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Subject: AW: libssh2_channel_read() issue

AW: libssh2_channel_read() issue

From: Belau, Rene (ext) <belau.rene.ext_at_siemens.com>
Date: Fri, 19 Feb 2016 09:14:22 +0000

Hi Amirul,

sorry but this sounds weird to me.

After call of libssh2_scp_recv() you got a handle and sb.mode = 0x0040(POSIX) or 0x0100(WIN) for read permissions?

If it is true

at the same usecase, as you described.

Logged in user and directory have rights. ->

Drectory >> me:me drwxrwxrwx
File inside >> me:me –w-------

My result: for libssh2(1.4.3 && 1.5.0) after 3 tries (test with blocking mode and tested again three different ssh servers)

1. libssh2_scp_recv() //handle = null, stat = {0}, libssh2_session_last_errno() //error -28
My result: for libssh2(1.4.3 && 1.5.0) after 3 tries (test with non-blocking mode and tested again three different ssh servers)

1. libssh2_scp_recv() //handle = null, stat = {0}, libssh2_session_last_errno() //error -37

2. libssh2_scp_recv() //handle = null, stat = {0}, libssh2_session_last_errno() //error -37

3. libssh2_scp_recv() //handle = null, stat = {0}, libssh2_session_last_errno() //error -28
Just fine, how it should be.


Do you use an older version? you could dig into libssh2 -> scp.c -> scp_recv state 2 or 3


Rene

---

Von: libssh2-devel [mailto:libssh2-devel-bounces_at_cool.haxx.se] Im Auftrag von Amirul Islam
Gesendet: Mittwoch, 17. Februar 2016 14:14
An: libssh2 development
Betreff: Re: libssh2_channel_read() issue

Hi Rene,

I have checked for last errno on both cases when libssh2_scp_recv() & libssh2_channel_read() is called, libssh2_session_last_errno() return 0. The issues is that my user has access to the remote folder, but does not have read permission on the target file which is contained in that folder. So the return value from libssh2_channel_read() is always 0 and sb.st_size is 1.

you can simulate and check what you get

On Wed, Feb 17, 2016 at 4:57 PM, Belau, Rene (ext) <belau.rene.ext_at_siemens.com<mailto:belau.rene.ext_at_siemens.com>> wrote:
You need to do an operation and then check session error.

libssh2_scp_recv() //handle null, return -37
libssh2_session_last_errno() //error -28 scp protocol error (libssh2 version 1.5.0) if you have no rights at target device

libssh2_channel_read() //got we some bytes ?
libssh2_session_last_errno() //without error?

libssh2_channel_read() -> 0 bytes => no payload, it is not an error -> libssh2 tells us if it is error ! -> libssh2_session_last_errno()


Rene

Von: libssh2-devel [mailto:libssh2-devel-bounces_at_cool.haxx.se<mailto:libssh2-devel-bounces_at_cool.haxx.se>] Im Auftrag von Amirul Islam
Gesendet: Mittwoch, 17. Februar 2016 11:24
An: libssh2-devel_at_cool.haxx.se<mailto:libssh2-devel_at_cool.haxx.se>
Betreff: libssh2_channel_read() issue

Hi All,

I am having an issue with the libssh2_channel_read() function. I am using it in blocking mode to download files from remote server. Now, I have an instance where the file I am trying to download, I do not have read permission. This is causing the read() function to return 0. I am not sure, if I should break my read loop when 0 is returned, since the documentation implies we should break when there is a negative value returned. I am not if breaking on 0 will have unpredictable behavior on other instances. need help

Also, I can check the file mode when I call libssh2_scp_recv() function, what would be the best way to check if my user has read permission?

Thank you in advance.

--

"Fame is a vapor; popularity an accident; the only earthly certainty is oblivion."

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--

"Fame is a vapor; popularity an accident; the only earthly certainty is oblivion."

_______________________________________________
libssh2-devel http://cool.haxx.se/cgi-bin/mailman/listinfo/libssh2-devel
Received on 2016-02-19

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