently must be to 0. */
+    int flags = 0;
+
+
+    if (count < 0) {
+        PyErr_SetString(PyExc_ValueError, "negative value for 'count' not allowed");
+        return NULL;
+    }
+
+    if (offset_src != Py_None) {
+        if (!Py_off_t_converter(offset_src, &offset_src_val)) {
+            return NULL;
+        }
+        p_offset_src = &offset_src_val;
+    }
 
+    if (offset_dst != Py_None) {
+        if (!Py_off_t_converter(offset_dst, &offset_dst_val)) {
+            return NULL;
+        }
+        p_offset_dst = &offset_dst_val;
+    }
 
+    do {
+        Py_BEGIN_ALLOW_THREADS
+        ret = copy_file_range(src, p_offset_src, dst, p_offset_dst, count, flags);
+        Py_END_ALLOW_THREADS
+    } while (ret < 0 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
+
+    if (ret < 0) {
+        return (!async_err) ? posix_error() : NULL;
+    }
+
+    return PyLong_FromSsize_t(ret);
+}
+#endif /* HAVE_COPY_FILE_RANGE*/
 
 #ifdef HAVE_MKFIFO
 /*[clinic input]
@@ -13432,6 +13502,7 @@ static PyMethodDef posix_methods[] = {
     OS_POSIX_SPAWN_METHODDEF
     OS_POSIX_SPAWNP_METHODDEF
     OS_READLINK_METHODDEF
+    OS_COPY_FILE_RANGE_METHODDEF
     OS_RENAME_METHODDEF
     OS_REPLACE_METHODDEF
     OS_RMDIR_METHODDEF