1 files changed, 106 insertions, 45 deletions

diff --git a/erts/emulator/nifs/unix/unix_prim_file.c b/erts/emulator/nifs/unix/unix_prim_file.c
index fbf312a3b8..e5099dd921 100644
--- a/erts/emulator/nifs/unix/unix_prim_file.c
+++ b/erts/emulator/nifs/unix/unix_prim_file.c
@@ -107,7 +107,7 @@ ERL_NIF_TERM efile_get_handle(ErlNifEnv *env, efile_data_t *d) {
     return result;
 }
 
-static int open_file_type_check(const efile_path_t *path, int fd) {
+static int open_file_is_dir(const efile_path_t *path, int fd) {
     struct stat file_info;
     int error;
 
@@ -119,27 +119,14 @@ static int open_file_type_check(const efile_path_t *path, int fd) {
     (void)path;
 #endif
 
-    if(error < 0) {
-        /* If we failed to stat assume success and let the next call handle the
-         * error. The old driver checked whether the file was to be used
-         * immediately in a read within the call, but the new implementation
-         * never does that. */
-         return 1;
-    }
-
-    /* Allow everything that isn't a directory, and error out on the next call
-     * if it's unsupported. */
-    if(S_ISDIR(file_info.st_mode)) {
-        return 0;
-    }
-
-    return 1;
+    /* Assume not a directory on error. */
+    return error == 0 && S_ISDIR(file_info.st_mode);
 }
 
 posix_errno_t efile_open(const efile_path_t *path, enum efile_modes_t modes,
         ErlNifResourceType *nif_type, efile_data_t **d) {
 
-    int flags, fd;
+    int mode, flags, fd;
 
     flags = 0;
 
@@ -174,18 +161,38 @@ posix_errno_t efile_open(const efile_path_t *path, enum efile_modes_t modes,
 #endif
     }
 
+    if(modes & EFILE_MODE_DIRECTORY) {
+        mode = DIR_MODE;
+#ifdef O_DIRECTORY
+        flags |= O_DIRECTORY;
+#endif
+    } else {
+        mode = FILE_MODE;
+    }
+
     do {
-        fd = open((const char*)path->data, flags, FILE_MODE);
+        fd = open((const char*)path->data, flags, mode);
     } while(fd == -1 && errno == EINTR);
 
     if(fd != -1) {
         efile_unix_t *u;
 
-        if(!(modes & EFILE_MODE_SKIP_TYPE_CHECK) && !open_file_type_check(path, fd)) {
+#ifndef O_DIRECTORY
+        /* On platforms without O_DIRECTORY support, ensure that using the
+         * directory flag to open a file fails. */
+        if(!(modes & EFILE_MODE_SKIP_TYPE_CHECK) &&
+           (modes & EFILE_MODE_DIRECTORY) && !open_file_is_dir(path, fd)) {
             close(fd);
+            return ENOTDIR;
+        }
+#endif
 
-            /* This is blatantly incorrect, but we're documented as returning
-             * this for everything that isn't a file. */
+        /* open() works on directories without the O_DIRECTORY flag but for
+         * consistency across platforms we require that the user has requested
+         * directory mode. */
+        if(!(modes & EFILE_MODE_SKIP_TYPE_CHECK) &&
+           !(modes & EFILE_MODE_DIRECTORY) && open_file_is_dir(path, fd)) {
+            close(fd);
             return EISDIR;
         }
 
@@ -656,6 +663,33 @@ int efile_truncate(efile_data_t *d) {
     return 1;
 }
 
+static void build_file_info(struct stat *data, efile_fileinfo_t *result) {
+    if(S_ISCHR(data->st_mode) || S_ISBLK(data->st_mode)) {
+        result->type = EFILE_FILETYPE_DEVICE;
+    } else if(S_ISDIR(data->st_mode)) {
+        result->type = EFILE_FILETYPE_DIRECTORY;
+    } else if(S_ISREG(data->st_mode)) {
+        result->type = EFILE_FILETYPE_REGULAR;
+    } else if(S_ISLNK(data->st_mode)) {
+        result->type = EFILE_FILETYPE_SYMLINK;
+    } else {
+        result->type = EFILE_FILETYPE_OTHER;
+    }
+
+    result->a_time = (Sint64)data->st_atime;
+    result->m_time = (Sint64)data->st_mtime;
+    result->c_time = (Sint64)data->st_ctime;
+    result->size = data->st_size;
+
+    result->major_device = data->st_dev;
+    result->minor_device = data->st_rdev;
+    result->links = data->st_nlink;
+    result->inode = data->st_ino;
+    result->mode = data->st_mode;
+    result->uid = data->st_uid;
+    result->gid = data->st_gid;
+}
+
 posix_errno_t efile_read_info(const efile_path_t *path, int follow_links, efile_fileinfo_t *result) {
     struct stat data;
 
@@ -669,30 +703,7 @@ posix_errno_t efile_read_info(const efile_path_t *path, int follow_links, efile_
         }
     }
 
-    if(S_ISCHR(data.st_mode) || S_ISBLK(data.st_mode)) {
-        result->type = EFILE_FILETYPE_DEVICE;
-    } else if(S_ISDIR(data.st_mode)) {
-        result->type = EFILE_FILETYPE_DIRECTORY;
-    } else if(S_ISREG(data.st_mode)) {
-        result->type = EFILE_FILETYPE_REGULAR;
-    } else if(S_ISLNK(data.st_mode)) {
-        result->type = EFILE_FILETYPE_SYMLINK;
-    } else {
-        result->type = EFILE_FILETYPE_OTHER;
-    }
-
-    result->a_time = (Sint64)data.st_atime;
-    result->m_time = (Sint64)data.st_mtime;
-    result->c_time = (Sint64)data.st_ctime;
-    result->size = data.st_size;
-
-    result->major_device = data.st_dev;
-    result->minor_device = data.st_rdev;
-    result->links = data.st_nlink;
-    result->inode = data.st_ino;
-    result->mode = data.st_mode;
-    result->uid = data.st_uid;
-    result->gid = data.st_gid;
+    build_file_info(&data, result);
 
 #ifndef NO_ACCESS
     result->access = EFILE_ACCESS_NONE;
@@ -711,6 +722,56 @@ posix_errno_t efile_read_info(const efile_path_t *path, int follow_links, efile_
     return 0;
 }
 
+static int check_access(struct stat *st) {
+    int ret = EFILE_ACCESS_NONE;
+
+    if(st->st_uid == getuid()) {
+        if(st->st_mode & S_IRUSR) {
+            ret |= EFILE_ACCESS_READ;
+        }
+        if(st->st_mode & S_IWUSR) {
+            ret |= EFILE_ACCESS_WRITE;
+        }
+        return ret;
+    }
+
+    if(st->st_gid == getgid()) {
+        if(st->st_mode & S_IRGRP) {
+            ret |= EFILE_ACCESS_READ;
+        }
+        if(st->st_mode & S_IWGRP) {
+            ret |= EFILE_ACCESS_WRITE;
+        }
+        return ret;
+    }
+
+    if(st->st_mode & S_IROTH) {
+        ret |= EFILE_ACCESS_READ;
+    }
+    if(st->st_mode & S_IWOTH) {
+        ret |= EFILE_ACCESS_WRITE;
+    }
+    return ret;
+}
+
+posix_errno_t efile_read_handle_info(efile_data_t *d, efile_fileinfo_t *result) {
+    struct stat data;
+    efile_unix_t *u = (efile_unix_t*)d;
+
+#ifdef HAVE_FSTAT
+    if(fstat(u->fd, &data) < 0) {
+        return errno;
+    }
+
+    build_file_info(&data, result);
+    result->access = check_access(&data);
+
+    return 0;
+#else
+    return ENOTSUP;
+#endif
+}
+
 posix_errno_t efile_set_permissions(const efile_path_t *path, Uint32 permissions) {
     const mode_t MUTABLE_MODES = (S_ISUID | S_ISGID | S_IRWXU | S_IRWXG | S_IRWXO);
     mode_t new_modes = permissions & MUTABLE_MODES;