examples: Tolerate incomplete writes in exec example

Previously, the exec example would fail if it could not write the whole
read buffer to stdout.  With this changes, the exec example will be able
to write parts of the buffer until the whole buffer is written.

This makes the exec example to run when the stdout buffer is small.

Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

1 files changed, 22 insertions, 7 deletions

diff --git a/examples/exec.c b/examples/exec.c
index 4d5e0c1a..7200ddef 100644
--- a/examples/exec.c
+++ b/examples/exec.c
@@ -8,7 +8,7 @@ int main(void) {
     ssh_session session;
     ssh_channel channel;
     char buffer[256];
-    int nbytes;
+    int rbytes, wbytes, total = 0;
     int rc;
 
     session = connect_ssh("localhost", NULL, 0);
@@ -35,15 +35,30 @@ int main(void) {
         goto failed;
     }
 
-    nbytes = ssh_channel_read(channel, buffer, sizeof(buffer), 0);
-    while (nbytes > 0) {
-        if (fwrite(buffer, 1, nbytes, stdout) != (unsigned int) nbytes) {
+    rbytes = ssh_channel_read(channel, buffer, sizeof(buffer), 0);
+    if (rbytes <= 0) {
+        goto failed;
+    }
+
+    do {
+        wbytes = fwrite(buffer + total, 1, rbytes, stdout);
+        if (wbytes <= 0) {
             goto failed;
         }
-        nbytes = ssh_channel_read(channel, buffer, sizeof(buffer), 0);
-    }
 
-    if (nbytes < 0) {
+        total += wbytes;
+
+        /* When it was not possible to write the whole buffer to stdout */
+        if (wbytes < rbytes) {
+            rbytes -= wbytes;
+            continue;
+        }
+
+        rbytes = ssh_channel_read(channel, buffer, sizeof(buffer), 0);
+        total = 0;
+    } while (rbytes > 0);
+
+    if (rbytes < 0) {
         goto failed;
     }