split out copy_file_fd

2 files changed, 53 insertions, 39 deletions

diff --git a/src/fileio.c b/src/fileio.c
index 6e2fe2f0b82..91e0efc0a83 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -1989,6 +1989,55 @@ clone_file (int dest, int source)
 }
 #endif
 
+/* Copy data to OFD from IFD if possible.  Return NEWSIZE.  */
+off_t
+copy_file_fd (int ofd, int ifd, struct stat *st, Lisp_Object newname,
+              Lisp_Object file)
+{
+  off_t newsize;
+
+  if (clone_file (ofd, ifd))
+    newsize = st->st_size;
+  else
+    {
+      off_t insize = st->st_size;
+      ssize_t copied;
+
+      for (newsize = 0; newsize < insize; newsize += copied)
+        {
+          /* Copy at most COPY_MAX bytes at a time; this is min
+             (PTRDIFF_MAX, SIZE_MAX) truncated to a value that is
+             surely aligned well.  */
+          ssize_t ssize_max = TYPE_MAXIMUM (ssize_t);
+          ptrdiff_t copy_max = min (ssize_max, SIZE_MAX) >> 30 << 30;
+          off_t intail = insize - newsize;
+          ptrdiff_t len = min (intail, copy_max);
+          copied = copy_file_range (ifd, NULL, ofd, NULL, len, 0);
+          if (copied <= 0)
+            break;
+          maybe_quit ();
+        }
+
+      /* Fall back on read+write if copy_file_range failed, or if the
+         input is empty and so could be a /proc file.  read+write will
+         either succeed, or report an error more precisely than
+         copy_file_range would.  */
+      if (newsize != insize || insize == 0)
+        {
+          char buf[MAX_ALLOCA];
+          for (; (copied = emacs_read_quit (ifd, buf, sizeof buf));
+               newsize += copied)
+            {
+              if (copied < 0)
+                report_file_error ("Read error", file);
+              if (emacs_write_quit (ofd, buf, copied) != copied)
+                report_file_error ("Write error", newname);
+            }
+        }
+    }
+  return newsize;
+}
+
 DEFUN ("copy-file", Fcopy_file, Scopy_file, 2, 6,
        "fCopy file: \nGCopy %s to file: \np\nP",
        doc: /* Copy FILE to NEWNAME.  Both args must be strings.
@@ -2143,45 +2192,7 @@ permissions.  */)
 
   maybe_quit ();
 
-  if (clone_file (ofd, ifd))
-    newsize = st.st_size;
-  else
-    {
-      off_t insize = st.st_size;
-      ssize_t copied;
-
-      for (newsize = 0; newsize < insize; newsize += copied)
-        {
-          /* Copy at most COPY_MAX bytes at a time; this is min
-             (PTRDIFF_MAX, SIZE_MAX) truncated to a value that is
-             surely aligned well.  */
-          ssize_t ssize_max = TYPE_MAXIMUM (ssize_t);
-          ptrdiff_t copy_max = min (ssize_max, SIZE_MAX) >> 30 << 30;
-          off_t intail = insize - newsize;
-          ptrdiff_t len = min (intail, copy_max);
-          copied = copy_file_range (ifd, NULL, ofd, NULL, len, 0);
-          if (copied <= 0)
-            break;
-          maybe_quit ();
-        }
-
-      /* Fall back on read+write if copy_file_range failed, or if the
-         input is empty and so could be a /proc file.  read+write will
-         either succeed, or report an error more precisely than
-         copy_file_range would.  */
-      if (newsize != insize || insize == 0)
-        {
-          char buf[MAX_ALLOCA];
-          for (; (copied = emacs_read_quit (ifd, buf, sizeof buf));
-               newsize += copied)
-            {
-              if (copied < 0)
-                report_file_error ("Read error", file);
-              if (emacs_write_quit (ofd, buf, copied) != copied)
-                report_file_error ("Write error", newname);
-            }
-        }
-    }
+  newsize = copy_file_fd (ofd, ifd, &st, newname, file);
 
   /* Truncate any existing output file after writing the data.  This
      is more likely to work than truncation before writing, if the
diff --git a/src/lisp.h b/src/lisp.h
index 05d6ef0d22a..7a4b3517574 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -34,6 +34,8 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include <intprops.h>
 #include <verify.h>
 
+#include <sys/stat.h>
+
 INLINE_HEADER_BEGIN
 
 /* Define a TYPE constant ID as an externally visible name.  Use like this:
@@ -4325,6 +4327,7 @@ extern char *splice_dir_file (char *, char const *, char const *);
 extern bool file_name_absolute_p (const char *);
 extern char const *get_homedir (void);
 extern Lisp_Object expand_and_dir_to_file (Lisp_Object);
+extern off_t copy_file_fd (int, int, struct stat *, Lisp_Object, Lisp_Object);
 extern Lisp_Object write_region (Lisp_Object, Lisp_Object, Lisp_Object,
                                  Lisp_Object, Lisp_Object, Lisp_Object,
                                  Lisp_Object, int);