Getting mail_fetch_body to work - IMAP

On Thu, 8 Jul 2004, Sebastian Schuberth wrote:
> But whenever I try to
> specify a section, an empty string (not NULL) is returned. I tried for
> example:
> char *text=mail_fetch_body(stream,number,"<0.500>",&length,FT_PEEK);
> char *text=mail_fetch_body(stream,number,"TEXT<0.500>",&length,FT_PEEK);
> char *text=mail_fetch_body(stream,number,"[TEXT]",&length,FT_PEEK);

The "section" argument to mail_fetch_body() is what RFC 3501 calls a
"section-part". You can't use an RFC 3501 "section-text"; that's what
those separate mail_fetch_body(), mail_fetch_header(), mail_fetch_text(),
and mail_fetch_mime() functions do. You most definitely can not use a
partial specifier (which isn't part of a RFC 3501 section at all!).

To do partial fetches you must use mail_partial_body() and/or
mail_partial_text(), which in turn means that you have to arm a mailgets_t
function prior to the call (and disarm it afterwards).

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.

> To do partial fetches you must use mail_partial_body() and/or
> mail_partial_text(), which in turn means that you have to arm a
> mailgets_t function prior to the call (and disarm it afterwards).

FYI: I'm trying to emulate the functionality of POP3's TOP command. So I
came up with this:

char* mailgets(readfn_t f,void* stream,unsigned long size,GETS_DATA* md) {
char *buffer=new char[size];
f(stream,size,buffer);
return buffer;
}

bool WINAPI TPluginProtocol::RetrieveTop(const int MsgNum,int
LineCount,char** pDest) {
// ...

mail_parameters(stream,SET_GETS,mailgets);
length=mail_partial_text(stream,number,NIL,0,500,FT_PEEK);
mail_parameters(stream,SET_GETS,NIL);

// ...
}

This is where i'm stuck. Questions:
- How do I obtain the bytes read as "mail_partial_text()" only returns a
long (the number of bytes read, I guess)?
- Do I need to make "buffer" global in order to access the bytes read
and be able to free it?

Thanks for your help!

BTW: Isn't there any more up-to-date documentation than "internal.txt"?
(I mean documentation, not example source code :-)

--
Sebastian Schuberth

On Fri, 9 Jul 2004, Sebastian Schuberth wrote:
> This is where i'm stuck. Questions:
> - How do I obtain the bytes read

That's the job of your mailgets_t callback routine.

> as "mail_partial_text()" only returns a long
> (the number of bytes read, I guess)?

mail_partial_text() returns a T vs. NIL success/fail indication.

> - Do I need to make "buffer" global in order to access the bytes read and be
> able to free it?

The GETS_DATA holds a lot of interesting pieces of data for your
mailgets_t callback routine to use. Among other things, it holds the open
MAILSTREAM, which has convenient members such as sparep which you can
stash data.

> BTW: Isn't there any more up-to-date documentation than "internal.txt"? (I
> mean documentation, not example source code :-)

No, there isn't. It would be a major (expensive) undertaking, and there
doesn't seem to be all that many people who would benefit from it.

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.

>> - Do I need to make "buffer" global in order to access the bytes read
>> and be able to free it?
>
> The GETS_DATA holds a lot of interesting pieces of data for your
> mailgets_t callback routine to use. Among other things, it holds the
> open MAILSTREAM, which has convenient members such as sparep which you
> can stash data.

Thanks, I got it working now. One slightly OT question: What is the
difference between "mail_partial_text" and "mail_partial_body"? In my
test, both deliver the same strings. Which one should I use if I want to
get the pure hand-written contents of a mail?

--
Sebastian Schuberth

On Fri, 9 Jul 2004, Sebastian Schuberth wrote:
> Thanks, I got it working now. One slightly OT question: What is the
> difference between "mail_partial_text" and "mail_partial_body"? In my test,
> both deliver the same strings.

mail_partial_text() and mail_partial_body() are ****ogous to
mail_fetch_text() and mail_fetch_body().

A "text" fetch is without regard to MIME, and only can be done to sections
that refer to a message (either top level or a MESSAGE/RFC822). It refers
to the entire text of the message (the part after the delimiting CRLFCRLF
at the end of the header).

A "body" fetch is a MIME body part fetch.

For a non-multipart message only, a text fetch and a body fetch of section
"1" return the same string.

> Which one should I use if I want to get the
> pure hand-written contents of a mail?

I have no idea what you mean by "pure hand-written contents of a mail."

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.

>> Which one should I use if I want to get the pure hand-written contents
>> of a mail?
>
> I have no idea what you mean by "pure hand-written contents of a mail."

:-) Your answer to my previous question already also answered this
question. Thanks again.

--
Sebastian Schuberth

>> Thanks, I got it working now. One slightly OT question: What is the
>> difference between "mail_partial_text" and "mail_partial_body"? In my
>> test, both deliver the same strings.

[...]

> A "text" fetch is without regard to MIME, and only can be done to
> sections that refer to a message (either top level or a
> MESSAGE/RFC822). It refers to the entire text of the message (the part
> after the delimiting CRLFCRLF at the end of the header).

Hmm, as mentioned above, it basically works. But from time to time I'm
getting exceptions whehn trying to preview messages. Can you see any
misuse of the way c-client is intended to work in this code:

char* mailgets(readfn_t f,void* stream,unsigned long size,GETS_DATA* md) {
md->stream->sparep=new char[size+1];
char *buffer=static_cast<char*>(md->stream->sparep);
f(stream,size,buffer);
buffer[size]='\0';
return buffer;
}

bool WINAPI TPluginProtocol::RetrieveTop(const int MsgNum,int
LineCount,char** pDest) {
// ...

char *header=mail_fetch_header(stream,number,NIL,NIL,NIL,FT_PEEK);
length=strlen(header);

// Assume an average number of bytes per line and get the body contents.
mail_parameters(stream,SET_GETS,mailgets);
bool
result=(mail_partial_body(stream,number,NIL,0,LineCount*50,FT_PEEK)!=NIL);
mail_parameters(stream,SET_GETS,NIL);
if (!result) return false;

char *string=static_cast<char*>(stream->sparep);

*pDest=new char[length+strlen(string)+1];
if (*pDest) {
strcpy(*pDest,header);
strcpy(*pDest+length,string);
result=(**pDest!='\0');
}

delete string;
stream->sparep=NIL;

// ...
}

--
Sebastian Schuberth

I'm sorry, I can't help you debug your code, especially not code written
in C++ (*not* my favorite language). I will comment that you probably
shouldn't put the string itself on the sparep, but rather a SIZEDTEXT
holding both the string and its size. In general, you should return the
string and its size instead of assuming null termination; SIZEDTEXT is
convenient but you can just have a char* and a ulong pair.

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.