diff options
Diffstat (limited to 'm4/sunos57-select.m4')
| -rw-r--r-- | m4/sunos57-select.m4 | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/m4/sunos57-select.m4 b/m4/sunos57-select.m4 new file mode 100644 index 0000000..d912dcc --- /dev/null +++ b/m4/sunos57-select.m4 @@ -0,0 +1,55 @@ +dnl From Mark D Baushke & Derek Price. +dnl +dnl See if select() on a /dev/null fd hangs when timeout is NULL. +dnl Also check to see that /dev/null is in the readfds set returned. +dnl +dnl Observed on Solaris 7: +dnl If /dev/null is in the readfds set, it will never be marked as +dnl ready by the OS. In the case of a /dev/null fd being the only fd +dnl in the select set and timeout == NULL, the select will hang. +dnl +dnl If the test fails, then arrange to use select only via a wrapper +dnl function that works around the problem. + +AC_DEFUN([ccvs_FUNC_SELECT], +[ + AC_CHECK_HEADERS([fcntl.h]) + AC_CACHE_CHECK([whether select hangs on /dev/null fd when timeout is NULL], + ccvs_cv_func_select_hang, + [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ +#include <stdio.h> +#include <sys/select.h> +#ifdef HAVE_FCNTL_H +# include <fcntl.h> +#endif +#include <errno.h>]], [[ + int numfds; + fd_set readfds; + struct timeval timeout; + int fd = open ("/dev/null", O_RDONLY); + + FD_ZERO (&readfds); + FD_SET (fd, &readfds); + timeout.tv_sec = 0; + timeout.tv_usec = 1; + + while ((numfds = select (fd + 1, &readfds, NULL, NULL, &timeout)) < 0 + && errno == EINTR); + return (numfds <= 0); + ]])], + ccvs_cv_func_select_hang=no, + ccvs_cv_func_select_hang=yes, + dnl When crosscompiling, assume it is broken. + ccvs_cv_func_select_hang=yes) + ]) + if test $ccvs_cv_func_select_hang = yes; then + ccvs_PREREQ_SELECT + + AC_LIBOBJ(sunos57-select) + AC_DEFINE(select, rpl_select, + [Define to rpl_select if the replacement function should be used.]) + fi +]) + +AC_DEFUN([ccvs_PREREQ_SELECT], [ + AC_CHECK_HEADERS(fcntl.h unistd.h)]) |