[Implementation] StatFS and supporting types

Sources/CSystem/include/CSystemLinux.h

@@ -1,7 +1,7 @@
 /*
  This source file is part of the Swift System open source project
 
- Copyright (c) 2020 Apple Inc. and the Swift System project authors
+ Copyright (c) 2020 - 2026 Apple Inc. and the Swift System project authors
  Licensed under Apache License v2.0 with Runtime Library Exception
 
  See https://swift.org/LICENSE.txt for license information
@@ -20,5 +20,25 @@
 #include <sched.h>
 #include <unistd.h>
 #include "io_uring.h"
+
+// The `ST_*` mount-flag constants in <sys/statvfs.h> require _GNU_SOURCE.
+// Rather than define _GNU_SOURCE module-wide, which clashes with SwiftGlibc,
+// expose them through these getters, defined in shims.c under _GNU_SOURCE.
+#include <stdint.h>
+uint64_t _system_get_ST_RDONLY(void);
+uint64_t _system_get_ST_NOSUID(void);
+uint64_t _system_get_ST_NODEV(void);
+uint64_t _system_get_ST_NOEXEC(void);
+uint64_t _system_get_ST_SYNCHRONOUS(void);
+uint64_t _system_get_ST_MANDLOCK(void);
+uint64_t _system_get_ST_NOATIME(void);
+uint64_t _system_get_ST_NODIRATIME(void);
+uint64_t _system_get_ST_RELATIME(void);
+uint64_t _system_get_ST_NOSYMFOLLOW(void);
+#if !defined(__ANDROID__)
+uint64_t _system_get_ST_WRITE(void);
+uint64_t _system_get_ST_APPEND(void);
+uint64_t _system_get_ST_IMMUTABLE(void);
+#endif
 #endif
 

Sources/CSystem/include/CSystemWASI.h

@@ -16,6 +16,10 @@
 #include <fcntl.h>
 #include <limits.h> // For NAME_MAX
 
+// wasi-libc ships <sys/statvfs.h>, but the Swift WASILibc module does not
+// surface it. Re-export them through CSystem here.
+#include <sys/statvfs.h>
+
 // wasi-libc defines the following constants in a way that Clang Importer can't
 // understand, so we need to expose them manually.
 static inline int32_t _getConst_O_ACCMODE(void) { return O_ACCMODE; }

Sources/CSystem/shims.c

@@ -19,7 +19,39 @@
 #endif
 
 #ifdef __linux__
+
+// The `ST_*` mount-flag constants in <sys/statvfs.h> require _GNU_SOURCE.
+// Define it here, in a dedicated translation unit, not in CSystemLinux.h,
+// since defining it there changes libc types like `fd_set` for every file
+// that imports CSystem and conflicts with SwiftGlibc.
 #define _GNU_SOURCE
+#include <sys/statvfs.h>
+#include <stdint.h>
+
+uint64_t _system_get_ST_RDONLY(void) { return ST_RDONLY; }
+uint64_t _system_get_ST_NOSUID(void) { return ST_NOSUID; }
+uint64_t _system_get_ST_NODEV(void) { return ST_NODEV; }
+uint64_t _system_get_ST_NOEXEC(void) { return ST_NOEXEC; }
+uint64_t _system_get_ST_SYNCHRONOUS(void) { return ST_SYNCHRONOUS; }
+uint64_t _system_get_ST_MANDLOCK(void) { return ST_MANDLOCK; }
+uint64_t _system_get_ST_NOATIME(void) { return ST_NOATIME; }
+uint64_t _system_get_ST_NODIRATIME(void) { return ST_NODIRATIME; }
+uint64_t _system_get_ST_RELATIME(void) { return ST_RELATIME; }
+
+// ST_NOSYMFOLLOW was added to glibc's <sys/statvfs.h> in Linux 5.10. For
+// older versions, fall back to the fixed kernel UAPI bit (<linux/statfs.h>),
+// which is the same value a newer glibc header defines.
+#ifndef ST_NOSYMFOLLOW
+#define ST_NOSYMFOLLOW 0x2000
+#endif
+uint64_t _system_get_ST_NOSYMFOLLOW(void) { return ST_NOSYMFOLLOW; }
+
+#if !defined(__ANDROID__)
+uint64_t _system_get_ST_WRITE(void) { return ST_WRITE; }
+uint64_t _system_get_ST_APPEND(void) { return ST_APPEND; }
+uint64_t _system_get_ST_IMMUTABLE(void) { return ST_IMMUTABLE; }
+#endif
+
 #include <CSystemLinux.h>
 #endif
 

Sources/System/CMakeLists.txt

@@ -1,7 +1,7 @@
 #[[
 This source file is part of the Swift System open source project
 
-Copyright (c) 2020 Apple Inc. and the Swift System project authors
+Copyright (c) 2020 - 2026 Apple Inc. and the Swift System project authors
 Licensed under Apache License v2.0 with Runtime Library Exception
 
 See https://swift.org/LICENSE.txt for license information
@@ -42,7 +42,9 @@ target_sources(SystemPackage PRIVATE
   FileSystem/FileMode.swift
   FileSystem/FileType.swift
   FileSystem/Identifiers.swift
-  FileSystem/Stat.swift)
+  FileSystem/MountFlags.swift
+  FileSystem/Stat.swift
+  FileSystem/StatFS.swift)
 if(CMAKE_SYSTEM_NAME STREQUAL Linux)
   target_sources(SystemPackage PRIVATE
     IORing/IOCompletion.swift