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Diffstat (limited to 'gnulib/lib/isapipe.c')
m--------- | gnulib | 0 | ||||
-rw-r--r-- | gnulib/lib/isapipe.c | 119 |
2 files changed, 119 insertions, 0 deletions
diff --git a/gnulib b/gnulib deleted file mode 160000 -Subproject 443bc5ffcf7429e557f4a371b0661abe98ddbc1 diff --git a/gnulib/lib/isapipe.c b/gnulib/lib/isapipe.c new file mode 100644 index 0000000..f6e16d1 --- /dev/null +++ b/gnulib/lib/isapipe.c @@ -0,0 +1,119 @@ +/* Test whether a file descriptor is a pipe. + + Copyright (C) 2006, 2008-2011 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 + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ + +/* Written by Paul Eggert. */ + +#include <config.h> + +#include "isapipe.h" + +#include <errno.h> + +#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ +/* Windows platforms. */ + +/* Get GetFileType. */ +# include <windows.h> + +/* Get _get_osfhandle. */ +# include "msvc-nothrow.h" + +int +isapipe (int fd) +{ + HANDLE h = (HANDLE) _get_osfhandle (fd); + + if (h == INVALID_HANDLE_VALUE) + { + errno = EBADF; + return -1; + } + + return (GetFileType (h) == FILE_TYPE_PIPE); +} + +#else +/* Unix platforms. */ + +# include <stdbool.h> +# include <sys/types.h> +# include <sys/stat.h> +# include <unistd.h> + +/* The maximum link count for pipes; (nlink_t) -1 if not known. */ +# ifndef PIPE_LINK_COUNT_MAX +# define PIPE_LINK_COUNT_MAX ((nlink_t) (-1)) +# endif + +/* Return 1 if FD is a pipe, 0 if not, -1 (setting errno) on error. + + Test fairly strictly whether FD is a pipe. lseek and checking for + ESPIPE does not suffice, since many non-pipe files cause lseek to + fail with errno == ESPIPE. */ + +int +isapipe (int fd) +{ + nlink_t pipe_link_count_max = PIPE_LINK_COUNT_MAX; + bool check_for_fifo = (HAVE_FIFO_PIPES == 1); + struct stat st; + int fstat_result = fstat (fd, &st); + + if (fstat_result != 0) + return fstat_result; + + /* We want something that succeeds only for pipes, but on + POSIX-conforming hosts S_ISFIFO succeeds for both FIFOs and pipes + and we know of no portable, reliable way to distinguish them in + general. However, in practice pipes always have a link count <= + PIPE_LINK_COUNT_MAX (unless someone attaches them to the file + system name space using fattach, in which case they're not really + pipes any more), so test for that as well. + + On Darwin 7.7, pipes are sockets, so check for those instead. */ + + if (! ((HAVE_FIFO_PIPES == 0 || HAVE_FIFO_PIPES == 1) + && PIPE_LINK_COUNT_MAX != (nlink_t) -1) + && (S_ISFIFO (st.st_mode) | S_ISSOCK (st.st_mode))) + { + int fd_pair[2]; + int pipe_result = pipe (fd_pair); + if (pipe_result != 0) + return pipe_result; + else + { + struct stat pipe_st; + int fstat_pipe_result = fstat (fd_pair[0], &pipe_st); + int fstat_pipe_errno = errno; + close (fd_pair[0]); + close (fd_pair[1]); + if (fstat_pipe_result != 0) + { + errno = fstat_pipe_errno; + return fstat_pipe_result; + } + check_for_fifo = (S_ISFIFO (pipe_st.st_mode) != 0); + pipe_link_count_max = pipe_st.st_nlink; + } + } + + return + (st.st_nlink <= pipe_link_count_max + && (check_for_fifo ? S_ISFIFO (st.st_mode) : S_ISSOCK (st.st_mode))); +} + +#endif |