Don't stash strings in the handle.

[libguestfs.git] / perl / lib / Sys / Guestfs.pm

diff --git a/perl/lib/Sys/Guestfs.pm b/perl/lib/Sys/Guestfs.pm
index 273e4fe..13c084f 100644 (file)
--- a/perl/lib/Sys/Guestfs.pm
+++ b/perl/lib/Sys/Guestfs.pm
@@ -405,6 +405,13 @@ The first element is the name of the program to run.
 Subsequent elements are parameters.  The list must be
 non-empty (ie. must contain a program name).
 
 Subsequent elements are parameters.  The list must be
 non-empty (ie. must contain a program name).
 

+The return value is anything printed to I<stdout> by
+the command.
+
+If the command returns a non-zero exit status, then
+this function returns an error message.  The error message
+string is the content of I<stderr> from the command.
+

 The C<$PATH> environment variable will contain at least
 C</usr/bin> and C</bin>.  If you require a program from
 another location, you should provide the full path in the
 The C<$PATH> environment variable will contain at least
 C</usr/bin> and C</bin>.  If you require a program from
 another location, you should provide the full path in the


@@ -416,11 +423,19 @@ correct places.  It is the caller's responsibility to ensure
 all filesystems that are needed are mounted at the right
 locations.
 
 all filesystems that are needed are mounted at the right
 locations.
 

+Because of the message protocol, there is a transfer limit 
+of somewhere between 2MB and 4MB.  To transfer large files you should use
+FTP.
+

 =item @lines = $h->command_lines (\@arguments);
 
 This is the same as C<$h-E<gt>command>, but splits the
 result into a list of lines.
 
 =item @lines = $h->command_lines (\@arguments);
 
 This is the same as C<$h-E<gt>command>, but splits the
 result into a list of lines.
 

+Because of the message protocol, there is a transfer limit 
+of somewhere between 2MB and 4MB.  To transfer large files you should use
+FTP.
+

 =item $h->config ($qemuparam, $qemuvalue);
 
 This can be used to add arbitrary qemu command line parameters
 =item $h->config ($qemuparam, $qemuvalue);
 
 This can be used to add arbitrary qemu command line parameters


@@ -432,6 +447,37 @@ The first character of C<param> string must be a C<-> (dash).
 
 C<value> can be NULL.
 
 
 C<value> can be NULL.
 

+=item $h->cp ($src, $dest);
+
+This copies a file from C<src> to C<dest> where C<dest> is
+either a destination filename or destination directory.
+
+=item $h->cp_a ($src, $dest);
+
+This copies a file or directory from C<src> to C<dest>
+recursively using the C<cp -a> command.
+
+=item $result = $h->debug ($subcmd, \@extraargs);
+
+The C<$h-E<gt>debug> command exposes some internals of
+C<guestfsd> (the guestfs daemon) that runs inside the
+qemu subprocess.
+
+There is no comprehensive help for this command.  You have
+to look at the file C<daemon/debug.c> in the libguestfs source
+to find out what you can do.
+
+=item $kmsgs = $h->dmesg ();
+
+This returns the kernel messages (C<dmesg> output) from
+the guest kernel.  This is sometimes useful for extended
+debugging of problems.
+
+Another way to get the same information is to enable
+verbose messages with C<$h-E<gt>set_verbose> or by setting
+the environment variable C<LIBGUESTFS_DEBUG=1> before
+running the program.
+

 =item $h->download ($remotefilename, $filename);
 
 Download file C<remotefilename> and save it as C<filename>
 =item $h->download ($remotefilename, $filename);
 
 Download file C<remotefilename> and save it as C<filename>


@@ -441,6 +487,33 @@ C<filename> can also be a named pipe.
 
 See also C<$h-E<gt>upload>, C<$h-E<gt>cat>.
 
 
 See also C<$h-E<gt>upload>, C<$h-E<gt>cat>.
 

+=item $h->drop_caches ($whattodrop);
+
+This instructs the guest kernel to drop its page cache,
+and/or dentries and inode caches.  The parameter C<whattodrop>
+tells the kernel what precisely to drop, see
+L<http://linux-mm.org/Drop_Caches>
+
+Setting C<whattodrop> to 3 should drop everything.
+
+This automatically calls L<sync(2)> before the operation,
+so that the maximum guest memory is freed.
+
+=item $h->end_busy ();
+
+This sets the state to C<READY>, or if in C<CONFIG> then it leaves the
+state as is.  This is only used when implementing
+actions using the low-level API.
+
+For more information on states, see L<guestfs(3)>.
+
+=item $equality = $h->equal ($file1, $file2);
+
+This compares the two files C<file1> and C<file2> and returns
+true if their content is exactly equal, or false otherwise.
+
+The external L<cmp(1)> program is used for the comparison.
+

 =item $existsflag = $h->exists ($path);
 
 This returns C<true> if and only if there is a file, directory
 =item $existsflag = $h->exists ($path);
 
 This returns C<true> if and only if there is a file, directory


@@ -458,10 +531,57 @@ The exact command which runs is C<file -bsL path>.  Note in
 particular that the filename is not prepended to the output
 (the C<-b> option).
 
 particular that the filename is not prepended to the output
 (the C<-b> option).
 

+=item $status = $h->fsck ($fstype, $device);
+
+This runs the filesystem checker (fsck) on C<device> which
+should have filesystem type C<fstype>.
+
+The returned integer is the status.  See L<fsck(8)> for the
+list of status codes from C<fsck>.
+
+Notes:
+
+=over 4
+
+=item *
+
+Multiple status codes can be summed together.
+
+=item *
+
+A non-zero return code can mean "success", for example if
+errors have been corrected on the filesystem.
+
+=item *
+
+Checking or repairing NTFS volumes is not supported
+(by linux-ntfs).
+
+=back
+
+This command is entirely equivalent to running C<fsck -a -t fstype device>.
+
+=item $append = $h->get_append ();
+
+Return the additional kernel options which are added to the
+guest kernel command line.
+
+If C<NULL> then no options are added.
+

 =item $autosync = $h->get_autosync ();
 
 Get the autosync flag.
 
 =item $autosync = $h->get_autosync ();
 
 Get the autosync flag.
 

+=item $label = $h->get_e2label ($device);
+
+This returns the ext2/3/4 filesystem label of the filesystem on
+C<device>.
+
+=item $uuid = $h->get_e2uuid ($device);
+
+This returns the ext2/3/4 filesystem UUID of the filesystem on
+C<device>.
+

 =item $path = $h->get_path ();
 
 Return the current search path.
 =item $path = $h->get_path ();
 
 Return the current search path.


@@ -487,6 +607,20 @@ For more information on states, see L<guestfs(3)>.
 
 This returns the verbose messages flag.
 
 
 This returns the verbose messages flag.
 

+=item $h->grub_install ($root, $device);
+
+This command installs GRUB (the Grand Unified Bootloader) on
+C<device>, with the root directory being C<root>.
+
+=item $dump = $h->hexdump ($path);
+
+This runs C<hexdump -C> on the given C<path>.  The result is
+the human-readable, canonical hex dump of the file.
+
+Because of the message protocol, there is a transfer limit 
+of somewhere between 2MB and 4MB.  To transfer large files you should use
+FTP.
+

 =item $busy = $h->is_busy ();
 
 This returns true iff this handle is busy processing a command
 =item $busy = $h->is_busy ();
 
 This returns true iff this handle is busy processing a command


@@ -598,6 +732,14 @@ and physical volumes.
 B<This command is dangerous.  Without careful use you
 can easily destroy all your data>.
 
 B<This command is dangerous.  Without careful use you
 can easily destroy all your data>.
 

+=item $h->lvremove ($device);
+
+Remove an LVM logical volume C<device>, where C<device> is
+the path to the LV, such as C</dev/VG/LV>.
+
+You can also remove all LVs in a volume group by specifying
+the VG name, C</dev/VG>.
+

 =item @logvols = $h->lvs ();
 
 List all the logical volumes detected.  This is the equivalent
 =item @logvols = $h->lvs ();
 
 List all the logical volumes detected.  This is the equivalent


@@ -625,7 +767,7 @@ as necessary.  This is like the C<mkdir -p> shell command.
 =item $h->mkfs ($fstype, $device);
 
 This creates a filesystem on C<device> (usually a partition
 =item $h->mkfs ($fstype, $device);
 
 This creates a filesystem on C<device> (usually a partition

-of LVM logical volume).  The filesystem type is C<fstype>, for
+or LVM logical volume).  The filesystem type is C<fstype>, for

 example C<ext3>.
 
 =item $h->mount ($device, $mountpoint);
 example C<ext3>.
 
 =item $h->mount ($device, $mountpoint);


@@ -647,6 +789,23 @@ on the underlying device.
 The filesystem options C<sync> and C<noatime> are set with this
 call, in order to improve reliability.
 
 The filesystem options C<sync> and C<noatime> are set with this
 call, in order to improve reliability.
 

+=item $h->mount_options ($options, $device, $mountpoint);
+
+This is the same as the C<$h-E<gt>mount> command, but it
+allows you to set the mount options as for the
+L<mount(8)> I<-o> flag.
+
+=item $h->mount_ro ($device, $mountpoint);
+
+This is the same as the C<$h-E<gt>mount> command, but it
+mounts the filesystem with the read-only (I<-o ro>) flag.
+
+=item $h->mount_vfs ($options, $vfstype, $device, $mountpoint);
+
+This is the same as the C<$h-E<gt>mount> command, but it
+allows you to set both the mount options and the vfstype
+as for the L<mount(8)> I<-o> and I<-t> flags.
+

 =item @devices = $h->mounts ();
 
 This returns the list of currently mounted filesystems.  It returns
 =item @devices = $h->mounts ();
 
 This returns the list of currently mounted filesystems.  It returns


@@ -654,12 +813,33 @@ the list of devices (eg. C</dev/sda1>, C</dev/VG/LV>).
 
 Some internal mounts are not shown.
 
 
 Some internal mounts are not shown.
 

+=item $h->mv ($src, $dest);
+
+This moves a file from C<src> to C<dest> where C<dest> is
+either a destination filename or destination directory.
+
+=item $h->ping_daemon ();
+
+This is a test probe into the guestfs daemon running inside
+the qemu subprocess.  Calling this function checks that the
+daemon responds to the ping message, without affecting the daemon
+or attached block device(s) in any other way.
+

 =item $h->pvcreate ($device);
 
 This creates an LVM physical volume on the named C<device>,
 where C<device> should usually be a partition name such
 as C</dev/sda1>.
 
 =item $h->pvcreate ($device);
 
 This creates an LVM physical volume on the named C<device>,
 where C<device> should usually be a partition name such
 as C</dev/sda1>.
 

+=item $h->pvremove ($device);
+
+This wipes a physical volume C<device> so that LVM will no longer
+recognise it.
+
+The implementation uses the C<pvremove> command which refuses to
+wipe physical volumes that contain any volume groups, so you have
+to remove those first.
+

 =item @physvols = $h->pvs ();
 
 List all the physical volumes detected.  This is the equivalent
 =item @physvols = $h->pvs ();
 
 List all the physical volumes detected.  This is the equivalent


@@ -701,12 +881,27 @@ command.
 
 Remove the single directory C<path>.
 
 
 Remove the single directory C<path>.
 

+=item $h->set_append ($append);
+
+This function is used to add additional options to the
+guest kernel command line.
+
+The default is C<NULL> unless overridden by setting
+C<LIBGUESTFS_APPEND> environment variable.
+
+Setting C<append> to C<NULL> means I<no> additional options
+are passed (libguestfs always adds a few of its own).
+

 =item $h->set_autosync ($autosync);
 
 If C<autosync> is true, this enables autosync.  Libguestfs will make a
 =item $h->set_autosync ($autosync);
 
 If C<autosync> is true, this enables autosync.  Libguestfs will make a

-best effort attempt to run C<$h-E<gt>sync> when the handle is closed
+best effort attempt to run C<$h-E<gt>umount_all> followed by
+C<$h-E<gt>sync> when the handle is closed

 (also if the program exits without closing handles).
 
 (also if the program exits without closing handles).
 

+This is disabled by default (except in guestfish where it is
+enabled by default).
+

 =item $h->set_busy ();
 
 This sets the state to C<BUSY>.  This is only used when implementing
 =item $h->set_busy ();
 
 This sets the state to C<BUSY>.  This is only used when implementing


@@ -714,6 +909,25 @@ actions using the low-level API.
 
 For more information on states, see L<guestfs(3)>.
 
 
 For more information on states, see L<guestfs(3)>.
 

+=item $h->set_e2label ($device, $label);
+
+This sets the ext2/3/4 filesystem label of the filesystem on
+C<device> to C<label>.  Filesystem labels are limited to
+16 characters.
+
+You can use either C<$h-E<gt>tune2fs_l> or C<$h-E<gt>get_e2label>
+to return the existing label on a filesystem.
+
+=item $h->set_e2uuid ($device, $uuid);
+
+This sets the ext2/3/4 filesystem UUID of the filesystem on
+C<device> to C<uuid>.  The format of the UUID and alternatives
+such as C<clear>, C<random> and C<time> are described in the
+L<tune2fs(8)> manpage.
+
+You can use either C<$h-E<gt>tune2fs_l> or C<$h-E<gt>get_e2uuid>
+to return the existing UUID of a filesystem.
+

 =item $h->set_path ($path);
 
 Set the path that libguestfs searches for kernel and initrd.img.
 =item $h->set_path ($path);
 
 Set the path that libguestfs searches for kernel and initrd.img.


@@ -721,9 +935,6 @@ Set the path that libguestfs searches for kernel and initrd.img.
 The default is C<$libdir/guestfs> unless overridden by setting
 C<LIBGUESTFS_PATH> environment variable.
 
 The default is C<$libdir/guestfs> unless overridden by setting
 C<LIBGUESTFS_PATH> environment variable.
 

-The string C<path> is stashed in the libguestfs handle, so the caller
-must make sure it remains valid for the lifetime of the handle.
-

 Setting C<path> to C<NULL> restores the default path.
 
 =item $h->set_qemu ($qemu);
 Setting C<path> to C<NULL> restores the default path.
 
 =item $h->set_qemu ($qemu);


@@ -736,9 +947,6 @@ configure script.
 You can also override this by setting the C<LIBGUESTFS_QEMU>
 environment variable.
 
 You can also override this by setting the C<LIBGUESTFS_QEMU>
 environment variable.
 

-The string C<qemu> is stashed in the libguestfs handle, so the caller
-must make sure it remains valid for the lifetime of the handle.
-

 Setting C<qemu> to C<NULL> restores the default qemu binary.
 
 =item $h->set_ready ();
 Setting C<qemu> to C<NULL> restores the default qemu binary.
 
 =item $h->set_ready ();


@@ -794,6 +1002,31 @@ C<path> should be a file or directory in the mounted file system
 
 This is the same as the C<statvfs(2)> system call.
 
 
 This is the same as the C<statvfs(2)> system call.
 

+=item @stringsout = $h->strings ($path);
+
+This runs the L<strings(1)> command on a file and returns
+the list of printable strings found.
+
+Because of the message protocol, there is a transfer limit 
+of somewhere between 2MB and 4MB.  To transfer large files you should use
+FTP.
+
+=item @stringsout = $h->strings_e ($encoding, $path);
+
+This is like the C<$h-E<gt>strings> command, but allows you to
+specify the encoding.
+
+See the L<strings(1)> manpage for the full list of encodings.
+
+Commonly useful encodings are C<l> (lower case L) which will
+show strings inside Windows/x86 files.
+
+The returned strings are transcoded to UTF-8.
+
+Because of the message protocol, there is a transfer limit 
+of somewhere between 2MB and 4MB.  To transfer large files you should use
+FTP.
+

 =item $h->sync ();
 
 This syncs the disk, so that any writes are flushed through to the
 =item $h->sync ();
 
 This syncs the disk, so that any writes are flushed through to the


@@ -838,8 +1071,8 @@ to create a new zero-length file.
 
 =item %superblock = $h->tune2fs_l ($device);
 
 
 =item %superblock = $h->tune2fs_l ($device);
 

-This returns the contents of the ext2 or ext3 filesystem superblock
-on C<device>.
+This returns the contents of the ext2, ext3 or ext4 filesystem
+superblock on C<device>.

 
 It is the same as running C<tune2fs -l device>.  See L<tune2fs(8)>
 manpage for more details.  The list of fields returned isn't
 
 It is the same as running C<tune2fs -l device>.  See L<tune2fs(8)>
 manpage for more details.  The list of fields returned isn't


@@ -872,6 +1105,13 @@ See also C<$h-E<gt>download>.
 This creates an LVM volume group called C<volgroup>
 from the non-empty list of physical volumes C<physvols>.
 
 This creates an LVM volume group called C<volgroup>
 from the non-empty list of physical volumes C<physvols>.
 

+=item $h->vgremove ($vgname);
+
+Remove an LVM volume group C<vgname>, (for example C<VG>).
+
+This also forcibly removes all logical volumes in the volume
+group (if any).
+

 =item @volgroups = $h->vgs ();
 
 List all the volumes groups detected.  This is the equivalent
 =item @volgroups = $h->vgs ();
 
 List all the volumes groups detected.  This is the equivalent


@@ -905,10 +1145,23 @@ As a special case, if C<size> is C<0>
 then the length is calculated using C<strlen> (so in this case
 the content cannot contain embedded ASCII NULs).
 
 then the length is calculated using C<strlen> (so in this case
 the content cannot contain embedded ASCII NULs).
 

+I<NB.> Owing to a bug, writing content containing ASCII NUL
+characters does I<not> work, even if the length is specified.
+We hope to resolve this bug in a future version.  In the meantime
+use C<$h-E<gt>upload>.
+

 Because of the message protocol, there is a transfer limit 
 of somewhere between 2MB and 4MB.  To transfer large files you should use
 FTP.
 
 Because of the message protocol, there is a transfer limit 
 of somewhere between 2MB and 4MB.  To transfer large files you should use
 FTP.
 

+=item $h->zero ($device);
+
+This command writes zeroes over the first few blocks of C<device>.
+
+How many blocks are zeroed isn't specified (but it's I<not> enough
+to securely wipe the device).  It should be sufficient to remove
+any partition tables, filesystem superblocks and so on.
+

 =cut
 
 1;
 =cut
 
 1;