lib-sieve: vacation extension: Enforce subject header limit in Unicode codepoints rather than bytes.

This conversion now includes a check that may fail. Pigeonhole currently only
uses this functionality to obtain an SMTP version of the postmaster address.
This code is now consolidated in the sieve_get_postmaster_smtp() function, which
provides postmaster address as an SMTP address.

Errors will trigger an implicit keep, not discard.

lib-sieve: variables extension: Fix duplicate const in definition of sieve_variables_modifier array.

This is wrong and leads to Clang compiler warnings.

This is now logged as a debug message instead.

This is a remnant of an older implementation and now triggered a scan-build report.

This occurred for example when the "fileinto" command is used with only the
"copy" extension in the require line.

Panic message was:

Panic: file hash.c: line 263 (hash_table_insert_node): assertion failed: (opcode == HASH_TABLE_OP_UPDATE)

Previously, this was only tested implicitly in the Sieve test suite. Now, it is
tested explicitly, which allows for more flexibility in the testing scenario.

It now extensively tests one scenario that used to fail.

This caused an assert panic when the application or child stream did not skip
all buffered data immediately. This was reproducible only when the message input
stream consisted of a concatenation of smaller streams, which is used in LMTP to
prepend a few headers.

The panic was:

Panic: file istream.c: line 329 (i_stream_read_memarea): assertion failed: ((size_t)ret+old_size == _stream->pos - _stream->skip)

This is tested already in the assertion that precedes it.

This allows using a seekable stream as mail directly.

Needed for use in test suite.

Recent changes in Dovecot make slashes allowed in mailbox names when this flag
is set. This flag is not useful for the test suite and it breaks one of the
tests because slashes are no longer invalid when this flag is set.

Before, the virtual mailbox name was not sanitized, which caused control
characters to be displayed in log messages. Also, the mailbox name would be
mentioned twice in the log message, once santized and once unsanitized.

The header guard defines should be on top.

Dovecot core doesn't have copyright notices in header files.

Satisfies static analyzer, these were forgotten from
b2de2aee

Satisfies static analyzer

The flag has been removed, and the setting is now the default.

plugins: imapsieve: Deal with messages being expunged concurrently by the time Sieve filter is to be applied.

Before, this was an assertion that got triggered transiently during imaptest.

The output buffer was on the data stack, which leads to big trouble when the
buffer needs to grow in a deeper stack level.

lib-sieve: imap4flags extension: Fix binary corruption occurring when setflag/addflag/removeflag flag-list is a variable.

The original implementation checked the first operand for being a variable.
Obviously, when the assigned flag string is just a variable, this doesn't work.
This causes the flag list to be recognized erroneously as a variable flags
string. Fixed the problem by explicitly emitting an omitted operand when there
is no second argument for a setflag/addflag/removeflag.

Because the new byte code format is incompatible, the extension version is
bumped to 1.

This was caused by recent lib-smtp changes.
There is no envelope in IMAPSieve context, so the rcpt parameters are NULL, causing the segfault.

The session ID is now already added by Dovecot.

lib-sieve: vacation extension: Use the correct address for "From:" outgoing header when original envelope recipient is found.

Caused by earlier adjustments for Dovecot lib-smtp.
Copy-paste problem detected by Coverity.

It is a remnant from debugging.

Only calls that require space allocation are to be changed.