Used the libfuse example as a foundation.

The main.c was completely replaced by one of the libfuse examples:
[passthrough_fh.c](https://github.com/libfuse/libfuse/blob/master/example/passthrough_fh.c)
. This choice is made based on that there is little point in spending
time on reinventing the wheel by reimplementing passthrough all over
again. Also, the [passthrough_hp.cc](https://github.com/libfuse/libfuse/blob/master/example/passthrough_hp.cc) wasn't used because it uses a vastly different and much more comlex API, even though the authors claim it to be faster.

sources/sourcefs.c

@@ -2,15 +2,24 @@
 
 #include "sourcefs.h"
 #include <dirent.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <string.h>
 #include <sys/stat.h>
+#include <unistd.h>
 
 static struct source_files_handle {
   int root_fd;
 } handle;
 
-void source_fname_translate(const char *filename) {}
+const char *source_fname_translate(const char *filename) {
+  if (strcmp("/", filename) == 0) {
+    return ".";
+  } else {
+    return filename + 1;
+  }
+}
 
 int source_init(const char *root_path) {
   int root_fd = open(root_path, O_PATH);
@@ -24,17 +33,43 @@ int source_init(const char *root_path) {
   return 0;
 }
 
-// Currently this literally is a fstatat wrapper.
-int source_stat(const char *restrict pathname, struct stat *restrict statbuf) {
-  int statret = fstatat(handle.root_fd, pathname, statbuf, 0);
-  return statret;
+int source_mkdir(const char *filename, mode_t mode) {
+  const char *relative_filename = source_fname_translate(filename);
+  return mkdirat(handle.root_fd, relative_filename, mode);
+}
+
+int source_unlink(const char *filename) {
+  const char *relative_filename = source_fname_translate(filename);
+  return unlinkat(handle.root_fd, relative_filename, 0);
+}
+
+int source_stat(const char *restrict filename, struct stat *restrict statbuf) {
+  const char *relative_filename = source_fname_translate(filename);
+  return fstatat(handle.root_fd, relative_filename, statbuf, 0);
+}
+
+int source_rmdir(const char *filename) {
+  const char *relative_filename = source_fname_translate(filename);
+  return unlinkat(handle.root_fd, relative_filename, AT_REMOVEDIR);
+}
+
+int source_symlink(const char *target, const char *linkpath) {
+  const char *relative_linkpath = source_fname_translate(linkpath);
+  return symlinkat(target, handle.root_fd, relative_linkpath);
 }
 
 DIR *source_opendir(const char *filename) {
-  int fd = openat(handle.root_fd, filename, NULL);
+  const char *relative_filename = source_fname_translate(filename);
+  int fd = openat(handle.root_fd, relative_filename, NULL);
+  if (fd < 0) {
+    perror("Openat failed");
+    return NULL;
+  }
   DIR *dir_pointer = fdopendir(fd);
   return dir_pointer;
 }
 
-// Just regular readdir in disguise.
-struct dirent *source_readdir(DIR *dirp) { return readdir(dirp); }
+int source_rename(const char *oldpath, const char *newpath) {
+  printf("{\"%s\", \"%s\"}\n", oldpath, newpath);
+  return -1;
+}