posix: fs: Fixes stat command to return file information

Fixes zephyrproject-rtos#58911. Previously the stat command returned
information on the filesystem, but not the file itself.
Because block size is still set this function is
backwards compatible with the previous faulty
behavior.

Signed-off-by: Vincent van Beveren <v.van.beveren@nikhef.nl>

lib/posix/fs.c

@@ -20,7 +20,7 @@ BUILD_ASSERT(PATH_MAX >= MAX_FILE_NAME, "PATH_MAX is less than MAX_FILE_NAME");
 struct posix_fs_desc {
 	union {
 		struct fs_file_t file;
-		struct fs_dir_t	dir;
+		struct fs_dir_t dir;
 	};
 	bool is_dir;
 	bool used;
@@ -349,22 +349,47 @@ int unlink(const char *path)
 int stat(const char *path, struct stat *buf)
 {
 	int rc;
-	struct fs_statvfs stat;
+	struct fs_statvfs stat_vfs;
+	struct fs_dirent stat_file;
 
 	if (buf == NULL) {
 		errno = EBADF;
 		return -1;
 	}
 
-	rc = fs_statvfs(path, &stat);
+	rc = fs_statvfs(path, &stat_vfs);
 	if (rc < 0) {
 		errno = -rc;
 		return -1;
 	}
 
-	buf->st_size = stat.f_bsize * stat.f_blocks;
-	buf->st_blksize = stat.f_bsize;
-	buf->st_blocks = stat.f_blocks;
+	rc = fs_stat(path, &stat_file);
+	if (rc < 0) {
+		errno = -rc;
+		return -1;
+	}
+
+	memset(buf, 0, sizeof(struct stat));
+
+	switch (stat_file.type) {
+	case FS_DIR_ENTRY_FILE:
+		buf->st_mode = S_IFREG;
+		break;
+	case FS_DIR_ENTRY_DIR:
+		buf->st_mode = S_IFDIR;
+		break;
+	default:
+		errno = EIO;
+		return -1;
+	}
+	buf->st_size = stat_file.size;
+	buf->st_blksize = stat_vfs.f_bsize;
+	/*
+	 * This is a best effort guess, as this information is not provided
+	 * by the fs_stat function.
+	 */
+	buf->st_blocks = (stat_file.size + stat_vfs.f_bsize - 1) / stat_vfs.f_bsize;
+
 	return 0;
 }