/* Copyright (C) 1989, 1990, 1991, 1992, 2000, 2002

 * Free Software Foundation, Inc.

 * Copyright (C) 2003-2017 Colin Watson.

 *   Written for groff by James Clark (jjc@jclark.com)

 *   Adapted for man-db by Colin Watson.

 *

 * This file is part of libpipeline.

 *

 * libpipeline 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 2 of the License, or (at

 * your option) any later version.

 *

 * libpipeline 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 libpipeline; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301

 * USA.

 */

#ifndef PIPELINE_H

#define PIPELINE_H

#ifdef __cplusplus

extern "C" {

#endif

#include <stdio.h>

#include <stdarg.h>

#include <sys/types.h>

/* GCC version checking borrowed from glibc. */

#if defined(__GNUC__) && defined(__GNUC_MINOR__)

#  define PIPELINE_GNUC_PREREQ(maj,min) \

	((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))

#else

#  define PIPELINE_GNUC_PREREQ(maj,min) 0

#endif

/* Does this compiler support format string checking? */

#if PIPELINE_GNUC_PREREQ(2,0)

#  define PIPELINE_ATTR_FORMAT_PRINTF(a,b) \

	__attribute__ ((__format__ (__printf__, a, b)))

#else

#  define PIPELINE_ATTR_FORMAT_PRINTF(a,b)

#endif

/* Does this compiler support marking variables as unused? */

#if PIPELINE_GNUC_PREREQ(2,4)

#  define PIPELINE_ATTR_UNUSED __attribute__ ((__unused__))

#else

#  define PIPELINE_ATTR_UNUSED

#endif

/* Does this compiler support marking functions as non-returning? */

#if PIPELINE_GNUC_PREREQ(2,5)

#  define PIPELINE_ATTR_NORETURN __attribute__ ((__noreturn__))

#else

#  define PIPELINE_ATTR_NORETURN

#endif

/* Does this compiler support unused result checking? */

#if PIPELINE_GNUC_PREREQ(3,4)

#  define PIPELINE_ATTR_WARN_UNUSED_RESULT \

	__attribute__ ((__warn_unused_result__))

#else

#  define PIPELINE_ATTR_WARN_UNUSED_RESULT

#endif

/* Does this compiler support sentinel checking? */

#if PIPELINE_GNUC_PREREQ(4,0)

#  define PIPELINE_ATTR_SENTINEL __attribute__ ((__sentinel__))

#else

#  define PIPELINE_ATTR_SENTINEL

#endif

typedef void pipecmd_function_type (void *);

typedef void pipecmd_function_free_type (void *);

struct pipecmd;

typedef struct pipecmd pipecmd;

struct pipeline;

typedef struct pipeline pipeline;

/* ---------------------------------------------------------------------- */

/* Functions to build individual commands. */

/* Construct a new command. */

pipecmd *pipecmd_new (const char *name);

/* Convenience constructors wrapping pipecmd_new() and pipecmd_arg().

 * Terminate arguments with NULL.

 */

pipecmd *pipecmd_new_argv (const char *name, va_list argv);

pipecmd *pipecmd_new_args (const char *name, ...) PIPELINE_ATTR_SENTINEL;

/* Split argstr on whitespace to construct a command and arguments,

 * honouring shell-style single-quoting, double-quoting, and backslashes,

 * but not other shell evil like wildcards, semicolons, or backquotes. This

 * is a backward-compatibility hack to support old configuration file

 * directives; please try to avoid using it in new code.

 */

pipecmd *pipecmd_new_argstr (const char *argstr);

/* Construct a new command that calls a given function rather than executing

 * a process. The data argument is passed as the function's only argument,

 * and will be freed before returning using free_func (if non-NULL).

 *

 * pipecmd_* functions that deal with arguments cannot be used with the

 * command returned by this function.

 */

pipecmd *pipecmd_new_function (const char *name,

			       pipecmd_function_type *func,

			       pipecmd_function_free_type *free_func,

			       void *data);

/* Construct a new command that runs a sequence of commands. The commands

 * will be executed in forked children; if any exits non-zero then it will

 * terminate the sequence, as with "&&" in shell.

 *

 * pipecmd_* functions that deal with arguments cannot be used with the

 * command returned by this function.

 */

pipecmd *pipecmd_new_sequencev (const char *name, va_list cmdv);

pipecmd *pipecmd_new_sequence (const char *name, ...) PIPELINE_ATTR_SENTINEL;

/* Return a new command that just passes data from its input to its output. */

pipecmd *pipecmd_new_passthrough (void);

/* Return a duplicate of a command. */

pipecmd *pipecmd_dup (pipecmd *cmd);

/* Add an argument to a command. */

void pipecmd_arg (pipecmd *cmd, const char *arg);

/* Convenience function to add an argument with printf substitutions. */

void pipecmd_argf (pipecmd *cmd, const char *format, ...)

	PIPELINE_ATTR_FORMAT_PRINTF(2, 3);

/* Convenience functions wrapping pipecmd_arg().

 * Terminate arguments with NULL.

 */

void pipecmd_argv (pipecmd *cmd, va_list argv);

void pipecmd_args (pipecmd *cmd, ...) PIPELINE_ATTR_SENTINEL;

/* Split argstr on whitespace to add a list of arguments, honouring

 * shell-style single-quoting, double-quoting, and backslashes, but not

 * other shell evil like wildcards, semicolons, or backquotes. This is a

 * backward-compatibility hack to support old configuration file directives;

 * please try to avoid using it in new code.

 */

void pipecmd_argstr (pipecmd *cmd, const char *argstr);

/* Return the number of arguments to this command.  Note that this includes

 * the command name as the first argument, so the command 'echo foo bar' is

 * counted as having three arguments.

 */

int pipecmd_get_nargs (pipecmd *cmd);

/* Set the nice(3) value for this command.  Defaults to 0.  Errors while

 * attempting to set the nice value are ignored, aside from emitting a debug

 * message.

 */

void pipecmd_nice (pipecmd *cmd, int nice);

/* If discard_err is non-zero, redirect this command's standard error to

 * /dev/null.  Otherwise, and by default, pass it through.

 */

void pipecmd_discard_err (pipecmd *cmd, int discard_err);

/* Change to this directory while running this command. */

void pipecmd_chdir (pipecmd *cmd, const char *directory);

/* Change to the directory given by this open file descriptor while running

 * this command. */

void pipecmd_fchdir (pipecmd *cmd, int directory_fd);

/* Set an environment variable while running this command. */

void pipecmd_setenv (pipecmd *cmd, const char *name, const char *value);

/* Unset an environment variable while running this command. */

void pipecmd_unsetenv (pipecmd *cmd, const char *name);

/* Clear the environment while running this command.  (Note that environment

 * operations work in sequence; pipecmd_clearenv followed by pipecmd_setenv

 * causes the command to have just a single environment variable set.)

 * Beware that this may cause unexpected failures, for example if some of

 * the contents of the environment are necessary to execute programs at all

 * (say, PATH).

 */

void pipecmd_clearenv (pipecmd *cmd);

/* Install a pre-exec handler.  This will be run immediately before

 * executing the command's payload (process or function).  Pass NULL to

 * clear any existing pre-exec handler.  The data argument is passed as the

 * function's only argument, and will be freed before returning using

 * free_func (if non-NULL).

 *

 * This is similar to pipeline_install_post_fork, except that is specific to

 * a single command rather than installing a global handler, and it runs

 * slightly later (immediately before exec rather than immediately after

 * fork).

 */

void pipecmd_pre_exec (pipecmd *cmd,

		       pipecmd_function_type *func,

		       pipecmd_function_free_type *free_func,

		       void *data);

/* Add a command to a sequence. */

void pipecmd_sequence_command (pipecmd *cmd, pipecmd *child);

/* Dump a string representation of a command to stream. */

void pipecmd_dump (pipecmd *cmd, FILE *stream);

/* Return a string representation of a command. The caller should free the

 * result.

 */

char *pipecmd_tostring (pipecmd *cmd);

/* Execute a single command, replacing the current process.  Never returns,

 * instead exiting non-zero on failure.

 */

void pipecmd_exec (pipecmd *cmd) PIPELINE_ATTR_NORETURN;

/* Destroy a command. Safely does nothing on NULL. */

void pipecmd_free (pipecmd *cmd);

/* ---------------------------------------------------------------------- */

/* Functions to build pipelines. */

/* Construct a new pipeline. */

pipeline *pipeline_new (void);

/* Convenience constructors wrapping pipeline_new() and pipeline_command().

 * Terminate commands with NULL.

 */

pipeline *pipeline_new_commandv (pipecmd *cmd1, va_list cmdv);

pipeline *pipeline_new_commands (pipecmd *cmd1, ...) PIPELINE_ATTR_SENTINEL;

/* Construct a new pipeline and add a single command to it. */

pipeline *pipeline_new_command_argv (const char *name, va_list argv);

pipeline *pipeline_new_command_args (const char *name, ...)

	PIPELINE_ATTR_SENTINEL;

/* Joins two pipelines, neither of which are allowed to be started. Discards

 * want_out, want_outfile, and outfd from p1, and want_in, want_infile, and

 * infd from p2.

 */

pipeline *pipeline_join (pipeline *p1, pipeline *p2);

/* Connect the input of one or more sink pipelines to the output of a source

 * pipeline. The source pipeline may be started, but in that case want_out

 * must be negative; otherwise, discards want_out from source. In any event,

 * discards want_in from all sinks, none of which are allowed to be started.

 * Terminate arguments with NULL.

 *

 * This is an application-level connection; data may be intercepted between

 * the pipelines by the program before calling pipeline_pump(), which sets

 * data flowing from the source to the sinks. It is primarily useful when

 * more than one sink pipeline is involved, in which case the pipelines

 * cannot simply be concatenated into one.

 */

void pipeline_connect (pipeline *source, pipeline *sink, ...)

	PIPELINE_ATTR_SENTINEL;

/* Add a command to a pipeline. */

void pipeline_command (pipeline *p, pipecmd *cmd);

/* Construct a new command and add it to a pipeline in one go. */

void pipeline_command_argv (pipeline *p, const char *name, va_list argv);

void pipeline_command_args (pipeline *p, const char *name, ...)

	PIPELINE_ATTR_SENTINEL;

/* Construct a new command from a shell-quoted string and add it to a

 * pipeline in one go. See the comment against pipecmd_new_argstr() above if

 * you're tempted to use this function.

 */

void pipeline_command_argstr (pipeline *p, const char *argstr);

/* Convenience functions wrapping pipeline_command().

 * Terminate commands with NULL.

 */

void pipeline_commandv (pipeline *p, va_list cmdv);

void pipeline_commands (pipeline *p, ...) PIPELINE_ATTR_SENTINEL;

/* Return the number of commands in this pipeline. */

int pipeline_get_ncommands (pipeline *p);

/* Return command number n from this pipeline, counting from zero, or NULL

 * if n is out of range.

 */

pipecmd *pipeline_get_command (pipeline *p, int n);

/* Set command number n in this pipeline, counting from zero, to cmd, and

 * return the previous command in that position.  Do nothing and return NULL

 * if n is out of range.

 */

pipecmd *pipeline_set_command (pipeline *p, int n, pipecmd *cmd);

/* Return the process ID of command number n from this pipeline, counting

 * from zero.  The pipeline must be started.  Return -1 if n is out of range

 * or if the command has already exited and been reaped.

 */

pid_t pipeline_get_pid (pipeline *p, int n);

/* Set file descriptors to use as the input and output of the whole

 * pipeline.  If non-negative, fd is used directly as a file descriptor.  If

 * negative, pipeline_start will create pipes and store the input writing

 * half and the output reading half in the pipeline's infd or outfd field as

 * appropriate.  The default is to leave input and output as stdin and

 * stdout unless pipeline_want_infile or pipeline_want_outfile respectively

 * has been called.

 *

 * Calling these functions supersedes any previous call to

 * pipeline_want_infile or pipeline_want_outfile respectively.

 */

void pipeline_want_in (pipeline *p, int fd);

void pipeline_want_out (pipeline *p, int fd);

/* Set file names to open and use as the input and output of the whole

 * pipeline.  This may be more convenient than supplying file descriptors,

 * and guarantees that the files are opened with the same privileges under

 * which the pipeline is run.

 *

 * Calling these functions (even with NULL, which returns to the default of

 * leaving input and output as stdin and stdout) supersedes any previous

 * call to pipeline_want_in or pipeline_want_outfile respectively.

 *

 * The given files will be opened when the pipeline is started.  If an

 * output file does not already exist, it is created (with mode 0666

 * modified in the usual way by umask); if it does exist, then it is

 * truncated.

 */

void pipeline_want_infile (pipeline *p, const char *file);

void pipeline_want_outfile (pipeline *p, const char *file);

/* If ignore_signals is non-zero (which is the default), ignore SIGINT and

 * SIGQUIT while the pipeline is running, like system().  Otherwise, leave

 * their dispositions unchanged.

 */

void pipeline_ignore_signals (pipeline *p, int ignore_signals);

/* Get streams corresponding to infd and outfd respectively. The pipeline

 * must be started.

 */

FILE *pipeline_get_infile (pipeline *p);

FILE *pipeline_get_outfile (pipeline *p);

/* Dump a string representation of p to stream. */

void pipeline_dump (pipeline *p, FILE *stream);

/* Return a string representation of p. The caller should free the result. */

char *pipeline_tostring (pipeline *p);

/* Destroy a pipeline and all its commands. Safely does nothing on NULL.

 * May wait for the pipeline to complete if it has not already done so.

 */

void pipeline_free (pipeline *p);

/* ---------------------------------------------------------------------- */

/* Functions to run pipelines and handle signals. */

typedef void pipeline_post_fork_fn (void);

/* Install a post-fork handler.  This will be run in any child process

 * immediately after it is forked.  For instance, this may be used for

 * cleaning up application-specific signal handlers.  Pass NULL to clear any

 * existing post-fork handler.

 *

 * See pipecmd_pre_exec for a similar facility limited to a single command

 * rather than global to the calling process.

 */

void pipeline_install_post_fork (pipeline_post_fork_fn *fn);

/* Start the processes in a pipeline. Installs this library's SIGCHLD

 * handler if not already installed. Calls error(FATAL) on error. */

void pipeline_start (pipeline *p);

/* Wait for a pipeline to complete.  Set *statuses to a newly-allocated

 * array of wait statuses, as returned by waitpid, and *n_statuses to the

 * length of that array.  The return value is similar to the exit status

 * that a shell would return, with some modifications.  If the last command

 * exits with a signal (other than SIGPIPE, which is considered equivalent

 * to exiting zero), then the return value is 128 plus the signal number; if

 * the last command exits normally but non-zero, then the return value is

 * its exit status; if any other command exits non-zero, then the return

 * value is 127; otherwise, the return value is 0.  This means that the

 * return value is only 0 if all commands in the pipeline exit successfully.

 */

int pipeline_wait_all (pipeline *p, int **statuses, int *n_statuses);

/* Wait for a pipeline to complete and return its combined exit status,

 * calculated as for pipeline_wait_all().

 */

int pipeline_wait (pipeline *p);

/* Start a pipeline, wait for it to complete, and free it, all in one go. */

int pipeline_run (pipeline *p);

/* Pump data among one or more pipelines connected using pipeline_connect()

 * until all source pipelines have reached end-of-file and all data has been

 * written to all sinks (or failed). All relevant pipelines must be

 * supplied: that is, no pipeline that has been connected to a source

 * pipeline may be supplied unless that source pipeline is also supplied.

 * Automatically starts all pipelines if they are not already started, but

 * does not wait for them. Terminate arguments with NULL.

 */

void pipeline_pump (pipeline *p, ...) PIPELINE_ATTR_SENTINEL;

/* ---------------------------------------------------------------------- */

/* Functions to read output from pipelines. */

/* Read len bytes of data from the pipeline, returning the data block. len

 * is updated with the number of bytes read.

 */

const char *pipeline_read (pipeline *p, size_t *len);

/* Look ahead in the pipeline's output for len bytes of data, returning the

 * data block. len is updated with the number of bytes read. The starting

 * position of the next read or peek is not affected by this call.

 */

const char *pipeline_peek (pipeline *p, size_t *len);

/* Return the number of bytes of data that can be read using pipeline_read

 * or pipeline_peek solely from the peek cache, without having to read from

 * the pipeline itself (and thus potentially block).

 */

size_t pipeline_peek_size (pipeline *p);

/* Skip over and discard len bytes of data from the peek cache. Asserts that

 * enough data is available to skip, so you may want to check using

 * pipeline_peek_size first.

 */

void pipeline_peek_skip (pipeline *p, size_t len);

/* Read a line of data from the pipeline, returning it. */

const char *pipeline_readline (pipeline *p);

/* Look ahead in the pipeline's output for a line of data, returning it. The

 * starting position of the next read or peek is not affected by this call.

 */

const char *pipeline_peekline (pipeline *p);

#ifdef __cplusplus

}

#endif

#endif /* PIPELINE_H */