Update of /export/home/ntop/ntop
In directory unknown:/tmp/cvs-serv8670
Modified Files:
globals-core.h
Log Message:
It turns out that the much loved construct,
if(snprintf(....) < 0) BufferTooShort();
is flawed for recent glibc libraries. Quoting (Linux - RH9) man snprintf:
Return value
Upon successful return, these functions return the number of characters
printed (not including the trailing '\0' used to end output to
strings). The functions snprintf and vsnprintf do not write more than
size bytes (including the trailing '\0'). If the output was truncated
due to this limit then the return value is the number of characters
(not including the trailing '\0') which would have been written to the
final string if enough space had been available. Thus, a return value
of size or more means that the output was truncated. (See also below
under NOTES.) If an output error is encountered, a negative value is
returned.
...
NOTES
The glibc implementation of the functions snprintf and vsnprintf con-
forms to the C99 standard, i.e., behaves as described above, since
glibc version 2.1. Until glibc 2.0.6 they would return -1 when the out-
put was truncated.
This large patch replaces that logic by a routine (actually a macro):
safe_snprintf()
which handles BOTH cases and automatically logs the error message, including
the file/line and minimum required size (glibc >= 2.1):
**ERROR** Buffer too short @ xxxxxxxxxx.c:3728 (increase to at least 25)
One difference - since it's a macro, you can not code
safe_snprintf(...
#ifdef WIN32
#else
#endif
);
instead the #ifdef needs to completely surround the macro:
#ifdef WIN32
safe_snprintf(...);
#else
safe_snprintf(...);
#endif
For cases where you genuinely need to old behavior (i.e. not a snprintf()),
a new BufferTooSmall() macro replaces BufferTooShort().
If you find problems, report them to the ntop-dev list. Thanks!
The development of this function was partly sponsored by an international
organization which wishes to remain anonymous.
-----Burton
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