1 files changed, 132 insertions, 0 deletions
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/readdir.c b/libc-bottom-half/cloudlibc/src/libc/dirent/readdir.c
new file mode 100644
index 0000000..bfd1921
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/readdir.c
@@ -0,0 +1,132 @@
+// Copyright (c) 2015-2017 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <dirent.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "dirent_impl.h"
+
+static_assert(DT_BLK == __WASI_FILETYPE_BLOCK_DEVICE, "Value mismatch");
+static_assert(DT_CHR == __WASI_FILETYPE_CHARACTER_DEVICE, "Value mismatch");
+static_assert(DT_DIR == __WASI_FILETYPE_DIRECTORY, "Value mismatch");
+static_assert(DT_FIFO == __WASI_FILETYPE_SOCKET_STREAM, "Value mismatch");
+static_assert(DT_LNK == __WASI_FILETYPE_SYMBOLIC_LINK, "Value mismatch");
+static_assert(DT_REG == __WASI_FILETYPE_REGULAR_FILE, "Value mismatch");
+static_assert(DT_UNKNOWN == __WASI_FILETYPE_UNKNOWN, "Value mismatch");
+
+// Grows a buffer to be large enough to hold a certain amount of data.
+#define GROW(buffer, buffer_size, target_size)      \
+  do {                                              \
+    if ((buffer_size) < (target_size)) {            \
+      size_t new_size = (buffer_size);              \
+      while (new_size < (target_size))              \
+        new_size *= 2;                              \
+      void *new_buffer = realloc(buffer, new_size); \
+      if (new_buffer == NULL)                       \
+        return NULL;                                \
+      (buffer) = new_buffer;                        \
+      (buffer_size) = new_size;                     \
+    }                                               \
+  } while (0)
+
+struct dirent *readdir(DIR *dirp) {
+  for (;;) {
+    // Extract the next dirent header.
+    size_t buffer_left = dirp->buffer_used - dirp->buffer_processed;
+    if (buffer_left < sizeof(__wasi_dirent_t)) {
+      // End-of-file.
+      if (dirp->buffer_used < dirp->buffer_size)
+        return NULL;
+      goto read_entries;
+    }
+    __wasi_dirent_t entry;
+    memcpy(&entry, dirp->buffer + dirp->buffer_processed, sizeof(entry));
+
+    size_t entry_size = sizeof(__wasi_dirent_t) + entry.d_namlen;
+    if (entry.d_namlen == 0) {
+      // Invalid pathname length. Skip the entry.
+      dirp->buffer_processed += entry_size;
+      continue;
+    }
+
+    // The entire entry must be present in buffer space. If not, read
+    // the entry another time. Ensure that the read buffer is large
+    // enough to fit at least this single entry.
+    if (buffer_left < entry_size) {
+      GROW(dirp->buffer, dirp->buffer_size, entry_size);
+      goto read_entries;
+    }
+
+    // Skip entries having null bytes in the filename.
+    const char *name = dirp->buffer + dirp->buffer_processed + sizeof(entry);
+    if (memchr(name, '\0', entry.d_namlen) != NULL) {
+      dirp->buffer_processed += entry_size;
+      continue;
+    }
+
+    // Return the next directory entry. Ensure that the dirent is large
+    // enough to fit the filename.
+    GROW(dirp->dirent, dirp->dirent_size,
+         offsetof(struct dirent, d_name) + entry.d_namlen + 1);
+    struct dirent *dirent = dirp->dirent;
+    dirent->d_type = entry.d_type;
+    memcpy(dirent->d_name, name, entry.d_namlen);
+    dirent->d_name[entry.d_namlen] = '\0';
+
+    // `fd_readdir` implementations may set the inode field to zero if the
+    // the inode number is unknown. In that case, do an `fstatat` to get the
+    // inode number.
+    off_t d_ino = entry.d_ino;
+    unsigned char d_type = entry.d_type;
+    if (d_ino == 0 && strcmp(dirent->d_name, "..") != 0) {
+      struct stat statbuf;
+      if (fstatat(dirp->fd, dirent->d_name, &statbuf, AT_SYMLINK_NOFOLLOW) != 0) {
+	if (errno == ENOENT) {
+	  // The file disappeared before we could read it, so skip it.
+	  dirp->buffer_processed += entry_size;
+	  continue;
+	}
+        return NULL;
+      }
+
+      // Fill in the inode.
+      d_ino = statbuf.st_ino;
+
+      // In case someone raced with us and replaced the object with this name
+      // with another of a different type, update the type too.
+      d_type = __wasilibc_iftodt(statbuf.st_mode & S_IFMT);
+    }
+    dirent->d_ino = d_ino;
+    dirent->d_type = d_type;
+
+    dirp->cookie = entry.d_next;
+    dirp->buffer_processed += entry_size;
+    return dirent;
+
+  read_entries:
+    // Discard data currently stored in the input buffer.
+    dirp->buffer_used = dirp->buffer_processed = dirp->buffer_size;
+
+    // Load more directory entries and continue.
+    __wasi_errno_t error =
+        // TODO: Remove the cast on `dirp->buffer` once the witx is updated with char8 support.
+        __wasi_fd_readdir(dirp->fd, (uint8_t *)dirp->buffer, dirp->buffer_size,
+                                  dirp->cookie, &dirp->buffer_used);
+    if (error != 0) {
+      errno = error;
+      return NULL;
+    }
+    dirp->buffer_processed = 0;
+  }
+}