istream-crlf optimization.

Based on patch by Len7hir

diff --git a/src/lib/istream-crlf.c b/src/lib/istream-crlf.c
index cf0d1b4624c2c471db4dd78d9f1057bd6557f4fc..9d97472ede63dfc759e674c3473487ed43cf53c9 100644 (file)
--- a/src/lib/istream-crlf.c
+++ b/src/lib/istream-crlf.c
@@ -38,38 +38,76 @@ static int i_stream_crlf_read_common(struct crlf_istream *cstream)
 static ssize_t i_stream_crlf_read_crlf(struct istream_private *stream)
 {
        struct crlf_istream *cstream = (struct crlf_istream *)stream;
-       const unsigned char *data;
-       size_t i, dest, size;
+       const unsigned char *data, *ptr, *src, *src_end;
+       unsigned char *dest, *dest_end;
+       size_t size, copy_len;
        ssize_t ret;
 
        ret = i_stream_crlf_read_common(cstream);
        if (ret <= 0)
                return ret;
 
+       /* at least one byte was read */
        data = i_stream_get_data(stream->parent, &size);
 
+       dest = stream->w_buffer + stream->pos;
+       dest_end = stream->w_buffer + stream->buffer_size;
+       src = data;
+       src_end = data + size;
+
        /* @UNSAFE: add missing CRs */
-       dest = stream->pos;
-       for (i = 0; i < size && dest < stream->buffer_size; i++) {
-               if (data[i] == '\n') {
-                       if (i == 0) {
-                               if (!cstream->last_cr)
-                                       stream->w_buffer[dest++] = '\r';
-                       } else {
-                               if (data[i-1] != '\r')
-                                       stream->w_buffer[dest++] = '\r';
-                       }
-                       if (dest == stream->buffer_size)
-                               break;
+       if (*src == '\n') {
+               if (!cstream->last_cr && dest < dest_end)
+                       *dest++ = '\r';
+
+               if (dest < dest_end) {
+                       *dest++ = '\n';
+                       src++;
                }
-               stream->w_buffer[dest++] = data[i];
        }
-       cstream->last_cr = stream->w_buffer[dest-1] == '\r';
-       i_stream_skip(stream->parent, i);
 
-       ret = dest - stream->pos;
+       while (dest < dest_end) {
+               ptr = memchr(src, '\n', src_end - src);
+               if (ptr == NULL)
+                       ptr = src_end;
+
+               /* copy data up to LF */
+               copy_len = ptr - src;
+               if (dest + copy_len > dest_end)
+                       copy_len = dest_end - dest;
+
+               if (copy_len > 0) {
+                       memcpy(dest, src, copy_len);
+
+                       dest += copy_len;
+                       src += copy_len;
+               }
+
+               i_assert(dest <= dest_end && src <= src_end);
+               if (dest == dest_end || src == src_end)
+                       break;
+
+               /* add the CR if necessary and copy the LF.
+                  (src >= data+1, because data[0]=='\n' was
+                  handled before this loop) */
+               if (src[-1] != '\r')
+                       *dest++ = '\r';
+
+               if (dest < dest_end) {
+                       *dest++ = '\n';
+                       src++;
+               }
+
+               i_assert(src == ptr + 1);
+       }
+
+       i_assert(dest != stream->w_buffer);
+       cstream->last_cr = dest[-1] == '\r';
+       i_stream_skip(stream->parent, src - data);
+
+       ret = (dest - stream->w_buffer) - stream->pos;
        i_assert(ret > 0);
-       stream->pos = dest;
+       stream->pos = dest - stream->w_buffer;
        return ret;
 }