libc: Add opendir, readdir and closedir

libc/CMakeLists.txt

@@ -13,6 +13,7 @@ set(SOURCES
     src/ctype.cpp
     src/time.cpp
     src/init.cpp
+    src/dirent.cpp
     src/setjmp.cpp
     src/sys/stat.cpp
     src/sys/mman.cpp

libc/include/dirent.h

@@ -0,0 +1,32 @@
+/* dirent.h: Directory streams interface. */
+
+#ifndef _DIRENT_H
+#define _DIRENT_H
+
+#include <sys/types.h>
+
+typedef struct
+{
+    int _fd;
+} DIR;
+
+struct dirent
+{
+    ino_t d_ino;
+    char d_name[129];
+};
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    DIR* opendir(const char* path);
+    struct dirent* readdir(DIR* stream);
+    int closedir(DIR* stream);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

libc/src/dirent.cpp

@@ -0,0 +1,55 @@
+#include <bits/getdents.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+extern "C"
+{
+    DIR* opendir(const char* path)
+    {
+        DIR* dp = (DIR*)malloc(sizeof(DIR));
+        if (!dp) { return nullptr; }
+
+        // FIXME: Use O_DIRECTORY (validate that path is actually a directory)
+        int fd = open(path, O_RDONLY);
+        if (fd < 0)
+        {
+            free(dp);
+            return nullptr;
+        }
+
+        dp->_fd = fd;
+
+        return dp;
+    }
+
+    struct dirent* readdir(DIR* stream)
+    {
+        // FIXME: Very hackish, right now luna_dirent and dirent have the same layout.
+        static luna_dirent ent;
+
+        long rc = syscall(SYS_getdents, stream->_fd, &ent, 1);
+        if (rc < 0)
+        {
+            errno = -rc;
+            return nullptr;
+        }
+
+        // End-of-file (no more directory entries)
+        if (rc < 1) return nullptr;
+
+        return (struct dirent*)&ent;
+    }
+
+    int closedir(DIR* stream)
+    {
+        if (close(stream->_fd) < 0) return -1;
+
+        free(stream);
+
+        return 0;
+    }
+}