lib: buffer - Add t_buffer_create Helper for making a datastack buffer

lib: Clarify that buffer_write() zero-fills buffer when writing past its size

lib: Add buffer truncate

global: Require comparisons to be strict boolean expressions * No implicit integer -> boolean or pointer -> boolean conversions * !expr can be used only if expr is boolean type These were checked with a patched clang. It found various actual bugs, which were fixed by the previous commits.

Removed buffer_reset(). It was just a wrapper to buffer_set_used_size() and its comment was a bit confusing (or obsolete), since it wasn't actually immediately zeroing out the buffer.

lib: Updated buffer_set_used_size() comment and added unit test.

lib: Fixed __builtin_object_size() usage in buffer.h With type=3 size for unknown objects is set to 0, which causes a compiler failure. With type=1 it's (size_t)-1, which passes the check.

lib: Added buffer_get_writable_size()

lib: compile time checks for buffer creation Ensure the data buffer has as much space as the size parameter claims. This uses the strictest test GCC provides - the smallest containing object, and returning 0 for unknown size. Signed-off-by: Phil Carmody <phil@dovecot.fi>

Added buffer_verify_pool()

Renamed buffer_create_*data() to buffer_create_from_*data() for consistency. Especially i_stream_create_from_data() was a very similar function, which made it difficult to remember which one should have "from" and which one shouldn't.

Marked functions parameters that are allowed to be NULL. Some APIs were also changed. The non-obvious APIs where NULL parameter was changed to "" are master_service_init() and auth_master_user_list_init(). These checks can currently be enabled only on a patched clang: http://llvm.org/bugs/show_bug.cgi?id=6786

Removed buffer_create_static_hard(). buffer_create_data() handles most of the situations where it was wanted. --HG-- branch : HEAD

buffer_create_[const_]data() API change: Take buffer_t as parameter instead of allocating it. --HG-- branch : HEAD

Added more consts, ATTR_CONSTs and ATTR_PUREs. --HG-- branch : HEAD

Changed buffer_free() and buffer_free_without_data() APIs to take ** pointer which is set to NULL instead of hiding it with a macro. --HG-- branch : HEAD

Changed .h ifdef/defines to use <NAME>_H format. --HG-- branch : HEAD

Added buffer_get_pool() --HG-- branch : HEAD

Array API redesigned to work using unions. It now provides type safety without having to enable DEBUG, as long as the compiler supports typeof(). Its API changed a bit. It now allows directly accessing the array contents, although that's not necessarily recommended. Changed existing array usage to be type safe in a bit more places. Removed array_t completely. Also did s/modifyable/modifiable/. --HG-- branch : HEAD

deinit, unref, destroy, close, free, etc. functions now take a pointer to their data pointer, and set it to NULL. This makes double-frees less likely to cause security holes. --HG-- branch : HEAD

Added "bool" type and changed all ints that were used as booleans to bool. --HG-- branch : HEAD

Added buffer_update_const_data(). --HG-- branch : HEAD

Added BUFFER_APPROX_SIZE which can be used to approximately calculate the memory used by buffer struct itself. --HG-- branch : HEAD

Added buffer_cmp(). --HG-- branch : HEAD

Minor cleanup: added _r suffix to used_size pointer parameters. --HG-- branch : HEAD

Buffer API change: we no longer support limited sized buffers where writes past limit wouldn't kill the process. They weren't used hardly anywhere, they could have hidden bugs and the code for handling them was too complex. This also changed base64 and hex-binary APIs. --HG-- branch : HEAD

Added buffer_insert_zero() --HG-- branch : HEAD

Added buffer_write_zero and buffer_append_zero. --HG-- branch : HEAD

Added buffer_reset() --HG-- branch : HEAD

buffer.data should be void, not unsigned char --HG-- branch : HEAD

Removed start_pos and limit handling, they weren't used much and were only making it more complex. Also made data and size variables directly accessible to make it easier to use buffers. --HG-- branch : HEAD

Use unsigned char for buffer_append_c and str_append_c. --HG-- branch : HEAD

Renamed buffer_*_space() to buffer_*_space_unsafe() and added several warnings about using them. Fixed their usage in a few places in sources where they could have produced invalid results (no buffer overflows, luckily). --HG-- branch : HEAD

Naming style changes, finally got tired of most of the typedefs. Also the previous enum -> macro change reverted so that we don't use the highest bit anymore, that's incompatible with old indexes so they will be rebuilt. --HG-- branch : HEAD

Marked all non-trivial buffer modifications with @UNSAFE tag. Several cleanups and a couple of minor bugfixes. --HG-- branch : HEAD

comment update --HG-- branch : HEAD

Added buffer API. Point is to hide all buffer writing behind this API which verifies that nothing overflows. Much better than doing the same checks all around the code, even if it is slightly slower. Buffer reading is still mostly done directly, that isn't such a big security risk and I can't think of a reasonable API for it anyway. --HG-- branch : HEAD