common: add generic input-line interface, and an implementation of it for text files

common/file.c

@@ -0,0 +1,42 @@
+#include <ivy/file.h>
+#include <stdlib.h>
+#include <string.h>
+
+static enum ivy_status file_readline(
+	struct ivy_line_source *src, char *buf, size_t count, size_t *nr_read,
+	const char *prompt)
+{
+	if (!count) {
+		*nr_read = 0;
+		return IVY_OK;
+	}
+
+	struct ivy_file *f = (struct ivy_file *)src;
+	if (!fgets(buf, count, f->f_fp)) {
+		return feof(f->f_fp) ? IVY_ERR_EOF : IVY_ERR_IO_FAILURE;
+	}
+
+	*nr_read = strlen(buf);
+	return IVY_OK;
+}
+
+struct ivy_file *ivy_file_from_fp(FILE *fp)
+{
+	struct ivy_file *file = malloc(sizeof *file);
+	if (!file) {
+		return NULL;
+	}
+
+	memset(file, 0x0, sizeof *file);
+
+	file->f_fp = fp;
+	file->f_base.s_readline = file_readline;
+
+	return file;
+}
+
+void ivy_file_close(struct ivy_file *file)
+{
+	fclose(file->f_fp);
+	free(file);
+}