Re: Noob libssh question

[Alan Dunn <amdunn@xxxxxxxxx>]

This bug: https://red.libssh.org/issues/115 , which the last comment
claims is fixed in 0.6.0.

On Thu, Feb 6, 2014 at 6:58 PM, Dustin Oprea <myselfasunder@xxxxxxxxx> wrote:
> I can't recall the bug number (I submitted it), but this was an issue until
> very recently. It's been fixed, reportedly.
>
> You might build off MASTER, and see if that works better.
>
>
> Dustin
>
> On Feb 6, 2014 7:22 PM, "craig and heather" <calhjh@xxxxxxxxx> wrote:
>>
>> Ok I've now found that waiting in the C program for the runfile to go away
>> is the cause of the problem. If I execute a C program that runs start to
>> finish without any waiting, ssh_channel_read returns 0 bytes.
>>
>> So should I check the result from ssh_channel_read and if -2 delay a bit
>> and then read it again until the value returned is >= 0?
>>
>> I thought this was a synchronous function. BTW, I'm using the newest
>> version of the library that I downloaded and built today.
>>
>>
>>
>>
>> On Thu, Feb 6, 2014 at 3:49 PM, craig and heather <calhjh@xxxxxxxxx>
>> wrote:
>>>
>>> Hello,
>>>
>>> I am using libssl to execute simple C programs between raspberry pi's.
>>> These programs are simple SDL graphics applications similar to that listed
>>> below that don't write anything to stderr (unless there is an error) or
>>> stdout.
>>>
>>> I am also doing some remote file creation and deletion using the same
>>> libssl functionality.
>>>
>>> When I remotely execute commands such as "touch runfile" or "rm runfile"
>>> I can see 0 bytes are returned from ssh_channel_read function as would be
>>> expected. However whenever I run one of my little C programs
>>> ssh_channel_read always returns -2 but the program runs successfully on the
>>> remote system.
>>>
>>> Is there something I need to do in my C programs to satisfy
>>> ssh_channel_read?
>>>
>>> Thanks for looking
>>>
>>>
>>> /*
>>>  * A Smart Screen Module
>>>  *
>>>  * Sets the entire screen to a specified RGB color
>>>  * Typical Call:
>>>  *      colorscreen 0 255 0
>>>  *
>>>  * Concept and Implementation by: Craig A. Lindley
>>>  * Last Update: 01/30/2014
>>>  */
>>>
>>> #include <stdio.h>
>>> #include <stdlib.h>
>>> #include <unistd.h>
>>> #include <sys/stat.h>
>>> #include <sys/types.h>
>>>
>>> #include "SDL/SDL.h"
>>>
>>> #define RUN_FILE_NAME "runfile"
>>> #define BUSY_FILE_NAME "busy"
>>>
>>> // Check for file existance
>>> int file_exists(char *filename) {
>>>
>>>     struct stat buffer;
>>>     return (stat (filename, &buffer) == 0);
>>> }
>>>
>>> int main (int argc, char* args[]) {
>>>
>>>     if (argc != 4) {
>>>         fprintf(stderr, "Wrong number of arguments\n");
>>>         return -1;
>>>     }
>>>
>>>     // Extract RGB values from the command line arguments
>>>     int red   = atoi(args[1]);
>>>     int green = atoi(args[2]);
>>>     int blue  = atoi(args[3]);
>>>
>>>     // Range check the specified color values
>>>     if ((red   < 0) || (red   > 255) ||
>>>         (green < 0) || (green > 255) ||
>>>         (blue  < 0) || (blue  > 255)) {
>>>         fprintf(stderr, "Color values in range 0 <= value < 256\n");
>>>         return -1;
>>>     }
>>>
>>>     // Create the busy file
>>>     FILE *pFile = fopen (BUSY_FILE_NAME,"w");
>>>     if (pFile != NULL) {
>>>         fclose(pFile);
>>>     }    else    {
>>>         fprintf(stderr, "Could not create busy file\n");
>>>         return -1;
>>>     }
>>>
>>>     putenv("SDL_FBDEV=/dev/fb1");
>>>     putenv("SDL_VIDEODRIVER=fbcon");
>>>
>>>     // Start SDL
>>>     SDL_Init(SDL_INIT_VIDEO);
>>>
>>>     // Turn off cursor
>>>     SDL_ShowCursor(SDL_DISABLE);
>>>
>>>     const SDL_VideoInfo *videoInfo = SDL_GetVideoInfo();
>>>
>>>     int width  = videoInfo->current_w;
>>>     int height = videoInfo->current_h;
>>>     uint8_t bpp = videoInfo->vfmt->BitsPerPixel;
>>>
>>>     // Set up screen
>>>     SDL_Surface *screen = SDL_SetVideoMode(width, height, bpp,
>>> SDL_SWSURFACE);
>>>     if (!screen) {
>>>         fprintf(stderr, "SDL_SetVideoMode failed\n");
>>>         return -1;
>>>     }
>>>     // Create the specified color
>>>     uint32_t color = SDL_MapRGB(screen->format, red, green, blue);
>>>
>>>     // Create rect the size of the screen
>>>     SDL_Rect rect = {0, 0, width, height};
>>>
>>>     // Fill the screen with the specified color
>>>     SDL_FillRect(screen, &rect, color);
>>>
>>>     // Update Screen
>>>     SDL_Flip(screen);
>>>
>>>     // Pause
>>>     SDL_Delay(1000);
>>>
>>>     // Wait until runfile is gone to terminate
>>>     while (file_exists(RUN_FILE_NAME)) {
>>>         SDL_Delay(50);
>>>     }
>>>
>>>     // Delete the busy file
>>>     if (remove(BUSY_FILE_NAME) != 0) {
>>>         fprintf(stderr, "Error deleting busy file\n");
>>>     }
>>>
>>>     // Quit SDL
>>>     SDL_Quit();
>>>
>>>     return 0;
>>> }
>>>
>>>
>>> --
>>> Craig Lindley
>>>
>>> If you're one in a million, there are now seven thousand people exactly
>>> like you.
>>
>>
>>
>>
>> --
>> Craig Lindley / Heather Hubbard
>>
>> New Recordings: craigandheather.net/cnmpage.html
>> Latest CD: craigandheather.net/songsilike2013cd.html
>>
>> Personal Website: craigandheather.net
>> Business Website: clockwork.craigandheather.net
>> Phone: (719) 495-1873
>> Cell: (719) 502-7925
>>
>> If you're one in a million, there are now seven thousand people exactly
>> like you.