Objective-C

Get the Byte Count of the Last SFTP Read

Demonstrates the Chilkat SFtp.LastReadNumBytes method, which returns the number of bytes received by the most recent read for a handle. The only argument is the handle.

Background: SFTP reads may return fewer bytes than requested even before the end of the file, so knowing the actual count is useful for tracking progress and for advancing an explicit offset by the right amount. Both a normal EOF read and a failed read report 0, so pair this with Eof and LastReadFailed to interpret a zero-byte result correctly.

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Objective-C

#import <CkoSFtp.h>
#import <NSString.h>
#import <CkoBinData.h>

BOOL success = NO;

//  Demonstrates the SFtp.LastReadNumBytes method, which returns the number of bytes received by
//  the most recent read for a handle.  The only argument is the handle.

CkoSFtp *sftp = [[CkoSFtp alloc] init];

//  Connect, authenticate, and initialize the SFTP subsystem.
int port = 22;
success = [sftp Connect: @"sftp.example.com" port: [NSNumber numberWithInt: port]];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
NSString *password = @"mySshPassword";

success = [sftp AuthenticatePw: @"mySshLogin" password: password];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

success = [sftp InitializeSftp];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

NSString *handle = [sftp OpenFile: @"subdir/data.txt" access: @"readOnly" createDisp: @"openExisting"];
if (sftp.LastMethodSuccess == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

CkoBinData *bd = [[CkoBinData alloc] init];
int chunkSize = 4096;
BOOL reading = YES;
while (reading) {
    success = [sftp ReadFileBd: handle numBytes: [NSNumber numberWithInt: chunkSize] bd: bd];
    if ([sftp LastReadFailed: handle]) {
        NSLog(@"%@",sftp.LastErrorText);
        return;
    }

    //  Report how many bytes the last read actually returned.  A normal EOF read reports 0.
    int lastCount = [[sftp LastReadNumBytes: handle] intValue];
    NSLog(@"%@%d%@",@"Last read returned ",lastCount,@" bytes.");

    reading = ![sftp Eof: handle];
}

success = [sftp CloseHandle: handle];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

NSLog(@"%@%d%@",@"Total: ",[bd.NumBytes intValue],@" bytes.");

[sftp Disconnect];