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curl_off_t explained
curl_off_t is a data type provided by the external libcurl include headers. It
is the type meant to be used for the curl_easy_setopt() options that end with
LARGE. The type is 64bit large on most modern platforms.
Transition from < 7.19.0 to >= 7.19.0
Applications that used libcurl before 7.19.0 that are rebuilt with a libcurl
that is 7.19.0 or later may or may not have to worry about anything of
this. We have made a significant effort to make the transition really seamless
and transparent.
You have have to take notice if you are in one of the following situations:
o Your app is using or will after the transition use a libcurl that is built
with LFS (large file support) disabled even though your system otherwise
supports it.
o Your app is using or will after the transition use a libcurl that doesn't
support LFS at all, but your system and compiler support 64bit data types.
In both these cases, the curl_off_t type will now (after the transition) be
64bit where it previously was 32bit. This will cause a binary incompatibility
that you MAY need to deal with.
This new way has several benefits:
o Platforms without LFS support can still use libcurl to do >32 bit file
transfers and range operations etc as long as they have >32 bit data-types
o Applications will no longer easily build with the curl_off_t size
mismatched, which has been a very frequent (and annoying) problem with
libcurl <= 7.18.2
Previously, before 7.19.0, the curl_off_t type would be rather strongly
connected to the size of the system off_t type, where currently curl_off_t is
independent of that.
The strong connection to off_t made it troublesome for application authors
since when they did mistakes, they could get curl_off_t type of different
sizes in the app vs libcurl, and that caused strange effects that were hard to
track and detect by users of libcurl.
We opted to not bump the soname for the library unconditionally, simply
because soname bumping is causing a lot of grief and moaning all over the
community so we try to keep that at minimum. Also, our selected design path
should be 100% backwards compatible for the vast majority of all libcurl
Enforce SONAME bump
If configure doesn't detect your case where a bump is necessary, re-run it
with the --enable-soname-bump command line option!