This file provides Dbmalloc1-compatible functions which are built on top of the mpatrol library. They are compatible with the last known public release of Dbmalloc (patch level 14), but only the Dbmalloc-specific functions are defined here, leaving the overriding of standard functions up to the mpatrol library. As the mpatrol library does not currently override the C library string functions and the X toolkit heap allocation functions, neither does this file.
The dbmallopt() function does not support the setting of all of the
Dbmalloc options. In fact, most of them do not make sense when applied to the
mpatrol library. Some of them have slightly changed behaviour due to the
mapping process and some of them cannot be implemented due to the mpatrol
library having been initialised beforehand.
The malloc_dump() function does not support the full recognition of the
MALLOC_DETAIL option in that it does not display the additional columns
and summary that the Dbmalloc library does. This is because this would make no
sense when applied to the mpatrol library, but it does still affect whether
freed allocations are shown in the listing (although the details for such
allocations are slightly different, and there are no entries displayed for free
memory blocks).
The output for the malloc_dump() and malloc_list() functions is
almost identical to that of the Dbmalloc library except for a slight change in
the pointer format when displaying the address of each memory allocation. The
stack information is obtained differently as well, since the mpatrol library
records symbolic stack tracebacks for each memory allocation. As a result,
malloc_enter() and malloc_leave() do nothing and the return
address in a stack frame is displayed if no associated symbol name, file and
line number could be determined. Parentheses are not printed at the end of
symbol names so that they can be processed properly by a C++ demangler if
necessary. Passing a file descriptor of `0' to malloc_dump() or
malloc_list() results in the output being sent to the mpatrol log file.
The malloc_size() and malloc_mark() functions do not give an error
message if the pointer passed in does not correspond to a heap allocation.
Neither of these functions automatically perform an integrity check of the
heap. Note that the malloc_chain_check() function will never return a
non-zero value — it always terminates with an error message in the mpatrol log
file whenever it detects heap corruption. As a result, the
malloc_abort() function is not used.
This file is initialised via the mpatrol library's initialiser function feature,
which means that if the __mp_init_dbmalloc() function is noted by the
mpatrol symbol manager then it will be called when the mpatrol library is being
initialised. If this feature is not supported then the dbmallinit()
function must be called as early on as possible, otherwise this file will not be
initialised until one of its functions are called.