Fallocate

src/libraries/Common/src/Interop/Unix/System.Native/Interop.FAllocate.cs

@@ -0,0 +1,14 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.InteropServices;
+using Microsoft.Win32.SafeHandles;
+
+internal static partial class Interop
+{
+    internal static partial class Sys
+    {
+        [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_FAllocate", SetLastError = false /* this is explicitly called out in the man page */)]
+        internal static extern int FAllocate(SafeFileHandle fd, long offset, long length);
+    }
+}

src/libraries/Native/Unix/Common/pal_config.h.in

@@ -34,6 +34,8 @@
 #cmakedefine01 HAVE_STRLCAT
 #cmakedefine01 HAVE_SHM_OPEN_THAT_WORKS_WELL_ENOUGH_WITH_MMAP
 #cmakedefine01 HAVE_POSIX_ADVISE
+#cmakedefine01 HAVE_POSIX_FALLOCATE
+#cmakedefine01 HAVE_POSIX_FALLOCATE64
 #cmakedefine01 PRIORITY_REQUIRES_INT_WHO
 #cmakedefine01 KEVENT_REQUIRES_INT_PARAMS
 #cmakedefine01 HAVE_IOCTL

src/libraries/Native/Unix/System.Native/entrypoints.c

@@ -89,6 +89,7 @@ static const Entry s_sysNative[] =
     DllImportEntry(SystemNative_FTruncate)
     DllImportEntry(SystemNative_Poll)
     DllImportEntry(SystemNative_PosixFAdvise)
+    DllImportEntry(SystemNative_FAllocate)
     DllImportEntry(SystemNative_Read)
     DllImportEntry(SystemNative_ReadLink)
     DllImportEntry(SystemNative_Rename)

src/libraries/Native/Unix/System.Native/pal_io.c

@@ -662,7 +662,7 @@ int32_t SystemNative_FSync(intptr_t fd)
     int fileDescriptor = ToFileDescriptor(fd);
 
     int32_t result;
-    while ((result = 
+    while ((result =
 #if defined(TARGET_OSX) && HAVE_F_FULLFSYNC
     fcntl(fileDescriptor, F_FULLFSYNC)
 #else
@@ -991,6 +991,58 @@ int32_t SystemNative_PosixFAdvise(intptr_t fd, int64_t offset, int64_t length, i
 #endif
 }
 
+int32_t SystemNative_FAllocate(intptr_t fd, int64_t offset, int64_t length)
+{
+    int fileDescriptor = ToFileDescriptor(fd);
+    int32_t result;
+#if HAVE_POSIX_FALLOCATE64 // 64-bit Linux
+    while ((result = posix_fallocate64(fileDescriptor, (off64_t)offset, (off64_t)length)) == EINTR);
+#elif HAVE_POSIX_FALLOCATE // 32-bit Linux
+    while ((result = posix_fallocate(fileDescriptor, (off_t)offset, (off_t)length)) == EINTR);
+#elif defined(F_PREALLOCATE) // macOS
+    fstore_t fstore;
+    fstore.fst_flags = F_ALLOCATECONTIG; // ensure contiguous space
+    fstore.fst_posmode = F_PEOFPOSMODE;  // allocate from the physical end of file, as offset MUST NOT be 0 for F_VOLPOSMODE
+    fstore.fst_offset = (off_t)offset;
+    fstore.fst_length = (off_t)length;
+    fstore.fst_bytesalloc = 0; // output size, can be > length
+
+    while ((result = fcntl(fileDescriptor, F_PREALLOCATE, &fstore)) == -1 && errno == EINTR) ;
+
+    if (result == -1)
+    {
+        // we have failed to allocate contiguous space, let's try non-contiguous
+        fstore.fst_flags = F_ALLOCATEALL; // all or nothing
+        while ((result = fcntl(fileDescriptor, F_PREALLOCATE, &fstore)) == -1 && errno == EINTR) ;
+    }
+#elif defined(F_ALLOCSP) || defined(F_ALLOCSP64) // FreeBSD
+    #if HAVE_FLOCK64
+    struct flock64 lockArgs;
+    int command = F_ALLOCSP64;
+    #else
+    struct flock lockArgs;
+    int command = F_ALLOCSP;
+    #endif
+
+    lockArgs.l_whence = SEEK_SET;
+    lockArgs.l_start = (off_t)offset;
+    lockArgs.l_len = (off_t)length;
+
+    while ((result = fcntl(fileDescriptor, command, &lockArgs)) == -1 && errno == EINTR) ;
+#endif
+
+#if defined(F_PREALLOCATE) || defined(F_ALLOCSP) || defined(F_ALLOCSP64)
+    // most of the Unixes implement posix_fallocate which does NOT set the last error
+    // fctnl does, but to mimic the posix_fallocate behaviour we just return error
+    if (result == -1)
+    {
+        result = errno;
+    }
+#endif
+
+    return result;
+}
+
 int32_t SystemNative_Read(intptr_t fd, void* buffer, int32_t bufferSize)
 {
     return Common_Read(fd, buffer, bufferSize);
@@ -1184,7 +1236,7 @@ int32_t SystemNative_CopyFile(intptr_t sourceFd, intptr_t destinationFd)
 #endif
     }
     // If we copied to a filesystem (eg EXFAT) that does not preserve POSIX ownership, all files appear
-    // to be owned by root. If we aren't running as root, then we won't be an owner of our new file, and 
+    // to be owned by root. If we aren't running as root, then we won't be an owner of our new file, and
     // attempting to copy metadata to it will fail with EPERM. We have copied successfully, we just can't
     // copy metadata. The best thing we can do is skip copying the metadata.
     if (ret != 0 && errno != EPERM)

src/libraries/Native/Unix/System.Native/pal_io.h

@@ -604,6 +604,13 @@ PALEXPORT int32_t SystemNative_Poll(PollEvent* pollEvents, uint32_t eventCount,
  */
 PALEXPORT int32_t SystemNative_PosixFAdvise(intptr_t fd, int64_t offset, int64_t length, int32_t advice);
 
+/**
+ * Ensures that disk space is allocated.
+ *
+ * Returns 0 on success; otherwise, the error code is returned and errno is NOT set.
+ */
+PALEXPORT int32_t SystemNative_FAllocate(intptr_t fd, int64_t offset, int64_t length);
+
 /**
  * Reads the number of bytes specified into the provided buffer from the specified, opened file descriptor.
  *

src/libraries/Native/Unix/configure.cmake

@@ -209,6 +209,16 @@ check_symbol_exists(
     fcntl.h
     HAVE_POSIX_ADVISE)
 
+check_symbol_exists(
+    posix_fallocate
+    fcntl.h
+    HAVE_POSIX_FALLOCATE)
+
+check_symbol_exists(
+    posix_fallocate64
+    fcntl.h
+    HAVE_POSIX_FALLOCATE64)
+
 check_symbol_exists(
     ioctl
     sys/ioctl.h

src/libraries/System.IO.FileSystem/tests/FileStream/FileStreamConformanceTests.cs

@@ -62,7 +62,7 @@ public async Task FileOffsetIsPreservedWhenFileStreamIsCreatedFromSafeFileHandle
 
             using FileStream createdFromHandle = new FileStream(stream.SafeFileHandle, FileAccess.Write);
 
-            Assert.Equal(buffer.Length, stream.Position); 
+            Assert.Equal(buffer.Length, stream.Position);
             Assert.Equal(stream.Position, createdFromHandle.Position);
         }
 
@@ -187,17 +187,22 @@ public async Task WriteByteFlushesTheBufferWhenItBecomesFull()
             byte[] allBytes = File.ReadAllBytes(filePath);
             Assert.Equal(writtenBytes.ToArray(), allBytes);
         }
-        
+
         [Fact]
         public void WhenFileStreamFailsToPreallocateDiskSpaceTheErrorMessageContainsAllTheDetails()
         {
             const long tooMuch = 1024L * 1024L * 1024L * 1024L; // 1 TB
 
             string filePath = GetTestFilePath();
-            IOException ex = Assert.Throws<IOException>(() => new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None, BufferSize, Options, tooMuch));
+
+            Assert.False(File.Exists(filePath));
+
+            IOException ex = Assert.Throws<IOException>(() => new FileStream(filePath, FileMode.Create, FileAccess.Write, FileShare.None, BufferSize, Options, tooMuch));
             Assert.Contains("disk was full", ex.Message);
             Assert.Contains(filePath, ex.Message);
             Assert.Contains(AllocationSize.ToString(), ex.Message);
+
+            Assert.False(File.Exists(filePath));
         }
     }
 

src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems

@@ -1,4 +1,4 @@
-<Project>
+<Project>
   <PropertyGroup>
     <HasSharedItems>true</HasSharedItems>
     <SharedGUID>c5ed3c1d-b572-46f1-8f96-522a85ce1179</SharedGUID>
@@ -1821,6 +1821,9 @@
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.PosixFAdvise.cs">
       <Link>Common\Interop\Unix\System.Native\Interop.PosixFAdvise.cs</Link>
     </Compile>
+    <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.FAllocate.cs">
+      <Link>Common\Interop\Unix\System.Native\Interop.FAllocate.cs</Link>
+    </Compile>
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Read.cs">
       <Link>Common\Interop\Unix\System.Native\Interop.Read.cs</Link>
     </Compile>

src/libraries/System.Private.CoreLib/src/System/IO/Strategies/FileStreamHelpers.Unix.cs

@@ -7,12 +7,15 @@
 using System.Runtime.Versioning;
 using System.Threading;
 using System.Threading.Tasks;
+using Internal.IO;
 
 namespace System.IO.Strategies
 {
     // this type defines a set of stateless FileStream/FileStreamStrategy helper methods
     internal static partial class FileStreamHelpers
     {
+        private const int ENOSPC_Linux = 28;
+
         // in the future we are most probably going to introduce more strategies (io_uring etc)
         private static FileStreamStrategy ChooseStrategyCore(SafeFileHandle handle, FileAccess access, FileShare share, int bufferSize, bool isAsync)
             => new Net5CompatFileStreamStrategy(handle, access, bufferSize, isAsync);
@@ -35,7 +38,22 @@ internal static SafeFileHandle OpenHandle(string path, FileMode mode, FileAccess
                 Interop.Sys.Permissions.S_IROTH | Interop.Sys.Permissions.S_IWOTH;
 
             // Open the file and store the safe handle.
-            return SafeFileHandle.Open(path!, openFlags, (int)OpenPermissions);
+            SafeFileHandle handle = SafeFileHandle.Open(path!, openFlags, (int)OpenPermissions);
+            // If allocationSize has been provided for a creatable and writeable file
+            if (allocationSize > 0 && (access & FileAccess.Write) != 0 && mode != FileMode.Open && mode != FileMode.Append)
+            {
+                int allocationResult = Interop.Sys.FAllocate(handle, 0, allocationSize);
+                if (allocationResult == (int)Interop.Error.ENOSPC || allocationResult == ENOSPC_Linux)
+                {
+                    handle.Dispose();
+                    Interop.Sys.Unlink(path); // remove the file to mimic Windows behaviour (atomic operation)
+
+                    throw new IOException(SR.Format(SR.IO_DiskFull_Path_AllocationSize, path, allocationSize));
+                }
+                // ignore not supported and other failures (pipe etc)
+            }
+
+            return handle;
         }
 
         internal static bool GetDefaultIsAsync(SafeFileHandle handle, bool defaultIsAsync) => handle.IsAsync ?? defaultIsAsync;