+2009-08-02 Bruno Haible <bruno@clisp.org>
+ Paolo Bonzini <bonzini@gnu.org>
+
+ New module 'pipe-filter-ii'.
+ * lib/pipe-filter.h: New file.
+ * lib/pipe-filter-ii.c: New file.
+ * lib/pipe-filter-aux.h: New file.
+ * modules/pipe-filter-ii: New file.
+
2009-08-02 Simon Josefsson <simon@josefsson.org>
* lib/gc-libgcrypt.c: Change copyright to FSF.
--- /dev/null
+/* Auxiliary code for filtering of data through a subprocess.
+ Copyright (C) 2001-2003, 2008-2009 Free Software Foundation, Inc.
+ Written by Bruno Haible <haible@clisp.cons.org>, 2009.
+
+ 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/>. */
+
+
+#ifndef SSIZE_MAX
+# define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
+#endif
+
+/* We use a child process, and communicate through a bidirectional pipe.
+ To avoid deadlocks, let the child process decide when it wants to read
+ or to write, and let the parent behave accordingly. The parent uses
+ select() to know whether it must write or read. On platforms without
+ select(), we use non-blocking I/O. (This means the parent is busy
+ looping while waiting for the child. Not good. But hardly any platform
+ lacks select() nowadays.) */
+
+/* On BeOS select() works only on sockets, not on normal file descriptors. */
+#ifdef __BEOS__
+# undef HAVE_SELECT
+#endif
+
+#ifdef EINTR
+
+/* EINTR handling for close(), read(), write(), select().
+ These functions can return -1/EINTR even though we don't have any
+ signal handlers set up, namely when we get interrupted via SIGSTOP. */
+
+static inline int
+nonintr_close (int fd)
+{
+ int retval;
+
+ do
+ retval = close (fd);
+ while (retval < 0 && errno == EINTR);
+
+ return retval;
+}
+#undef close /* avoid warning related to gnulib module unistd */
+#define close nonintr_close
+
+static inline ssize_t
+nonintr_read (int fd, void *buf, size_t count)
+{
+ ssize_t retval;
+
+ do
+ retval = read (fd, buf, count);
+ while (retval < 0 && errno == EINTR);
+
+ return retval;
+}
+#define read nonintr_read
+
+static inline ssize_t
+nonintr_write (int fd, const void *buf, size_t count)
+{
+ ssize_t retval;
+
+ do
+ retval = write (fd, buf, count);
+ while (retval < 0 && errno == EINTR);
+
+ return retval;
+}
+#undef write /* avoid warning on VMS */
+#define write nonintr_write
+
+# if HAVE_SELECT
+
+static inline int
+nonintr_select (int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
+ struct timeval *timeout)
+{
+ int retval;
+
+ do
+ retval = select (n, readfds, writefds, exceptfds, timeout);
+ while (retval < 0 && errno == EINTR);
+
+ return retval;
+}
+# undef select /* avoid warning on VMS */
+# define select nonintr_select
+
+# endif
+
+#endif
+
+/* Non-blocking I/O. */
+#ifndef O_NONBLOCK
+# define O_NONBLOCK O_NDELAY
+#endif
+#if HAVE_SELECT
+# define IS_EAGAIN(errcode) 0
+#else
+# ifdef EWOULDBLOCK
+# define IS_EAGAIN(errcode) ((errcode) == EAGAIN || (errcode) == EWOULDBLOCK)
+# else
+# define IS_EAGAIN(errcode) ((errcode) == EAGAIN)
+# endif
+#endif
--- /dev/null
+/* Filtering of data through a subprocess.
+ Copyright (C) 2001-2003, 2008-2009 Free Software Foundation, Inc.
+ Written by Bruno Haible <bruno@clisp.org>, 2009.
+
+ 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/>. */
+
+#include <config.h>
+
+#include "pipe-filter.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+# include <windows.h>
+#else
+# include <signal.h>
+# include <sys/select.h>
+#endif
+
+#include "error.h"
+#include "pipe.h"
+#include "wait-process.h"
+#include "gettext.h"
+
+#define _(str) gettext (str)
+
+#include "pipe-filter-aux.h"
+
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+
+struct locals
+{
+ /* Arguments passed to pipe_filter_ii_execute. */
+ prepare_write_fn prepare_write;
+ done_write_fn done_write;
+ prepare_read_fn prepare_read;
+ done_read_fn done_read;
+
+ /* Management of the subprocess. */
+ void *private_data;
+ int fd[2];
+
+ /* Status of the writer part. */
+ volatile bool writer_terminated;
+ volatile int writer_errno;
+ /* Status of the reader part. */
+ volatile bool reader_terminated;
+ volatile int reader_errno;
+};
+
+static unsigned int WINAPI
+writer_thread_func (void *thread_arg)
+{
+ struct locals *l = (struct locals *) thread_arg;
+
+ for (;;)
+ {
+ size_t bufsize;
+ const void *buf = l->prepare_write (&bufsize, l->private_data);
+ if (buf != NULL)
+ {
+ ssize_t nwritten =
+ write (l->fd[1], buf, bufsize > SSIZE_MAX ? SSIZE_MAX : bufsize);
+ if (nwritten < 0)
+ {
+ /* Don't assume that the gnulib modules 'write' and 'sigpipe' are
+ used. */
+ if (GetLastError () == ERROR_NO_DATA)
+ errno = EPIPE;
+ l->writer_errno = errno;
+ break;
+ }
+ else if (nwritten > 0)
+ l->done_write ((void *) buf, nwritten, l->private_data);
+ }
+ else
+ break;
+ }
+
+ l->writer_terminated = true;
+ _endthreadex (0); /* calls ExitThread (0) */
+ abort ();
+}
+
+static unsigned int WINAPI
+reader_thread_func (void *thread_arg)
+{
+ struct locals *l = (struct locals *) thread_arg;
+
+ for (;;)
+ {
+ size_t bufsize;
+ void *buf = l->prepare_read (&bufsize, l->private_data);
+ if (!(buf != NULL && bufsize > 0))
+ /* prepare_read returned wrong values. */
+ abort ();
+ {
+ ssize_t nread =
+ read (l->fd[0], buf, bufsize > SSIZE_MAX ? SSIZE_MAX : bufsize);
+ if (nread < 0)
+ {
+ l->reader_errno = errno;
+ break;
+ }
+ else if (nread > 0)
+ l->done_read (buf, nread, l->private_data);
+ else /* nread == 0 */
+ break;
+ }
+ }
+
+ l->reader_terminated = true;
+ _endthreadex (0); /* calls ExitThread (0) */
+ abort ();
+}
+
+#endif
+
+int
+pipe_filter_ii_execute (const char *progname,
+ const char *prog_path, const char **prog_argv,
+ bool null_stderr, bool exit_on_error,
+ prepare_write_fn prepare_write,
+ done_write_fn done_write,
+ prepare_read_fn prepare_read,
+ done_read_fn done_read,
+ void *private_data)
+{
+ pid_t child;
+ int fd[2];
+#if !((defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__)
+ struct sigaction orig_sigpipe_action;
+#endif
+
+ /* Open a bidirectional pipe to a subprocess. */
+ child = create_pipe_bidi (progname, prog_path, (char **) prog_argv,
+ null_stderr, true, exit_on_error,
+ fd);
+ if (child == -1)
+ return -1;
+
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+ /* Native Woe32 API. */
+ /* Pipes have a non-blocking mode, see function SetNamedPipeHandleState and
+ the article "Named Pipe Type, Read, and Wait Modes", but Microsoft's
+ documentation discourages its use. So don't use it.
+ Asynchronous I/O is also not suitable because it notifies the caller only
+ about completion of the I/O request, not about intermediate progress.
+ So do the writing and the reading in separate threads. */
+ {
+ struct locals l;
+ HANDLE handles[2];
+ #define writer_thread_handle handles[0]
+ #define reader_thread_handle handles[1]
+ bool writer_cleaned_up;
+ bool reader_cleaned_up;
+
+ l.prepare_write = prepare_write;
+ l.done_write = done_write;
+ l.prepare_read = prepare_read;
+ l.done_read = done_read;
+ l.private_data = private_data;
+ l.fd[0] = fd[0];
+ l.fd[1] = fd[1];
+ l.writer_terminated = false;
+ l.writer_errno = 0;
+ l.reader_terminated = false;
+ l.reader_errno = 0;
+
+ writer_thread_handle =
+ (HANDLE) _beginthreadex (NULL, 100000, writer_thread_func, &l, 0, NULL);
+ reader_thread_handle =
+ (HANDLE) _beginthreadex (NULL, 100000, reader_thread_func, &l, 0, NULL);
+ if (writer_thread_handle == NULL || reader_thread_handle == NULL)
+ {
+ if (exit_on_error)
+ error (EXIT_FAILURE, 0, _("creation of threads failed"));
+ if (reader_thread_handle != NULL)
+ CloseHandle (reader_thread_handle);
+ if (writer_thread_handle != NULL)
+ CloseHandle (writer_thread_handle);
+ goto fail;
+ }
+ writer_cleaned_up = false;
+ reader_cleaned_up = false;
+ for (;;)
+ {
+ DWORD ret;
+
+ /* Here !(writer_cleaned_up && reader_cleaned_up). */
+ if (writer_cleaned_up)
+ ret = WaitForSingleObject (reader_thread_handle, INFINITE);
+ else if (reader_cleaned_up)
+ ret = WaitForSingleObject (writer_thread_handle, INFINITE);
+ else
+ ret = WaitForMultipleObjects (2, handles, FALSE, INFINITE);
+ if (!(ret == WAIT_OBJECT_0 + 0 || ret == WAIT_OBJECT_0 + 1))
+ abort ();
+
+ if (l.writer_terminated)
+ {
+ /* The writer thread has just terminated. */
+ l.writer_terminated = false;
+ CloseHandle (writer_thread_handle);
+ if (l.writer_errno)
+ {
+ if (exit_on_error)
+ error (EXIT_FAILURE, l.writer_errno,
+ _("write to %s subprocess failed"), progname);
+ if (!reader_cleaned_up)
+ {
+ TerminateThread (reader_thread_handle, 1);
+ CloseHandle (reader_thread_handle);
+ }
+ goto fail;
+ }
+ /* Tell the child there is nothing more the parent will send. */
+ close (fd[1]);
+ writer_cleaned_up = true;
+ }
+ if (l.reader_terminated)
+ {
+ /* The reader thread has just terminated. */
+ l.reader_terminated = false;
+ CloseHandle (reader_thread_handle);
+ if (l.reader_errno)
+ {
+ if (exit_on_error)
+ error (EXIT_FAILURE, l.reader_errno,
+ _("read from %s subprocess failed"), progname);
+ if (!writer_cleaned_up)
+ {
+ TerminateThread (writer_thread_handle, 1);
+ CloseHandle (writer_thread_handle);
+ }
+ goto fail;
+ }
+ reader_cleaned_up = true;
+ }
+ if (writer_cleaned_up && reader_cleaned_up)
+ break;
+ }
+ }
+#else
+ /* When we write to the child process and it has just terminated,
+ we don't want to die from a SIGPIPE signal. So set the SIGPIPE
+ handler to SIG_IGN, and handle EPIPE error codes in write(). */
+ {
+ struct sigaction sigpipe_action;
+
+ sigpipe_action.sa_handler = SIG_IGN;
+ sigpipe_action.sa_flags = 0;
+ sigemptyset (&sigpipe_action.sa_mask);
+ if (sigaction (SIGPIPE, &sigpipe_action, &orig_sigpipe_action) < 0)
+ abort ();
+ }
+
+ {
+# if HAVE_SELECT
+ fd_set readfds; /* All bits except fd[0] are always cleared. */
+ fd_set writefds; /* All bits except fd[1] are always cleared. */
+# endif
+ bool done_writing;
+
+ /* Enable non-blocking I/O. This permits the read() and write() calls
+ to return -1/EAGAIN without blocking; this is important for polling
+ if HAVE_SELECT is not defined. It also permits the read() and write()
+ calls to return after partial reads/writes; this is important if
+ HAVE_SELECT is defined, because select() only says that some data
+ can be read or written, not how many. Without non-blocking I/O,
+ Linux 2.2.17 and BSD systems prefer to block instead of returning
+ with partial results. */
+ {
+ int fcntl_flags;
+
+ if ((fcntl_flags = fcntl (fd[1], F_GETFL, 0)) < 0
+ || fcntl (fd[1], F_SETFL, fcntl_flags | O_NONBLOCK) < 0
+ || (fcntl_flags = fcntl (fd[0], F_GETFL, 0)) < 0
+ || fcntl (fd[0], F_SETFL, fcntl_flags | O_NONBLOCK) < 0)
+ {
+ if (exit_on_error)
+ error (EXIT_FAILURE, errno,
+ _("cannot set up nonblocking I/O to %s subprocess"),
+ progname);
+ goto fail;
+ }
+ }
+
+# if HAVE_SELECT
+ FD_ZERO (&readfds);
+ FD_ZERO (&writefds);
+# endif
+ done_writing = false;
+ for (;;)
+ {
+# if HAVE_SELECT
+ int n;
+
+ FD_SET (fd[0], &readfds);
+ n = fd[0] + 1;
+ if (!done_writing)
+ {
+ FD_SET (fd[1], &writefds);
+ if (n <= fd[1])
+ n = fd[1] + 1;
+ }
+
+ n = select (n, &readfds, (!done_writing ? &writefds : NULL), NULL,
+ NULL);
+ if (n < 0)
+ {
+ if (exit_on_error)
+ error (EXIT_FAILURE, errno,
+ _("communication with %s subprocess failed"), progname);
+ goto fail;
+ }
+ if (!done_writing && FD_ISSET (fd[1], &writefds))
+ goto try_write;
+ if (FD_ISSET (fd[0], &readfds))
+ goto try_read;
+ /* How could select() return if none of the two descriptors is ready? */
+ abort ();
+# endif
+
+ /* Attempt to write. */
+# if HAVE_SELECT
+ try_write:
+# endif
+ if (!done_writing)
+ {
+ size_t bufsize;
+ const void *buf = prepare_write (&bufsize, private_data);
+ if (buf != NULL)
+ {
+ ssize_t nwritten =
+ write (fd[1], buf,
+ bufsize > SSIZE_MAX ? SSIZE_MAX : bufsize);
+ if (nwritten < 0)
+ {
+ if (!IS_EAGAIN (errno))
+ {
+ if (exit_on_error)
+ error (EXIT_FAILURE, errno,
+ _("write to %s subprocess failed"), progname);
+ goto fail;
+ }
+ }
+ else if (nwritten > 0)
+ done_write ((void *) buf, nwritten, private_data);
+ }
+ else
+ {
+ /* Tell the child there is nothing more the parent will send. */
+ close (fd[1]);
+ done_writing = true;
+ }
+ }
+# if HAVE_SELECT
+ continue;
+# endif
+
+ /* Attempt to read. */
+# if HAVE_SELECT
+ try_read:
+# endif
+ {
+ size_t bufsize;
+ void *buf = prepare_read (&bufsize, private_data);
+ if (!(buf != NULL && bufsize > 0))
+ /* prepare_read returned wrong values. */
+ abort ();
+ {
+ ssize_t nread =
+ read (fd[0], buf, bufsize > SSIZE_MAX ? SSIZE_MAX : bufsize);
+ if (nread < 0)
+ {
+ if (!IS_EAGAIN (errno))
+ {
+ if (exit_on_error)
+ error (EXIT_FAILURE, errno,
+ _("read from %s subprocess failed"), progname);
+ goto fail;
+ }
+ }
+ else if (nread > 0)
+ done_read (buf, nread, private_data);
+ else /* nread == 0 */
+ {
+ if (done_writing)
+ break;
+ }
+ }
+ }
+# if HAVE_SELECT
+ continue;
+# endif
+ }
+ }
+
+ /* Restore SIGPIPE signal handler. */
+ if (sigaction (SIGPIPE, &orig_sigpipe_action, NULL) < 0)
+ abort ();
+#endif
+
+ close (fd[0]);
+
+ /* Remove zombie process from process list. */
+ {
+ int exitstatus =
+ wait_subprocess (child, progname, false, null_stderr,
+ true, exit_on_error, NULL);
+ if (exitstatus != 0 && exit_on_error)
+ error (EXIT_FAILURE, 0, _("%s subprocess terminated with exit code %d"),
+ progname, exitstatus);
+ return exitstatus;
+ }
+
+ fail:
+ {
+ int saved_errno = errno;
+ close (fd[1]);
+#if !((defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__)
+ if (sigaction (SIGPIPE, &orig_sigpipe_action, NULL) < 0)
+ abort ();
+#endif
+ close (fd[0]);
+ wait_subprocess (child, progname, true, true, true, false, NULL);
+ errno = saved_errno;
+ return -1;
+ }
+}
--- /dev/null
+/* Filtering of data through a subprocess.
+ Copyright (C) 2009 Free Software Foundation, Inc.
+ Written by Bruno Haible <haible@clisp.cons.org>, 2009,
+ and Paolo Bonzini <bonzini@gnu.org>, 2009.
+
+ 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/>. */
+
+#ifndef _PIPE_FILTER_H
+#define _PIPE_FILTER_H
+
+#include <stdbool.h>
+#include <stddef.h>
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/* Piping data through a subprocess in the naïve way - write data to the
+ subprocess and read from the subprocess when you expect it to have
+ produced results - is subject to two kinds of deadlocks:
+ 1) If you write more than PIPE_MAX bytes or, more generally, if you write
+ more bytes than the subprocess can handle at once, the subprocess
+ may write its data and wait on you to read it, but you are currently
+ busy writing.
+ 2) When you don't know ahead of time how many bytes the subprocess
+ will produce, the usual technique of calling read (fd, buf, BUFSIZ)
+ with a fixed BUFSIZ will, on Linux 2.2.17 and on BSD systems, cause
+ the read() call to block until *all* of the buffer has been filled.
+ But the subprocess cannot produce more data until you gave it more
+ input. But you are currently busy reading from it.
+
+ This header file declares four set of functions that pipes data through
+ the subprocess, without risking these deadlocks.
+
+ The side that writes data to the subprocess can be seen as a "generator",
+ that is, as a subroutine that produces and writes a piece of data here and
+ there, see <http://en.wikipedia.org/wiki/Generator_(computer_science)>.
+ But often, it can be written in the form of an "iterator", that is, as a
+ function that, each time it is invoked, produces and writes one more piece
+ of data.
+
+ Similarly, the side that reads data from the subprocess can be seen as
+ a "generator", that is, as a subroutine that consumes a piece of data here
+ and there. Often, it can be written in the form of an "iterator", that
+ is, as a function that, each time it is invoked, consumes one more piece
+ of data.
+
+ This header file declares four set of functions:
+
+ | writer | reader |
+ ----------------+------------+------------+
+ pipe_filter_ii | iterator | iterator |
+ pipe_filter_ig | iterator | generator |
+ pipe_filter_gi | generator | iterator |
+ pipe_filter_gg | generator | generator |
+ ----------------+------------+------------+
+
+ The last one uses threads in order to implement two generators running at
+ the same time. (For the relation between generators, coroutines, and
+ threads, see <http://en.wikipedia.org/wiki/Generator_(computer_science)>
+ and <http://en.wikipedia.org/wiki/Coroutine>.) It is therefore only
+ portable to platforms with kernel-based POSIX threads. */
+
+/* These two functions together describe the side that writes data to the
+ subprocess when it has the form of an iterator.
+ - prepare_write (&num_bytes, p) must either return a pointer to data that
+ is ready to be written and set num_bytes to the number of bytes ready to
+ be written, or return NULL when no more bytes are to be written.
+ - done_write (data_written, num_bytes_written) is called after
+ num_bytes_written bytes were written. It is guaranteed that
+ num_bytes_written > 0.
+ Here p is always the private_data argument passed to the main function. */
+typedef const void * (*prepare_write_fn) (size_t *num_bytes_p,
+ void *private_data);
+typedef void (*done_write_fn) (void *data_written, size_t num_bytes_written,
+ void *private_data);
+
+/* These two functions together describe the side that reads data from the
+ subprocess when it has the form of an iterator.
+ - prepare_read (&num_bytes, p) must return a pointer to a buffer for data
+ that can be read and set num_bytes to the size of that buffer
+ (must be > 0).
+ - done_read (data_read, num_bytes_read, p) is called after num_bytes_read
+ bytes were read into the buffer.
+ Here p is always the private_data argument passed to the main function. */
+typedef void * (*prepare_read_fn) (size_t *num_bytes_p,
+ void *private_data);
+typedef void (*done_read_fn) (void *data_read, size_t num_bytes_read,
+ void *private_data);
+
+
+/* ============================ pipe_filter_ii ============================ */
+
+/* Create a subprocess and pipe some data through it.
+ Arguments:
+ - progname is the program name used in error messages.
+ - prog_path is the file name of the program to invoke.
+ - prog_argv is a NULL terminated argument list, starting with prog_path as
+ first element.
+ - If null_stderr is true, the subprocess' stderr will be redirected to
+ /dev/null, and the usual error message to stderr will be omitted.
+ This is suitable when the subprocess does not fulfill an important task.
+ - If exit_on_error is true, any error will cause the main process to exit
+ with an error status.
+ If the subprocess does not terminate correctly, exit if exit_on_error is
+ true, otherwise return 127.
+ Callback arguments are as described above.
+
+ Data is alternatingly written to the subprocess, through the functions
+ prepare_write and done_write, and read from the subprocess, through the
+ functions prepare_read and done_read.
+
+ Note that the prepare_write/done_write functions and the
+ prepare_read/done_read functions may be called in different threads than
+ the current thread (depending on the platform). But they will not be
+ called after the pipe_filter_ii_execute function has returned.
+
+ Return 0 upon success, or (only if exit_on_error is false):
+ - -1 with errno set upon failure,
+ - the positive exit code of the subprocess if that failed. */
+extern int
+ pipe_filter_ii_execute (const char *progname,
+ const char *prog_path, const char **prog_argv,
+ bool null_stderr, bool exit_on_error,
+ prepare_write_fn prepare_write,
+ done_write_fn done_write,
+ prepare_read_fn prepare_read,
+ done_read_fn done_read,
+ void *private_data);
+
+
+/* ============================ pipe_filter_ig ============================ */
+
+struct pipe_filter_ig;
+
+
+/* ============================ pipe_filter_gi ============================ */
+
+struct pipe_filter_gi;
+
+/* Create a subprocess and pipe some data through it.
+ Arguments:
+ - progname is the program name used in error messages.
+ - prog_path is the file name of the program to invoke.
+ - prog_argv is a NULL terminated argument list, starting with
+ prog_path as first element.
+ - If null_stderr is true, the subprocess' stderr will be redirected
+ to /dev/null, and the usual error message to stderr will be
+ omitted. This is suitable when the subprocess does not fulfill an
+ important task.
+ - If exit_on_error is true, any error will cause the main process to
+ exit with an error status.
+ If the subprocess does not start correctly, exit if exit_on_error is
+ true, otherwise return NULL and set errno.
+
+ The caller will write to the subprocess through pipe_filter_gi_write
+ and finally call pipe_filter_gi_write. During such calls, the
+ prepare_read and done_read function may be called to process any data
+ that the subprocess has written.
+
+ Note that the prepare_read/done_read functions may be called in a
+ different thread than the current thread (depending on the platform).
+ But they will not be called after the pipe_filter_gi_close function has
+ returned.
+
+ Return the freshly created 'struct pipe_filter_gi'. */
+extern struct pipe_filter_gi *
+ pipe_filter_gi_create (const char *progname,
+ const char *prog_path, const char **prog_argv,
+ bool null_stderr, bool exit_on_error,
+ prepare_read_fn prepare_read,
+ done_read_fn done_read,
+ void *private_data);
+
+/* Write size bytes starting at buf into the pipe and in the meanwhile
+ possibly call the prepare_read and done_read functions specified to
+ pipe_filter_gi_create.
+
+ Note that the prepare_read/done_read functions may be called in a
+ different thread than the current thread (depending on the platform).
+ However, they will always be called before pipe_filter_gi_write has
+ returned, or otherwise not sooner than the next call to
+ pipe_filter_gi_write or pipe_filter_gi_close.
+
+ Return only after all the entire buffer has been written to the pipe or
+ the subprocess has exited.
+
+ Return 0 upon success, or (only if exit_on_error is false):
+ - -1 with errno set upon failure,
+ - the positive exit code of the subprocess if that failed. */
+extern int
+ pipe_filter_gi_write (struct pipe_filter_gi *filter,
+ const void *buf, size_t size);
+
+/* Finish reading the output via the prepare_read/done_read functions
+ specified to pipe_filter_gi_create.
+
+ Note that the prepare_read/done_read functions may be called in a
+ different thread than the current thread (depending on the platform).
+ However, they will always be called before pipe_filter_gi_close has
+ returned.
+
+ The write side of the pipe is closed as soon as pipe_filter_gi_close
+ starts, while the read side will be closed just before it finishes.
+
+ Return 0 upon success, or (only if exit_on_error is false):
+ - -1 with errno set upon failure,
+ - the positive exit code of the subprocess if that failed. */
+extern int
+ pipe_filter_gi_close (struct pipe_filter_gi *filter);
+
+
+/* ============================ pipe_filter_gg ============================ */
+
+
+/* ======================================================================== */
+
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif /* _PIPE_FILTER_H */
--- /dev/null
+Description:
+Filtering of data through a subprocess.
+
+Files:
+lib/pipe-filter.h
+lib/pipe-filter-ii.c
+lib/pipe-filter-aux.h
+
+Depends-on:
+pipe
+wait-process
+error
+exit
+gettext-h
+stdbool
+stdint
+sys_select
+unistd
+
+configure.ac:
+AC_REQUIRE([AC_C_INLINE])
+AC_CHECK_FUNCS([select])
+
+Makefile.am:
+lib_SOURCES += pipe-filter-ii.c
+
+Include:
+"pipe-filter.h"
+
+License:
+GPL
+
+Maintainer:
+Bruno Haible
projects / pspp / commitdiff