- always (unless we get an error while reading the first byte)
- NUL-terminate the line buffer. */
-
- if (nbytes_avail < 2 && size < nmax)
- {
- size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size;
- char *newptr;
-
- if (! (size < newsize && newsize <= nmax))
- newsize = nmax;
-
- if (GETNDELIM2_MAXIMUM < newsize - offset)
- {
- size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1;
- if (size == newsizemax)
- goto done;
- newsize = newsizemax;
- }
-
- nbytes_avail = newsize - (read_pos - ptr);
- newptr = realloc (ptr, newsize);
- if (!newptr)
- goto done;
- ptr = newptr;
- size = newsize;
- read_pos = size - nbytes_avail + ptr;
- }
-
- c = getc (stream);
- if (c == EOF)
- {
- /* Return partial line, if any. */
- if (read_pos == ptr)
- goto done;
- else
- break;
- }
-
- if (nbytes_avail >= 2)
- {
- *read_pos++ = c;
- nbytes_avail--;
- }
-
- if (c == delim1 || c == delim2)
- /* Return the line. */
- break;
+ always (unless we get an error while reading the first byte)
+ NUL-terminate the line buffer. */
+
+ if (nbytes_avail < buffer_len + 1 && size < nmax)
+ {
+ /* Grow size proportionally, not linearly, to avoid O(n^2)
+ running time. */
+ size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size;
+ char *newptr;
+
+ /* Increase newsize so that it becomes
+ >= (read_pos - ptr) + buffer_len. */
+ if (newsize - (read_pos - ptr) < buffer_len + 1)
+ newsize = (read_pos - ptr) + buffer_len + 1;
+ /* Respect nmax. This handles possible integer overflow. */
+ if (! (size < newsize && newsize <= nmax))
+ newsize = nmax;
+
+ if (GETNDELIM2_MAXIMUM < newsize - offset)
+ {
+ size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1;
+ if (size == newsizemax)
+ goto unlock_done;
+ newsize = newsizemax;
+ }
+
+ nbytes_avail = newsize - (read_pos - ptr);
+ newptr = realloc (ptr, newsize);
+ if (!newptr)
+ goto unlock_done;
+ ptr = newptr;
+ size = newsize;
+ read_pos = size - nbytes_avail + ptr;
+ }
+
+ /* Here, if size < nmax, nbytes_avail >= buffer_len + 1.
+ If size == nmax, nbytes_avail > 0. */
+
+ if (1 < nbytes_avail)
+ {
+ size_t copy_len = nbytes_avail - 1;
+ if (buffer_len < copy_len)
+ copy_len = buffer_len;
+ if (buffer)
+ memcpy (read_pos, buffer, copy_len);
+ else
+ *read_pos = c;
+ read_pos += copy_len;
+ nbytes_avail -= copy_len;
+ }
+
+ /* Here still nbytes_avail > 0. */
+
+ if (buffer && freadseek (stream, buffer_len))
+ goto unlock_done;