iolib.c

VxWorks操作系统内核源代码

/* ioLib.c - I/O interface library */

/* Copyright 1984-2003 Wind River Systems, Inc. */
#include "copyright_wrs.h"

/*
modification history
--------------------
04z,31jan03,pmr  SPR 82273: fixed linkCount declaration in ioCreateOrOpen().
		 SPR 80447: fixed remove() to follow symbolic links.
04y,13jan03,gls  moved check for NULL name in ioCreateOrOpen() (SPR #82909)
04x,02Aug00,jgn  merge DOT-4 pthreads code +
		 add validation of null pointer for name as well as null string
04w,03oct01,dcb  Fix SPR 20033 side effect --- handle new return code from
                 iosFdSet.  Combine open() and creat() into one function.
04v,01mar99,yp   SPR 21655 - if iosDevFind() fails open() dosn't free fd
04u,21feb99,jdi  doc: listed errnos.
04t,03sep97,dgp  doc: SPR 9023 - correct reference to FIOGETNAME in ioctl()
04s,10jul97,dgp  doc: fix SPR 6117, rename() not supported on all devices
04r,20oct95,jdi  doc: addition for rename() (SPR 4167); added bit values
		    for open() and creat() flags (SPR 4276).
04q,10feb95,rhp  added names of stdio fd macros to ioLib man page
04p,26jul94,dvs  added doc for read/write if no driver routine (SPR #2019/2020).
04o,30sep93,jmm  resubmitted change originally in scd 10148
04n,08feb93,smb  changed int to size_t for read and write.
04m,21jan93,jdi  documentation cleanup for 5.1.
04l,29jul92,smb  added isatty for use by stdio library.
04k,22jul92,kdl  Replaced delete() with remove().
04j,18jul92,smb  Changed errno.h to errnoLib.h.
04i,04jul92,jcf  scalable/ANSI/cleanup effort.
04h,26may92,rrr  the tree shuffle
04g,28feb92,wmd  added bzero() call in ioFullFileNameGet() to init to 0's
		 fullPathName[] buffer before it is passed to subordinates.
04f,05dec91,rrr  made lseek take posix arguments (SEEK_)
04e,25nov91,llk  ansi stuff.  Modified remove() and rename().
		 included stdio.h.
04d,25nov91,rrr  cleanup of some ansi warings.
04c,04oct91,rrr  passed through the ansification filter
                  -changed functions to ansi style
		  -changed includes to have absolute path from h/
		  -changed READ, WRITE and UPDATE to O_RDONLY O_WRONLY and ...
		  -changed VOID to void
		  -changed copyright notice
04b,05apr91,jdi	 documentation -- removed header parens and x-ref numbers;
		 doc review by dnw.
04a,08feb91,jaa	 documentation cleanup.
03z,15oct90,dnw  made ioFullFileNameGet() be NOMANUAL
03y,05oct90,dnw  made readv, writev, ioDefDevGet, ioDefDirGet be NOMANUAL
		 made ioFullFileNameGet() use pathCat()
		 added chdir(), getcwd(), rename() for POSIX compliance
		 added remove() for ANSI compliance
		 added ioDefPathCat() (NOMANUAL)
03x,06jun90,rdc  added readv and writev.
03w,25may90,dnw  changed creat and open to NOT malloc filename before calling
		   iosFdSet.  This is now left up to iosFdSet.
03v,11may90,yao	 added missing modification history (03u) for the last checkin.
03u,09may90,yao	 typecasted malloc to (char *).
03t,01may90,llk  changed call to pathCat().  Now, pathCat() checks if a name
		   is too long, and returns ERROR if it is.
03s,14apr90,jcf  removed tcb extension dependencies.
03r,01apr90,llk  changed ioFullFileNameGet() and ioDefPathSet() so that only
		   filenames of MAX_FILENAME_LENGTH characters or less will
		   be accepted.
03q,14mar90,jdi  documentation cleanup.
03p,12dec89,dab  documentation.
03o,15nov89,dab  changed variable name mode to flag in creat().  documentation.
            rdc  added unlink, getwd for unix compatibility.
03n,02may89,dab  documentation touchup in lseek().
03m,23mar89,dab  made L_XTND option work in lseek(); fixed L_INCR bug in
		 lseek(); documentation touchup in creat().
03l,23nov88,llk  fixed bug in handling multiple links.
	    dnw  changed ioTaskStd{Set,Get} to take taskId arg.
03k,08oct88,gae  made global standard fd array local.
03j,07sep88,gae  documentation.
03i,29aug88,gae  documentation.
03h,15aug88,jcf  lint.
03g,15jul88,llk  changed to allocate an fd name before calling iosFdSet or
		   iosFdNew.
03f,30jun88,llk  changed open and create so that they handle links.
03e,04jun88,llk  uses a default path instead of a default device.
		 changed ioDefDev to ioDefPath.
		 added ioDefPathPrompt, ioDefPathShow, ioDefPathSet,
		    ioDefPathGet, ioDefDirGet.
		 rewrote ioDefDevGet.
		 removed ioSetDefDev.
		 added ioFullFileNameGet.
03d,30may88,dnw  changed to v4 names.
03c,28may88,dnw  deleted obsolete create().
03b,27may88,llk  see change 03e above.
03a,30mar88,gae  made I/O system, i.e. iosLib, responsible for low-level
		   creat,open,read,write,close calls to drivers as
		   fdTable & drvTable are now hidden.
                 added parameters to open() for UNIX compatibility.
		 made L_INCR option work in lseek().
		 added io{G,S}et{Global,Task}Std().
02u,19apr88,llk  added a parameter to open.  Inspired by NFS and aspirations
		   toward UNIX compatibility.
02t,31dec87,jlf  made creat and open follow links.
02s,05nov87,jlf  documentation
02r,30sep87,gae  removed usage of fdTable by using new iosFdSet().
		 added FIOGETNAME to ioctl.
02q,28aug87,dnw  changed creat() and open() to only treat ERROR (-1) as error
		   indication from driver routines instead of < 0 to allow
		   driver values (i.e. structure pointers) to be in memory
		   with high bit set.
02p,28apr87,gae  close() now returns status; added UNIX compatible creat().
02o,24mar87,jlf  documentation
02n,25feb87,ecs  minor documentation.
		 added include of strLib.h.
02m,14feb87,dnw  changed create(), open(), delete() to return ERROR if null
		   filename is specified.  However, filename "." is turned
		   into null filename before being passed to driver routine.
02l,20dec86,dnw  fixed ioGetDefDevTail() to require complete match of dev name.
		 changed to not get include files from default directories.
02k,07oct86,gae	 added ioGetDefDevTail().
02j,04sep86,jlf  minor documentation
02i,01jul86,jlf  minor documentation
02h,03apr86,llk	 fixed syntax error in lseek.
02g,03mar86,jlf  changed ioctrl calls to ioctl.
		 added lseek.
...deleted pre 86 history - see RCS
*/

/*
DESCRIPTION
This library contains the interface to the basic I/O system.
It includes:
.iP "" 4
Interfaces to the seven basic driver-provided functions:
creat(), remove(), open(), close(), read(), write(), and ioctl().
.iP
Interfaces to several file system functions, including
rename() and lseek().
.iP
Routines to set and get the current working directory.
.iP
Routines to assign task and global standard file descriptors.

FILE DESCRIPTORS
At the basic I/O level, files are referred to by a file descriptor.
A file descriptor is a small integer returned by a call to open() or creat().  
The other basic I/O calls take a file descriptor as a parameter to specify 
the intended file.

Three file descriptors are reserved and have special meanings:

    0 (`STD_IN')  - standard input
    1 (`STD_OUT') - standard output
    2 (`STD_ERR') - standard error output

VxWorks allows two levels of redirection.  First, there is a global
assignment of the three standard file descriptors.  By default, new tasks use
this global assignment.  The global assignment of the three standard
file descriptors is controlled by the routines ioGlobalStdSet() and 
ioGlobalStdGet().

Second, individual tasks may override the global assignment of these
file descriptors with their own assignments that apply only to that task.  
The assignment of task-specific standard file descriptors is controlled 
by the routines ioTaskStdSet() and ioTaskStdGet().  

INCLUDE FILES: ioLib.h

SEE ALSO: iosLib, ansiStdio,
.pG "I/O System"
*/

/* LINTLIBRARY */

#include "vxWorks.h"
#include "sys/types.h"
#include "memLib.h"
#include "ioLib.h"
#include "iosLib.h"
#include "string.h"
#include "taskLib.h"
#include "net/uio.h"
#include "errnoLib.h"
#include "stdio.h"
#include "fcntl.h"
#include "unistd.h"
#include "pathLib.h"
#include "string.h"
#define __PTHREAD_SRC
#include "pthread.h"

IMPORT char ioDefPath [MAX_FILENAME_LENGTH];	/* current default i/o prefix */

#define	STD_VALID(fd)	(((fd) >= 0) && ((fd) < 3))

/* globals */

BOOL ioMaxLinkLevels = 20;	/* maximum number of symlinks to traverse */

/* forward declarations */
LOCAL int ioCreateOrOpen (const char *name, int flags, int mode, BOOL create);

/* locals */

LOCAL int ioStdFd [3];		/* global standard input/output/error */


/*******************************************************************************
*
* creat - create a file
*
* This routine creates a file called <name> and opens it with a specified
* <flag>.  This routine determines on which device to create the file; 
* it then calls the create routine of the device driver to do most of the work.
* Therefore, much of what transpires is device/driver-dependent.
*
* The parameter <flag> is set to O_RDONLY (0), O_WRONLY (1), or O_RDWR (2)
* for the duration of time the file is open.  To create NFS files with a
* UNIX chmod-type file mode, call open() with the file mode specified in
* the third argument.
*
* INTERNAL
* A driver's create routine will return FOLLOW_LINK if any part of the file name
* contains a link (in the directory path).  In this case, it will also
* have changed the name of the file being opened to incorporate the name of
* the link.  The new file name is then repeatedly resubmitted to the driver's
* open routine until all links are resolved.
*
* NOTE
* For more information about situations when there are no file descriptors
* available, see the manual entry for iosInit().
*
* RETURNS:
* A file descriptor number, or ERROR if a filename is not specified, the
* device does not exist, no file descriptors are available, or the driver
* returns ERROR.
*
* SEE ALSO: open()
*
*/

int creat
    (
    const char *name,   /* name of the file to create    */
    int        flag   	/* O_RDONLY, O_WRONLY, or O_RDWR */
    )
    {
    return ioCreateOrOpen (name, flag, 0, TRUE);
    }


/*******************************************************************************
*
* open - open a file
*
* This routine opens a file for reading, writing, or updating, and returns
* a file descriptor for that file.  The arguments to open() are the filename 
* and the type of access:
*
* .TS
* tab(|);
* 8l l l.
* O_RDONLY  (0)    |(or READ)   |- open for reading only.
* O_WRONLY  (1)    |(or WRITE)  |- open for writing only.
* O_RDWR  (2)      |(or UPDATE) |- open for reading and writing.
* O_CREAT  (0x0200)|            |- create a file.
* .TE
*
* In general, open() can only open pre-existing devices and files.  However,
* for NFS network devices only, files can also be created with open() by
* performing a logical OR operation with O_CREAT and the <flags> argument.
* In this case, the file is created with a UNIX chmod-style file mode, as
* indicated with <mode>.  For example:
* .CS
*     fd = open ("/usr/myFile", O_CREAT | O_RDWR, 0644);
* .CE
* Only the NFS driver uses the <mode> argument.
*
* INTERNAL
* A driver's open routine will return FOLLOW_LINK if any part of the file name
* contains a link (directory path or file name).  In this case, it will also
* have changed the name of the file being opened to incorporate the name of
* the link.  The new file name is then repeatedly resubmitted to the driver's
* open routine until all links are resolved.
*
* NOTE
* For more information about situations when there are no file descriptors
* available, see the manual entry for iosInit().
*
* RETURNS:
* A file descriptor number, or ERROR if a file name is not specified, the
* device does not exist, no file descriptors are available, or the driver
* returns ERROR.
*
* ERRNO: ELOOP
*
* SEE ALSO: creat()
*
* VARARGS2
*
*/

int open
    (
    const char *name,   /* name of the file to open                  */
    int flags,          /* O_RDONLY, O_WRONLY, O_RDWR, or O_CREAT    */
    int mode            /* mode of file to create (UNIX chmod style) */
    )
    {
    return ioCreateOrOpen (name, flags, mode, FALSE);
    }


/*******************************************************************************
*
* ioCreateOrOpen - creat() or open() a file
*
* This is the worker function for creat() and for open().  See their
* descriptions.
*
* NOMANUAL
*/

LOCAL int ioCreateOrOpen
    (
    const char *name,   /* name of the file to create    */
    int        flags,   /* O_RDONLY, O_WRONLY, O_RDWR or O_CREAT (open call) */
    int        mode,    /* mode of ile to create (if open call) */
    BOOL       create   /* set to TRUE if this is a creat() call */
    )
    {
    DEV_HDR *pDevHdr1;
    DEV_HDR *pDevHdr2 = NULL;
    int     value;
    int     fd = (int)ERROR;
    char    fullFileName [MAX_FILENAME_LENGTH];
    int     error = 0;
    int linkCount = 1;

    char *pPartFileName;
    int savtype;
    
    /* don't allow null filename (for user protection) but change
     * "." into what null filename would be if we allowed it */

    if ((name == NULL) || (name[0] == EOS))
	{
	errnoSet (S_ioLib_NO_FILENAME);

	/* fd is already defined as ERROR */

	return (fd);
	}

    if (_func_pthread_setcanceltype != NULL)
        {
        _func_pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &savtype);
        }

    if (strcmp (name, ".") == 0)
	{
	/* point to EOS (turn it into null filename) */
	++name;
	}

    
    if (ioFullFileNameGet (name, &pDevHdr1, fullFileName) == ERROR)
	{
	error = 1;
	goto handleError;
	}

    
    if ((fd = iosFdNew (pDevHdr1, (char *)NULL, 0)) == ERROR)
	{
	error = 1;
	goto handleError;
	}

    
    if (create == TRUE)
	{
	value = iosCreate (pDevHdr1, fullFileName, flags);
	}
    else
	{
	value = iosOpen (pDevHdr1, fullFileName, flags, mode);
	}
    
    if (value == ERROR)
	{
	error = 2;
	goto handleError;
	}

    
    /* In case the path does not follow the while loop, get the pDevHdr1
       recorded in pDevHdr2 for error handling. */
    pDevHdr2 = pDevHdr1;

    
    while (value == FOLLOW_LINK)
	{
	/* if a file name contains a link, the driver's create routine changed
	 * fullFileName to incorporate the link's name. Try to create the file
	 * that the driver's create routine handed back.
	 */

	if (linkCount++ > ioMaxLinkLevels)
	    {
	    errno = ELOOP;
	    error = 2;
	    goto handleError;
	    }

	if ((pDevHdr2 = iosDevFind (fullFileName, &pPartFileName)) == NULL)
	    {
	    error = 2;
	    goto handleError;
	    }

	if (fullFileName != pPartFileName)
	    {
	    /* link file name starts with a vxWorks device name,
	     * possibly a different device from the current one.
	     */

	    strncpy (fullFileName, pPartFileName, MAX_FILENAME_LENGTH);
	    pDevHdr1 = pDevHdr2;
	    }
	
	if (create == TRUE)
	    {
	    value = iosCreate (pDevHdr1, fullFileName, flags);
	    }
	else
	    {
	    value = iosOpen (pDevHdr1, fullFileName, flags, mode);
	    }
	
	if (value == ERROR)
	    {
	    error = 2;
	    goto handleError;
	    }	
	}


    
    if ((iosFdSet (fd, pDevHdr1, CHAR_FROM_CONST(name), value)) == ERROR)
	{
	error = 3;   
	goto handleError;
	}

    if (_func_pthread_setcanceltype != NULL)
        {
        _func_pthread_setcanceltype(savtype, NULL);
        }