miscinit.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 947 行 · 第 1/2 页

/*-------------------------------------------------------------------------
 *
 * miscinit.c
 *	  miscellaneous initialization support stuff
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.116 2003/09/26 15:27:37 petere Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <sys/param.h>
#include <signal.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <fcntl.h>
#include <unistd.h>
#include <grp.h>
#include <pwd.h>
#include <errno.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#ifdef HAVE_UTIME_H
#include <utime.h>
#endif

#include "catalog/catname.h"
#include "catalog/pg_shadow.h"
#include "libpq/libpq-be.h"
#include "miscadmin.h"
#include "storage/ipc.h"
#include "storage/pg_shmem.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"


ProcessingMode Mode = InitProcessing;

/* Note: we rely on these to initialize as zeroes */
static char directoryLockFile[MAXPGPATH];
static char socketLockFile[MAXPGPATH];


/* ----------------------------------------------------------------
 *		ignoring system indexes support stuff
 *
 * NOTE: "ignoring system indexes" means we do not use the system indexes
 * for lookups (either in hardwired catalog accesses or in planner-generated
 * plans).  We do, however, still update the indexes when a catalog
 * modification is made.
 * ----------------------------------------------------------------
 */

static bool isIgnoringSystemIndexes = false;

/*
 * IsIgnoringSystemIndexes
 *		True if ignoring system indexes.
 */
bool
IsIgnoringSystemIndexes(void)
{
	return isIgnoringSystemIndexes;
}

/*
 * IgnoreSystemIndexes
 *		Set true or false whether PostgreSQL ignores system indexes.
 */
void
IgnoreSystemIndexes(bool mode)
{
	isIgnoringSystemIndexes = mode;
}

/* ----------------------------------------------------------------
 *		system index reindexing support
 *
 * When we are busy reindexing a system index, this code provides support
 * for preventing catalog lookups from using that index.
 * ----------------------------------------------------------------
 */

static Oid	currentlyReindexedHeap = InvalidOid;
static Oid	currentlyReindexedIndex = InvalidOid;

/*
 * ReindexIsProcessingHeap
 *		True if heap specified by OID is currently being reindexed.
 */
bool
ReindexIsProcessingHeap(Oid heapOid)
{
	return heapOid == currentlyReindexedHeap;
}

/*
 * ReindexIsProcessingIndex
 *		True if index specified by OID is currently being reindexed.
 */
bool
ReindexIsProcessingIndex(Oid indexOid)
{
	return indexOid == currentlyReindexedIndex;
}

/*
 * SetReindexProcessing
 *		Set flag that specified heap/index are being reindexed.
 *		Pass InvalidOid to indicate that reindexing is not active.
 */
void
SetReindexProcessing(Oid heapOid, Oid indexOid)
{
	/* Args should be both, or neither, InvalidOid */
	Assert((heapOid == InvalidOid) == (indexOid == InvalidOid));
	/* Reindexing is not re-entrant. */
	Assert(indexOid == InvalidOid || currentlyReindexedIndex == InvalidOid);
	currentlyReindexedHeap = heapOid;
	currentlyReindexedIndex = indexOid;
}

/* ----------------------------------------------------------------
 *				database path / name support stuff
 * ----------------------------------------------------------------
 */

void
SetDatabasePath(const char *path)
{
	if (DatabasePath)
	{
		free(DatabasePath);
		DatabasePath = NULL;
	}
	/* use strdup since this is done before memory contexts are set up */
	if (path)
	{
		DatabasePath = strdup(path);
		AssertState(DatabasePath);
	}
}

/*
 * Set data directory, but make sure it's an absolute path.  Use this,
 * never set DataDir directly.
 */
void
SetDataDir(const char *dir)
{
	char	   *new;
	int			newlen;

	AssertArg(dir);

	/* If presented path is relative, convert to absolute */
	if (!is_absolute_path(dir))
	{
		char	   *buf;
		size_t		buflen;

		buflen = MAXPGPATH;
		for (;;)
		{
			buf = malloc(buflen);
			if (!buf)
				ereport(FATAL,
						(errcode(ERRCODE_OUT_OF_MEMORY),
						 errmsg("out of memory")));

			if (getcwd(buf, buflen))
				break;
			else if (errno == ERANGE)
			{
				free(buf);
				buflen *= 2;
				continue;
			}
			else
			{
				free(buf);
				elog(FATAL, "could not get current working directory: %m");
			}
		}

		new = malloc(strlen(buf) + 1 + strlen(dir) + 1);
		if (!new)
			ereport(FATAL,
					(errcode(ERRCODE_OUT_OF_MEMORY),
					 errmsg("out of memory")));
		sprintf(new, "%s/%s", buf, dir);
		free(buf);
	}
	else
	{
		new = strdup(dir);
		if (!new)
			ereport(FATAL,
					(errcode(ERRCODE_OUT_OF_MEMORY),
					 errmsg("out of memory")));
	}

	/*
	 * Strip any trailing slash.  Not strictly necessary, but avoids
	 * generating funny-looking paths to individual files.
	 */
	newlen = strlen(new);
	if (newlen > 1 && new[newlen - 1] == '/'
#ifdef WIN32
		|| new[newlen - 1] == '\\'
#endif
		)
		new[newlen - 1] = '\0';

	if (DataDir)
		free(DataDir);
	DataDir = new;
}


/* ----------------------------------------------------------------
 *	User ID things
 *
 * The authenticated user is determined at connection start and never
 * changes.  The session user can be changed only by SET SESSION
 * AUTHORIZATION.  The current user may change when "setuid" functions
 * are implemented.  Conceptually there is a stack, whose bottom
 * is the session user.  You are yourself responsible to save and
 * restore the current user id if you need to change it.
 * ----------------------------------------------------------------
 */
static AclId AuthenticatedUserId = 0;
static AclId SessionUserId = 0;
static AclId CurrentUserId = 0;

static bool AuthenticatedUserIsSuperuser = false;

/*
 * This function is relevant for all privilege checks.
 */
AclId
GetUserId(void)
{
	AssertState(AclIdIsValid(CurrentUserId));
	return CurrentUserId;
}


void
SetUserId(AclId newid)
{
	AssertArg(AclIdIsValid(newid));
	CurrentUserId = newid;
}


/*
 * This value is only relevant for informational purposes.
 */
AclId
GetSessionUserId(void)
{
	AssertState(AclIdIsValid(SessionUserId));
	return SessionUserId;
}


void
SetSessionUserId(AclId newid)
{
	AssertArg(AclIdIsValid(newid));
	SessionUserId = newid;
	/* Current user defaults to session user. */
	if (!AclIdIsValid(CurrentUserId))
		CurrentUserId = newid;
}


void
InitializeSessionUserId(const char *username)
{
	HeapTuple	userTup;
	Datum		datum;
	bool		isnull;
	AclId		usesysid;

	/*
	 * Don't do scans if we're bootstrapping, none of the system catalogs
	 * exist yet, and they should be owned by postgres anyway.
	 */
	AssertState(!IsBootstrapProcessingMode());

	/* call only once */
	AssertState(!OidIsValid(AuthenticatedUserId));

	userTup = SearchSysCache(SHADOWNAME,
							 PointerGetDatum(username),
							 0, 0, 0);
	if (!HeapTupleIsValid(userTup))
		ereport(FATAL,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("user \"%s\" does not exist", username)));

	usesysid = ((Form_pg_shadow) GETSTRUCT(userTup))->usesysid;

	AuthenticatedUserId = usesysid;
	AuthenticatedUserIsSuperuser = ((Form_pg_shadow) GETSTRUCT(userTup))->usesuper;

	SetSessionUserId(usesysid); /* sets CurrentUserId too */

	/* Record username and superuser status as GUC settings too */
	SetConfigOption("session_authorization", username,
					PGC_BACKEND, PGC_S_OVERRIDE);
	SetConfigOption("is_superuser",
					AuthenticatedUserIsSuperuser ? "on" : "off",
					PGC_INTERNAL, PGC_S_OVERRIDE);

	/*
	 * Set up user-specific configuration variables.  This is a good place
	 * to do it so we don't have to read pg_shadow twice during session
	 * startup.
	 */
	datum = SysCacheGetAttr(SHADOWNAME, userTup,
							Anum_pg_shadow_useconfig, &isnull);
	if (!isnull)
	{
		ArrayType  *a = DatumGetArrayTypeP(datum);

		ProcessGUCArray(a, PGC_S_USER);
	}

	ReleaseSysCache(userTup);
}


void
InitializeSessionUserIdStandalone(void)
{
	/* This function should only be called in a single-user backend. */
	AssertState(!IsUnderPostmaster);

	/* call only once */
	AssertState(!OidIsValid(AuthenticatedUserId));

	AuthenticatedUserId = BOOTSTRAP_USESYSID;
	AuthenticatedUserIsSuperuser = true;

	SetSessionUserId(BOOTSTRAP_USESYSID);
}


/*
 * Change session auth ID while running
 *
 * Only a superuser may set auth ID to something other than himself.  Note
 * that in case of multiple SETs in a single session, the original userid's
 * superuserness is what matters.  But we set the GUC variable is_superuser
 * to indicate whether the *current* session userid is a superuser.
 */
void
SetSessionAuthorization(AclId userid, bool is_superuser)
{
	/* Must have authenticated already, else can't make permission check */
	AssertState(AclIdIsValid(AuthenticatedUserId));

	if (userid != AuthenticatedUserId &&
		!AuthenticatedUserIsSuperuser)
		ereport(ERROR,
				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
			  errmsg("permission denied to set session authorization")));

	SetSessionUserId(userid);
	SetUserId(userid);

	SetConfigOption("is_superuser",
					is_superuser ? "on" : "off",
					PGC_INTERNAL, PGC_S_OVERRIDE);
}


/*
 * Get user name from user id
 */
char *
GetUserNameFromId(AclId userid)
{
	HeapTuple	tuple;
	char	   *result;

	tuple = SearchSysCache(SHADOWSYSID,
						   ObjectIdGetDatum(userid),
						   0, 0, 0);
	if (!HeapTupleIsValid(tuple))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("invalid user ID: %d", userid)));

	result = pstrdup(NameStr(((Form_pg_shadow) GETSTRUCT(tuple))->usename));

	ReleaseSysCache(tuple);
	return result;
}



/*-------------------------------------------------------------------------
 *				Interlock-file support
 *
 * These routines are used to create both a data-directory lockfile
 * ($DATADIR/postmaster.pid) and a Unix-socket-file lockfile ($SOCKFILE.lock).
 * Both kinds of files contain the same info:
 *
 *		Owning process' PID
 *		Data directory path
 *
 * By convention, the owning process' PID is negated if it is a standalone
 * backend rather than a postmaster.  This is just for informational purposes.
 * The path is also just for informational purposes (so that a socket lockfile
 * can be more easily traced to the associated postmaster).
 *
 * A data-directory lockfile can optionally contain a third line, containing
 * the key and ID for the shared memory block used by this postmaster.
 *
 * On successful lockfile creation, a proc_exit callback to remove the
 * lockfile is automatically created.
 *-------------------------------------------------------------------------
 */

/*
 * proc_exit callback to remove a lockfile.
 */
static void
UnlinkLockFile(int status, Datum filename)
{
	char	   *fname = (char *) DatumGetPointer(filename);

	if (fname != NULL)
	{
		if (unlink(fname) != 0)
		{
			/* Should we complain if the unlink fails? */
		}
		free(fname);
	}
}

/*
 * Create a lockfile.
 *
 * filename is the name of the lockfile to create.
 * amPostmaster is used to determine how to encode the output PID.
 * isDDLock and refName are used to determine what error message to produce.
 */
static void
CreateLockFile(const char *filename, bool amPostmaster,
			   bool isDDLock, const char *refName)
{
	int			fd;
	char		buffer[MAXPGPATH + 100];
	int			ntries;
	int			len;
	int			encoded_pid;
	pid_t		other_pid;
	pid_t		my_pid = getpid();

	/*