Hi Bruno, On Sat, 12 Apr 2025 15:21:12 +0200 Bruno Haible wrote: > Hi, > > In Gnulib, we have a unit test that compiles the program below as a > native Windows program (either with mingw or with MSVC), that exercises > the Gnulib select() function > > <https://git.savannah.gnu.org/gitweb/?p=gnulib.git;a=blob;f=lib/select.c;h=5a58d6ee47f5b10413d97cb7a1996d424eefc796;hb=HEAD> > > Then it does (in a Cygwin shell): > > rm -f t-select-in.tmp > ./test-select-fd.exe r 0 t-select-in.tmp < /dev/null > cat t-select-in.tmp > > Up to Cygwin 3.6.0, the contents of the file t-select-in.tmp was "1", > like on most other OSes, indicating that the program can read() from > file descriptor 0. > > In Cygwin 3.6.1, the contents of the file t-select-in.tmp is "0", > indicating that read()ing from file descriptor 0 would block. > This is a regression. > > Looking through the commits between 3.6.0 and 3.6.1, the most likely culprit > is commit d750786e7de013b58e2968eeb6a7fd59dcc535c9 . > > Bruno > > > =============================== test-select-fd.c > =============================== > #include <config.h> > > #include <stdio.h> > #include <stdlib.h> > #include <sys/select.h> > > int > main (int argc, char *argv[]) > { > if (argc == 4) > { > char mode = argv[1][0]; > > if (mode == 'r' || mode == 'w') > { > int fd = atoi (argv[2]); > > if (fd >= 0) > { > const char *result_file_name = argv[3]; > FILE *result_file = fopen (result_file_name, "wb"); > > if (result_file != NULL) > { > fd_set fds; > struct timeval timeout; > int ret; > > FD_ZERO (&fds); > FD_SET (fd, &fds); > timeout.tv_sec = 0; > timeout.tv_usec = 10000; > ret = (mode == 'r' > ? select (fd + 1, &fds, NULL, NULL, &timeout) > : select (fd + 1, NULL, &fds, NULL, &timeout)); > if (ret < 0) > { > perror ("select failed"); > exit (1); > } > if ((ret == 0) != ! FD_ISSET (fd, &fds)) > { > fprintf (stderr, "incorrect return value\n"); > exit (1); > } > fprintf (result_file, "%d\n", ret); > exit (0); > } > } > } > } > fprintf (stderr, "Usage: test-select-fd mode fd result-file-name\n"); > exit (1); > } > ================================================================================
Thanks for the report. I tryied to compile your testcase as mingw binary, but config.h and sys/select.h are missing from mingw. Could you plsese let us know how to compile it? -- Takashi Yano <takashi.y...@nifty.ne.jp> -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
