src/config/rcxml.c: parse xml from buffer

Avoid unit tests writing to/from files by using xmlParseMemory() instead
of xmlReadFile().

src/common/buf.c

@@ -0,0 +1,23 @@
+#include "buf.h"
+
+void buf_init(struct buf *s)
+{
+	s->alloc = 256;
+	s->buf = malloc(s->alloc);
+	s->buf[0] = '\0';
+	s->len = 0;
+}
+
+void buf_add(struct buf *s, const char *data)
+{
+	if (!data || data[0] == '\0')
+		return;
+	int len = strlen(data);
+	if (s->alloc <= s->len + len + 1) {
+		s->alloc = s->alloc + len;
+		s->buf = realloc(s->buf, s->alloc);
+	}
+	memcpy(s->buf + s->len, data, len);
+	s->len += len;
+	s->buf[s->len] = 0;
+}

src/common/meson.build

@@ -0,0 +1,3 @@
+labwc_sources += files(
+  'buf.c',
+)

src/config/rcxml.c

@@ -1,4 +1,4 @@
-#define _POSIX_C_SOURCE 200112L
+#define _POSIX_C_SOURCE 200809L
 #include <stdio.h>
 #include <string.h>
 #include <strings.h>
@@ -143,11 +143,12 @@ static void xml_tree_walk(xmlNode *node)
 	}
 }
 
-static void parse_xml(const char *filename)
+/* Exposed in header file to allow unit tests to parse buffers */
+void rcxml_parse_xml(struct buf *b)
 {
-	xmlDoc *d = xmlReadFile(filename, NULL, 0);
+	xmlDoc *d = xmlParseMemory(b->buf, b->len);
 	if (!d) {
-		fprintf(stderr, "fatal: error reading file '%s'\n", filename);
+		fprintf(stderr, "fatal: xmlParseMemory()\n");
 		exit(EXIT_FAILURE);
 	}
 	xml_tree_walk(xmlDocGetRootElement(d));
@@ -162,7 +163,29 @@ void rcxml_init(struct rcxml *rc)
 
 void rcxml_read(const char *filename)
 {
-	parse_xml(filename);
+	FILE *stream;
+	char *line = NULL;
+	size_t len = 0;
+	ssize_t n_read;
+	struct buf b;
+
+	/* Read <filename> into buffer and then call rcxml_parse_xml() */
+	stream = fopen(filename, "r");
+	if (!stream) {
+		fprintf(stderr, "warn: cannot read '%s'\n", filename);
+		return;
+	}
+	buf_init(&b);
+	while ((n_read = getline(&line, &len, stream) != -1)) {
+		char *p = strrchr(line, '\n');
+		if (p)
+			*p = '\0';
+		buf_add(&b, line);
+	}
+	free(line);
+	fclose(stream);
+	rcxml_parse_xml(&b);
+	free(b.buf);
 }
 
 void rcxml_set_verbose(void)

src/meson.build

@@ -11,5 +11,6 @@ labwc_sources = files(
   'xwl.c',
 )
 
+subdir('common')
 subdir('config')
 subdir('debug')