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/* Copyright 2019 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/* Library for creating subprocesses in a high level manner. */
#ifndef VBOOT_REFERENCE_SUBPROCESS_H_
#define VBOOT_REFERENCE_SUBPROCESS_H_
#include <stdio.h>
#include <stdlib.h>
/**
* subprocess_target is the "mini language" of the subprocess
* library. It describes where to read or write data from the process.
*
* There are currently five target of targets:
*
* - TARGET_NULL: /dev/null, no need to describe any other fields.
*
* - TARGET_FD: file descriptor, put the fd in the fd field.
*
* - TARGET_FILE: FILE *, put the FILE pointer in the file field.
*
* - TARGET_BUFFER: read to, or write from, a buffer. Fields:
* - buffer->buf: the buffer
* - buffer->size: the size of that buffer
* - buffer->bytes_consumed: do not fill out this field.
* subprocess_run will set it to the number of bytes read from the
* process (if writing to a buffer). Goes unused when reading from
* a buffer.
*
* - TARGET_BUFFER_NULL_TERMINATED: when reading from a buffer, don't
* fill out the size field and subprocess_run will strlen for you.
* When writing to a buffer, subprocess_run will reserve one byte of
* the size for a null terminator and guarantee that the output is
* always NULL terminated.
*/
struct subprocess_target {
enum {
TARGET_NULL,
TARGET_FD,
TARGET_FILE,
TARGET_BUFFER,
TARGET_BUFFER_NULL_TERMINATED,
} type;
union {
int fd;
FILE *file;
struct {
char *buf;
size_t size;
/* This variable is used internally by "run" and
* shouldn't be operated on by the caller.
*/
int _pipefd[2];
/* This variable is the output of the number of bytes
* read or written. It should be read by the caller, not
* set.
*/
size_t bytes_consumed;
} buffer;
};
};
/**
* A convenience subprocess target which uses TARGET_NULL.
*/
struct subprocess_target subprocess_null;
/**
* A convenience subprocess target which uses TARGET_FD to
* STDIN_FILENO.
*/
struct subprocess_target subprocess_stdin;
/**
* A convenience subprocess target which uses TARGET_FD to
* STDOUT_FILENO.
*/
struct subprocess_target subprocess_stdout;
/**
* A convenience subprocess target which uses TARGET_FD to
* STDERR_FILENO.
*/
struct subprocess_target subprocess_stderr;
/**
* Call a process described by argv and run until completion. Provide
* input from the subprocess target input, output to the subprocess
* target output, and error to the subprocess target error.
*
* If either input, output, or error are set to NULL, the will be
* &subprocess_stdin, &subprocess_stdout, or &subprocess_stderr
* respectively.
*
* Returns the exit status on success, or negative values on error.
*/
int subprocess_run(const char *const argv[],
struct subprocess_target *input,
struct subprocess_target *output,
struct subprocess_target *error);
#endif /* VBOOT_REFERENCE_SUBPROCESS_H_ */
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