docs: Standard C examples, and guestfs-examples(3) man page.

[libguestfs.git] / examples / create_disk.c

diff --git a/examples/create_disk.c b/examples/create_disk.c
new file mode 100644 (file)
index 0000000..f4b9044
--- /dev/null
+++ b/examples/create_disk.c
@@ -0,0 +1,122 @@
+/* Example showing how to create a disk image. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <guestfs.h>
+
+int                                                                            
+main (int argc, char *argv[])
+{
+  guestfs_h *g;
+  size_t i;
+
+  g = guestfs_create ();
+  if (g == NULL) {
+    perror ("failed to create libguestfs handle");
+    exit (EXIT_FAILURE);
+ }
+
+  /* Create a raw-format sparse disk image, 512 MB in size. */
+  int fd = open ("disk.img", O_CREAT|O_WRONLY|O_TRUNC|O_NOCTTY, 0666);
+  if (fd == -1) {
+    perror ("disk.img");
+    exit (EXIT_FAILURE);
+  }
+  if (ftruncate (fd, 512 * 1024 * 1024) == -1) {
+    perror ("disk.img: truncate");
+    exit (EXIT_FAILURE);
+  }
+  if (close (fd) == -1) {
+    perror ("disk.img: close");
+    exit (EXIT_FAILURE);
+  }
+
+  /* Set the trace flag so that we can see each libguestfs call. */
+  guestfs_set_trace (g, 1);
+
+  /* Set the autosync flag so that the disk will be synchronized
+   * automatically when the libguestfs handle is closed.
+   */
+  guestfs_set_autosync (g, 1);
+
+  /* Add the disk image to libguestfs. */
+  if (guestfs_add_drive_opts (g, "disk.img",
+        GUESTFS_ADD_DRIVE_OPTS_FORMAT, "raw", /* raw format */
+        GUESTFS_ADD_DRIVE_OPTS_READONLY, 0, /* for write */
+        -1) /* this marks end of optional arguments */
+      == -1)
+    exit (EXIT_FAILURE);
+
+  /* Run the libguestfs back-end. */
+  if (guestfs_launch (g) == -1)
+    exit (EXIT_FAILURE);
+
+  /* Get the list of devices.  Because we only added one drive
+   * above, we expect that this list should contain a single
+   * element.
+   */
+  char **devices = guestfs_list_devices (g);
+  if (devices == NULL)
+    exit (EXIT_FAILURE);
+  if (devices[0] == NULL || devices[1] != NULL) {
+    fprintf (stderr, "error: expected a single device from list-devices\n");
+    exit (EXIT_FAILURE);
+  }
+
+  /* Partition the disk as one single MBR partition. */
+  if (guestfs_part_disk (g, devices[0], "mbr") == -1)
+    exit (EXIT_FAILURE);
+
+  /* Get the list of partitions.  We expect a single element, which
+   * is the partition we have just created.
+   */
+  char **partitions = guestfs_list_partitions (g);
+  if (partitions == NULL)
+    exit (EXIT_FAILURE);
+  if (partitions[0] == NULL || partitions[1] != NULL) {
+    fprintf (stderr, "error: expected a single partition from list-partitions\n");
+    exit (EXIT_FAILURE);
+  }
+
+  /* Create a filesystem on the partition. */
+  if (guestfs_mkfs (g, "ext4", partitions[0]) == -1)
+    exit (EXIT_FAILURE);
+
+  /* Now mount the filesystem so that we can add files. */
+  if (guestfs_mount_options (g, "", partitions[0], "/") == -1)
+    exit (EXIT_FAILURE);
+
+  /* Create some files and directories. */
+  if (guestfs_touch (g, "/empty") == -1)
+    exit (EXIT_FAILURE);
+  const char *message = "Hello, world\n";
+  if (guestfs_write (g, "/hello", message, strlen (message)) == -1)
+    exit (EXIT_FAILURE);
+  if (guestfs_mkdir (g, "/foo") == -1)
+    exit (EXIT_FAILURE);
+
+  /* This one uploads the local file /etc/resolv.conf into
+   * the disk image.
+   */
+  if (guestfs_upload (g, "/etc/resolv.conf", "/foo/resolv.conf") == -1)
+    exit (EXIT_FAILURE);
+
+  /* Because 'autosync' was set (above) we can just close the handle
+   * and the disk contents will be synchronized.  You can also do
+   * this manually by calling guestfs_umount_all and guestfs_sync.
+   */
+  guestfs_close (g);
+
+  /* Free up the lists. */
+  for (i = 0; devices[i] != NULL; ++i)
+    free (devices[i]);
+  free (devices);
+  for (i = 0; partitions[i] != NULL; ++i)
+    free (partitions[i]);
+  free (partitions);
+
+  exit (EXIT_SUCCESS);
+}