(struct buffer.newline_free): New member.

(initbuf, findlines): Set it.
(fillbuf): Do not double the size of a full buffer to append a newline
unless the buffer is known to be newline free.

diff --git a/src/sort.c b/src/sort.c
index 2b064db..acd5642 100644 (file)
--- a/src/sort.c
+++ b/src/sort.c
@@ -127,7 +127,9 @@ struct buffer
   char *buf;                   /* Dynamically allocated buffer. */
   int used;                    /* Number of bytes used. */
   int alloc;                   /* Number of bytes allocated. */
-  int left;                    /* Number of bytes left after line parsing. */
+  int left;                    /* Number of bytes left from previous reads. */
+  int newline_free;            /* Number of left bytes that are known
+                                   to be newline-free.  */
 };
 
 struct keyfield
@@ -534,7 +536,7 @@ initbuf (struct buffer *buf, int alloc)
 {
   buf->alloc = alloc;
   buf->buf = xmalloc (buf->alloc);
-  buf->used = buf->left = 0;
+  buf->used = buf->left = buf->newline_free = 0;
 }
 
 /* Fill BUF reading from FP, moving buf->left bytes from the end
@@ -575,6 +577,11 @@ fillbuf (struct buffer *buf, FILE *fp)
     {
       if (buf->used == buf->alloc)
        {
+         /* If the buffer isn't parsed yet, don't increase the buffer
+            size to append a newline, as this won't be needed unless
+            the buffer turns out to be newline-free.  */
+         if (buf->newline_free != buf->used)
+           return buf->used;
          buf->alloc *= 2;
          buf->buf = xrealloc (buf->buf, buf->alloc);
        }
@@ -795,7 +802,7 @@ findlines (struct buffer *buf, struct lines *lines)
       beg = ptr + 1;
     }
 
-  buf->left = lim - beg;
+  buf->newline_free = buf->left = lim - beg;
 }
 
 /* Compare strings A and B containing decimal fractions < 1.  Each string