patch 8.0.1774: reading very long lines can be slow
Problem: Reading very long lines can be slow.
Solution: Read up to 1 Mbyte at a time to avoid a lot of copying. Add a
check for going over the column limit.
diff --git a/src/fileio.c b/src/fileio.c
index 35f4fd2..6b48c39 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -1209,28 +1209,42 @@
* The amount is limited by the fact that read() only can read
* upto max_unsigned characters (and other things).
*/
+ if (!skip_read)
+ {
+#if VIM_SIZEOF_INT > 2
+# if defined(SSIZE_MAX) && (SSIZE_MAX < 0x10000L)
+ size = SSIZE_MAX; /* use max I/O size, 52K */
+# else
+ /* Use buffer >= 64K. Add linerest to double the size if the
+ * line gets very long, to avoid a lot of copying. But don't
+ * read more than 1 Mbyte at a time, so we can be interrupted.
+ */
+ size = 0x10000L + linerest;
+ if (size > 0x100000L)
+ size = 0x100000L;
+# endif
+#else
+ size = 0x7ff0L - linerest; /* limit buffer to 32K */
+#endif
+ }
+
+ /* Protect against the argument of lalloc() going negative. */
+ if (
#if VIM_SIZEOF_INT <= 2
- if (linerest >= 0x7ff0)
+ linerest >= 0x7ff0
+#else
+ size < 0 || size + linerest + 1 < 0 || linerest >= MAXCOL
+#endif
+ )
{
++split;
*ptr = NL; /* split line by inserting a NL */
size = 1;
}
else
-#endif
{
if (!skip_read)
{
-#if VIM_SIZEOF_INT > 2
-# if defined(SSIZE_MAX) && (SSIZE_MAX < 0x10000L)
- size = SSIZE_MAX; /* use max I/O size, 52K */
-# else
- size = 0x10000L; /* use buffer >= 64K */
-# endif
-#else
- size = 0x7ff0L - linerest; /* limit buffer to 32K */
-#endif
-
for ( ; size >= 10; size = (long)((long_u)size >> 1))
{
if ((new_buffer = lalloc((long_u)(size + linerest + 1),