io: Remove copy_file_range emulation [BZ #24744]

The kernel is evolving this interface (e.g., removal of the
restriction on cross-device copies), and keeping up with that
is difficult.  Applications which need the function should
run kernels which support the system call instead of relying on
the imperfect glibc emulation.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

1 files changed, 9 insertions, 551 deletions

diff --git a/io/tst-copy_file_range.c b/io/tst-copy_file_range.c
index a5dcf3c1f6..a9237cb384 100644
--- a/io/tst-copy_file_range.c
+++ b/io/tst-copy_file_range.c
@@ -20,22 +20,15 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
-#include <libgen.h>
-#include <poll.h>
-#include <sched.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <support/check.h>
-#include <support/namespace.h>
 #include <support/support.h>
 #include <support/temp_file.h>
 #include <support/test-driver.h>
 #include <support/xunistd.h>
-#ifdef CLONE_NEWNS
-# include <sys/mount.h>
-#endif
 
 /* Boolean flags which indicate whether to use pointers with explicit
    output flags.  */
@@ -49,10 +42,6 @@ static int infd;
 static char *outfile;
 static int outfd;
 
-/* Like the above, but on a different file system.  xdevfile can be
-   NULL if no suitable file system has been found.  */
-static char *xdevfile;
-
 /* Input and output offsets.  Set according to do_inoff and do_outoff
    before the test.  The offsets themselves are always set to
    zero.  */
@@ -61,13 +50,10 @@ static off64_t *pinoff;
 static off64_t outoff;
 static off64_t *poutoff;
 
-/* These are a collection of copy sizes used in tests.  The selection
-   takes into account that the fallback implementation uses an
-   internal buffer of 8192 bytes.  */
+/* These are a collection of copy sizes used in tests.    */
 enum { maximum_size = 99999 };
 static const int typical_sizes[] =
-  { 0, 1, 2, 3, 1024, 2048, 4096, 8191, 8192, 8193, 16383, 16384, 16385,
-    maximum_size };
+  { 0, 1, 2, 3, 1024, 2048, 4096, 8191, 8192, 8193, maximum_size };
 
 /* The random contents of this array can be used as a pattern to check
    for correct write operations.  */
@@ -76,101 +62,6 @@ static unsigned char random_data[maximum_size];
 /* The size chosen by the test harness.  */
 static int current_size;
 
-/* Maximum writable file offset.  Updated by find_maximum_offset
-   below.  */
-static off64_t maximum_offset;
-
-/* Error code when crossing the offset.  */
-static int maximum_offset_errno;
-
-/* If true: Writes which cross the limit will fail.  If false: Writes
-   which cross the limit will result in a partial write.  */
-static bool maximum_offset_hard_limit;
-
-/* Fills maximum_offset etc. above.  Truncates outfd as a side
-   effect.  */
-static void
-find_maximum_offset (void)
-{
-  xftruncate (outfd, 0);
-  if (maximum_offset != 0)
-    return;
-
-  uint64_t upper = -1;
-  upper >>= 1;                  /* Maximum of off64_t.  */
-  TEST_VERIFY ((off64_t) upper > 0);
-  TEST_VERIFY ((off64_t) (upper + 1) < 0);
-  if (lseek64 (outfd, upper, SEEK_SET) >= 0)
-    {
-      if (write (outfd, "", 1) == 1)
-        FAIL_EXIT1 ("created a file larger than the off64_t range");
-    }
-
-  uint64_t lower = 1024 * 1024; /* A reasonable minimum file size.  */
-  /* Loop invariant: writing at lower succeeds, writing at upper fails.  */
-  while (lower + 1 < upper)
-    {
-      uint64_t middle = (lower + upper) / 2;
-      if (test_verbose > 0)
-        printf ("info: %s: remaining test range %" PRIu64 " .. %" PRIu64
-                ", probe at %" PRIu64 "\n", __func__, lower, upper, middle);
-      xftruncate (outfd, 0);
-      if (lseek64 (outfd, middle, SEEK_SET) >= 0
-          && write (outfd, "", 1) == 1)
-        lower = middle;
-      else
-        upper = middle;
-    }
-  TEST_VERIFY (lower + 1 == upper);
-  maximum_offset = lower;
-  printf ("info: maximum writable file offset: %" PRIu64 " (%" PRIx64 ")\n",
-          lower, lower);
-
-  /* Check that writing at the valid offset actually works.  */
-  xftruncate (outfd, 0);
-  xlseek (outfd, lower, SEEK_SET);
-  TEST_COMPARE (write (outfd, "", 1), 1);
-
-  /* Cross the boundary with a two-byte write.  This can either result
-     in a short write, or a failure.  */
-  xlseek (outfd, lower, SEEK_SET);
-  ssize_t ret = write (outfd, " ", 2);
-  if (ret < 0)
-    {
-      maximum_offset_errno = errno;
-      maximum_offset_hard_limit = true;
-    }
-  else
-    maximum_offset_hard_limit = false;
-
-  /* Check that writing at the next offset actually fails.  This also
-     obtains the expected errno value.  */
-  xftruncate (outfd, 0);
-  const char *action;
-  if (lseek64 (outfd, lower + 1, SEEK_SET) != 0)
-    {
-      if (write (outfd, "", 1) != -1)
-        FAIL_EXIT1 ("write to impossible offset %" PRIu64 " succeeded",
-                    lower + 1);
-      action = "writing";
-      int errno_copy = errno;
-      if (maximum_offset_hard_limit)
-        TEST_COMPARE (errno_copy, maximum_offset_errno);
-      else
-        maximum_offset_errno = errno_copy;
-    }
-  else
-    {
-      action = "seeking";
-      maximum_offset_errno = errno;
-    }
-  printf ("info: %s out of range fails with %m (%d)\n",
-          action, maximum_offset_errno);
-
-  xftruncate (outfd, 0);
-  xlseek (outfd, 0, SEEK_SET);
-}
-
 /* Perform a copy of a file.  */
 static void
 simple_file_copy (void)
@@ -247,390 +138,6 @@ simple_file_copy (void)
   free (bytes);
 }
 
-/* Test that reading from a pipe willfails.  */
-static void
-pipe_as_source (void)
-{
-  int pipefds[2];
-  xpipe (pipefds);
-
-  for (int length = 0; length < 2; ++length)
-    {
-      if (test_verbose > 0)
-        printf ("info: %s: length=%d\n", __func__, length);
-
-      /* Make sure that there is something to copy in the pipe.  */
-      xwrite (pipefds[1], "@", 1);
-
-      TEST_COMPARE (copy_file_range (pipefds[0], pinoff, outfd, poutoff,
-                                     length, 0), -1);
-      /* Linux 4.10 and later return EINVAL.  Older kernels return
-         EXDEV.  */
-      TEST_VERIFY (errno == EINVAL || errno == EXDEV);
-      TEST_COMPARE (inoff, 0);
-      TEST_COMPARE (outoff, 0);
-      TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), 0);
-
-      /* Make sure that nothing was read.  */
-      char buf = 'A';
-      TEST_COMPARE (read (pipefds[0], &buf, 1), 1);
-      TEST_COMPARE (buf, '@');
-    }
-
-  xclose (pipefds[0]);
-  xclose (pipefds[1]);
-}
-
-/* Test that writing to a pipe fails.  */
-static void
-pipe_as_destination (void)
-{
-  /* Make sure that there is something to read in the input file.  */
-  xwrite (infd, "abc", 3);
-  xlseek (infd, 0, SEEK_SET);
-
-  int pipefds[2];
-  xpipe (pipefds);
-
-  for (int length = 0; length < 2; ++length)
-    {
-      if (test_verbose > 0)
-        printf ("info: %s: length=%d\n", __func__, length);
-
-      TEST_COMPARE (copy_file_range (infd, pinoff, pipefds[1], poutoff,
-                                     length, 0), -1);
-      /* Linux 4.10 and later return EINVAL.  Older kernels return
-         EXDEV.  */
-      TEST_VERIFY (errno == EINVAL || errno == EXDEV);
-      TEST_COMPARE (inoff, 0);
-      TEST_COMPARE (outoff, 0);
-      TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 0);
-
-      /* Make sure that nothing was written.  */
-      struct pollfd pollfd = { .fd = pipefds[0], .events = POLLIN, };
-      TEST_COMPARE (poll (&pollfd, 1, 0), 0);
-    }
-
-  xclose (pipefds[0]);
-  xclose (pipefds[1]);
-}
-
-/* Test a write failure after (potentially) writing some bytes.
-   Failure occurs near the start of the buffer.  */
-static void
-delayed_write_failure_beginning (void)
-{
-  /* We need to write something to provoke the error.  */
-  if (current_size == 0)
-    return;
-  xwrite (infd, random_data, sizeof (random_data));
-  xlseek (infd, 0, SEEK_SET);
-
-  /* Write failure near the start.  The actual error code varies among
-     file systems.  */
-  find_maximum_offset ();
-  off64_t where = maximum_offset;
-
-  if (current_size == 1)
-    ++where;
-  outoff = where;
-  if (do_outoff)
-    xlseek (outfd, 1, SEEK_SET);
-  else
-    xlseek (outfd, where, SEEK_SET);
-  if (maximum_offset_hard_limit || where > maximum_offset)
-    {
-      TEST_COMPARE (copy_file_range (infd, pinoff, outfd, poutoff,
-                                     sizeof (random_data), 0), -1);
-      TEST_COMPARE (errno, maximum_offset_errno);
-      TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 0);
-      TEST_COMPARE (inoff, 0);
-      if (do_outoff)
-        TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), 1);
-      else
-        TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), where);
-      TEST_COMPARE (outoff, where);
-      struct stat64 st;
-      xfstat (outfd, &st);
-      TEST_COMPARE (st.st_size, 0);
-    }
-  else
-    {
-      /* The offset is not a hard limit.  This means we write one
-         byte.  */
-      TEST_COMPARE (copy_file_range (infd, pinoff, outfd, poutoff,
-                                     sizeof (random_data), 0), 1);
-      if (do_inoff)
-        {
-          TEST_COMPARE (inoff, 1);
-          TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 0);
-        }
-      else
-        {
-          TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 1);
-          TEST_COMPARE (inoff, 0);
-        }
-      if (do_outoff)
-        {
-          TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), 1);
-          TEST_COMPARE (outoff, where + 1);
-        }
-      else
-        {
-          TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), where + 1);
-          TEST_COMPARE (outoff, where);
-        }
-      struct stat64 st;
-      xfstat (outfd, &st);
-      TEST_COMPARE (st.st_size, where + 1);
-    }
-}
-
-/* Test a write failure after (potentially) writing some bytes.
-   Failure occurs near the end of the buffer.  */
-static void
-delayed_write_failure_end (void)
-{
-  if (current_size <= 1)
-    /* This would be same as the first test because there is not
-       enough data to write to make a difference.  */
-    return;
-  xwrite (infd, random_data, sizeof (random_data));
-  xlseek (infd, 0, SEEK_SET);
-
-  find_maximum_offset ();
-  off64_t where = maximum_offset - current_size + 1;
-  if (current_size == sizeof (random_data))
-    /* Otherwise we do not reach the non-writable byte.  */
-    ++where;
-  outoff = where;
-  if (do_outoff)
-    xlseek (outfd, 1, SEEK_SET);
-  else
-    xlseek (outfd, where, SEEK_SET);
-  ssize_t ret = copy_file_range (infd, pinoff, outfd, poutoff,
-                                 sizeof (random_data), 0);
-  if (ret < 0)
-    {
-      TEST_COMPARE (ret, -1);
-      TEST_COMPARE (errno, maximum_offset_errno);
-      struct stat64 st;
-      xfstat (outfd, &st);
-      TEST_COMPARE (st.st_size, 0);
-    }
-  else
-    {
-      /* The first copy succeeded.  This happens in the emulation
-         because the internal buffer of limited size does not
-         necessarily cross the off64_t boundary on the first write
-         operation.  */
-      if (test_verbose > 0)
-        printf ("info:   copy_file_range (%zu) returned %zd\n",
-                sizeof (random_data), ret);
-      TEST_VERIFY (ret > 0);
-      TEST_VERIFY (ret < maximum_size);
-      struct stat64 st;
-      xfstat (outfd, &st);
-      TEST_COMPARE (st.st_size, where + ret);
-      if (do_inoff)
-        {
-          TEST_COMPARE (inoff, ret);
-          TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 0);
-        }
-      else
-          TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), ret);
-
-      char *buffer = xmalloc (ret);
-      TEST_COMPARE (pread64 (outfd, buffer, ret, where), ret);
-      TEST_VERIFY (memcmp (buffer, random_data, ret) == 0);
-      free (buffer);
-
-      /* The second copy fails.  */
-      TEST_COMPARE (copy_file_range (infd, pinoff, outfd, poutoff,
-                                     sizeof (random_data), 0), -1);
-      TEST_COMPARE (errno, maximum_offset_errno);
-    }
-}
-
-/* Test a write failure across devices.  */
-static void
-cross_device_failure (void)
-{
-  if (xdevfile == NULL)
-    /* Subtest not supported due to missing cross-device file.  */
-    return;
-
-  /* We need something to write.  */
-  xwrite (infd, random_data, sizeof (random_data));
-  xlseek (infd, 0, SEEK_SET);
-
-  int xdevfd = xopen (xdevfile, O_RDWR | O_LARGEFILE, 0);
-  TEST_COMPARE (copy_file_range (infd, pinoff, xdevfd, poutoff,
-                                 current_size, 0), -1);
-  TEST_COMPARE (errno, EXDEV);
-  TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 0);
-  struct stat64 st;
-  xfstat (xdevfd, &st);
-  TEST_COMPARE (st.st_size, 0);
-
-  xclose (xdevfd);
-}
-
-/* Try to exercise ENOSPC behavior with a tempfs file system (so that
-   we do not have to fill up a regular file system to get the error).
-   This function runs in a subprocess, so that we do not change the
-   mount namespace of the actual test process.  */
-static void
-enospc_failure_1 (void *closure)
-{
-#ifdef CLONE_NEWNS
-  support_become_root ();
-
-  /* Make sure that we do not alter the file system mounts of the
-     parents.  */
-  if (! support_enter_mount_namespace ())
-    {
-      printf ("warning: ENOSPC test skipped\n");
-      return;
-    }
-
-  char *mountpoint = closure;
-  if (mount ("none", mountpoint, "tmpfs", MS_NODEV | MS_NOEXEC,
-             "size=500k") != 0)
-    {
-      printf ("warning: could not mount tmpfs at %s: %m\n", mountpoint);
-      return;
-    }
-
-  /* The source file must reside on the same file system.  */
-  char *intmpfsfile = xasprintf ("%s/%s", mountpoint, "in");
-  int intmpfsfd = xopen (intmpfsfile, O_RDWR | O_CREAT | O_LARGEFILE, 0600);
-  xwrite (intmpfsfd, random_data, sizeof (random_data));
-  xlseek (intmpfsfd, 1, SEEK_SET);
-  inoff = 1;
-
-  char *outtmpfsfile = xasprintf ("%s/%s", mountpoint, "out");
-  int outtmpfsfd = xopen (outtmpfsfile, O_RDWR | O_CREAT | O_LARGEFILE, 0600);
-
-  /* Fill the file with data until ENOSPC is reached.  */
-  while (true)
-    {
-      ssize_t ret = write (outtmpfsfd, random_data, sizeof (random_data));
-      if (ret < 0 && errno != ENOSPC)
-        FAIL_EXIT1 ("write to %s: %m", outtmpfsfile);
-      if (ret < sizeof (random_data))
-        break;
-    }
-  TEST_COMPARE (write (outtmpfsfd, "", 1), -1);
-  TEST_COMPARE (errno, ENOSPC);
-  off64_t maxsize = xlseek (outtmpfsfd, 0, SEEK_CUR);
-  TEST_VERIFY_EXIT (maxsize > sizeof (random_data));
-
-  /* Constructed the expected file contents.  */
-  char *expected = xmalloc (maxsize);
-  TEST_COMPARE (pread64 (outtmpfsfd, expected, maxsize, 0), maxsize);
-  /* Go back a little, so some bytes can be written.  */
-  enum { offset = 20000 };
-  TEST_VERIFY_EXIT (offset < maxsize);
-  TEST_VERIFY_EXIT (offset < sizeof (random_data));
-  memcpy (expected + maxsize - offset, random_data + 1, offset);
-
-  if (do_outoff)
-    {
-      outoff = maxsize - offset;
-      xlseek (outtmpfsfd, 2, SEEK_SET);
-    }
-  else
-    xlseek (outtmpfsfd, -offset, SEEK_CUR);
-
-  /* First call is expected to succeed because we made room for some
-     bytes.  */
-  TEST_COMPARE (copy_file_range (intmpfsfd, pinoff, outtmpfsfd, poutoff,
-                                 maximum_size, 0), offset);
-  if (do_inoff)
-    {
-      TEST_COMPARE (inoff, 1 + offset);
-      TEST_COMPARE (xlseek (intmpfsfd, 0, SEEK_CUR), 1);
-    }
-  else
-      TEST_COMPARE (xlseek (intmpfsfd, 0, SEEK_CUR), 1 + offset);
-  if (do_outoff)
-    {
-      TEST_COMPARE (outoff, maxsize);
-      TEST_COMPARE (xlseek (outtmpfsfd, 0, SEEK_CUR), 2);
-    }
-  else
-    TEST_COMPARE (xlseek (outtmpfsfd, 0, SEEK_CUR), maxsize);
-  struct stat64 st;
-  xfstat (outtmpfsfd, &st);
-  TEST_COMPARE (st.st_size, maxsize);
-  char *actual = xmalloc (st.st_size);
-  TEST_COMPARE (pread64 (outtmpfsfd, actual, st.st_size, 0), st.st_size);
-  TEST_VERIFY (memcmp (expected, actual, maxsize) == 0);
-
-  /* Second call should fail with ENOSPC.  */
-  TEST_COMPARE (copy_file_range (intmpfsfd, pinoff, outtmpfsfd, poutoff,
-                                 maximum_size, 0), -1);
-  TEST_COMPARE (errno, ENOSPC);
-
-  /* Offsets should be unchanged.  */
-  if (do_inoff)
-    {
-      TEST_COMPARE (inoff, 1 + offset);
-      TEST_COMPARE (xlseek (intmpfsfd, 0, SEEK_CUR), 1);
-    }
-  else
-    TEST_COMPARE (xlseek (intmpfsfd, 0, SEEK_CUR), 1 + offset);
-  if (do_outoff)
-    {
-      TEST_COMPARE (outoff, maxsize);
-      TEST_COMPARE (xlseek (outtmpfsfd, 0, SEEK_CUR), 2);
-    }
-  else
-    TEST_COMPARE (xlseek (outtmpfsfd, 0, SEEK_CUR), maxsize);
-  TEST_COMPARE (xlseek (outtmpfsfd, 0, SEEK_END), maxsize);
-  TEST_COMPARE (pread64 (outtmpfsfd, actual, maxsize, 0), maxsize);
-  TEST_VERIFY (memcmp (expected, actual, maxsize) == 0);
-
-  free (actual);
-  free (expected);
-
-  xclose (intmpfsfd);
-  xclose (outtmpfsfd);
-  free (intmpfsfile);
-  free (outtmpfsfile);
-
-#else /* !CLONE_NEWNS */
-  puts ("warning: ENOSPC test skipped (no mount namespaces)");
-#endif
-}
-
-/* Call enospc_failure_1 in a subprocess.  */
-static void
-enospc_failure (void)
-{
-  char *mountpoint
-    = support_create_temp_directory ("tst-copy_file_range-enospc-");
-  support_isolate_in_subprocess (enospc_failure_1, mountpoint);
-  free (mountpoint);
-}
-
-/* The target file descriptor must have O_APPEND enabled.  */
-static void
-oappend_failure (void)
-{
-  /* Add data, to make sure we do not fail because there is
-     insufficient input data.  */
-  xwrite (infd, random_data, current_size);
-  xlseek (infd, 0, SEEK_SET);
-
-  xclose (outfd);
-  outfd = xopen (outfile, O_RDWR | O_APPEND, 0);
-  TEST_COMPARE (copy_file_range (infd, pinoff, outfd, poutoff,
-                                 current_size, 0), -1);
-  TEST_COMPARE (errno, EBADF);
-}
-
 /* Test that a short input file results in a shortened copy.  */
 static void
 short_copy (void)
@@ -721,14 +228,6 @@ struct test_case
 static struct test_case tests[] =
   {
     { "simple_file_copy", simple_file_copy, .sizes = true },
-    { "pipe_as_source", pipe_as_source, },
-    { "pipe_as_destination", pipe_as_destination, },
-    { "delayed_write_failure_beginning", delayed_write_failure_beginning,
-      .sizes = true },
-    { "delayed_write_failure_end", delayed_write_failure_end, .sizes = true },
-    { "cross_device_failure", cross_device_failure, .sizes = true },
-    { "enospc_failure", enospc_failure, },
-    { "oappend_failure", oappend_failure, .sizes = true },
     { "short_copy", short_copy, .sizes = true },
   };
 
@@ -739,58 +238,18 @@ do_test (void)
     *p = rand () >> 24;
 
   infd = create_temp_file ("tst-copy_file_range-in-", &infile);
+  outfd = create_temp_file ("tst-copy_file_range-out-", &outfile);
   {
-    int outfd = create_temp_file ("tst-copy_file_range-out-", &outfile);
-    if (!support_descriptor_supports_holes (outfd))
-      FAIL_UNSUPPORTED ("File %s does not support holes", outfile);
-    xclose (outfd);
-  }
-
-  /* Try to find a different directory from the default input/output
-     file.  */
-  {
-    struct stat64 instat;
-    xfstat (infd, &instat);
-    static const char *const candidates[] =
-      { NULL, "/var/tmp", "/dev/shm" };
-    for (const char *const *c = candidates; c < array_end (candidates); ++c)
-      {
-        const char *path = *c;
-        char *to_free = NULL;
-        if (path == NULL)
-          {
-            to_free = xreadlink ("/proc/self/exe");
-            path = dirname (to_free);
-          }
-
-        struct stat64 cstat;
-        xstat (path, &cstat);
-        if (cstat.st_dev == instat.st_dev)
-          {
-            free (to_free);
-            continue;
-          }
-
-        printf ("info: using alternate temporary files directory: %s\n", path);
-        xdevfile = xasprintf ("%s/tst-copy_file_range-xdev-XXXXXX", path);
-        free (to_free);
-        break;
-      }
-    if (xdevfile != NULL)
+    ssize_t ret = copy_file_range (infd, NULL, outfd, NULL, 0, 0);
+    if (ret != 0)
       {
-        int xdevfd = mkstemp (xdevfile);
-        if (xdevfd < 0)
-          FAIL_EXIT1 ("mkstemp (\"%s\"): %m", xdevfile);
-        struct stat64 xdevst;
-        xfstat (xdevfd, &xdevst);
-        TEST_VERIFY (xdevst.st_dev != instat.st_dev);
-        add_temp_file (xdevfile);
-        xclose (xdevfd);
+        if (errno == ENOSYS)
+          FAIL_UNSUPPORTED ("copy_file_range is not support on this system");
+        FAIL_EXIT1 ("copy_file_range probing call: %m");
       }
-    else
-      puts ("warning: no alternate directory on different file system found");
   }
   xclose (infd);
+  xclose (outfd);
 
   for (do_inoff = 0; do_inoff < 2; ++do_inoff)
     for (do_outoff = 0; do_outoff < 2; ++do_outoff)
@@ -832,7 +291,6 @@ do_test (void)
 
   free (infile);
   free (outfile);
-  free (xdevfile);
 
   return 0;
 }