Fix SystemNative_SendFile on iOS/tvOS devices (#69436)

Even though the `sendfile()` function exists it causes a SIGSYS signal which crashes the process on devices whenever you use it (this doesn't happen on simulators). Implement a read/write loop as a fallback to fix this, loosely based on CopyFile_ReadWrite in pal_io.c. See similar issues in other projects: - golang/go@029dfbc - ndfred/iperf-ios#17
dotnet · May 21, 2022 · f832309 · f832309
1 parent 7626c5d
commit f832309
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Showing 10 changed files with 166 additions and 112 deletions.
diff --git a/src/libraries/System.Net.Sockets/tests/FunctionalTests/Connect.cs b/src/libraries/System.Net.Sockets/tests/FunctionalTests/Connect.cs
@@ -123,7 +123,7 @@ public async Task Connect_AfterDisconnect_Fails()
         }
 
         [OuterLoop("Connects to external server")]
-        [SkipOnPlatform(TestPlatforms.OSX | TestPlatforms.FreeBSD, "Not supported on BSD like OSes.")]
+        [SkipOnPlatform(TestPlatforms.OSX | TestPlatforms.MacCatalyst | TestPlatforms.iOS | TestPlatforms.tvOS | TestPlatforms.FreeBSD, "Not supported on BSD like OSes.")]
         [Theory]
         [InlineData("1.1.1.1", false)]
         [InlineData("1.1.1.1", true)]

diff --git a/src/libraries/System.Net.Sockets/tests/FunctionalTests/DualModeSocketTest.cs b/src/libraries/System.Net.Sockets/tests/FunctionalTests/DualModeSocketTest.cs
diff --git a/src/libraries/System.Net.Sockets/tests/FunctionalTests/ExecutionContextFlowTest.cs b/src/libraries/System.Net.Sockets/tests/FunctionalTests/ExecutionContextFlowTest.cs
@@ -501,7 +501,7 @@ public async Task APM_ExecutionContextFlowsAcrossBeginSendFileOperation(bool sup
         }
 
         [OuterLoop("Relies on finalization")]
-        [Fact]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsPreciseGcSupported))]
         public void ExecutionContext_NotCachedInSocketAsyncEventArgs()
         {
             using (var listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))

diff --git a/src/libraries/System.Net.Sockets/tests/FunctionalTests/InlineCompletions.Unix.cs b/src/libraries/System.Net.Sockets/tests/FunctionalTests/InlineCompletions.Unix.cs
@@ -13,7 +13,7 @@ namespace System.Net.Sockets.Tests
     public class InlineContinuations
     {
         [OuterLoop]
-        [Fact]
+        [ConditionalFact(typeof(RemoteExecutor), nameof(RemoteExecutor.IsSupported))]
         [PlatformSpecific(TestPlatforms.AnyUnix)] // Inline Socket mode is specific to Unix Socket implementation.
         public void InlineSocketContinuations()
         {

diff --git a/src/libraries/System.Net.Sockets/tests/FunctionalTests/LingerStateTest.cs b/src/libraries/System.Net.Sockets/tests/FunctionalTests/LingerStateTest.cs
@@ -43,7 +43,7 @@ public void Socket_LingerState_Common_Boundaries_CorrectBehavior()
 
         [OuterLoop]
         [Fact]
-        [SkipOnPlatform(TestPlatforms.OSX, "The upper bound for linger time is drastically different on OS X.")]
+        [SkipOnPlatform(TestPlatforms.OSX | TestPlatforms.MacCatalyst | TestPlatforms.iOS | TestPlatforms.tvOS, "The upper bound for linger time is drastically different on Apple platforms.")]
         public void Socket_LingerState_Upper_Boundaries_CorrectBehavior()
         {
             Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
@@ -55,10 +55,10 @@ public void Socket_LingerState_Upper_Boundaries_CorrectBehavior()
 
         [OuterLoop]
         [Fact]
-        [PlatformSpecific(TestPlatforms.OSX)]  // The upper bound for linger time is drastically different on OS X.
-        public void Socket_LingerState_Upper_Boundaries_CorrectBehavior_OSX()
+        [PlatformSpecific(TestPlatforms.OSX | TestPlatforms.MacCatalyst | TestPlatforms.iOS | TestPlatforms.tvOS)]  // The upper bound for linger time is drastically different on Apple platforms.
+        public void Socket_LingerState_Upper_Boundaries_CorrectBehavior_Apple()
         {
-            // The upper bound for linger time is drastically different on OS X.
+            // The upper bound for linger time is drastically different on Apple platforms.
             Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
 
             Assert.Throws<SocketException>(() =>

diff --git a/src/libraries/System.Net.Sockets/tests/FunctionalTests/SendReceive/SendReceive.cs b/src/libraries/System.Net.Sockets/tests/FunctionalTests/SendReceive/SendReceive.cs
@@ -831,7 +831,7 @@ await Task.WhenAll(
         }
 
         [Fact]
-        [PlatformSpecific(TestPlatforms.OSX)]
+        [PlatformSpecific(TestPlatforms.OSX | TestPlatforms.MacCatalyst | TestPlatforms.iOS | TestPlatforms.tvOS)]
         public void SocketSendReceiveBufferSize_SetZero_ThrowsSocketException()
         {
             using (Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))

diff --git a/src/mono/cmake/config.h.in b/src/mono/cmake/config.h.in
@@ -563,9 +563,6 @@
 /* Have mktemp */
 #cmakedefine HAVE_MKTEMP 1
 
-/* Define to 1 if you have the <sys/sendfile.h> header file. */
-#cmakedefine HAVE_SYS_SENDFILE_H 1
-
 /* Define to 1 if you have the <sys/statvfs.h> header file. */
 #cmakedefine HAVE_SYS_STATVFS_H 1
 
@@ -590,9 +587,6 @@
 /* Define to 1 if you have the `vsnprintf' function. */
 #cmakedefine HAVE_VSNPRINTF 1
 
-/* Define to 1 if you have the `sendfile' function. */
-#cmakedefine HAVE_SENDFILE 1
-
 /* struct statfs */
 #cmakedefine HAVE_STATFS 1
 

diff --git a/src/mono/cmake/configure.cmake b/src/mono/cmake/configure.cmake
@@ -67,7 +67,7 @@ endfunction()
 ac_check_headers (
   sys/types.h sys/stat.h sys/filio.h sys/sockio.h sys/utime.h sys/un.h sys/syscall.h sys/uio.h sys/param.h
   sys/prctl.h sys/socket.h sys/utsname.h sys/select.h sys/poll.h sys/wait.h sys/resource.h
-  sys/ioctl.h sys/errno.h sys/sendfile.h sys/statvfs.h sys/statfs.h sys/mman.h sys/mount.h sys/time.h sys/random.h
+  sys/ioctl.h sys/errno.h sys/statvfs.h sys/statfs.h sys/mman.h sys/mount.h sys/time.h sys/random.h
   strings.h stdint.h unistd.h signal.h setjmp.h syslog.h netdb.h utime.h semaphore.h alloca.h ucontext.h pwd.h elf.h
   gnu/lib-names.h netinet/tcp.h netinet/in.h link.h arpa/inet.h unwind.h poll.h wchar.h
   android/legacy_signal_inlines.h execinfo.h pthread.h pthread_np.h net/if.h dirent.h
@@ -79,7 +79,7 @@ ac_check_funcs (
   getrusage dladdr sysconf getrlimit prctl nl_langinfo
   sched_getaffinity sched_setaffinity getpwuid_r chmod lstat getdtablesize ftruncate msync
   getpeername utime utimes openlog closelog atexit popen strerror_r inet_pton inet_aton
-  poll getfsstat mremap posix_fadvise vsnprintf sendfile statfs statvfs setpgid system
+  poll getfsstat mremap posix_fadvise vsnprintf statfs statvfs setpgid system
   fork execv execve waitpid localtime_r mkdtemp getrandom execvp strlcpy stpcpy strtok_r rewinddir
   vasprintf strndup getpwuid_r getprotobyname getprotobyname_r getaddrinfo mach_absolute_time
   gethrtime read_real_time gethostbyname gethostbyname2 getnameinfo getifaddrs

diff --git a/src/native/libs/System.Native/pal_networking.c b/src/native/libs/System.Native/pal_networking.c
@@ -3125,10 +3125,9 @@ int32_t SystemNative_SendFile(intptr_t out_fd, intptr_t in_fd, int64_t offset, i
 
     int outfd = ToFileDescriptor(out_fd);
     int infd = ToFileDescriptor(in_fd);
-
-#if HAVE_SENDFILE_4
     off_t offtOffset = (off_t)offset;
 
+#if HAVE_SENDFILE_4
     ssize_t res;
     while ((res = sendfile(outfd, infd, &offtOffset, (size_t)count)) < 0 && errno == EINTR);
     if (res != -1)
@@ -3146,9 +3145,9 @@ int32_t SystemNative_SendFile(intptr_t out_fd, intptr_t in_fd, int64_t offset, i
     {
         off_t len = count;
 #if HAVE_SENDFILE_7
-        ssize_t res = sendfile(infd, outfd, (off_t)offset, (size_t)count, NULL, &len, 0);
+        ssize_t res = sendfile(infd, outfd, offtOffset, (size_t)count, NULL, &len, 0);
 #else
-        ssize_t res = sendfile(infd, outfd, (off_t)offset, &len, NULL, 0);
+        ssize_t res = sendfile(infd, outfd, offtOffset, &len, NULL, 0);
 #endif
         assert(len >= 0);
 
@@ -3180,18 +3179,76 @@ int32_t SystemNative_SendFile(intptr_t out_fd, intptr_t in_fd, int64_t offset, i
         // For everything other than EINTR, bail.
         return SystemNative_ConvertErrorPlatformToPal(errno);
     }
-
 #else
-    // If we ever need to run on a platform that doesn't have sendfile,
-    // we can implement this with a simple read/send loop.  For now,
-    // we just mark it as not supported.
-    (void)outfd;
-    (void)infd;
-    (void)offset;
-    (void)count;
+    // Emulate sendfile using a simple read/send loop.
     *sent = 0;
-    errno = ENOTSUP;
-    return SystemNative_ConvertErrorPlatformToPal(errno);
+    char* buffer = NULL;
+
+    // Save the original input file position and seek to the offset position
+    off_t inputFileOrigOffset = lseek(in_fd, 0, SEEK_CUR);
+    if (inputFileOrigOffset == -1 || lseek(in_fd, offtOffset, SEEK_SET) == -1)
+    {
+        goto error;
+    }
+
+    // Allocate a buffer
+    size_t bufferLength = Min((size_t)count, 80 * 1024 * sizeof(char));
+    buffer = (char*)malloc(bufferLength);
+    if (buffer == NULL)
+    {
+        goto error;
+    }
+
+    // Repeatedly read from the source and write to the destination
+    while (count > 0)
+    {
+        size_t numBytesToRead = Min((size_t)count, bufferLength);
+
+        // Read up to what will fit in our buffer.  We're done if we get back 0 bytes or read 'count' bytes
+        ssize_t bytesRead;
+        while ((bytesRead = read(in_fd, buffer, numBytesToRead)) < 0 && errno == EINTR);
+        if (bytesRead == -1)
+        {
+            goto error;
+        }
+        if (bytesRead == 0)
+        {
+            break;
+        }
+        assert(bytesRead > 0);
+
+        // Write what was read.
+        ssize_t writeOffset = 0;
+        while (bytesRead > 0)
+        {
+            ssize_t bytesWritten;
+            while ((bytesWritten = write(out_fd, buffer + writeOffset, (size_t)bytesRead)) < 0 && errno == EINTR);
+            if (bytesWritten == -1)
+            {
+                goto error;
+            }
+            assert(bytesWritten >= 0);
+            bytesRead -= bytesWritten;
+            count -= bytesWritten;
+            writeOffset += bytesWritten;
+            *sent += bytesWritten;
+        }
+    }
+
+    // Restore the original input file position
+    if (lseek(in_fd, inputFileOrigOffset, SEEK_SET) == -1)
+    {
+        goto error;
+    }
+
+    free(buffer);
+    return Error_SUCCESS;
+
+error:
+    int savedErrno = errno;
+    free(buffer);
+    return SystemNative_ConvertErrorPlatformToPal(savedErrno);
+
 #endif
 }
 

diff --git a/src/native/libs/configure.cmake b/src/native/libs/configure.cmake
@@ -434,32 +434,35 @@ check_struct_has_member(
     "sys/select.h"
     HAVE_PRIVATE_FDS_BITS)
 
-check_c_source_compiles(
-    "
-    #include <sys/sendfile.h>
-    int main(void) { int i = sendfile(0, 0, 0, 0); return 0; }
-    "
-    HAVE_SENDFILE_4)
+# do not use sendfile() on iOS/tvOS, it causes SIGSYS at runtime on devices
+if(NOT CLR_CMAKE_TARGET_IOS AND NOT CLR_CMAKE_TARGET_TVOS)
+    check_c_source_compiles(
+        "
+        #include <sys/sendfile.h>
+        int main(void) { int i = sendfile(0, 0, 0, 0); return 0; }
+        "
+        HAVE_SENDFILE_4)
 
-check_c_source_compiles(
-    "
-    #include <stdlib.h>
-    #include <sys/types.h>
-    #include <sys/socket.h>
-    #include <sys/uio.h>
-    int main(void) { int i = sendfile(0, 0, 0, NULL, NULL, 0); return 0; }
-    "
-    HAVE_SENDFILE_6)
+    check_c_source_compiles(
+        "
+        #include <stdlib.h>
+        #include <sys/types.h>
+        #include <sys/socket.h>
+        #include <sys/uio.h>
+        int main(void) { int i = sendfile(0, 0, 0, NULL, NULL, 0); return 0; }
+        "
+        HAVE_SENDFILE_6)
 
-check_c_source_compiles(
-    "
-    #include <stdlib.h>
-    #include <sys/types.h>
-    #include <sys/socket.h>
-    #include <sys/uio.h>
-    int main(void) { int i = sendfile(0, 0, 0, 0, NULL, NULL, 0); return 0; }
-    "
-    HAVE_SENDFILE_7)
+    check_c_source_compiles(
+        "
+        #include <stdlib.h>
+        #include <sys/types.h>
+        #include <sys/socket.h>
+        #include <sys/uio.h>
+        int main(void) { int i = sendfile(0, 0, 0, 0, NULL, NULL, 0); return 0; }
+        "
+        HAVE_SENDFILE_7)
+endif()
 
 check_symbol_exists(
     fcopyfile