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wrong assumptions about pthread_t being numeric
- From: John Spencer <maillist-gdbpatches at barfooze dot de>
- To: gdb-patches at sourceware dot org
- Date: Sat, 17 Sep 2011 00:40:47 +0200
- Subject: wrong assumptions about pthread_t being numeric
there are a couple of spots in thread handling which assume that
thread_t (typedef of pthread_t) is of a numeric type.
according to POSIX
http://pubs.opengroup.org/onlinepubs/007904875/basedefs/sys/types.h.html
pthread_t is a non-arithmetic type.
thus whenever a "thread id" of type pthread_t is used in a numeric
context, it invokes undefined behaviour, since pthread_t could be a
struct, a pointer, etc.
for example, it is implemented as a pointer to a struct in musl libc for
efficiency.
i basically wanted to fix my compile error and send a patch, but i think
this should be discussed first.
thread-db.c: In function 'find_one_thread':
thread-db.c:295:7: error: format '%ld' expects type 'long int', but
argument 3 has type 'thread_t'
thread-db.c: In function 'attach_thread':
thread-db.c:335:7: error: format '%ld' expects type 'long int', but
argument 3 has type 'thread_t'
thread-db.c:341:9: error: format '%ld' expects type 'long int', but
argument 2 has type 'thread_t'
$ grep ti_tid `find gdb-7.3.1 -name '*.c'`
gdb-7.3.1/gdb/sol-thread.c: return BUILD_THREAD (ti.ti_tid, PIDGET (lwp));
gdb-7.3.1/gdb/sol-thread.c: ptid = BUILD_THREAD (ti.ti_tid, PIDGET
(inferior_ptid));
gdb-7.3.1/gdb/sol-thread.c: ti.ti_tid, ti.ti_lid);
gdb-7.3.1/gdb/linux-thread-db.c: gdb_assert (ti_p->ti_tid != 0);
gdb-7.3.1/gdb/linux-thread-db.c: private->tid = ti_p->ti_tid;
gdb-7.3.1/gdb/linux-thread-db.c: if (ti.ti_tid == 0 &&
target_has_execution)
gdb-7.3.1/gdb/gdbserver/thread-db.c: ti.ti_tid, ti.ti_lid);
gdb-7.3.1/gdb/gdbserver/thread-db.c: if (ti.ti_tid == 0)
gdb-7.3.1/gdb/gdbserver/thread-db.c: ti_p->ti_tid, ti_p->ti_lid);
gdb-7.3.1/gdb/gdbserver/thread-db.c: ti_p->ti_tid, ti_p->ti_lid);
gdb-7.3.1/gdb/aix-thread.c: return thrinf.ti_tid;
-- JS