/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*--------------------------------------------------------------------
 * ps_status.c
 *
 * Routines to support changing the ps display of PostgreSQL backends
 * to contain some useful information. Mechanism differs wildly across
 * platforms.
 *
 * $PostgreSQL: pgsql/src/backend/utils/misc/ps_status.c,v 1.33 2006/10/04 00:30:04 momjian Exp $
 *
 * Portions Copyright (c) 2005-2009, Greenplum inc
 * Copyright (c) 2000-2009, PostgreSQL Global Development Group
 * various details abducted from various places
 *--------------------------------------------------------------------
 */

#include "postgres.h"

#include <unistd.h>
#ifdef HAVE_SYS_PSTAT_H
#include <sys/pstat.h>			/* for HP-UX */
#endif
#ifdef HAVE_PS_STRINGS
#include <machine/vmparam.h>	/* for old BSD */
#include <sys/exec.h>
#endif
#if defined(__darwin__)
#include <crt_externs.h>
#endif

#include "libpq/libpq.h"
#include "miscadmin.h"
#include "utils/ps_status.h"

#include "cdb/cdbvars.h"        /* Gp_role, Gp_segment, currentSliceId */

extern char **environ;
extern int PostPortNumber;
bool		update_process_title = true;

/*
 * Alternative ways of updating ps display:
 *
 * PS_USE_SETPROCTITLE
 *	   use the function setproctitle(const char *, ...)
 *	   (newer BSD systems)
 * PS_USE_PSTAT
 *	   use the pstat(PSTAT_SETCMD, )
 *	   (HPUX)
 * PS_USE_PS_STRINGS
 *	   assign PS_STRINGS->ps_argvstr = "string"
 *	   (some BSD systems)
 * PS_USE_CHANGE_ARGV
 *	   assign argv[0] = "string"
 *	   (some other BSD systems)
 * PS_USE_CLOBBER_ARGV
 *	   write over the argv and environment area
 *	   (most SysV-like systems)
 * PS_USE_WIN32
 *	   push the string out as the name of a Windows event
 * PS_USE_NONE
 *	   don't update ps display
 *	   (This is the default, as it is safest.)
 */
#if defined(HAVE_SETPROCTITLE)
#define PS_USE_SETPROCTITLE
#elif defined(HAVE_PSTAT) && defined(PSTAT_SETCMD)
#define PS_USE_PSTAT
#elif defined(HAVE_PS_STRINGS)
#define PS_USE_PS_STRINGS
#elif (defined(BSD) || defined(__bsdi__) || defined(__hurd__)) && !defined(__darwin__)
#define PS_USE_CHANGE_ARGV
#elif defined(__linux__) || defined(_AIX) || defined(__sgi) || (defined(sun) && !defined(BSD)) || defined(ultrix) || defined(__ksr__) || defined(__osf__) || defined(__svr4__) || defined(__svr5__) || defined(__darwin__)
#define PS_USE_CLOBBER_ARGV
#elif defined(WIN32)
#define PS_USE_WIN32
#else
#define PS_USE_NONE
#endif

/* Different systems want the buffer padded differently */

#if defined(_AIX) || defined(__linux__) || defined(__svr4__)
#define PS_PADDING '\0'
#else
#define PS_PADDING ' '
#endif

#ifndef PS_USE_CLOBBER_ARGV
/* all but one options need a buffer to write their ps line in */
#define PS_BUFFER_SIZE 256
static char ps_buffer[PS_BUFFER_SIZE];
static const size_t ps_buffer_size = PS_BUFFER_SIZE;
#else							/* PS_USE_CLOBBER_ARGV */
static char *ps_buffer;			/* will point to argv area */
static size_t ps_buffer_size;	/* space determined at run time */
static size_t last_status_len;  /* use to minimize length of clobber */
#endif   /* PS_USE_CLOBBER_ARGV */

static size_t ps_buffer_fixed_size;		/* size of the constant prefix */
#if (defined(sun) && !defined(BSD))
static size_t ps_argument_size; /* size for the first argument */
#endif

static size_t   ps_host_info_size;		/*CDB*/
static char     ps_host_info[64];       /*CDB*/
static char     ps_username[64];        /*CDB*/

/* save the original argv[] location here */
static int	save_argc;
static char **save_argv;

/* maximum database name string length */
#define DBNAME_MAX	10

/*
 * GPDB: the real activity location, the location right after
 * those "con1 seg1 cmd1" strings. Sometimes we need to modify
 * the original activity string in the ps display output. Use
 * this pointer to get the real original activity string instead
 * of get_ps_display(). See MPP-2329.
 */
static size_t real_act_prefix_size;

/*
 * Call this early in startup to save the original argc/argv values.
 * If needed, we make a copy of the original argv[] array to preserve it
 * from being clobbered by subsequent ps_display actions.
 *
 * (The original argv[] will not be overwritten by this routine, but may be
 * overwritten during init_ps_display.	Also, the physical location of the
 * environment strings may be moved, so this should be called before any code
 * that might try to hang onto a getenv() result.)
 */
char	  **
save_ps_display_args(int argc, char **argv)
{
	save_argc = argc;
	save_argv = argv;

#if defined(PS_USE_CLOBBER_ARGV)

	/*
	 * If we're going to overwrite the argv area, count the available space.
	 * Also move the environment to make additional room.
	 */
	{
		char	   *end_of_area = NULL;
		int			i;

#if (defined(sun) && !defined(BSD))
		ps_argument_size = 0;
#endif
		
		/*
		 * check for contiguous argv strings
		 */
		for (i = 0; i < argc; i++)
		{
			if (i == 0 || end_of_area + 1 == argv[i])
				end_of_area = argv[i] + strlen(argv[i]);
		}

		if (end_of_area == NULL)	/* probably can't happen? */
		{
			ps_buffer = NULL;
			ps_buffer_size = 0;
			return argv;
		}

#if (defined(sun) && !defined(BSD))
		ps_argument_size = strlen(argv[0]);
#endif

		/* 
		 * MPP-14501: only use argv area for status to preserve environment 
		 *
		 * Prior to this change, the code here would use all of the memory with
		 * the initial contents of argv and environ as a buffer for the process
		 * status line.  However that has the side effect of preventing other
		 * processes from examining the initial argv/environ of this process.
		 * Although we aren't concerned about argv, as of MPP-14501 we want
		 * other processes to be able to read this process's environment to
		 * detect the presence of the GPKILL environment variable.  So instead
		 * of using all of the argv+environ area, we instead just use the argv
		 * area.  We should not have to worry about the argv area on it's own
		 * being too small to display the status information because it's
		 * fairly large with all the arguments we pass and if that ever does
		 * become an issue we can always just have gpstart add more arguments.
		 */
		ps_buffer = argv[0];
		last_status_len = ps_buffer_size = (end_of_area - ps_buffer);
	}
#endif   /* PS_USE_CLOBBER_ARGV */

#if defined(PS_USE_CHANGE_ARGV) || defined(PS_USE_CLOBBER_ARGV)

	/*
	 * If we're going to change the original argv[] then make a copy for
	 * argument parsing purposes.
	 *
	 * (NB: do NOT think to remove the copying of argv[], even though
	 * postmaster.c finishes looking at argv[] long before we ever consider
	 * changing the ps display.  On some platforms, getopt() keeps pointers
	 * into the argv array, and will get horribly confused when it is
	 * re-called to analyze a subprocess' argument string if the argv storage
	 * has been clobbered meanwhile.  Other platforms have other dependencies
	 * on argv[].
	 */
	{
		char	  **new_argv;
		int			i;

		new_argv = (char **) malloc((argc + 1) * sizeof(char *));

		if(!new_argv)
		{
			write_stderr("Failed to change/set argv: Out of Memory");
			exit(1);
		}

		for (i = 0; i < argc; i++)
		{
			new_argv[i] = strdup(argv[i]);
			if(!new_argv[i])
			{
				write_stderr("Failed to change/set argv: Out of Memory");
				exit(1);
			}
		}

		new_argv[argc] = NULL;

#if defined(__darwin__)

		/*
		 * Darwin (and perhaps other NeXT-derived platforms?) has a static
		 * copy of the argv pointer, which we may fix like so:
		 */
		*_NSGetArgv() = new_argv;
#endif

		argv = new_argv;
	}
#endif   /* PS_USE_CHANGE_ARGV or PS_USE_CLOBBER_ARGV */

	return argv;
}

/*
 * Call this once during subprocess startup to set the identification
 * values.  At this point, the original argv[] array may be overwritten.
 */
void
init_ps_display(const char *username, const char *dbname,
				const char *host_info, const char *initial_str)
{
	Assert(username);
    Assert(dbname);
    Assert(host_info);
	
	StrNCpy(ps_username, username, sizeof(ps_username));    /*CDB*/

#ifndef PS_USE_NONE
    /* no ps display for stand-alone backend */
    if (!IsUnderPostmaster)
        return;

    /* no ps display if you didn't call save_ps_display_args() */
    if (!save_argv)
        return;
#ifdef PS_USE_CLOBBER_ARGV
    /* If ps_buffer is a pointer, it might still be null */
    if (!ps_buffer)
        return;
#endif

    /*
     * Overwrite argv[] to point at appropriate space, if needed
     */

#ifdef PS_USE_CHANGE_ARGV
    save_argv[0] = ps_buffer;
    save_argv[1] = NULL;
#endif   /* PS_USE_CHANGE_ARGV */

#ifdef PS_USE_CLOBBER_ARGV

#if defined(__darwin__)
    /* 
	 * MPP-14501, keep heuristic ps and other tools appear to use working
	 */
	if (ps_buffer_size > save_argc)
	{
		last_status_len -= save_argc;
		ps_buffer_size  -= save_argc;
		memset(ps_buffer+ps_buffer_size, 0, save_argc);
		ps_buffer[ps_buffer_size] = PS_PADDING;
	}
#endif /* darwin */

    {
        int         i;

        /* make extra argv slots point at end_of_area (a NUL) */
        for (i = 1; i < save_argc; i++)
            save_argv[i] = (ps_buffer + ps_buffer_size);
    }


#endif /* PS_USE_CLOBBER_ARGV */

    /*
     * Make fixed prefix of ps display.
     */

    /* Cut displayed database name to a short string if necessary. */
    char dbname2[DBNAME_MAX+4];
    int dbnamelen = strlen(dbname);
    if ( dbnamelen <= DBNAME_MAX )
    {
    	strcpy(dbname2, dbname);
    }
    else
    {
    	strncpy(dbname2, dbname, DBNAME_MAX);
    	dbname2[DBNAME_MAX  ] = '.';
    	dbname2[DBNAME_MAX+1] = '.';
    	dbname2[DBNAME_MAX+2] = '.';
    	dbname2[DBNAME_MAX+3] = '\0';
    }

#ifdef PS_USE_SETPROCTITLE

    /*
     * apparently setproctitle() already adds a `progname:' prefix to the ps
     * line
     */
    snprintf(ps_buffer, ps_buffer_size,
             "port %5d, %s %s %s ",
             PostPortNumber, username, dbname2, host_info);
#else
    snprintf(ps_buffer, ps_buffer_size,
             "postgres: port %5d, %s %s %s ",
             PostPortNumber, username, dbname2, host_info);
#endif /* not PS_USE_SETPROCTITLE */

    ps_buffer_fixed_size = strlen(ps_buffer);

	real_act_prefix_size = ps_buffer_fixed_size;

    set_ps_display(initial_str, true);
    
    /* CDB */
    StrNCpy(ps_host_info, host_info, sizeof(ps_host_info));
    ps_host_info_size = snprintf(ps_buffer + ps_buffer_fixed_size,
                                 ps_buffer_size - ps_buffer_fixed_size,
                                 "%s ", host_info);
	
	/* 
	 * MPP-14501, don't let a NUL from snprintf mess up our padding
	 */
#if defined(__darwin__)
	ps_buffer[ps_buffer_fixed_size + ps_host_info_size] = PS_PADDING;
#endif

    ps_buffer_fixed_size += ps_host_info_size;
	real_act_prefix_size = ps_buffer_fixed_size;
#endif   /* not PS_USE_NONE */
}


/*
 * Call this to update the ps status display to a fixed prefix plus an
 * indication of what you're currently doing passed in the argument.
 */
void
set_ps_display(const char *activity, bool force)
{
    char   *cp = ps_buffer + ps_buffer_fixed_size;
    char   *ep = ps_buffer + ps_buffer_size;

    if (!force && !update_process_title)
        return;

#ifndef PS_USE_NONE
    /* no ps display for stand-alone backend */
    if (!IsUnderPostmaster)
        return;

#ifdef PS_USE_CLOBBER_ARGV
    /* If ps_buffer is a pointer, it might still be null */
    if (!ps_buffer)
        return;
#endif
    
    /* Drop the remote host and port from the fixed prefix. */
    if (ps_host_info_size > 0)
    {
        ps_buffer_fixed_size -= ps_host_info_size;
        cp -= ps_host_info_size;
        ps_host_info_size = 0;
    }

    /* Add client session's global id. */
    if (ep > cp && gp_session_id > 0)
        cp += snprintf(cp, ep-cp, "con%d ", gp_session_id);

    /* Which segment is accessed by this qExec? */
    if (ep > cp && Gp_role == GP_ROLE_EXECUTE && GetQEIndex() >= MASTER_CONTENT_ID)
        cp += snprintf(cp, ep-cp, "seg%d ", GetQEIndex());

    /* Add count of commands received from client session. */
    if (ep > cp && gp_command_count > 0)
        cp += snprintf(cp, ep-cp, "cmd%d ", gp_command_count);

	/* Add slice number information */
	if (ep > cp && currentSliceId > 0)
		cp += snprintf(cp, ep-cp,"slice%d ", currentSliceId);

	real_act_prefix_size = cp - ps_buffer;

    /* Append caller's activity string. */
	if ( ep > cp )
		cp += snprintf(cp, ep-cp, "%s ", activity);

    /* Add host and port.  (Not very useful for qExecs, so skip.) */
    if (ep > cp && Gp_role != GP_ROLE_EXECUTE && ps_host_info[0] != '\0')
        cp += snprintf(cp, ep-cp, "%s ", ps_host_info);

    /* Transmit new setting to kernel, if necessary */
#ifdef PS_USE_SETPROCTITLE
    setproctitle("%s", ps_buffer);
#endif

#ifdef PS_USE_PSTAT
    {
        union pstun pst;

        pst.pst_command = ps_buffer;
        pstat(PSTAT_SETCMD, pst, strlen(ps_buffer), 0, 0);
    }
#endif   /* PS_USE_PSTAT */

#ifdef PS_USE_PS_STRINGS
    PS_STRINGS->ps_nargvstr = 1;
    PS_STRINGS->ps_argvstr = ps_buffer;
#endif   /* PS_USE_PS_STRINGS */

#ifdef PS_USE_CLOBBER_ARGV
    {
        int         buflen;
#if (defined(sun) && !defined(BSD))
		int         request_buflen = 2 * ps_argument_size + 1;
#endif

        /* pad unused memory */
        buflen = strlen(ps_buffer);

#if (defined(sun) && !defined(BSD))
		/*
		 * In Solaris, to properly show the ps status display, it requires the length of
		 * the status at least twice of the original arguments. We pad the '.'s
		 * if buflen is not big enough. Note that using spaces to pad does not work, 
		 * and I don't know why.
		 */
		if (buflen < request_buflen)
		{
			int pad_len = request_buflen - buflen;
			if (ps_buffer_size < request_buflen)
				pad_len = ps_buffer_size - buflen;
			MemSet(ps_buffer + buflen, '.', pad_len);
			buflen += pad_len;
		}
#endif

		if (last_status_len > buflen)
			MemSet(ps_buffer + buflen, PS_PADDING, last_status_len - buflen);
		last_status_len = buflen;
    }
#endif   /* PS_USE_CLOBBER_ARGV */

#ifdef PS_USE_WIN32
	{
		/*
		 * Win32 does not support showing any changed arguments. To make it at
		 * all possible to track which backend is doing what, we create a
		 * named object that can be viewed with for example Process Explorer.
		 */
		static HANDLE ident_handle = INVALID_HANDLE_VALUE;
		char		name[PS_BUFFER_SIZE + 32];

		if (ident_handle != INVALID_HANDLE_VALUE)
			CloseHandle(ident_handle);

		sprintf(name, "pgident(%d): %s", MyProcPid, ps_buffer);

		ident_handle = CreateEvent(NULL, TRUE, FALSE, name);
	}
#endif   /* PS_USE_WIN32 */
#endif   /* not PS_USE_NONE */
}

/*
 * Returns what's currently in the ps display with a given starting
 * position. On some platforms the string will not be null-terminated,
 * so return the effective length into *displen.
 */
static inline const char *
get_ps_display_from_position(size_t pos, int *displen)
{
#ifdef PS_USE_CLOBBER_ARGV
	size_t		offset;

	/* If ps_buffer is a pointer, it might still be null */
	if (!ps_buffer)
	{
		*displen = 0;
		return "";
	}

	/* Remove any trailing spaces to offset the effect of PS_PADDING */
	offset = ps_buffer_size;
	while (offset > pos && ps_buffer[offset-1] == PS_PADDING)
		offset--;

	*displen = offset - pos;
#else
	*displen = strlen(ps_buffer + pos);
#endif

	return ps_buffer + pos;
}

/*
 * Returns what's currently in the ps display, in case someone needs
 * it.	Note that only the activity part is returned.  On some platforms
 * the string will not be null-terminated, so return the effective
 * length into *displen.
 */
const char *
get_ps_display(int *displen)
{
	return get_ps_display_from_position(ps_buffer_fixed_size, displen);
}


/* CDB: Get the "username" string saved by init_ps_display().  */
const char *
get_ps_display_username(void)
{
    return ps_username;
}                               /* get_ps_display_username */

/*
 * Returns the real activity string in the ps display without prefix
 * strings like "con1 seg1 cmd1" for GPDB. On some platforms the
 * string will not be null-terminated, so return the effective length
 * into *displen.
 */
const char *
get_real_act_ps_display(int *displen)
{
	return get_ps_display_from_position(real_act_prefix_size, displen);
}