diff options
Diffstat (limited to 'Misc')
| -rw-r--r-- | Misc/SpecialBuilds.txt | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/Misc/SpecialBuilds.txt b/Misc/SpecialBuilds.txt index 0851aa5..0507c6e 100644 --- a/Misc/SpecialBuilds.txt +++ b/Misc/SpecialBuilds.txt @@ -80,7 +80,9 @@ ASCII strings. 8 bytes are added at each end of each block of N bytes requested. The memory layout is like so, where p represents the address returned by a -malloc-like or realloc-like function: +malloc-like or realloc-like function (p[i:j] means the slice of bytes +from *(p+i) inclusive up to *(p+j) exclusive; note that the treatment +of negative indices differs from a Python slice): p[-8:-4] Number of bytes originally asked for. 4-byte unsigned integer, @@ -104,7 +106,9 @@ p[N+4:N+8] 4-byte unsigned integer, big-endian. If "bad memory" is detected later, the serial number gives an excellent way to set a breakpoint on the next run, to capture the - instant at which this block was passed out. + instant at which this block was passed out. The static function + bumpserialno() in obmalloc.c is the only place the serial number + is incremented, and exists so you can set such a breakpoint easily. A malloc-like or free-like function first checks that the FORBIDDENBYTEs at each end are intact. If they've been altered, diagnostic output is @@ -124,7 +128,9 @@ Py_DEBUG This is what is generally meant by "a debug build" of Python. Py_DEBUG implies Py_REF_DEBUG, Py_TRACE_REFS, and PYMALLOC_DEBUG (if -WITH_PYMALLOC is enabled). +WITH_PYMALLOC is enabled). In addition, C assert()s are enabled (via +the C way: by not defining NDEBUG), and some routines do additional +sanity checks inside "#ifdef Py_DEBUG" blocks. --------------------------------------------------------------------------- COUNT_ALLOCS |