minimal read-only passthrough of /

.gitignore

@@ -0,0 +1 @@
+/rgpgfs

Makefile

@@ -0,0 +1,9 @@
+SOURCES = *.c
+
+.PHONY = format
+
+rgpgfs : $(SOURCES)
+	gcc -Wall $^ $(shell pkg-config fuse3 --cflags --libs) -o $@
+
+format : $(SOURCES)
+	clang-format -i -verbose $^

rgpgfs.c

@@ -0,0 +1,87 @@
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+// posix
+#include <dirent.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#define FUSE_USE_VERSION 31
+#include <fuse.h>
+
+static int rgpgfs_getattr(const char *path, struct stat *statbuf,
+                          struct fuse_file_info *fi) {
+  int res = lstat(path, statbuf);
+  // printf("rgpgfs_getattr(%s, ...) = %d\n", path, res);
+  if (res == -1)
+    return -errno;
+  return 0;
+}
+
+static int rgpgfs_access(const char *path, int mask) {
+  int res = access(path, mask);
+  // printf("rgpgfs_access(%s, %d) = %d\n", path, mask, res);
+  if (res == -1)
+    return -errno;
+  return 0;
+}
+
+static int rgpgfs_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
+                          off_t offset, struct fuse_file_info *fi,
+                          enum fuse_readdir_flags flags) {
+  DIR *dirp = opendir(path);
+  if (dirp == NULL)
+    return -errno;
+
+  struct dirent *entp;
+  while ((entp = readdir(dirp)) != NULL) {
+    struct stat statbf;
+    memset(&statbf, 0, sizeof(statbf));
+    statbf.st_ino = entp->d_ino;
+    statbf.st_mode = entp->d_type << 12;
+    if (filler(buf, entp->d_name, &statbf, 0, 0))
+      break;
+  }
+
+  closedir(dirp);
+  return 0;
+}
+
+static int rgpgfs_open(const char *path, struct fuse_file_info *fi) {
+  int res = open(path, fi->flags);
+  if (res == -1)
+    return -errno;
+
+  fi->fh = res;
+  return 0;
+}
+
+static int rgpgfs_read(const char *path, char *buf, size_t count, off_t offset,
+                       struct fuse_file_info *fi) {
+  if (fi == NULL) {
+    return ENOTSUP;
+  }
+  ssize_t bytes_num = pread(fi->fh, buf, count, offset);
+  if (bytes_num == -1)
+    return -errno;
+  return bytes_num;
+}
+
+static int rgpgfs_release(const char *path, struct fuse_file_info *fi) {
+  close(fi->fh);
+  return 0;
+}
+
+static struct fuse_operations rgpgfs_fuse_operations = {
+    .getattr = rgpgfs_getattr,
+    .open = rgpgfs_open,
+    .read = rgpgfs_read,
+    .release = rgpgfs_release,
+    .readdir = rgpgfs_readdir,
+    .access = rgpgfs_access,
+};
+
+int main(int argc, char *argv[]) {
+  return fuse_main(argc, argv, &rgpgfs_fuse_operations, NULL);
+}