text_file: allocate line buffers dynamically

Use a single GString buffer object in all functions loading the
database.  Enlarge it automatically for long lines.  This eliminates
the maximum line length for tag values.  There is still an upper limit
of 512 kB to prevent denial of service, but that's reasonable I guess.

1 files changed, 62 insertions, 0 deletions

diff --git a/src/text_file.c b/src/text_file.c
new file mode 100644
index 00000000..16698fc5
--- /dev/null
+++ b/src/text_file.c
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "text_file.h"
+
+#include <assert.h>
+#include <string.h>
+
+char *
+read_text_line(FILE *file, GString *buffer)
+{
+	enum {
+		max_length = 512 * 1024,
+		step = 1024,
+	};
+
+	gsize length = 0, i;
+	char *p;
+
+	assert(file != NULL);
+	assert(buffer != NULL);
+
+	if (buffer->allocated_len < step)
+		g_string_set_size(buffer, step);
+
+	while (buffer->len < max_length) {
+		p = fgets(buffer->str + length,
+			  buffer->allocated_len - length, file);
+		if (p == NULL) {
+			if (length == 0 || ferror(file))
+				return NULL;
+			break;
+		}
+
+		i = strlen(buffer->str + length);
+		length += i;
+		if (i < step - 1 || buffer->str[length - 1] == '\n')
+			break;
+
+		g_string_set_size(buffer, length + step);
+	}
+
+	g_string_set_size(buffer, length);
+	g_strchomp(buffer->str);
+	return buffer->str;
+}