8303942: os::write should write completely

8316468: os::write incorrectly handles partial write
8183227: read/write APIs in class os shall return ssize_t

Reviewed-by: phh, shade
Backport-of: bddf48380e658df630fecad5eda40106a24b6e1c

src/hotspot/os/linux/attachListener_linux.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -384,7 +384,7 @@ LinuxAttachOperation* LinuxAttachListener::dequeue() {
 // write the given buffer to the socket
 int LinuxAttachListener::write_fully(int s, char* buf, int len) {
   do {
-    int n = ::write(s, buf, len);
+    ssize_t n = ::write(s, buf, len);
     if (n == -1) {
       if (errno != EINTR) return -1;
     } else {

src/hotspot/os/posix/os_posix.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -739,9 +739,9 @@ FILE* os::open(int fd, const char* mode) {
   return ::fdopen(fd, mode);
 }
 
-size_t os::write(int fd, const void *buf, unsigned int nBytes) {
-  size_t res;
-  RESTARTABLE((size_t) ::write(fd, buf, (size_t) nBytes), res);
+ssize_t os::pd_write(int fd, const void *buf, size_t nBytes) {
+  ssize_t res;
+  RESTARTABLE(::write(fd, buf, nBytes), res);
   return res;
 }
 

src/hotspot/os/posix/perfMemory_posix.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2022, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2012, 2021 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -89,38 +89,25 @@ static void save_memory_to_file(char* addr, size_t size) {
   const char* destfile = PerfMemory::get_perfdata_file_path();
   assert(destfile[0] != '\0', "invalid PerfData file path");
 
-  int result;
+  int fd;
 
-  RESTARTABLE(os::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IRUSR|S_IWUSR),
-              result);
-  if (result == OS_ERR) {
-    if (PrintMiscellaneous && Verbose) {
-      warning("Could not create Perfdata save file: %s: %s\n",
-              destfile, os::strerror(errno));
-    }
+  RESTARTABLE(os::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IRUSR|S_IWUSR), fd);
+  if (fd == OS_ERR) {
+    warning("Could not create Perfdata save file: %s: %s\n",
+            destfile, os::strerror(errno));
   } else {
-    int fd = result;
+    ssize_t result;
 
-    for (size_t remaining = size; remaining > 0;) {
-
-      RESTARTABLE(::write(fd, addr, remaining), result);
-      if (result == OS_ERR) {
-        if (PrintMiscellaneous && Verbose) {
-          warning("Could not write Perfdata save file: %s: %s\n",
-                  destfile, os::strerror(errno));
-        }
-        break;
-      }
-
-      remaining -= (size_t)result;
-      addr += result;
+    bool successful_write = os::write(fd, addr, size);
+    if (!successful_write) {
+      warning("Could not write Perfdata save file: %s: %s\n",
+              destfile, os::strerror(errno));
     }
 
+
     result = ::close(fd);
-    if (PrintMiscellaneous && Verbose) {
-      if (result == OS_ERR) {
-        warning("Could not close %s: %s\n", destfile, os::strerror(errno));
-      }
+    if (result == OS_ERR) {
+      warning("Could not close %s: %s\n", destfile, os::strerror(errno));
     }
   }
   FREE_C_HEAP_ARRAY(char, destfile);
@@ -880,9 +867,9 @@ static int create_sharedmem_file(const char* dirname, const char* filename, size
   // Open the filename in the current directory.
   // Cannot use O_TRUNC here; truncation of an existing file has to happen
   // after the is_file_secure() check below.
-  int result;
-  RESTARTABLE(os::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IRUSR|S_IWUSR), result);
-  if (result == OS_ERR) {
+  int fd;
+  RESTARTABLE(os::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IRUSR|S_IWUSR), fd);
+  if (fd == OS_ERR) {
     if (PrintMiscellaneous && Verbose) {
       if (errno == ELOOP) {
         warning("file %s is a symlink and is not secure\n", filename);
@@ -898,9 +885,6 @@ static int create_sharedmem_file(const char* dirname, const char* filename, size
   // close the directory and reset the current working directory
   close_directory_secure_cwd(dirp, saved_cwd_fd);
 
-  // save the file descriptor
-  int fd = result;
-
   // check to see if the file is secure
   if (!is_file_secure(fd, filename)) {
     ::close(fd);
@@ -933,6 +917,8 @@ static int create_sharedmem_file(const char* dirname, const char* filename, size
   }
 #endif
 
+ ssize_t result;
+
   // truncate the file to get rid of any existing data
   RESTARTABLE(::ftruncate(fd, (off_t)0), result);
   if (result == OS_ERR) {
@@ -959,19 +945,19 @@ static int create_sharedmem_file(const char* dirname, const char* filename, size
     int zero_int = 0;
     result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos));
     if (result == -1 ) break;
-    RESTARTABLE(::write(fd, &zero_int, 1), result);
-    if (result != 1) {
+    if (!os::write(fd, &zero_int, 1)) {
       if (errno == ENOSPC) {
         warning("Insufficient space for shared memory file:\n   %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename);
       }
+      result = OS_ERR;
       break;
     }
   }
 
   if (result != -1) {
     return fd;
   } else {
-    ::close(fd);
+    os::close(fd);
     return -1;
   }
 }

src/hotspot/os/windows/os_windows.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -4842,8 +4842,19 @@ FILE* os::open(int fd, const char* mode) {
   return ::_fdopen(fd, mode);
 }
 
-size_t os::write(int fd, const void *buf, unsigned int nBytes) {
-  return ::write(fd, buf, nBytes);
+ssize_t os::pd_write(int fd, const void *buf, size_t nBytes) {
+  ssize_t original_len = (ssize_t)nBytes;
+  while (nBytes > 0) {
+    unsigned int len = nBytes > INT_MAX ? INT_MAX : (unsigned int)nBytes;
+    // On Windows, ::write takes 'unsigned int' no of bytes, so nBytes should be split if larger.
+    ssize_t written_bytes = ::write(fd, buf, len);
+    if (written_bytes < 0) {
+      return OS_ERR;
+    }
+    nBytes -= written_bytes;
+    buf = (char *)buf + written_bytes;
+  }
+  return original_len;
 }
 
 int os::close(int fd) {

src/hotspot/share/cds/filemap.cpp

@@ -1420,8 +1420,7 @@ size_t FileMapInfo::write_archive_heap_regions(GrowableArray<MemRegion> *heap_me
 
 void FileMapInfo::write_bytes(const void* buffer, size_t nbytes) {
   assert(_file_open, "must be");
-  size_t n = os::write(_fd, buffer, (unsigned int)nbytes);
-  if (n != nbytes) {
+  if (!os::write(_fd, buffer, nbytes)) {
     // If the shared archive is corrupted, close it and remove it.
     close();
     remove(_full_path);

src/hotspot/share/jfr/recorder/repository/jfrEmergencyDump.cpp

@@ -350,13 +350,17 @@ static void write_repository_files(const RepositoryIterator& iterator, char* con
         const ssize_t read_result = os::read_at(current_fd, copy_block, (int)block_size, bytes_read);
         if (-1 == read_result) {
           log_info(jfr)( // For user, should not be "jfr, system"
-              "Unable to recover JFR data");
+              "Unable to recover JFR data, read failed.");
           break;
         }
         bytes_read += (int64_t)read_result;
         assert(bytes_read - bytes_written <= (int64_t)block_size, "invariant");
-        bytes_written += (int64_t)os::write(emergency_fd, copy_block, bytes_read - bytes_written);
-        assert(bytes_read == bytes_written, "invariant");
+        if (!os::write(emergency_fd, copy_block, bytes_read - bytes_written)) {
+          log_info(jfr)( // For user, should not be "jfr, system"
+              "Unable to recover JFR data, write failed.");
+          break;
+        }
+        bytes_written = bytes_read;
       }
       os::close(current_fd);
     }

src/hotspot/share/jfr/writers/jfrStreamWriterHost.inline.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -76,14 +76,14 @@ inline void StreamWriterHost<Adapter, AP>::write_bytes(const u1* buf, intptr_t l
   assert(len >= 0, "invariant");
   while (len > 0) {
     const unsigned int nBytes = len > INT_MAX ? INT_MAX : (unsigned int)len;
-    const ssize_t num_written = (ssize_t)os::write(_fd, buf, nBytes);
-    if (errno == ENOSPC) {
+    const bool successful_write = os::write(_fd, buf, nBytes);
+    if (!successful_write && errno == ENOSPC) {
       JfrJavaSupport::abort("Failed to write to jfr stream because no space left on device", false);
     }
-    guarantee(num_written > 0, "Nothing got written, or os::write() failed");
-    _stream_pos += num_written;
-    len -= num_written;
-    buf += num_written;
+    guarantee(successful_write, "Not all the bytes got written, or os::write() failed");
+    _stream_pos += nBytes;
+    len -= nBytes;
+    buf += nBytes;
   }
 }
 

src/hotspot/share/prims/jvm.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -2823,7 +2823,7 @@ void jio_print(const char* s, size_t len) {
     jio_fprintf(defaultStream::output_stream(), "%.*s", (int)len, s);
   } else {
     // Make an unused local variable to avoid warning from gcc compiler.
-    size_t count = ::write(defaultStream::output_fd(), s, (int)len);
+    bool dummy = os::write(defaultStream::output_fd(), s, len);
   }
 }
 

src/hotspot/share/runtime/os.cpp

@@ -1356,6 +1356,22 @@ bool os::file_exists(const char* filename) {
   return os::stat(filename, &statbuf) == 0;
 }
 
+bool os::write(int fd, const void *buf, size_t nBytes) {
+  ssize_t res;
+
+  while (nBytes > 0) {
+    res = pd_write(fd, buf, nBytes);
+    if (res == OS_ERR) {
+      return false;
+    }
+    buf = (void *)((char *)buf + res);
+    nBytes -= res;
+  }
+
+  return true;
+}
+
+
 // Splits a path, based on its separator, the number of
 // elements is returned back in "elements".
 // file_name_length is used as a modifier for each path's

src/hotspot/share/runtime/os.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -169,6 +169,8 @@ class os: AllStatic {
   // Get summary strings for system information in buffer provided
   static void  get_summary_cpu_info(char* buf, size_t buflen);
   static void  get_summary_os_info(char* buf, size_t buflen);
+  // Returns number of bytes written on success, OS_ERR on failure.
+  static ssize_t pd_write(int fd, const void *buf, size_t nBytes);
 
   static void initialize_initial_active_processor_count();
 
@@ -580,7 +582,8 @@ class os: AllStatic {
 
   static ssize_t read(int fd, void *buf, unsigned int nBytes);
   static ssize_t read_at(int fd, void *buf, unsigned int nBytes, jlong offset);
-  static size_t write(int fd, const void *buf, unsigned int nBytes);
+  // Writes the bytes completely. Returns true on success, false otherwise.
+  static bool write(int fd, const void *buf, size_t nBytes);
 
   // Reading directories.
   static DIR*           opendir(const char* dirname);

src/hotspot/share/services/heapDumperCompression.cpp

@@ -1,4 +1,5 @@
 /*
+ * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2020 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -54,14 +55,8 @@ char const* FileWriter::write_buf(char* buf, ssize_t size) {
   assert(_fd >= 0, "Must be open");
   assert(size > 0, "Must write at least one byte");
 
-  while (size > 0) {
-    ssize_t n = os::write(_fd, buf, (uint) size);
-    if (n <= 0) {
-      return os::strerror(errno);
-    }
-
-    buf += n;
-    size -= n;
+  if (!os::write(_fd, buf, (size_t)size)) {
+    return os::strerror(errno);
   }
 
   return NULL;

src/hotspot/share/utilities/ostream.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -614,7 +614,7 @@ void fileStream::flush() {
 void fdStream::write(const char* s, size_t len) {
   if (_fd != -1) {
     // Make an unused local variable to avoid warning from gcc compiler.
-    size_t count = ::write(_fd, s, (int)len);
+    ssize_t count = ::write(_fd, s, (int)len);
     update_position(s, len);
   }
 }