Remove all the "assert(len>0)" which forbade zero-length writes across the

from_backend() interface, after having made all implementations safe against
being called with len==0 and possibly-NULL/undefined "data".

(This includes making misc.c:bufchain_add() more robust in this area.)

Assertion was originally added 2002-03-01; e.g., see plink.c:1.53 [r1571].

I believe this now shouldn't break anything.

This should hopefully make `ppk-empty-comment' finally GO AWAY. (Tested
with Unix PuTTY.)

[originally from svn r3500]
[r1571 == fdbd6978016e9fd87db7b3bfc33ff0da8bd3eea9]

1 files changed, 3 insertions, 4 deletions

diff --git a/psftp.c b/psftp.c
index ca01f12a..c7cd8701 100644
--- a/psftp.c
+++ b/psftp.c
@@ -1639,14 +1639,13 @@ int from_backend(void *frontend, int is_stderr, const char *data, int datalen)
     unsigned char *p = (unsigned char *) data;
     unsigned len = (unsigned) datalen;
 
-    assert(len > 0);
-
     /*
      * stderr data is just spouted to local stderr and otherwise
      * ignored.
      */
     if (is_stderr) {
-	fwrite(data, 1, len, stderr);
+	if (len > 0)
+	    fwrite(data, 1, len, stderr);
 	return 0;
     }
 
@@ -1656,7 +1655,7 @@ int from_backend(void *frontend, int is_stderr, const char *data, int datalen)
     if (!outptr)
 	return 0;
 
-    if (outlen > 0) {
+    if ((outlen > 0) && (len > 0)) {
 	unsigned used = outlen;
 	if (used > len)
 	    used = len;