From 6eac94633434f7b84151cec8cf11d35e07e3ff81 Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbaren@mit.edu>
Date: Sat, 13 Feb 2016 20:04:45 -0500
Subject: Implement enough to get ls to work

---
 src/operations.cc | 131 +++++++++++++++++++++++++++++++++++++++++++++++++++---
 src/scoville.cc   |   4 --
 2 files changed, 124 insertions(+), 11 deletions(-)

diff --git a/src/operations.cc b/src/operations.cc
index 17ce2a3..abd2f0c 100644
--- a/src/operations.cc
+++ b/src/operations.cc
@@ -15,12 +15,20 @@
 // You should have received a copy of the GNU General Public License along with
 // this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#define BSD_SOURCE
+#define _POSIX_C_SOURCE 201602L
+
 #include "operations.h"
 
 #include <cerrno>
+#include <cstring>
+#include <memory>
+#include <new>
 
 #define FUSE_USE_VERSION 26
+#include <dirent.h>
 #include <fuse.h>
+#include <glog/logging.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ -29,19 +37,117 @@ namespace scoville {
 
 namespace {
 
-int GetAttr(const char* const path, struct stat* output) {
+struct Directory {
+  DIR* fd;
+  dirent* entry;
+  off_t offset;
+};
+
+Directory* FileInfoDirectory(fuse_file_info* const file_info) {
+  return reinterpret_cast<Directory*>(file_info->fh);
+}
+
+mode_t DirectoryTypeToFileType(const unsigned char type) {
+  switch (type) {
+    case DT_BLK:
+      return S_IFBLK;
+    case DT_CHR:
+      return S_IFCHR;
+    case DT_DIR:
+      return S_IFDIR;
+    case DT_FIFO:
+      return S_IFIFO;
+    case DT_LNK:
+      return S_IFLNK;
+    case DT_REG:
+      return S_IFREG;
+    case DT_SOCK:
+      return S_IFSOCK;
+    default:
+      return 0;
+  }
+}
+
+void* Initialize(fuse_conn_info*) {
+  LOG(INFO) << "initialize";
+  return nullptr;
+}
+
+void Destroy(void*) {
+  LOG(INFO) << "destroy";
+}
+
+int Getattr(const char* const path, struct stat* output) {
+  LOG(INFO) << "getattr(" << path << ")";
   if (lstat(path, output) == -1) {
     return -errno;
   }
   return 0;
 }
 
-int ReadLink(const char* const path, char *const output, const size_t output_size) {
-  const ssize_t bytes_written = readlink(path, output, output_size);
-  if (bytes_written == -1) {
+int Opendir(const char* const path, fuse_file_info* const file_info) {
+  LOG(INFO) << "opendir(" << path << ")";
+
+  std::unique_ptr<Directory> directory;
+  try {
+    directory.reset(new Directory);
+  } catch (std::bad_alloc) {
+    return -ENOMEM;
+  }
+
+  if ((directory->fd = opendir(path)) == nullptr) {
     return -errno;
   }
-  output[bytes_written] = '\0';
+  directory->entry = nullptr;
+  directory->offset = 0;
+
+  static_assert(sizeof(file_info->fh) == sizeof(uintptr_t),
+                "FUSE file handles are a different size than pointers");
+  file_info->fh = reinterpret_cast<uintptr_t>(directory.release());
+  return 0;
+}
+
+int Readdir(const char*, void* const buffer, fuse_fill_dir_t filler,
+            const off_t offset, fuse_file_info* const file_info) {
+  LOG(INFO) << "readdir";
+
+  Directory* const directory = FileInfoDirectory(file_info);
+
+  if (offset != directory->offset) {
+    seekdir(directory->fd, offset);
+    directory->entry = nullptr;
+    directory->offset = offset;
+  }
+
+  while (true) {
+    if (!directory->entry) {
+      directory->entry = readdir(directory->fd);
+      if (!directory->entry) {
+        break;
+      }
+    }
+
+    struct stat stats;
+    std::memset(&stats, 0, sizeof(stats));
+    stats.st_ino = directory->entry->d_ino;
+    stats.st_mode = DirectoryTypeToFileType(directory->entry->d_type);
+    const off_t next_offset = telldir(directory->fd);
+    if (filler(buffer, directory->entry->d_name, &stats, next_offset)) {
+      break;
+    }
+
+    directory->entry = nullptr;
+    directory->offset = next_offset;
+  }
+
+  return 0;
+}
+
+int Releasedir(const char*, fuse_file_info* const file_info) {
+  LOG(INFO) << "releasedir";
+  Directory* const directory = FileInfoDirectory(file_info);
+  closedir(directory->fd);
+  delete directory;
   return 0;
 }
 
@@ -49,8 +155,19 @@ int ReadLink(const char* const path, char *const output, const size_t output_siz
 
 fuse_operations FuseOperations() {
   fuse_operations result;
-  result.getattr = &GetAttr;
-  result.readlink = &ReadLink;
+
+  result.flag_nullpath_ok = true;
+  result.flag_nopath = true;
+  result.flag_utime_omit_ok = true;
+
+  result.init = &Initialize;
+  result.destroy = &Destroy;
+
+  result.getattr = &Getattr;
+  result.opendir = &Opendir;
+  result.readdir = &Readdir;
+  result.releasedir = &Releasedir;
+
   return result;
 }
 
diff --git a/src/scoville.cc b/src/scoville.cc
index db39ee8..054a6cd 100644
--- a/src/scoville.cc
+++ b/src/scoville.cc
@@ -19,10 +19,6 @@
 
 #include "operations.h"
 
-namespace {
-
-}  // namespace
-
 int main(const int argc, char* argv[]) {
   FLAGS_logtostderr = true;
   google::InstallFailureSignalHandler();
-- 
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