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Old 12-14-2012, 02:42 PM   #1
PoleStar
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Registered: Jul 2010
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libssh2 compile issue


Took this code from libssh2 project website.

Code:
[me@horse ssh2]$ cat test.c 
#include<stdio.h>
#include <libssh2.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <netinet/in.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <sys/types.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <ctype.h>

static int waitsocket(int socket_fd, LIBSSH2_SESSION *session)
{
    struct timeval timeout;
    int rc;
    fd_set fd;
    fd_set *writefd = NULL;
    fd_set *readfd = NULL;
    int dir;
 
    timeout.tv_sec = 10;
    timeout.tv_usec = 0;
 
    FD_ZERO(&fd);
 
    FD_SET(socket_fd, &fd);
 
    /* now make sure we wait in the correct direction */ 
    dir = libssh2_session_block_directions(session);

 
    if(dir & LIBSSH2_SESSION_BLOCK_INBOUND)
        readfd = &fd;
 
    if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND)
        writefd = &fd;
 
    rc = select(socket_fd + 1, readfd, writefd, NULL, &timeout);
 
    return rc;
}


main(){
	printf ("at the end \n");

}
Code:

Compiling it bring the error as "libssh2_session_block_direction" does not exist. [me@horse ssh2]$ gcc -o test test.c /tmp/ccwC6mej.o: In function `waitsocket': test.c:(.text+0x91): undefined reference to `libssh2_session_block_directions' collect2: ld returned 1 exit status [me@horse ssh2]$

But it does exist in the header file libssh2.h
Code:
[me@horse ssh2]$ grep -i2  libssh2_session_block_directions /usr/include/libssh2.h 
                                           int *errmsg_len, int want_buf);
LIBSSH2_API int libssh2_session_last_errno(LIBSSH2_SESSION *session);
LIBSSH2_API int libssh2_session_block_directions(LIBSSH2_SESSION *session);

LIBSSH2_API int libssh2_session_flag(LIBSSH2_SESSION *session, int flag,
[me@horse ssh2]$


My versions of ssh and co.

Code:
[me@horse ssh2]$ rpm -aq | grep ssh
libssh2-1.2.7-4.fc16.i686
openssh-5.8p2-25.fc16.i686
libssh2-devel-1.2.7-4.fc16.i686
openssh-server-5.8p2-25.fc16.i686
openssh-askpass-5.8p2-25.fc16.i686
openssh-clients-5.8p2-25.fc16.i686
[me@horse ssh2]$

Last edited by PoleStar; 12-14-2012 at 02:46 PM.
 
Old 12-16-2012, 05:22 AM   #2
knudfl
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Location: Copenhagen, DK
Distribution: pclos2016, Slack14.1 Deb Jessie, + 50+ other Linux OS, for test only.
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$ rpm -ql libssh2-devel
/usr/include/libssh2.h
/usr/include/libssh2_publickey.h
/usr/include/libssh2_sftp.h
etc.

If you have no /usr/include/libssh2.h, please reinstall :

# yum install --reinstall libssh2-devel


.
 
Old 12-17-2012, 11:04 AM   #3
PoleStar
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Registered: Jul 2010
Posts: 165

Original Poster
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Thanks.

Its still the same.


Code:
Installing : libssh2-devel-1.2.7-4.fc16.i686                                                 1/1 
  Verifying  : libssh2-devel-1.2.7-4.fc16.i686                                                 1/1 

Installed:
  libssh2-devel.i686 0:1.2.7-4.fc16                                                                

Complete!
[me@horse ~]$ rpm -ql libssh2-devel
/usr/include/libssh2.h
/usr/include/libssh2_publickey.h
/usr/include/libssh2_sftp.h
/usr/lib/libssh2.so
/usr/lib/pkgconfig/libssh2.pc
/usr/share/doc/libssh2-devel-1.2.7
/usr/share/doc/libssh2-devel-1.2.7/COPYING
[me@horse ~]$ 
[me@horse ~]$
Code:
[me@horse ssh2]$ gcc -o test  test.c 
/tmp/cc2uJ7xL.o: In function `waitsocket':
test.c:(.text+0x91): undefined reference to `libssh2_session_block_directions'
collect2: ld returned 1 exit status
[me@horse ssh2]$
Code:
me@horse ssh2]$ ls -l  /usr/include/libssh2.h
-rw-r--r--. 1 root root 45303 Aug 17  2010 /usr/include/libssh2.h
[me@horse ssh2]$ ls -l  /usr/include/libssh2.h
 
Old 12-17-2012, 11:43 AM   #4
ntubski
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Quote:
Originally Posted by PoleStar View Post
But it does exist in the header file libssh2.h
A C library generally provides 2 things: the declarations (in the header files) and the definitions (in the library file, .a for static libraries, .so for shared libraries). To tell the linker to use the library file you use -lfoo which tells the linker to look for libfoo.a or libfoo.so, in your case to get libssh2.so you pass -lssh2:
Code:
gcc -o test  test.c -lssh2
 
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