Diagnostic messages

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Appendix D Diagnostic messages

The following table lists the warnings and errors that are likely to appear in the mpatrol log file when problems with dynamic memory allocations and memory operations occur. Other types of warnings and errors may also appear in the log file, but they are likely to be associated with parsing options and reading symbols from executable files and so should be self-explanatory.

In all cases, if a warning or error is caused by one of the memory access checking functions (invoked through the use of the -fcheck-memory-usage option to the GNU compiler) then execution will halt regardless, despite what the description of the diagnostic message says.

If a warning or error occurs due to a direct call to an mpatrol library function then an attempt will be made to provide a log entry for the call. If the diagnostic was not caused by a normal memory allocation, reallocation or deallocation function then the log entry will be preceded by `LOG:'. The function type will be listed as `check' if it does not fall into the normal categories or if not enough information is available.

Note that on UNIX platforms, if the diagnostic message is caused by a line in the program source then the EDIT and LIST options can be used to illustrate more clearly where in the source code the warning or error occurred.

`ALLOVF'

Message
`allocation %1 has a corrupted overflow buffer at %2'
Type
Error
`%1'
The pointer to the memory allocation that has a corrupted overflow buffer.
`%2'
The pointer to the first byte of corruption in the memory allocation's overflow buffer.
Cause
Something has corrupted the overflow buffer of a memory allocation and this has been caught at the next invocation of an mpatrol function when the OFLOWSIZE or PAGEALLOC options were used. This particular error message will not occur if the OFLOWWATCH option was used since all overflow buffers will be write protected.
Additional
The log file entry, the library summary, the contents of the overflow buffer and information about the original memory allocation.
Result
Execution terminates.
`ALLZER'

Message
`attempt to create an allocation of size 0'
Type
Warning
Cause
A function was called to allocate memory with a size of `0' when either of the CHECKALL or CHECKALLOCS options were used. This warning will not occur by default as the ANSI C/C++ standards allow this behaviour, and it is really only a portability issue.
Additional
The log file entry.
Result
The size is increased to 1 byte and execution continues.
`BADALN'

Message
`alignment %1 is not a power of two'
Type
Warning
`%1'
The alignment in bytes.
Cause
The memalign() function was called to allocate memory with an alignment which was not a power of two when either of the CHECKALL or CHECKALLOCS options were used.
Additional
The log file entry.
Result
The alignment is rounded up to the nearest power of two and execution continues.
`FRDCOR'

Message
`freed allocation %1 has memory corruption at %2'
Type
Error
`%1'
The pointer to the freed memory allocation that has been corrupted.
`%2'
The pointer to the first byte of corruption in the freed memory allocation.
Cause
Something has corrupted the contents of a previously freed memory allocation and this has been caught at the next invocation of an mpatrol function when the NOFREE option was used. This particular error message will not occur if the PAGEALLOC option was used since all freed memory allocations will be write protected and will also not occur if the PRESERVE option was used since the free byte cannot be used to verify the freed allocation's contents.
Additional
The log file entry, the library summary, the contents of the freed memory block and information about the original memory allocation.
Result
Execution terminates.
`FRDOPN'

Message
`attempt to perform operation on freed memory'
Type
Error
Cause
A memory operation function was called to operate on a previously freed memory allocation when the NOFREE option was used.
Additional
The log file entry and information about the original memory allocation.
Result
The memory operation fails and execution continues.
`FRDOVF'

Message
`freed allocation %1 has a corrupted overflow buffer at %2'
Type
Error
`%1'
The pointer to the freed memory allocation that has a corrupted overflow buffer.
`%2'
The pointer to the first byte of corruption in the freed memory allocation's overflow buffer.
Cause
Something has corrupted the overflow buffer of a previously freed memory allocation and this has been caught at the next invocation of an mpatrol function when the NOFREE option was used in conjunction with the OFLOWSIZE or PAGEALLOC options. This particular error message will not occur if the OFLOWWATCH option was used since all overflow buffers will be write protected.
Additional
The log file entry, the library summary, the contents of the overflow buffer and information about the original memory allocation.
Result
Execution terminates.
`FRECOR'

Message
`free memory corruption at %1'
Type
Error
`%1'
The pointer to the first byte of corruption in free memory.
Cause
Something has corrupted the contents of the free memory pool and this has been caught at the next invocation of an mpatrol function. This particular error message will not occur if the PAGEALLOC option was used since all free memory will be write protected.
Additional
The log file entry, the library summary and the contents of the free memory block.
Result
Execution terminates.
`FREMRK'

Message
`attempt to free marked allocation %1'
Type
Error
`%1'
The pointer to the memory allocation that has been requested to be freed.
Cause
An attempt was made to free a marked memory allocation. This is not allowed since any memory allocations that have been marked indicate to the mpatrol library that they should remain allocated for the duration of the program.
Additional
The log file entry and information about the original memory allocation.
Result
No memory allocation will be freed and execution continues.
`FRENUL'

Message
`attempt to free a NULL pointer'
Type
Warning
Cause
A function was called to free an existing memory allocation with a pointer of `NULL' when either of the CHECKALL or CHECKFREES options were used. This warning will not occur by default as the ANSI C/C++ standards allow this behaviour, and it is really only a portability issue.
Additional
The log file entry.
Result
No memory allocation will be freed and execution continues.
`FREOPN'

Message
`attempt to perform operation on free memory'
Type
Error
Cause
A memory operation function was called to operate on free memory.
Additional
The log file entry.
Result
The memory operation fails and execution continues.
`ILLMEM'

Message
`illegal memory access at address %1'
Type
Error
`%1'
The address at which the illegal memory access occurred.
Cause
An attempt was made to read from or write to an illegal address on systems which have virtual memory. This address may or may not exist in the heap, or it may be a perfectly valid address that was misaligned and caused a bus error. In either case, the mpatrol library will attempt to associate the address with an existing memory allocation. This error may also appear instead of memory corruption errors if the PAGEALLOC or OFLOWWATCH options were used.
Additional
The library summary, information about the original memory allocation (if possible) and the call stack of where the error occurred.
Result
Execution terminates.
`INCOMP'

Message
`%1 was allocated with %2'
Type
Error
`%1'
The pointer to the memory allocation that is to be resized or freed.
`%2'
The name of the function which originally allocated the memory allocation.
Cause
A function was called to resize or free a memory allocation that was allocated with a function that is incompatible with the current request. For example, a memory allocation which was allocated with operator new being resized with realloc().
Additional
The log file entry and information about the original memory allocation.
Result
The reallocation or deallocation fails and execution continues.
`MAXALN'

Message
`alignment %1 is greater than the system page size'
Type
Warning
`%1'
The alignment in bytes.
Cause
The memalign() function was called to allocate memory with an alignment which was greater than the system page size when either of the CHECKALL or CHECKALLOCS options were used. The mpatrol library cannot currently align memory allocations to a byte alignment over this limit, but then neither can most other implementations.
Additional
The log file entry.
Result
The alignment is set to the system page size and execution continues.
`MISMAT'

Message
`%1 does not match allocation of %2'
Type
Error
`%1'
The pointer to the memory allocation that is to be resized or freed.
`%2'
The pointer to the memory allocation that the mpatrol library knows about.
Cause
A function was called to resize or free a memory allocation that begins at a different address from that supplied.
Additional
The log file entry and information about the original memory allocation.
Result
The reallocation or deallocation fails and execution continues.
`NOTALL'

Message
`%1 has not been allocated'
Type
Error
`%1'
The pointer to the memory allocation that is to be resized or freed.
Cause
A function was called to resize or free a memory allocation that has not been allocated. It may be that the memory allocation has just been freed, in which case the NOFREE option should be used to provide a better diagnostic message.
Additional
The log file entry.
Result
The reallocation or deallocation fails and execution continues.
`NULOPN'

Message
`attempt to perform operation on a NULL pointer'
Type
Error
Cause
A memory operation function was called to operate on a `NULL' pointer. If the length of the operation was zero then this error will only occur when the CHECKALL or CHECKMEMORY options were used as the ANSI C/C++ standards allow this behaviour, and it is really only a portability issue.
Additional
The log file entry.
Result
The memory operation fails and execution continues.
`OUTMEM'

Message
`out of memory'
Type
Error
Cause
The alloca(), xmalloc() or MP_MALLOC() families of functions were called to allocate memory, but no more memory was available to allocate and the low-memory handler, if installed, could not free up sufficient memory. This error can also be caused by a call to the operator new or operator new[] C++ operators (not the nothrow versions) when they would otherwise return a `NULL' pointer and the mpatrol library was compiled with a C compiler (which means that it cannot throw a std::bad_alloc exception).
Additional
The library summary.
Result
Execution terminates.
`PRVFRD'

Message
`%1 was freed with %2'
Type
Error
`%1'
The pointer to the memory allocation that is to be resized or freed.
`%2'
The name of the function which originally freed the memory allocation.
Cause
A function was called to resize or free a memory allocation that had previously been freed when the NOFREE option was used.
Additional
The log file entry and information about the original memory allocation.
Result
The reallocation or deallocation fails and execution continues.
`RNGOVF'

Message
`range [%1,%2] overflows [%3,%4]'
Type
Warning/Error
`%1'
The start address of the memory region.
`%2'
The end address of the memory region.
`%3'
The start address of the memory allocation.
`%4'
The end address of the memory allocation.
Cause
A memory operation function was called to operate on a range of memory which overflowed the boundaries of a memory allocation.
Additional
The log file entry and information about the original memory allocation.
Result
The operation will be only be performed (and will be changed from an error to a warning) if the ALLOWOFLOW option was used, but execution will continue regardless.
`RNGOVL'

Message
`range [%1,%2] overlaps [%3,%4]'
Type
Warning
`%1'
The start address of the source memory region.
`%2'
The end address of the source memory region.
`%3'
The start address of the destination memory region.
`%4'
The end address of the destination memory region.
Cause
The memcpy() or memccpy() function was called to copy overlapping memory regions. This is an error on many systems and the ANSI C/C++ standards specify that memmove() should be used instead.
Additional
The log file entry.
Result
The copy operation will still be performed but it will deal correctly with overlapping memory regions.
`RSZNUL'

Message
`attempt to resize a NULL pointer'
Type
Warning
Cause
A function was called to resize an existing memory allocation with a pointer of `NULL' when either of the CHECKALL or CHECKREALLOCS options were used. This warning will not occur by default as the ANSI C/C++ standards allow this behaviour, and it is really only a portability issue.
Additional
The log file entry.
Result
A new memory allocation is returned and execution continues.
`RSZZER'

Message
`attempt to resize an allocation to size 0'
Type
Warning
Cause
A function was called to resize an existing memory allocation to a size of `0' when either of the CHECKALL or CHECKREALLOCS options were used. This warning will not occur by default as the ANSI C/C++ standards allow this behaviour, and it is really only a portability issue.
Additional
The log file entry.
Result
The existing memory allocation will be freed and execution continues.
`STROVF'

Message
`string %1 overflows [%2,%3]'
Type
Error
`%1'
The start address of the string.
`%2'
The start address of the memory allocation.
`%3'
The end address of the memory allocation.
Cause
A string function was called to operate on a string which overflowed the boundaries of a memory allocation.
Additional
The log file entry and information about the original memory allocation.
Result
The operation will not be performed and execution continues.
`ZERALN'

Message
`alignment 0 is invalid'
Type
Warning
Cause
The memalign() function was called to allocate memory with an alignment of `0' when either of the CHECKALL or CHECKALLOCS options were used.
Additional
The log file entry.
Result
The alignment is set to the default system alignment and execution continues.
`ZEROPN'

Message
`attempt to perform a zero-sized operation'
Type
Warning
Cause
A memory operation function was called with a length of zero. This warning will only occur when the CHECKALL or CHECKMEMORY options were used as the ANSI C/C++ standards allow this behaviour, and it is really only a portability issue.
Additional
The log file entry.
Result
The operation will not be performed and execution continues.