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(scm_ttyname): Use scm_i_misc_mutex for thread safety.

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This commit is contained in:
Kevin Ryde 2004-07-29 00:12:25 +00:00
parent 8d20b7af9e
commit e8a590639c
1 changed files with 23 additions and 4 deletions
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27
libguile/posix.c
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@ -768,6 +768,15 @@ SCM_DEFINE (scm_setsid, "setsid", 0, 0, 0,
#undef FUNC_NAME #undef FUNC_NAME
#endif /* HAVE_SETSID */ #endif /* HAVE_SETSID */
/* ttyname returns its result in a single static buffer, hence
scm_i_misc_mutex for thread safety. In glibc 2.3.2 two threads
continuously calling ttyname will otherwise get an overwrite quite
easily.
ttyname_r (when available) could be used instead of scm_i_misc_mutex, but
there's probably little to be gained in either speed or parallelism. */
#ifdef HAVE_TTYNAME #ifdef HAVE_TTYNAME
SCM_DEFINE (scm_ttyname, "ttyname", 1, 0, 0, SCM_DEFINE (scm_ttyname, "ttyname", 1, 0, 0,
(SCM port), (SCM port),
@ -776,22 +785,32 @@ SCM_DEFINE (scm_ttyname, "ttyname", 1, 0, 0,
#define FUNC_NAME s_scm_ttyname #define FUNC_NAME s_scm_ttyname
{ {
char *result; char *result;
int fd; int fd, err;
SCM ret;
port = SCM_COERCE_OUTPORT (port); port = SCM_COERCE_OUTPORT (port);
SCM_VALIDATE_OPPORT (1, port); SCM_VALIDATE_OPPORT (1, port);
if (!SCM_FPORTP (port)) if (!SCM_FPORTP (port))
return SCM_BOOL_F; return SCM_BOOL_F;
fd = SCM_FPORT_FDES (port); fd = SCM_FPORT_FDES (port);
scm_mutex_lock (&scm_i_misc_mutex);
SCM_SYSCALL (result = ttyname (fd)); SCM_SYSCALL (result = ttyname (fd));
err = errno;
ret = scm_makfrom0str (result);
scm_mutex_unlock (&scm_i_misc_mutex);
if (!result) if (!result)
SCM_SYSERROR; {
/* result could be overwritten by another call to ttyname */ errno = err;
return (scm_makfrom0str (result)); SCM_SYSERROR;
}
return ret;
} }
#undef FUNC_NAME #undef FUNC_NAME
#endif /* HAVE_TTYNAME */ #endif /* HAVE_TTYNAME */
/* For thread safety "buf" is used instead of NULL for the ctermid static /* For thread safety "buf" is used instead of NULL for the ctermid static
buffer. Actually it's unlikely the controlling terminal will change buffer. Actually it's unlikely the controlling terminal will change
during program execution, and indeed on glibc (2.3.2) it's always just during program execution, and indeed on glibc (2.3.2) it's always just