Split configuration parser and utility library

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>

1 files changed, 174 insertions, 0 deletions

diff --git a/lib/libcfg/rdline.c b/lib/libcfg/rdline.c
new file mode 100644
index 0000000..ffbfd89
--- /dev/null
+++ b/lib/libcfg/rdline.c
@@ -0,0 +1,174 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * Copyright (C) 2018 - David Oberhollenzer
+ *
+ * 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 3 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, see <https://www.gnu.org/licenses/>.
+ */
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+#include <stdio.h>
+
+#include "libcfg.h"
+
+static int rdline_getc(rdline_t *t)
+{
+	int ret;
+	char c;
+
+	if (t->argstr != NULL) {
+		c = *(t->argstr++);
+		if (c != '\0')
+			goto out;
+
+		t->argstr = NULL;
+	}
+
+	do {
+		ret = read(t->fd, &c, 1);
+	} while (ret < 0 && errno == EINTR);
+
+	if (ret < 0)
+		return -1;
+
+	if (ret == 0) {
+		if (t->i == 0) {
+			errno = 0;
+			return -1;
+		}
+		c = '\0';
+	}
+out:
+	return (c == '\n') ? '\0' : c;
+}
+
+static int rdline_append(rdline_t *t, int c)
+{
+	if (t->comment) {
+		if (c != '\0')
+			return 0;
+	} else if (t->string) {
+		if (t->escape) {
+			t->escape = false;
+		} else {
+			if (c == '\\')
+				t->escape = true;
+			if (c == '"')
+				t->string = false;
+		}
+	} else {
+		if (isspace(c))
+			c = ' ';
+		if (c == ' ' && (t->i == 0 || t->buffer[t->i - 1] == ' '))
+			return 0;
+		if (c == '#') {
+			t->comment = true;
+			return 0;
+		}
+		if (c == '"')
+			t->string = true;
+	}
+
+	if (c == '\0') {
+		while (t->i > 0 && t->buffer[t->i - 1] == ' ')
+			t->i -= 1;
+	}
+
+	if (t->i == sizeof(t->buffer))
+		return -1;
+
+	t->buffer[t->i++] = c;
+	return 0;
+}
+
+void rdline_init(rdline_t *t, int fd, const char *filename,
+		 int argc, const char *const *argv)
+{
+	memset(t, 0, sizeof(*t));
+	t->fd = fd;
+	t->filename = filename;
+	t->argc = argc;
+	t->argv = argv;
+}
+
+int rdline(rdline_t *t)
+{
+	const char *errstr;
+	int c;
+retry:
+	t->i = 0;
+	t->argstr = NULL;
+	t->string = t->escape = t->comment = false;
+	t->lineno += 1;
+
+	do {
+		errno = 0;
+		c = rdline_getc(t);
+		if (c < 0) {
+			if (errno == 0)
+				return 1;
+			errstr = strerror(errno);
+			goto fail;
+		}
+		if (c == 0 && t->string) {
+			errstr = "missing \"";
+			goto fail;
+		}
+
+		if (c == '%') {
+			c = rdline_getc(t);
+			if (c == 0) {
+				errstr = "unexpected end of line after '%%'";
+				goto fail;
+			}
+			if (c < 0) {
+				errstr = strerror(errno);
+				goto fail;
+			}
+
+			if (c != '%') {
+				if (!isdigit(c)) {
+					errstr = "exptected digit after '%%'";
+					goto fail;
+				}
+				if ((c - '0') >= t->argc) {
+					errstr = "argument out of range";
+					goto fail;
+				}
+				if (t->argstr != NULL) {
+					errstr = "recursive argument "
+						 "expansion";
+					goto fail;
+				}
+				t->argstr = t->argv[c - '0'];
+				continue;
+			}
+		}
+
+		if (rdline_append(t, c)) {
+			errstr = "line too long";
+			goto fail;
+		}
+	} while (c != '\0');
+
+	if (t->buffer[0] == '\0')
+		goto retry;
+
+	return 0;
+fail:
+	fprintf(stderr, "%s: %zu: %s\n", t->filename, t->lineno, errstr);
+	return -1;
+}