Merge pull request #2388 from djones6/fallback_on_statx_eperm

Fallback if statx syscall is not permitted

Author: millenomi

CoreFoundation/Base.subproj/ForSwiftFoundationOnly.h

@@ -538,20 +538,21 @@ static inline unsigned int _dev_minor(dev_t rdev) {
 
 // There is no glibc statx() function, it must be called using syscall().
 
-static inline ssize_t
+static inline int
 _statx(int dfd, const char *filename, unsigned int flags, unsigned int mask, struct statx *buffer) {
-    return syscall(__NR_statx, dfd, filename, flags, mask, buffer);
+    int ret = syscall(__NR_statx, dfd, filename, flags, mask, buffer);
+    return ret == 0 ? ret : errno;
 }
 
 // At the moment the only extra information statx() is used for is to get the btime (file creation time).
 // This function is here instead of in FileManager.swift because there is no way of setting a conditional
 // define that could be used with a #if in the Swift code.
-static inline ssize_t
+static inline int
 _stat_with_btime(const char *filename, struct stat *buffer, struct timespec *btime) {
     struct statx statx_buffer = {0};
     *btime = (struct timespec) {0};
 
-    ssize_t ret = _statx(AT_FDCWD, filename, AT_SYMLINK_NOFOLLOW | AT_STATX_SYNC_AS_STAT, STATX_ALL, &statx_buffer);
+    int ret = _statx(AT_FDCWD, filename, AT_SYMLINK_NOFOLLOW | AT_STATX_SYNC_AS_STAT, STATX_ALL, &statx_buffer);
     if (ret == 0) {
         *buffer = (struct stat) {
             .st_dev = makedev(statx_buffer.stx_dev_major, statx_buffer.stx_dev_minor),
@@ -587,10 +588,10 @@ _stat_with_btime(const char *filename, struct stat *buffer, struct timespec *bti
 
 // Dummy version when compiled where struct statx is not defined in the headers.
 // Just calles lstat() instead.
-static inline ssize_t
+static inline int
 _stat_with_btime(const char *filename, struct stat *buffer, struct timespec *btime) {
     *btime = (struct timespec) {0};
-    return lstat(filename, buffer);
+    return lstat(filename, buffer) == 0 ? 0 : errno;
 }
 #endif // __NR_statx
 

Foundation/FileManager+POSIX.swift

@@ -927,13 +927,24 @@ extension FileManager {
     // structure and optional creation date.
 
     internal func _statxFile(atPath path: String) throws -> (stat, Date?) {
-        return try _fileSystemRepresentation(withPath: path) { fsRep in
+        // Fallback if statx() is unavailable or fails
+        func _statxFallback(atPath path: String, withFileSystemRepresentation fsRep: UnsafePointer<Int8>?) throws -> (stat, Date?) {
+            let statInfo = try _lstatFile(atPath: path, withFileSystemRepresentation: fsRep)
+            return (statInfo, nil)
+        }
 
+        return try _fileSystemRepresentation(withPath: path) { fsRep in
             if supportsStatx {
                 var statInfo = stat()
                 var btime = timespec()
-                guard _stat_with_btime(fsRep, &statInfo, &btime) == 0 else {
-                    throw _NSErrorWithErrno(errno, reading: true, path: path)
+                let statxErrno = _stat_with_btime(fsRep, &statInfo, &btime)
+                guard statxErrno == 0 else {
+                    switch statxErrno {
+                    case EPERM:
+                      return try _statxFallback(atPath: path, withFileSystemRepresentation: fsRep)
+                    default:
+                      throw _NSErrorWithErrno(statxErrno, reading: true, path: path)
+                    }
                 }
 
                 let sec = btime.tv_sec
@@ -947,9 +958,7 @@ extension FileManager {
                 }
                 return (statInfo, creationDate)
             } else {
-                // fallback if statx() is unavailable or fails
-                let statInfo = try _lstatFile(atPath: path, withFileSystemRepresentation: fsRep)
-                return (statInfo, nil)
+                return try _statxFallback(atPath: path, withFileSystemRepresentation: fsRep)
             }
         }
     }