examples: fixed and made them more similar

The channel read/write functions can return 0 in legitimate cases
without it being an error, and we need to loop properly if they
return short.

example/scp_write.c

@@ -47,7 +47,7 @@ int main(int argc, char *argv[])
     FILE *local;
     int rc;
     char mem[1024];
-    size_t nread, sent;
+    size_t nread;
     char *ptr;
     struct stat fileinfo;
 
@@ -168,20 +168,21 @@ int main(int argc, char *argv[])
             break;
         }
         ptr = mem;
-        sent = 0;
 
         do {
             /* write the same data over and over, until error or completion */
             rc = libssh2_channel_write(channel, ptr, nread);
             if (rc < 0) {
                 fprintf(stderr, "ERROR %d\n", rc);
-            } else {
-                /* rc indicates how many bytes were written this time */
-                sent += rc;
+                break;
             }
-        } while (rc > 0 && sent < nread);
+            else {
+                /* rc indicates how many bytes were written this time */
+                ptr += rc;
+                nread -= rc;
+            }
+        } while (nread);
 
-        nread -= sent;
     } while (1);
 
     fprintf(stderr, "Sending EOF\n");

example/scp_write_nonblock.c

@@ -51,7 +51,7 @@ int main(int argc, char *argv[])
     long flag = 1;
 #endif
     char mem[1024];
-    size_t nread, sent;
+    size_t nread;
     char *ptr;
     struct stat fileinfo;
 
@@ -182,7 +182,6 @@ int main(int argc, char *argv[])
             break;
         }
         ptr = mem;
-        sent = 0;
 
         do {
             /* write the same data over and over, until error or completion */
@@ -191,12 +190,14 @@ int main(int argc, char *argv[])
                 continue;
             } else if (rc < 0) {
                 fprintf(stderr, "ERROR %d\n", rc);
+                break;
             } else {
                 /* rc indicates how many bytes were written this time */
-                sent += rc;
+                nread -= rc;
+                ptr += rc;
             }
-        } while (rc > 0 && sent < nread);
-    } while (1);
+        } while (nread);
+    } while (!nread); /* only continue if nread was drained */
 
     fprintf(stderr, "Sending EOF\n");
     while (libssh2_channel_send_eof(channel) == LIBSSH2_ERROR_EAGAIN);

example/sftp_RW_nonblock.c

@@ -246,7 +246,7 @@ int main(int argc, char *argv[])
                                         nread);
                 ptr += rc;
                 nread -= nread;
-            } while (rc > 0);
+            } while (rc >= 0);
 
             if(rc != LIBSSH2_ERROR_EAGAIN) {
                 /* error or end of file */

example/sftp_write.c

@@ -185,10 +185,13 @@ int main(int argc, char *argv[])
         do {
             /* write data in a loop until we block */
             rc = libssh2_sftp_write(sftp_handle, ptr, nread);
+            if(rc < 0)
+                break;
             ptr += rc;
-            nread -= nread;
-        } while (rc > 0);
-    } while (1);
+            nread -= rc;
+        } while (nread);
+
+    } while (rc > 0);
 
     libssh2_sftp_close(sftp_handle);
     libssh2_sftp_shutdown(sftp_session);

example/sftp_write_nonblock.c

@@ -199,9 +199,9 @@ int main(int argc, char *argv[])
                 ;
             }
             ptr += rc;
-            nread -= nread;
-        } while (rc > 0);
-    } while (1);
+            nread -= rc;
+        } while (nread);
+    } while (rc > 0);
 
     fclose(local);
     libssh2_sftp_close(sftp_handle);