libbb: unified config parser (By Vladimir Dronnikov)

mdev: use it

function                                             old     new   delta
config_read                                            -     400    +400
config_open                                            -      43     +43
config_close                                           -       9      +9
qrealloc                                              33      36      +3
compare_keys                                         735     737      +2
xstrtoull_range_sfx                                  296     295      -1
qgravechar                                           109     106      -3
get_address                                          181     178      -3
next_token                                           928     923      -5
sv_main                                             1228    1222      -6
find_main                                            418     406     -12
next_field                                            32       -     -32
make_device                                         1269    1184     -85
------------------------------------------------------------------------------
(add/remove: 3/1 grow/shrink: 2/7 up/down: 457/-147)          Total: 310 bytes

2 files changed, 248 insertions, 0 deletions

diff --git a/libbb/Kbuild b/libbb/Kbuild
index ab85ffc..7262006 100644
--- a/libbb/Kbuild
+++ b/libbb/Kbuild
@@ -63,6 +63,7 @@ lib-y += mode_string.o
 lib-y += mtab_file.o
 lib-y += obscure.o
 lib-y += parse_mode.o
+lib-y += parse_config.o
 lib-y += perror_msg.o
 lib-y += perror_msg_and_die.o
 lib-y += perror_nomsg.o
diff --git a/libbb/parse_config.c b/libbb/parse_config.c
new file mode 100644
index 0000000..6612db3
--- /dev/null
+++ b/libbb/parse_config.c
@@ -0,0 +1,247 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * config file parser helper
+ *
+ * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
+#include "libbb.h"
+
+/*
+
+Typical usage:
+
+----- CUT -----
+	char *t[3];	// tokens placeholder
+	parser_t p;	// parser structure
+	// open file
+	if (config_open(filename, &p)) {
+		// parse line-by-line
+		while (*config_read(&p, t, 3, 0, delimiters, comment_char)) { // 0..3 tokens
+			// use tokens
+			bb_error_msg("TOKENS: [%s][%s][%s]", t[0], t[1], t[2]);
+		}
+		...
+		// free parser
+		config_close(&p);
+	}
+----- CUT -----
+
+*/
+
+#if !PARSER_STDIO_BASED
+
+char* FAST_FUNC config_open(parser_t *parser, const char *filename)
+{
+	// empty file configures nothing!
+	char *data = xmalloc_open_read_close(filename, NULL);
+	if (!data)
+		return data;
+
+	// convert 0x5c 0x0a (backslashes at the very end of line) to 0x20 0x20 (spaces)
+	for (char *s = data; (s = strchr(s, '\\')) != NULL; ++s)
+		if ('\n' == s[1]) {
+			s[0] = s[1] = ' ';
+		}
+
+	// init parser
+	parser->line = parser->data = data;
+	parser->lineno = 0;
+
+	return data;
+}
+
+void FAST_FUNC config_close(parser_t *parser)
+{
+	// for now just free config data
+	free(parser->data);
+}
+
+char* FAST_FUNC config_read(parser_t *parser, char **tokens, int ntokens, int mintokens, const char *delims, char comment)
+{
+	char *ret, *line;
+	int noreduce = (ntokens<0); // do not treat subsequent delimiters as one delimiter
+	if (ntokens < 0)
+		ntokens = -ntokens;
+	ret = line = parser->line;
+	// nullify tokens
+	memset(tokens, 0, sizeof(void *) * ntokens);
+	// now split to lines
+	while (*line) {
+		int token_num = 0;
+		// limit the line
+		char *ptr = strchrnul(line, '\n');
+		*ptr++ = '\0';
+		// line number
+		parser->lineno++;
+		// comments mean EOLs
+		if (comment)
+			*strchrnul(line, comment) = '\0';
+		// skip leading delimiters
+		while (*line && strchr(delims, *line))
+			line++;
+		// skip empty lines
+		if (*line) {
+			char *s;
+			// now split line to tokens
+			s = line;
+			while (s) {
+				char *p;
+				// get next token
+				if (token_num+1 >= ntokens)
+					break;
+				p = s;
+				while (*p && !strchr(delims, *p))
+					p++;
+				if (!*p)
+					break;
+				*p++ = '\0';
+				// pin token
+				if (noreduce || *s) {
+					tokens[token_num++] = s;
+//bb_error_msg("L[%d] T[%s]", token_num, s);
+				}
+				s = p;
+	 		}
+			// non-empty remainder is also a token. So if ntokens == 0, we just return the whole line
+			if (s && (noreduce || *s))
+				tokens[token_num++] = s;
+			// sanity check: have we got all required tokens?
+			if (token_num < mintokens)
+				bb_error_msg_and_die("bad line %u, %d tokens found, %d needed", parser->lineno, token_num, mintokens);
+			// advance data for the next call
+			line = ptr;
+			break;
+		}
+		// line didn't contain any token -> try next line
+		ret = line = ptr;
+ 	}
+	parser->line = line;
+
+	// return current line. caller must check *ret to determine whether to continue
+	return ret;
+}
+
+#else // stdio-based
+
+FILE* FAST_FUNC config_open(parser_t *parser, const char *filename)
+{
+	// empty file configures nothing!
+	parser->fp = fopen_or_warn(filename, "r");
+	if (!parser->fp)
+		return parser->fp;
+
+	// init parser
+	parser->line = NULL;
+	parser->lineno = 0;
+
+	return parser->fp;
+}
+
+void FAST_FUNC config_close(parser_t *parser)
+{
+	fclose(parser->fp);
+}
+
+char* FAST_FUNC config_read(parser_t *parser, char **tokens, int ntokens, int mintokens, const char *delims, char comment)
+{
+	char *line, *q;
+	int token_num, len;
+	int noreduce = (ntokens < 0); // do not treat subsequent delimiters as one delimiter
+
+	if (ntokens < 0)
+		ntokens = -ntokens;
+
+	// nullify tokens
+	memset(tokens, 0, sizeof(void *) * ntokens);
+
+	// free used line
+	free(parser->line);
+	parser->line = NULL;
+
+	while (1) {
+		int n;
+
+		// get fresh line
+//TODO: speed up xmalloc_fgetline by internally using fgets, not fgetc
+		line = xmalloc_fgetline(parser->fp);
+		if (!line)
+			return line;
+
+		parser->lineno++;
+		// handle continuations. Tito's code stolen :)
+		while (1) {
+			len = strlen(line);
+			if (!len)
+				goto free_and_cont;
+			if (line[len - 1] != '\\')
+				break;
+			// multi-line object
+			line[--len] = '\0';
+//TODO: add xmalloc_fgetline-like iface but with appending to existing str
+			q = xmalloc_fgetline(parser->fp);
+			if (q) {
+				parser->lineno++;
+				line = xasprintf("%s%s", line, q);
+				free(q);
+			}
+		}
+		// comments mean EOLs
+		if (comment) {
+			q = strchrnul(line, comment);
+			*q = '\0';
+			len = q - line;
+		}
+		// skip leading delimiters
+		n = strspn(line, delims);
+		if (n) {
+			len -= n;
+			strcpy(line, line + n);
+		}
+		if (len)
+			break;
+		// skip empty lines
+ free_and_cont:
+		free(line);
+	}
+
+	// non-empty line found, parse and return
+
+	// store line
+	parser->line = line = xrealloc(line, len + 1);
+
+	// now split line to tokens
+//TODO: discard consecutive delimiters?
+	token_num = 0;
+	ntokens--; // now it's max allowed token no
+	while (1) {
+		// get next token
+		if (token_num == ntokens)
+			break;
+		q = line + strcspn(line, delims);
+		if (!*q)
+			break;
+		// pin token
+		*q++ = '\0';
+		if (noreduce || *line) {
+			tokens[token_num++] = line;
+//bb_error_msg("L[%d] T[%s]", token_num, line);
+		}
+		line = q;
+ 	}
+
+	// non-empty remainder is also a token,
+	// so if ntokens <= 1, we just return the whole line
+	if (noreduce || *line)
+		tokens[token_num++] = line;
+
+	if (token_num < mintokens)
+		bb_error_msg_and_die("bad line %u: %d tokens found, %d needed",
+				parser->lineno, token_num, mintokens);
+
+	return parser->line; // maybe token_num instead?
+}
+
+#endif