/*	$OpenPackages$ */
/*	$OpenBSD: cmd_exec.c,v 1.6 2007/07/24 21:09:07 espie Exp $ */
/*
 * Copyright (c) 2001 Marc Espie.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE OPENBSD PROJECT AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OPENBSD
 * PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include "config.h"
#include "defines.h"
#include "cmd_exec.h"
#include "buf.h"
#include "memory.h"
#include "pathnames.h"

char *
Cmd_Exec(const char *cmd, char **err)
{
	char	*args[4];	/* Args for invoking the shell */
	int 	fds[2]; 	/* Pipe streams */
	pid_t 	cpid;		/* Child PID */
	pid_t 	pid;		/* PID from wait() */
	char	*result;	/* Result */
	int 	status; 	/* Command exit status */
	BUFFER	buf;		/* Buffer to store the result. */
	char	*cp;		/* Pointer into result. */
	ssize_t	cc;		/* Characters read from pipe. */
	size_t	length;		/* Total length of result. */


	*err = NULL;

	/* Set up arguments for the shell. */
	args[0] = "sh";
	args[1] = "-c";
	args[2] = (char *)cmd;
	args[3] = NULL;

	/* Open a pipe for retrieving shell's output. */
	if (pipe(fds) == -1) {
		*err = "Couldn't create pipe for \"%s\"";
		goto bad;
	}

	/* Fork */
	switch (cpid = fork()) {
	case 0:
		/* Close input side of pipe */
		(void)close(fds[0]);

		/* Duplicate the output stream to the shell's output, then
		 * shut the extra thing down. Note we don't fetch the error
		 * stream: user can use redirection to grab it as this goes
		 * through /bin/sh.
		 */
		if (fds[1] != 1) {
			(void)dup2(fds[1], 1);
			(void)close(fds[1]);
		}

		(void)execv(_PATH_BSHELL, args);
		_exit(1);
		/*NOTREACHED*/

	case -1:
		*err = "Couldn't exec \"%s\"";
		goto bad;

	default:
		/* No need for the writing half. */
		(void)close(fds[1]);

		Buf_Init(&buf, MAKE_BSIZE);

		do {
			char   grab[BUFSIZ];

			cc = read(fds[0], grab, sizeof(grab));
			if (cc > 0)
				Buf_AddChars(&buf, cc, grab);
		} while (cc > 0 || (cc == -1 && errno == EINTR));

		/* Close the input side of the pipe.  */
		(void)close(fds[0]);

		/* Wait for the child to exit.  */
		while ((pid = wait(&status)) != cpid && pid >= 0)
			continue;

		if (cc == -1)
			*err = "Couldn't read shell's output for \"%s\"";

		if (status)
			*err = "\"%s\" returned non-zero status";

		length = Buf_Size(&buf);
		result = Buf_Retrieve(&buf);

		/* The result is null terminated, Convert newlines to spaces. */
		cp = result + length - 1;

		if (cp >= result && *cp == '\n')
			/* A final newline is just stripped.  */
			*cp-- = '\0';

		while (cp >= result) {
			if (*cp == '\n')
				*cp = ' ';
			cp--;
		}
		break;
	}
	return result;
    bad:
	return estrdup("");
}