On 12/6/22 15:50, Timothe Litt via curl-library wrote:
On 06-Dec-22 09:24, Patrick Monnerat via curl-library wrote:
It's a good idea.
Thanks!
I don't think your seek() semantics are correct. seek(SEEK_END)
terminates connection, which isn't what seek does, or what a C program
would expect. seek just positions. I think that what you're doing
maps to fclose().
No, I know it is not !
The reasons why I did it this way is there is no way to get an internal
handle (struct cookie *) from a FILE * thus is it not possible to
implement a user-callable flush function (without close) elsewhere. But
a caller might want to flush without close, to check if no error
occurred. The standard fflush drains the output buffer, but does not
wait for request completion. In addition, a real full-featured fseek is
meaningless, so I decide to use it. I wish glibc designers have provided
a "void *fcookie(FILE *fp)" to avoid this problem. We have to do with
what is provided.
Fclose() should not be waiting (or at least not able to hang). In
addition, you cannot retrieve the error status after the close, so
you'll never know if the request was successful or not.
I'm aware this deviates from the standard semantics, but I did not find
yet any other elegant way to do it.
seek should return errno = EBADF if not implemented. EINVAL is for a
bad 'whence' .
Thanks for pointing to it. In fact, it IS implemented but in certain
cases it should rather return ESPIPE.
The idea of doing range requests based on seek from fcurll's issues
has merit. May need some support in the library.
Why not! But this will rather be an FTP-like RESTART command than a real
range.
You might also provide these as curl_xxx(), using curl handles. While
transparency is nice, you can't always hook the C RTL. curl_xxx could
be the portable version - it's a pretty simple search-and-replace for
users. And your hooked version, if available at configure time, can
be used where it's available.
Well... this is fcurl!
You may also want to consider other key functions, including delete
and rename. With ftp, at least: chmod, chown...
I also had this ikind of idea. But I'm stuck with the missing
fcookie(fp) problem here too! And chmod, chown... are file systems API,
not IO.
There's quite a bit to making network operations look exactly like
local files. But you're definitely on to a useful subset.
Perfection cannot be reached with "patched pieces" :-)
Many thanks for your comments,
Patrick
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