Hi Marcus, > __errno_location and __h_errno_location are no longer weak symbols > and so can not be overwritten any longer. The internal glibc systemcall > wrappers no longer call the functions by reference, but directly. the real problem is even worse. glibc has switched to using thread-local storage for errno (i.e. it is declared as 'extern __thread int errno') when the tool chain supports the __thread keyword. This means that C source code compiled against the new headers will result in assembler code that *directly* accesses a thread-local variable as defined by the TLS ABI. In the case of errno, this will involve accessing the %gs segment using an offset from the GOT, without any function call being performed. (errno is defined to use the initial-exec TLS storage model.) The __errno_location routine is provided only for backwards compatibility reasons, it is no longer guaranteed that every access to errno calls it. Thus, if you overwrite the implementation of __errno_location, you will only catch *some* errno accesses, not all of them ... Bye, Ulrich (who has just implemented TLS for s390 ;-/) -- Dr. Ulrich Weigand weigand@informatik.uni-erlangen.de
