/*************************************************************************\
* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
*     National Laboratory.
* Copyright (c) 2002 The Regents of the University of California, as
*     Operator of Los Alamos National Laboratory.
* EPICS BASE Versions 3.13.7
* and higher are distributed subject to a Software License Agreement found
* in file LICENSE that is included with this distribution. 
\*************************************************************************/

/* 
 * Revision-Id: anj@aps.anl.gov-20101005192737-disfz3vs0f3fiixd
 * 
 * Operating System Dependent Implementation of osiProcess.h
 *
 * Author: Jeff Hill
 *
 */

#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <pwd.h>

#define epicsExportSharedSymbols
#include "osiProcess.h"
#include "errlog.h"
#include "epicsAssert.h"

epicsShareFunc osiGetUserNameReturn epicsShareAPI osiGetUserName (char *pBuf, unsigned bufSizeIn)
{
    struct passwd *p;

    p = getpwuid ( getuid () );
    if ( p && p->pw_name ) {
        size_t len = strlen ( p->pw_name );
        unsigned uiLength;

        if ( len > UINT_MAX || len <= 0 ) {
            return osiGetUserNameFail;
        }
        uiLength = (unsigned) len;

        if ( uiLength + 1 >= bufSizeIn ) {
            return osiGetUserNameFail;
        }

        strncpy ( pBuf, p->pw_name, (size_t) bufSizeIn );

        return osiGetUserNameSuccess;
    }
    else {
        return osiGetUserNameFail;
    }
}

epicsShareFunc osiSpawnDetachedProcessReturn epicsShareAPI osiSpawnDetachedProcess 
    (const char *pProcessName, const char *pBaseExecutableName)
{
    int status;
    
    /*
     * create a duplicate process
     */
    status = fork ();
    if (status < 0) {
        return osiSpawnDetachedProcessFail;
    }

    /*
     * return to the caller
     * if its in the initiating process
     */
    if (status) {
        return osiSpawnDetachedProcessSuccess;
    }

    /*
     * close all open files except for STDIO so they will not
     * be inherited by the spawned process.
     */
    {
        int fd, maxfd = sysconf ( _SC_OPEN_MAX );
        for ( fd = 0; fd <= maxfd; fd++ ) {
            if (fd==STDIN_FILENO) continue;
            if (fd==STDOUT_FILENO) continue;
            if (fd==STDERR_FILENO) continue;
            close (fd);
        }
    }

    /*
     * overlay the specified executable
     */
    status = execlp (pBaseExecutableName, pBaseExecutableName, (char *)NULL);
    if ( status < 0 ) { 
        fprintf ( stderr, "**** The executable \"%s\" couldn't be located\n", pBaseExecutableName );
        fprintf ( stderr, "**** because of errno = \"%s\".\n", strerror (errno) );
        fprintf ( stderr, "**** You may need to modify your PATH environment variable.\n" );
        fprintf ( stderr, "**** Unable to start \"%s\" process.\n", pProcessName);
    }
    /* Don't run our parent's atexit() handlers */
    _exit ( -1 );
}