[PATCH 3/3] parse_config: use getline to read config

[Timo Teräs]

Speeds up considerably config file parsing.

Signed-off-by: Timo Teräs <timo.teras at iki.fi>
---
 include/libbb.h      |    3 +-
 libbb/parse_config.c |   74 +++++++++++++++++++++++++------------------------
 2 files changed, 40 insertions(+), 37 deletions(-)

diff --git a/include/libbb.h b/include/libbb.h
index 2cac7e6..953bec3 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1184,8 +1184,9 @@ enum {
 };
 typedef struct parser_t {
 	FILE *fp;
-	char *line;
 	char *data;
+	char *line, *nline;
+	size_t line_alloc, nline_alloc;
 	int lineno;
 } parser_t;
 parser_t* config_open(const char *filename) FAST_FUNC;
diff --git a/libbb/parse_config.c b/libbb/parse_config.c
index c0c34f3..bb5832d 100644
--- a/libbb/parse_config.c
+++ b/libbb/parse_config.c
@@ -85,8 +85,6 @@ parser_t* FAST_FUNC config_open(const char *filename)
 
 static void config_free_data(parser_t *parser)
 {
-	free(parser->line);
-	parser->line = NULL;
 	if (PARSE_KEEP_COPY) { /* compile-time constant */
 		free(parser->data);
 		parser->data = NULL;
@@ -98,45 +96,49 @@ void FAST_FUNC config_close(parser_t *parser)
 	if (parser) {
 		config_free_data(parser);
 		fclose(parser->fp);
+		free(parser->line);
+		free(parser->nline);
 		free(parser);
 	}
 }
 
-/* This function reads an entire line from a text file, up to a newline
- * or NUL byte, exclusive.  It returns a malloc'ed char*.
- * *lineno is incremented for each line.
+/* This function reads an entire line from a text file,
+ * up to a newline, exclusive.
  * Trailing '\' is recognized as line continuation.
- * Returns NULL if EOF/error.
+ * Returns -1 if EOF/error.
  */
-static char* get_line_with_continuation(FILE *file, int *lineno)
+static int get_line_with_continuation(parser_t *parser)
 {
-	int ch;
-	unsigned idx = 0;
-	char *linebuf = NULL;
-
-	while ((ch = getc(file)) != EOF) {
-		/* grow the line buffer as necessary */
-		if (!(idx & 0xff))
-			linebuf = xrealloc(linebuf, idx + 0x101);
-		if (ch == '\n')
-			ch = '\0';
-		linebuf[idx] = (char) ch;
-		if (ch == '\0') {
-			(*lineno)++;
-			if (idx == 0 || linebuf[idx-1] != '\\')
-				break;
-			idx--; /* go back to '/' */
-			continue;
+	ssize_t len, nlen;
+	char *line;
+
+	len = getline(&parser->line, &parser->line_alloc, parser->fp);
+	if (len < 0)
+		return -1;
+
+	line = parser->line;
+	do {
+		parser->lineno++;
+		if (len && line[len-1] == '\n')
+			len--;
+		if (len == 0 || line[len-1] != '\\')
+			break;
+		len--;
+
+		nlen = getline(&parser->nline, &parser->nline_alloc, parser->fp);
+		if (nlen < 0)
+			break;
+
+		if (parser->line_alloc < len + nlen + 1) {
+			parser->line_alloc = len + nlen + 1;
+			line = parser->line = xrealloc(line, parser->line_alloc);
 		}
-		idx++;
-	}
-	if (ch == EOF) {
-		/* handle corner case when the file is not ended with '\n' */
-		(*lineno)++;
-		if (linebuf)
-			linebuf[idx] = '\0';
-	}
-	return linebuf;
+		memcpy(&line[len], parser->nline, nlen);
+		len += nlen;
+	} while (1);
+
+	line[len] = 0;
+	return len;
 }
 
 
@@ -181,10 +183,10 @@ again:
 	config_free_data(parser);
 
 	/* Read one line (handling continuations with backslash) */
-	line = get_line_with_continuation(parser->fp, &parser->lineno);
-	if (line == NULL)
+	if (get_line_with_continuation(parser) < 0)
 		return 0;
-	parser->line = line;
+
+	line = parser->line;
 
 	/* Skip token in the start of line? */
 	if (flags & PARSE_TRIM)
-- 
1.7.1