# HG changeset patch # User Eric Blake # Date 1258600064 25200 # Node ID 25e64e77bb53a5b8a88de043d154b13799dffd61 # Parent 444e305ec8cc7d285b209cf0fd41103e165593d6 sleep: work around cygwin bug On cygwin 1.5.x, sleep amounts larger than 49.7 days (2**32 milliseconds) failed instantly, but with a garbage return value from uninitialized memory. * lib/sleep.c (rpl_sleep): Work around the bug. * m4/sleep.m4 (gl_FUNC_SLEEP): Detect the bug. (gl_PREREQ_SLEEP): Delete unused macro. * modules/sleep (Depends-on): Add verify. * m4/unistd_h.m4 (gl_UNISTD_H_DEFAULTS): Add default. * modules/unistd (Makefile.am): Substitute witness. * lib/unistd.in.h (sleep): Update prototype. * doc/posix-functions/sleep.texi (sleep): Document the bug. * tests/test-sleep.c (main) [HAVE_DECL_ALARM]: Test it. * modules/sleep-tests (Depends-on): Check for alarm. Signed-off-by: Eric Blake diff --git a/ChangeLog b/ChangeLog --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,17 @@ +2009-11-20 Eric Blake + + sleep: work around cygwin bug + * lib/sleep.c (rpl_sleep): Work around the bug. + * m4/sleep.m4 (gl_FUNC_SLEEP): Detect the bug. + (gl_PREREQ_SLEEP): Delete unused macro. + * modules/sleep (Depends-on): Add verify. + * m4/unistd_h.m4 (gl_UNISTD_H_DEFAULTS): Add default. + * modules/unistd (Makefile.am): Substitute witness. + * lib/unistd.in.h (sleep): Update prototype. + * doc/posix-functions/sleep.texi (sleep): Document the bug. + * tests/test-sleep.c (main) [HAVE_DECL_ALARM]: Test it. + * modules/sleep-tests (Depends-on): Check for alarm. + 2009-11-20 Jim Meyering maint.mk: improve sc_prohibit_magic_number_exit diff --git a/doc/posix-functions/sleep.texi b/doc/posix-functions/sleep.texi --- a/doc/posix-functions/sleep.texi +++ b/doc/posix-functions/sleep.texi @@ -15,6 +15,9 @@ This function takes milliseconds as argument and returns @code{void} on some platforms: mingw (2005 and older). +@item +This function cannot sleep longer than 49.7 days on some platforms: +Cygwin 1.5.x. @end itemize Portability problems not fixed by Gnulib: diff --git a/lib/sleep.c b/lib/sleep.c --- a/lib/sleep.c +++ b/lib/sleep.c @@ -1,5 +1,5 @@ /* Pausing execution of the current thread. - Copyright (C) 2007 Free Software Foundation, Inc. + Copyright (C) 2007, 2009 Free Software Foundation, Inc. Written by Bruno Haible , 2007. This program is free software: you can redistribute it and/or modify @@ -20,6 +20,10 @@ /* Specification. */ #include +#include + +#include "verify.h" + #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ # define WIN32_LEAN_AND_MEAN /* avoid including junk */ @@ -39,7 +43,32 @@ return remaining; } -#else +#elif HAVE_SLEEP + +# undef sleep + +/* Guarantee unlimited sleep and a reasonable return value. Cygwin + 1.5.x rejects attempts to sleep more than 49.7 days (2**32 + milliseconds), but uses uninitialized memory which results in a + garbage answer. */ +unsigned int +rpl_sleep (unsigned int seconds) +{ + /* This requires int larger than 16 bits. */ + verify (UINT_MAX / 49 / 24 / 60 / 60); + const unsigned int limit = 49 * 24 * 60 * 60; + while (limit < seconds) + { + unsigned int result; + seconds -= limit; + result = sleep (limit); + if (result) + return seconds + result; + } + return sleep (seconds); +} + +#else /* !HAVE_SLEEP */ #error "Please port gnulib sleep.c to your platform, possibly using usleep() or select(), then report this to bug-gnulib." diff --git a/lib/unistd.in.h b/lib/unistd.in.h --- a/lib/unistd.in.h +++ b/lib/unistd.in.h @@ -714,11 +714,15 @@ #if @GNULIB_SLEEP@ +# if @REPLACE_SLEEP@ +# undef sleep +# define sleep rpl_sleep +# endif /* Pause the execution of the current thread for N seconds. Returns the number of seconds left to sleep. See the POSIX:2001 specification . */ -# if !@HAVE_SLEEP@ +# if !@HAVE_SLEEP@ || @REPLACE_SLEEP@ extern unsigned int sleep (unsigned int n); # endif #elif defined GNULIB_POSIXCHECK diff --git a/m4/sleep.m4 b/m4/sleep.m4 --- a/m4/sleep.m4 +++ b/m4/sleep.m4 @@ -1,5 +1,5 @@ -# sleep.m4 serial 2 -dnl Copyright (C) 2007-2008 Free Software Foundation, Inc. +# sleep.m4 serial 3 +dnl Copyright (C) 2007-2009 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. @@ -13,12 +13,37 @@ dnl it takes the number of milliseconds as argument and returns void. dnl mingw does not declare this function. AC_CHECK_DECLS([sleep], , , [#include ]) + AC_CHECK_FUNCS_ONCE([sleep]) if test $ac_cv_have_decl_sleep != yes; then HAVE_SLEEP=0 AC_LIBOBJ([sleep]) - gl_PREREQ_SLEEP + else + dnl Cygwin 1.5.x has a bug where sleep can't exceed 49.7 days. + AC_CACHE_CHECK([for working sleep], [gl_cv_func_sleep_works], + [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ +#include +#include +#include +static void +handle_alarm (int sig) +{ + if (sig != SIGALRM) + _exit (2); +} +]], [[ + /* Failure to compile this test due to missing alarm is okay, + since all such platforms (mingw) also lack sleep. */ + unsigned int pentecost = 50 * 24 * 60 * 60; /* 50 days. */ + unsigned int remaining; + signal (SIGALRM, handle_alarm); + alarm (1); + remaining = sleep (pentecost); + return !(pentecost - 10 < remaining && remaining <= pentecost);]])], + [gl_cv_func_sleep_works=yes], [gl_cv_func_sleep_works=no], + [gl_cv_func_sleep_works="guessing no"])]) + if test "$gl_cv_func_sleep_works" != yes; then + REPLACE_SLEEP=1 + AC_LIBOBJ([sleep]) + fi fi ]) - -# Prerequisites of lib/sleep.c. -AC_DEFUN([gl_PREREQ_SLEEP], [:]) diff --git a/m4/unistd_h.m4 b/m4/unistd_h.m4 --- a/m4/unistd_h.m4 +++ b/m4/unistd_h.m4 @@ -1,4 +1,4 @@ -# unistd_h.m4 serial 35 +# unistd_h.m4 serial 36 dnl Copyright (C) 2006-2009 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -113,6 +113,7 @@ REPLACE_LSEEK=0; AC_SUBST([REPLACE_LSEEK]) REPLACE_READLINK=0; AC_SUBST([REPLACE_READLINK]) REPLACE_RMDIR=0; AC_SUBST([REPLACE_RMDIR]) + REPLACE_SLEEP=0; AC_SUBST([REPLACE_SLEEP]) REPLACE_SYMLINK=0; AC_SUBST([REPLACE_SYMLINK]) REPLACE_UNLINK=0; AC_SUBST([REPLACE_UNLINK]) REPLACE_UNLINKAT=0; AC_SUBST([REPLACE_UNLINKAT]) diff --git a/modules/sleep b/modules/sleep --- a/modules/sleep +++ b/modules/sleep @@ -6,7 +6,9 @@ m4/sleep.m4 Depends-on: +stdint unistd +verify configure.ac: gl_FUNC_SLEEP diff --git a/modules/sleep-tests b/modules/sleep-tests --- a/modules/sleep-tests +++ b/modules/sleep-tests @@ -4,8 +4,8 @@ Depends-on: configure.ac: +AC_CHECK_DECLS_ONCE([alarm]) Makefile.am: TESTS += test-sleep check_PROGRAMS += test-sleep - diff --git a/modules/unistd b/modules/unistd --- a/modules/unistd +++ b/modules/unistd @@ -105,6 +105,7 @@ -e 's|@''REPLACE_LSEEK''@|$(REPLACE_LSEEK)|g' \ -e 's|@''REPLACE_READLINK''@|$(REPLACE_READLINK)|g' \ -e 's|@''REPLACE_RMDIR''@|$(REPLACE_RMDIR)|g' \ + -e 's|@''REPLACE_SLEEP''@|$(REPLACE_SLEEP)|g' \ -e 's|@''REPLACE_SYMLINK''@|$(REPLACE_SYMLINK)|g' \ -e 's|@''REPLACE_UNLINK''@|$(REPLACE_UNLINK)|g' \ -e 's|@''REPLACE_UNLINKAT''@|$(REPLACE_UNLINKAT)|g' \ diff --git a/tests/test-sleep.c b/tests/test-sleep.c --- a/tests/test-sleep.c +++ b/tests/test-sleep.c @@ -1,5 +1,5 @@ /* Test of sleep() function. - Copyright (C) 2007-2008 Free Software Foundation, Inc. + Copyright (C) 2007-2009 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -20,21 +20,31 @@ #include +#include #include #include #define ASSERT(expr) \ - do \ - { \ - if (!(expr)) \ - { \ + do \ + { \ + if (!(expr)) \ + { \ fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \ - fflush (stderr); \ - abort (); \ - } \ - } \ + fflush (stderr); \ + abort (); \ + } \ + } \ while (0) +#if HAVE_DECL_ALARM +static void +handle_alarm (int sig) +{ + if (sig != SIGALRM) + _exit (1); +} +#endif + int main() { @@ -42,6 +52,16 @@ ASSERT (sleep (0) == 0); +#if HAVE_DECL_ALARM + { + const unsigned int pentecost = 50 * 24 * 60 * 60; /* 50 days. */ + unsigned int remaining; + signal (SIGALRM, handle_alarm); + alarm (1); + remaining = sleep (pentecost); + ASSERT (pentecost - 10 < remaining && remaining <= pentecost); + } +#endif + return 0; } -