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Verify that the contents of a file on the local system are the
same as the specified file on the server..
Syntax
object.VerifyFile( LocalFile,
RemoteFile, [Options] )
Parameters
- LocalFile
- A string that specifies the name of the file on the local
system.
- RemoteFile
- A string that specifies the name of the file on the
server.
- Options
- A numeric bitmask which specifies the options that may be used
when comparing the files. This argument may be any one of the
following values:
| Value |
Description |
| ftpVerifyDefault |
File verification should use the best option available
based on the available server features. If the server supports
the XMD5 command, the control will calculate an MD5 hash of the
local file contents and compare the value with the file on the
server. If the server does not support the XMD5 command, but it
does support the XCRC command, the control will calculate a
CRC32 checksum of the local file contents and compare the value
with the file on the server. If the server does not support
either the XMD5 or XCRC commands, the control will compare the
size of the local and remote files. |
| ftpVerifySize |
Files are verified by comparing the number of bytes of data
in the local and remote files. This is the least reliable
method, and should only be used if the server does not support
either the XMD5 or XCRC commands. |
| ftpVerifyCRC32 |
Files are verified by calculating a CRC-32 checksum of the
local file contents and comparing it with the value returned by
the server in response to the XCRC command. This method should
only be used if the server does not support the XMD5
command. |
| ftpVerifyMD5 |
Files are verified by calculating an MD5 hash of the local
file contents and comparing it with the value returned by the
server in response to the XMD5 command. This is the preferred
method for performing file verification. |
Return Value
A value of zero is returned if the operation was successful,
otherwise a non-zero error code is returned which indicates the cause
of the failure.
Remarks
The VerifyFile method will attempt to verify that the
contents of the local and remote files are identical using one of
several methods, based on the features that the server supports.
Preference will be given to the most reliable method available, using
either an MD5 hash, a CRC-32 checksum or comparing the size of the
file, in that order.
It is not recommended that you use this method with text files
because of the different end-of-line conventions used by different
operating systems. For example, a text file on a Windows system uses
a carriage-return and linefeed pair to indicate the end of a line of
text. However, on a UNIX system, a single linefeed is used to
indicate the end of a line. This can cause the VerifyFile
method to indicate the files are not identical, even though the only
difference is in the end-of-line characters that are used.
See Also
BufferSize Property,
Priority Property,
GetData Method,
GetFile Method,
GetMultipleFiles Method,
PutData Method,
PutFile Method,
OnGetFile Event,
OnProgress Event
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