libc: Add readdir_multi

This is a faster, zero allocation function for reading directory
entries. It has massive speed increases for certain applications since
malloc(especially my implementation) is really slow in comparison.

2 files changed, 14 insertions, 0 deletions

diff --git a/include/dirent.h b/include/dirent.h
index dcd7f59..66e8e8f 100644
--- a/include/dirent.h
+++ b/include/dirent.h
@@ -34,5 +34,6 @@ int scandir_sane(const char *dir, struct dirent ***namelist,
                  int (*compar)(const struct dirent **,
                                const struct dirent **));
 void scandir_sane_free(struct dirent **namelist);
+int readdir_multi(DIR *dir, struct dirent *entries, int num_entries);
 #endif // KERNEL
 #endif // DIRENT_H
diff --git a/userland/libc/dirent/readdir.c b/userland/libc/dirent/readdir.c
index 8b825cb..9a9f8fa 100644
--- a/userland/libc/dirent/readdir.c
+++ b/userland/libc/dirent/readdir.c
@@ -1,6 +1,19 @@
 #include <dirent.h>
 #include <unistd.h>
 
+int readdir_multi(DIR *dir, struct dirent *entries, int num_entries) {
+  size_t offset = dir->dir_num * sizeof(struct dirent);
+  int rc;
+  if (-1 == (rc = pread(dir->fd, entries, num_entries * sizeof(struct dirent),
+                        offset))) {
+    return -1;
+  }
+
+  int num_read_entries = rc / sizeof(struct dirent);
+  dir->dir_num += num_read_entries;
+  return num_read_entries;
+}
+
 struct dirent *readdir(DIR *dir) {
   size_t offset = dir->dir_num * sizeof(struct dirent);
   int rc;