source: trunk/third/sendmail/libsm/fopen.c @ 19204

/*
 * Copyright (c) 2000-2002 Sendmail, Inc. and its suppliers.
 *      All rights reserved.
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 */

#include <sm/gen.h>
SM_RCSID("@(#)$Id: fopen.c,v 1.1.1.1 2003-04-08 15:06:43 zacheiss Exp $")
#include <errno.h>
#include <setjmp.h>
#include <sys/time.h>
#include <sm/heap.h>
#include <sm/signal.h>
#include <sm/assert.h>
#include <sm/io.h>
#include <sm/clock.h>
#include "local.h"

extern int      sm_io_fclose __P((SM_FILE_T *));

static jmp_buf OpenTimeOut, ReopenTimeOut;

/*
**  OPENALRM -- handler when timeout activated for sm_io_open()
**
**  Returns flow of control to where setjmp(OpenTimeOut) was set.
**
**      Parameters:
**              sig -- unused
**
**      Returns:
**              does not return
**
**      Side Effects:
**              returns flow of control to setjmp(OpenTimeOut).
**
**      NOTE:   THIS CAN BE CALLED FROM A SIGNAL HANDLER.  DO NOT ADD
**              ANYTHING TO THIS ROUTINE UNLESS YOU KNOW WHAT YOU ARE
**              DOING.
*/

/* ARGSUSED0 */
static void
openalrm(sig)
        int sig;
{
        longjmp(OpenTimeOut, 1);
}
/*
**  REOPENALRM -- handler when timeout activated for sm_io_reopen()
**
**  Returns flow of control to where setjmp(ReopenTimeOut) was set.
**
**      Parameters:
**              sig -- unused
**
**      Returns:
**              does not return
**
**      Side Effects:
**              returns flow of control to setjmp(ReopenTimeOut).
**
**      NOTE:   THIS CAN BE CALLED FROM A SIGNAL HANDLER.  DO NOT ADD
**              ANYTHING TO THIS ROUTINE UNLESS YOU KNOW WHAT YOU ARE
**              DOING.
*/

/* ARGSUSED0 */
static void
reopenalrm(sig)
        int sig;
{
        longjmp(ReopenTimeOut, 1);
}

/*
**  SM_IO_OPEN -- open a file of a specific type
**
**      Parameters:
**              type -- type of file to open
**              timeout -- time to complete the open
**              info -- info describing what is to be opened (type dependant)
**              flags -- user selected flags
**              rpool -- pointer to rpool to be used for this open
**
**      Returns:
**              Raises exception on heap exhaustion.
**              Aborts if type is invalid.
**              Returns NULL and sets errno
**                      - when the type specific open fails
**                      - when open vector errors
**                      - when flags not set or invalid
**              Success returns a file pointer to the opened file type.
*/

SM_FILE_T *
sm_io_open(type, timeout, info, flags, rpool)
        const SM_FILE_T *type;
        int SM_NONVOLATILE timeout;     /* this is not the file type timeout */
        const void *info;
        int flags;
        const void *rpool;
{
        register SM_FILE_T *fp;
        int ioflags;
        SM_EVENT *evt = NULL;

        ioflags = sm_flags(flags);

        if (ioflags == 0)
        {
                /* must give some indication/intent */
                errno = EINVAL;
                return NULL;
        }

        if (timeout == SM_TIME_DEFAULT)
                timeout = SM_TIME_FOREVER;
        if (timeout == SM_TIME_IMMEDIATE)
        {
                errno = EAGAIN;
                return NULL;
        }

        fp = sm_fp(type, ioflags, NULL);

        /*  Okay, this is where we set the timeout.  */
        if (timeout != SM_TIME_FOREVER)
        {
                if (setjmp(OpenTimeOut) != 0)
                {
                        errno = EAGAIN;
                        return NULL;
                }
                evt = sm_seteventm(timeout, openalrm, 0);
        }

        if ((*fp->f_open)(fp, info, flags, rpool) < 0)
        {
                fp->f_flags = 0;        /* release */
                fp->sm_magic = NULL;    /* release */
                return NULL;
        }

        /*  We're back. So undo our timeout and handler */
        if (evt != NULL)
                sm_clrevent(evt);

#if SM_RPOOL
        if (rpool != NULL)
                sm_rpool_attach_x(rpool, sm_io_fclose, fp);
#endif /* SM_RPOOL */

        return fp;
}
/*
**  SM_IO_DUP -- duplicate a file pointer
**
**      Parameters:
**              fp -- file pointer to duplicate
**
**      Returns:
**              Success - the duplicated file pointer
**              Failure - NULL (was an invalid file pointer or too many open)
**
**      Increments the duplicate counter (dup_cnt) for the open file pointer.
**      The counter counts the number of duplicates. When the duplicate
**      counter is 0 (zero) then the file pointer is the only one left
**      (no duplicates, it is the only one).
*/

SM_FILE_T *
sm_io_dup(fp)
        SM_FILE_T *fp;
{

        SM_REQUIRE_ISA(fp, SmFileMagic);
        if (fp->sm_magic != SmFileMagic)
        {
                errno = EBADF;
                return NULL;
        }
        if (fp->f_dup_cnt >= INT_MAX - 1)
        {
                /* Can't let f_dup_cnt wrap! */
                errno = EMFILE;
                return NULL;
        }
        fp->f_dup_cnt++;
        return fp;
}
/*
**  SM_IO_REOPEN -- open a new file using the old file pointer
**
**      Parameters:
**              type -- file type to be opened
**              timeout -- time to complete the reopen
**              info -- infomation about what is to be "re-opened" (type dep.)
**              flags -- user flags to map to internal flags
**              rpool -- rpool file to be associated with
**              fp -- the file pointer to reuse
**
**      Returns:
**              Raises an exception on heap exhaustion.
**              Aborts if type is invalid.
**              Failure: returns NULL
**              Success: returns "reopened" file pointer
*/

SM_FILE_T *
sm_io_reopen(type, timeout, info, flags, rpool, fp)
        const SM_FILE_T *type;
        int SM_NONVOLATILE timeout;
        const void *info;
        int flags;
        const void *rpool;
        SM_FILE_T *fp;
{
        int ioflags, ret;
        SM_FILE_T *fp2;
        SM_EVENT *evt = NULL;

        if ((ioflags = sm_flags(flags)) == 0)
        {
                (void) sm_io_close(fp, timeout);
                return NULL;
        }

        if (!Sm_IO_DidInit)
                sm_init();

        if (timeout == SM_TIME_DEFAULT)
                timeout = SM_TIME_FOREVER;
        if (timeout == SM_TIME_IMMEDIATE)
        {
                /*
                **  Filling the buffer will take time and we are wanted to
                **  return immediately. So...
                */

                errno = EAGAIN;
                return NULL;
        }
        /*  Okay, this is where we set the timeout.  */
        if (timeout != SM_TIME_FOREVER)
        {
                if (setjmp(ReopenTimeOut) != 0)
                {
                        errno = EAGAIN;
                        return NULL;
                }

                evt = sm_seteventm(timeout, reopenalrm, 0);
        }

        /*
        **  There are actually programs that depend on being able to "reopen"
        **  descriptors that weren't originally open.  Keep this from breaking.
        **  Remember whether the stream was open to begin with, and which file
        **  descriptor (if any) was associated with it.  If it was attached to
        **  a descriptor, defer closing it; reopen("/dev/stdin", "r", stdin)
        **  should work.  This is unnecessary if it was not a Unix file.
        */

        if (fp != NULL)
        {
                if (fp->sm_magic != SmFileMagic)
                        fp->f_flags = SMFEOF;   /* hold on to it */
                else
                {
                        /* flush the stream; ANSI doesn't require this. */
                        (void) sm_io_flush(fp, SM_TIME_FOREVER);
                        (void) sm_io_close(fp, SM_TIME_FOREVER);
                }
        }

        fp2 = sm_fp(type, ioflags, fp);
        ret = (*fp2->f_open)(fp2, info, flags, rpool);

        /*  We're back. So undo our timeout and handler */
        if (evt != NULL)
                sm_clrevent(evt);

        if (ret < 0)
        {
                fp2->f_flags = 0;       /* release */
                fp2->sm_magic = NULL;   /* release */
                return NULL;
        }

        /*
        **  We're not preserving this logic (below) for sm_io because it is now
        **  abstracted at least one "layer" away. By closing and reopening
        **  the 1st fd used should be the just released one (when Unix
        **  behavior followed). Old comment::
        **  If reopening something that was open before on a real file, try
        **  to maintain the descriptor.  Various C library routines (perror)
        **  assume stderr is always fd STDERR_FILENO, even if being reopen'd.
        */

#if SM_RPOOL
        if (rpool != NULL)
                sm_rpool_attach_x(rpool, sm_io_close, fp2);
#endif /* SM_RPOOL */

        return fp2;
}
/*
**  SM_IO_AUTOFLUSH -- link another file to this for auto-flushing
**
**      When a read occurs on fp, fp2 will be flushed iff there is no
**      data waiting on fp.
**
**      Parameters:
**              fp -- the file opened for reading.
**              fp2 -- the file opened for writing.
**
**      Returns:
**              The old flush file pointer.
*/

SM_FILE_T *
sm_io_autoflush(fp, fp2)
        SM_FILE_T *fp;
        SM_FILE_T *fp2;
{
        SM_FILE_T *savefp;

        SM_REQUIRE_ISA(fp, SmFileMagic);
        if (fp2 != NULL)
                SM_REQUIRE_ISA(fp2, SmFileMagic);

        savefp = fp->f_flushfp;
        fp->f_flushfp = fp2;
        return savefp;
}
/*
**  SM_IO_AUTOMODE -- link another file to this for auto-moding
**
**      When the mode (blocking or non-blocking) changes for fp1 then
**      update fp2's mode at the same time. This is to be used when
**      a system dup() has generated a second file descriptor for
**      another sm_io_open() by file descriptor. The modes have been
**      linked in the system and this formalizes it for sm_io internally.
**
**      Parameters:
**              fp1 -- the first file
**              fp2 -- the second file
**
**      Returns:
**              nothing
*/

void
sm_io_automode(fp1, fp2)
        SM_FILE_T *fp1;
        SM_FILE_T *fp2;
{
        SM_REQUIRE_ISA(fp1, SmFileMagic);
        SM_REQUIRE_ISA(fp2, SmFileMagic);

        fp1->f_modefp = fp2;
        fp2->f_modefp = fp1;
}