61c3357ce1
It is required to prevent deadlocks in single-threaded select-based IO
programs (namely: qrexec). POSIX API doesn't support checking how much
can be written to pipe/socket without blocking, so to prevent blocking
application must use O_NONBLOCK mode, and somehow deal with non-written
data (buffer it).
QubesOS/qubes-issues#1347
(cherry picked from commit 6a44eaeb09)
65 lines
2.3 KiB
C
65 lines
2.3 KiB
C
/*
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* The Qubes OS Project, http://www.qubes-os.org
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*
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* Copyright (C) 2010 Rafal Wojtczuk <rafal@invisiblethingslab.com>
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* Copyright (C) 2013 Marek Marczykowski <marmarek@invisiblethingslab.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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#include <sys/select.h>
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#include <libvchan.h>
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struct buffer {
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char *data;
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int buflen;
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};
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/* return codes for buffered writes */
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#define WRITE_STDIN_OK 0 /* all written */
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#define WRITE_STDIN_BUFFERED 1 /* something still in the buffer */
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#define WRITE_STDIN_ERROR 2 /* write error, errno set */
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typedef void (do_exec_t)(const char *);
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void register_exec_func(do_exec_t *func);
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void buffer_init(struct buffer *b);
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void buffer_free(struct buffer *b);
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void buffer_append(struct buffer *b, const char *data, int len);
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void buffer_remove(struct buffer *b, int len);
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int buffer_len(struct buffer *b);
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void *buffer_data(struct buffer *b);
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int flush_client_data(int fd, struct buffer *buffer);
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int write_stdin(int fd, const char *data, int len, struct buffer *buffer);
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int fork_and_flush_stdin(int fd, struct buffer *buffer);
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void do_fork_exec(const char *cmdline, int *pid, int *stdin_fd, int *stdout_fd,
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int *stderr_fd);
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void wait_for_vchan_or_argfd(libvchan_t *vchan, int max, fd_set * rdset, fd_set * wrset);
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int read_vchan_all(libvchan_t *vchan, void *data, size_t size);
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int write_vchan_all(libvchan_t *vchan, const void *data, size_t size);
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int read_all(int fd, void *buf, int size);
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int write_all(int fd, const void *buf, int size);
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void fix_fds(int fdin, int fdout, int fderr);
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void set_nonblock(int fd);
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void set_block(int fd);
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int get_server_socket(const char *);
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int do_accept(int s);
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void set_nonblock(int fd);
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