sendmail/libsm/fopen.c

/*
 * Copyright (c) 2000-2002, 2004 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.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sm/gen.h>
SM_RCSID("@(#)$Id: fopen.c,v 1.62 2005/06/14 23:07:20 ca Exp $")
#include <errno.h>
#include <setjmp.h>
#include <sm/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"

static void openalrm __P((int));
static void reopenalrm __P((int));
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;
}