Add user cancellation to the C API.

This allows long transfers (FileIn and FileOut operations) to be
cancelled by calling the signal and thread safe guestfs_user_cancel
function.

Most of this commit consists of a multithreaded program that tests
user cancellation of uploads and downloads.

2 files changed, 337 insertions, 0 deletions

diff --git a/capitests/Makefile.am b/capitests/Makefile.am
index 487a33f9..7e35872e 100644
--- a/capitests/Makefile.am
+++ b/capitests/Makefile.am
@@ -32,6 +32,7 @@ check_PROGRAMS = \
 	test-add-drive-opts \
 	test-last-errno \
 	test-private-data \
+	test-user-cancel \
 	test-debug-to-file
 
 TESTS = \
@@ -42,6 +43,7 @@ TESTS = \
 	test-add-drive-opts \
 	test-last-errno \
 	test-private-data \
+	test-user-cancel \
 	test-debug-to-file
 
 # The API behind this test is not baked yet.
@@ -114,6 +116,14 @@ test_private_data_CFLAGS = \
 test_private_data_LDADD = \
 	$(top_builddir)/src/libguestfs.la
 
+test_user_cancel_SOURCES = test-user-cancel.c
+test_user_cancel_CFLAGS = \
+	-pthread \
+	-I$(top_srcdir)/src -I$(top_builddir)/src \
+	$(WARN_CFLAGS) $(WERROR_CFLAGS)
+test_user_cancel_LDADD = \
+	$(top_builddir)/src/libguestfs.la
+
 test_debug_to_file_SOURCES = test-debug-to-file.c
 test_debug_to_file_CFLAGS = \
 	-I$(top_srcdir)/src -I$(top_builddir)/src \
diff --git a/capitests/test-user-cancel.c b/capitests/test-user-cancel.c
new file mode 100644
index 00000000..429998e7
--- /dev/null
+++ b/capitests/test-user-cancel.c
@@ -0,0 +1,327 @@
+/* libguestfs
+ * Copyright (C) 2011 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/* Test user cancellation.
+ *
+ * We perform the test using two threads.  The main thread issues
+ * guestfs commands to download and upload large files.  Uploads and
+ * downloads are done to/from a pipe which is connected back to the
+ * current process.  The second test thread sits on the other end of
+ * the pipe, feeding or consuming data slowly, and injecting the user
+ * cancel events at a particular place in the transfer.
+ *
+ * It is important to test both download and upload separately, since
+ * these exercise different code paths in the library.  However this
+ * adds complexity here because these tests are symmetric-but-opposite
+ * cases.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/time.h>
+
+#include <pthread.h>
+
+#include "guestfs.h"
+
+static const char *filename = "test.img";
+static const off_t filesize = 1024*1024*1024;
+
+static void remove_test_img (void);
+static void *start_test_thread (void *);
+
+struct test_thread_data {
+  guestfs_h *g;                /* handle */
+  int direction;               /* direction of transfer */
+#define DIRECTION_UP 1         /* upload (test thread is writing) */
+#define DIRECTION_DOWN 2       /* download (test thread is reading) */
+  int fd;                      /* pipe to read/write */
+  off_t cancel_posn;           /* position at which to cancel */
+  off_t transfer_size;         /* how much data thread wrote/read */
+};
+
+int
+main (int argc, char *argv[])
+{
+  guestfs_h *g;
+  int fd;
+  char c = 0;
+  pthread_t test_thread;
+  struct test_thread_data data;
+  int fds[2], r, op_error, op_errno, errors = 0;
+  char dev_fd[64];
+
+  srandom (time (NULL));
+
+  g = guestfs_create ();
+  if (g == NULL) {
+    fprintf (stderr, "failed to create handle\n");
+    exit (EXIT_FAILURE);
+  }
+
+  /* Create a test image and test data. */
+  fd = open (filename, O_WRONLY|O_CREAT|O_TRUNC|O_NOCTTY, 0666);
+  if (fd == -1) {
+    perror (filename);
+    exit (EXIT_FAILURE);
+  }
+
+  atexit (remove_test_img);
+
+  if (lseek (fd, filesize - 1, SEEK_SET) == (off_t) -1) {
+    perror ("lseek");
+    close (fd);
+    exit (EXIT_FAILURE);
+  }
+
+  if (write (fd, &c, 1) != 1) {
+    perror ("write");
+    close (fd);
+    exit (EXIT_FAILURE);
+  }
+
+  if (close (fd) == -1) {
+    perror ("test.img");
+    exit (EXIT_FAILURE);
+  }
+
+  if (guestfs_add_drive_opts (g, filename,
+                              GUESTFS_ADD_DRIVE_OPTS_FORMAT, "raw",
+                              -1) == -1)
+    exit (EXIT_FAILURE);
+
+  if (guestfs_launch (g) == -1)
+    exit (EXIT_FAILURE);
+
+  if (guestfs_part_disk (g, "/dev/sda", "mbr") == -1)
+    exit (EXIT_FAILURE);
+
+  if (guestfs_mkfs (g, "ext2", "/dev/sda1") == -1)
+    exit (EXIT_FAILURE);
+
+  if (guestfs_mount_options (g, "", "/dev/sda1", "/") == -1)
+    exit (EXIT_FAILURE);
+
+  /*----- Upload cancellation test -----*/
+
+  data.g = g;
+  data.direction = DIRECTION_UP;
+
+  if (pipe (fds) == -1) {
+    perror ("pipe");
+    exit (EXIT_FAILURE);
+  }
+
+  data.fd = fds[1];
+  snprintf (dev_fd, sizeof dev_fd, "/dev/fd/%d", fds[0]);
+
+  data.cancel_posn = random () % (filesize/4);
+
+  /* Create the test thread. */
+  r = pthread_create (&test_thread, NULL, start_test_thread, &data);
+  if (r != 0) {
+    fprintf (stderr, "pthread_create: %s", strerror (r));
+    exit (EXIT_FAILURE);
+  }
+
+  /* Do the upload. */
+  op_error = guestfs_upload (g, dev_fd, "/upload");
+  op_errno = guestfs_last_errno (g);
+
+  /* Kill the test thread and clean up. */
+  r = pthread_cancel (test_thread);
+  if (r != 0) {
+    fprintf (stderr, "pthread_cancel: %s", strerror (r));
+    exit (EXIT_FAILURE);
+  }
+  r = pthread_join (test_thread, NULL);
+  if (r != 0) {
+    fprintf (stderr, "pthread_join: %s", strerror (r));
+    exit (EXIT_FAILURE);
+  }
+
+  close (fds[0]);
+  close (fds[1]);
+
+  /* We expect to get an error, with errno == EINTR. */
+  if (op_error == -1 && op_errno == EINTR)
+    printf ("test-user-cancel: upload cancellation test passed (%ld/%ld)\n",
+            (long) data.cancel_posn, (long) data.transfer_size);
+  else {
+    fprintf (stderr, "test-user-cancel: upload cancellation test FAILED\n");
+    fprintf (stderr, "cancel_posn %ld, upload returned %d, errno = %d (%s)\n",
+             (long) data.cancel_posn, op_error, op_errno, strerror (op_errno));
+    errors++;
+  }
+
+  if (guestfs_rm (g, "/upload") == -1)
+    exit (EXIT_FAILURE);
+
+  /*----- Download cancellation test -----*/
+
+  if (guestfs_touch (g, "/download") == -1)
+    exit (EXIT_FAILURE);
+
+  if (guestfs_truncate_size (g, "/download", filesize/4) == -1)
+    exit (EXIT_FAILURE);
+
+  data.g = g;
+  data.direction = DIRECTION_DOWN;
+
+  if (pipe (fds) == -1) {
+    perror ("pipe");
+    exit (EXIT_FAILURE);
+  }
+
+  data.fd = fds[0];
+  snprintf (dev_fd, sizeof dev_fd, "/dev/fd/%d", fds[1]);
+
+  data.cancel_posn = random () % (filesize/4);
+
+  /* Create the test thread. */
+  r = pthread_create (&test_thread, NULL, start_test_thread, &data);
+  if (r != 0) {
+    fprintf (stderr, "pthread_create: %s", strerror (r));
+    exit (EXIT_FAILURE);
+  }
+
+  /* Do the download. */
+  op_error = guestfs_download (g, "/download", dev_fd);
+  op_errno = guestfs_last_errno (g);
+
+  /* Kill the test thread and clean up. */
+  r = pthread_cancel (test_thread);
+  if (r != 0) {
+    fprintf (stderr, "pthread_cancel: %s", strerror (r));
+    exit (EXIT_FAILURE);
+  }
+  r = pthread_join (test_thread, NULL);
+  if (r != 0) {
+    fprintf (stderr, "pthread_join: %s", strerror (r));
+    exit (EXIT_FAILURE);
+  }
+
+  close (fds[0]);
+  close (fds[1]);
+
+  /* We expect to get an error, with errno == EINTR. */
+  if (op_error == -1 && op_errno == EINTR)
+    printf ("test-user-cancel: download cancellation test passed (%ld/%ld)\n",
+            (long) data.cancel_posn, (long) data.transfer_size);
+  else {
+    fprintf (stderr, "test-user-cancel: download cancellation test FAILED\n");
+    fprintf (stderr, "cancel_posn %ld, upload returned %d, errno = %d (%s)\n",
+             (long) data.cancel_posn, op_error, op_errno, strerror (op_errno));
+    errors++;
+  }
+
+  exit (errors == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
+}
+
+static void
+remove_test_img (void)
+{
+  unlink (filename);
+}
+
+static char buffer[BUFSIZ];
+
+#ifndef MIN
+#define MIN(a,b) ((a)<(b)?(a):(b))
+#endif
+
+static void *
+start_test_thread (void *datav)
+{
+  struct test_thread_data *data = datav;
+  ssize_t r;
+  size_t n;
+
+  data->transfer_size = 0;
+
+  if (data->direction == DIRECTION_UP) { /* thread is writing */
+    /* Feed data in, up to the cancellation point. */
+    while (data->transfer_size < data->cancel_posn) {
+      n = MIN (sizeof buffer,
+               (size_t) (data->cancel_posn - data->transfer_size));
+      r = write (data->fd, buffer, n);
+      if (r == -1) {
+        perror ("test thread: write to pipe before user cancel");
+        exit (EXIT_FAILURE);
+      }
+      data->transfer_size += r;
+    }
+
+    /* Do user cancellation. */
+    guestfs_user_cancel (data->g);
+
+    /* Keep feeding data after the cancellation point for as long as
+     * the main thread wants it.
+     */
+    while (1) {
+      r = write (data->fd, buffer, sizeof buffer);
+      if (r == -1) {
+        perror ("test thread: write to pipe after user cancel");
+        exit (EXIT_FAILURE);
+      }
+      data->transfer_size += r;
+    }
+  } else {                      /* thread is reading */
+    /* Sink data, up to the cancellation point. */
+    while (data->transfer_size < data->cancel_posn) {
+      n = MIN (sizeof buffer,
+               (size_t) (data->cancel_posn - data->transfer_size));
+      r = read (data->fd, buffer, n);
+      if (r == -1) {
+        perror ("test thread: read from pipe before user cancel");
+        exit (EXIT_FAILURE);
+      }
+      if (r == 0) {
+        perror ("test thread: unexpected end of file before user cancel");
+        exit (EXIT_FAILURE);
+      }
+      data->transfer_size += r;
+    }
+
+    /* Do user cancellation. */
+    guestfs_user_cancel (data->g);
+
+    /* Keep sinking data as long as the main thread is writing. */
+    while (1) {
+      r = read (data->fd, buffer, sizeof buffer);
+      if (r == -1) {
+        perror ("test thread: read from pipe after user cancel");
+        exit (EXIT_FAILURE);
+      }
+      if (r == 0)
+        break;
+      data->transfer_size += r;
+    }
+
+    while (1)
+      pause ();
+  }
+
+  return NULL;
+}