sendf.c:450:81: warning: Longer than 79 columns

Introduced in commit 2a4ee0d2 sending of data via the FILE
protocol would always return CURLE_WRITE_ERROR regardless of whether
CURL_WRITEFUNC_PAUSE was returned from the callback function or not.

Make sure that we detect such attempts and return a proper error code
instead of silently handling this in problematic ways.

Updated the documentation to mention this limitation.

Bug: http://curl.haxx.se/bug/view.cgi?id=1286

Previously this memdebug free() replacement didn't properly work with a
NULL argument which has made us write code that avoids calling
free(NULL) - which causes some extra nuisance and unnecessary code.
Starting now, we should allow free(NULL) even when built with the
memdebug system enabled.

free(NULL) is permitted by POSIX

free() itself allows a NULL input but our memory debug system requires
Curl_safefree() to be used instead when a "legitimate" NULL may be freed. Like
in the code here.

Pointed-out-by: Steve Holme

... since pthread_t may be non-scalar and/or may represent a real thread
with scalar 0.

Bug: http://curl.haxx.se/bug/view.cgi?id=1314

If a user indicated they preferred to authenticate using a SASL
mechanism, but SASL authentication wasn't supported by the server, curl
would always fall back to clear text when CAPABILITY wasn't supported,
even though the user didn't want to use this.

If a user indicated they preferred to authenticate using APOP or a SASL
mechanism, but neither were supported by the server, curl would always
fall back to clear text when CAPA wasn't supported, even though the
user didn't want to use this.

This also fixes the auto build failure caused by commit 6f2d5f05.

Fixes commit 1deac31e

This commit replaces that of 9f260b5d because according to RFC-2449,
section 6, there is no APOP capability "...even though APOP is an
optional command in [POP3].  Clients discover server support of APOP by
the presence in the greeting banner of an initial challenge enclosed in
angle brackets."

The FILE:// code doesn't support this option - and it doesn't make sense
to support it as long as it works as it does since then it'd only block
even longer.

But: setting CURLOPT_MAX_RECV_SPEED_LARGE would make the transfer first
get done and then libcurl would wait until the average speed would get
low enough. This happened because the transfer happens completely in the
DO state for FILE:// but then it would still unconditionally continue in
to the PERFORM state where the speed check is made.

Starting now, the code will skip from DO_DONE to DONE immediately if no
socket is set to be recv()ed or send()ed to.

Bug: http://curl.haxx.se/bug/view.cgi?id=1312
Reported-by: Mohammad AlSaleh

The comment in the code mentions the zero terminating after having
copied data, but it mistakingly zero terminated the source data and not
the destination! This caused the test 864 problem discussed on the list:

http://curl.haxx.se/mail/lib-2013-12/0113.html


Signed-off-by: Daniel Stenberg <daniel@haxx.se>

This reverts commit 727d798d.

Although highlighted by a bug in commit 1cfb436a, APOP
authentication could be chosen if the server was to reply with an empty
or missing timestamp in the server greeting and APOP was given in the
capability list by the server.

Added a loop to pop3_statemach_act() in which Curl_pp_readresp() is
called until the cache is drained. Without this multiple responses
received in a single packet could result in a hang or delay.

Similar to the processing of untagged CAPABILITY responses in IMAP and
multi-line EHLO responses in SMTP, moved the processing of multi-line
CAPA responses to pop3_state_capa_resp().

In an effort to reduce what pop3_endofresp() does and bring the POP3
source back inline with the IMAP and SMTP protocols, moved the APOP
detection into pop3_state_servergreet_resp().

Added support for downgrading the SASL authentication mechanism when the
decoding of CRAM-MD5, DIGEST-MD5 and NTLM messages fails. This enhances
the previously added support for graceful cancellation by allowing the
client to retry a lesser SASL mechanism such as LOGIN or PLAIN, or even
APOP / clear text (in the case of POP3 and IMAP) when supported by the
server.

smtp.c:478:21: error: unused variable 'smtpc' [-Werror=unused-variable]

In preparation for the upcoming SASL downgrade feature renamed the
imap__perform_authenticate(), pop3__perform_authenticate() and
smtp__perform_authenticate() functions.