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[netbsd-mini2440.git] / external / ibm-public / postfix / dist / src / util / vstream.c

/*      $NetBSD$        */

/*++
/* NAME
/*      vstream 3
/* SUMMARY
/*      light-weight buffered I/O package
/* SYNOPSIS
/*      #include <vstream.h>
/*
/*      VSTREAM *vstream_fopen(path, flags, mode)
/*      const char *path;
/*      int     flags;
/*      mode_t  mode;
/*
/*      VSTREAM *vstream_fdopen(fd, flags)
/*      int     fd;
/*      int     flags;
/*
/*      int     vstream_fclose(stream)
/*      VSTREAM *stream;
/*
/*      int     vstream_fdclose(stream)
/*      VSTREAM *stream;
/*
/*      VSTREAM *vstream_printf(format, ...)
/*      const char *format;
/*
/*      VSTREAM *vstream_fprintf(stream, format, ...)
/*      VSTREAM *stream;
/*      const char *format;
/*
/*      int     VSTREAM_GETC(stream)
/*      VSTREAM *stream;
/*
/*      int     VSTREAM_PUTC(ch, stream)
/*      int     ch;
/*
/*      int     VSTREAM_GETCHAR(void)
/*
/*      int     VSTREAM_PUTCHAR(ch)
/*      int     ch;
/*
/*      int     vstream_ungetc(stream, ch)
/*      VSTREAM *stream;
/*      int     ch;
/*
/*      int     vstream_fputs(str, stream)
/*      const char *str;
/*      VSTREAM *stream;
/*
/*      off_t   vstream_ftell(stream)
/*      VSTREAM *stream;
/*
/*      off_t   vstream_fseek(stream, offset, whence)
/*      VSTREAM *stream;
/*      off_t   offset;
/*      int     whence;
/*
/*      int     vstream_fflush(stream)
/*      VSTREAM *stream;
/*
/*      int     vstream_fpurge(stream, direction)
/*      VSTREAM *stream;
/*      int     direction;
/*
/*      ssize_t vstream_fread(stream, buf, len)
/*      VSTREAM *stream;
/*      char    *buf;
/*      ssize_t len;
/*
/*      ssize_t vstream_fwrite(stream, buf, len)
/*      VSTREAM *stream;
/*      const char *buf;
/*      ssize_t len;
/*
/*      void    vstream_control(stream, name, ...)
/*      VSTREAM *stream;
/*      int     name;
/*
/*      int     vstream_fileno(stream)
/*      VSTREAM *stream;
/*
/*      void    *vstream_context(stream)
/*      VSTREAM *stream;
/*
/*      int     vstream_ferror(stream)
/*      VSTREAM *stream;
/*
/*      int     vstream_ftimeout(stream)
/*      VSTREAM *stream;
/*
/*      int     vstream_feof(stream)
/*      VSTREAM *stream;
/*
/*      int     vstream_clearerr(stream)
/*      VSTREAM *stream;
/*
/*      const char *VSTREAM_PATH(stream)
/*      VSTREAM *stream;
/*
/*      char    *vstream_vfprintf(vp, format, ap)
/*      const char *format;
/*      va_list *ap;
/*
/*      ssize_t vstream_bufstat(stream, command)
/*      VSTREAM *stream;
/*      int     command;
/*
/*      ssize_t vstream_peek(stream)
/*      VSTREAM *stream;
/*
/*      int     vstream_setjmp(stream)
/*      VSTREAM *stream;
/*
/*      void    vstream_longjmp(stream, val)
/*      VSTREAM *stream;
/*      int     val;
/*
/*      time_t  vstream_ftime(stream)
/*      VSTREAM *stream;
/*
/*      struct timeval vstream_ftimeval(stream)
/*      VSTREAM *stream;
/* DESCRIPTION
/*      The \fIvstream\fR module implements light-weight buffered I/O
/*      similar to the standard I/O routines.
/*
/*      The interface is implemented in terms of VSTREAM structure
/*      pointers, also called streams. For convenience, three streams
/*      are predefined: VSTREAM_IN, VSTREAM_OUT, and VSTREAM_ERR. These
/*      streams are connected to the standard input, output and error
/*      file descriptors, respectively.
/*
/*      Although the interface is patterned after the standard I/O
/*      library, there are some major differences:
/* .IP \(bu
/*      File descriptors are not limited to the range 0..255. This
/*      was reason #1 to write these routines in the first place.
/* .IP \(bu
/*      The application can switch between reading and writing on
/*      the same stream without having to perform a flush or seek
/*      operation, and can change write position without having to
/*      flush.  This was reason #2. Upon position or direction change,
/*      unread input is discarded, and unwritten output is flushed
/*      automatically. Exception: with double-buffered streams, unread
/*      input is not discarded upon change of I/O direction, and
/*      output flushing is delayed until the read buffer must be refilled.
/* .IP \(bu
/*      A bidirectional stream can read and write with the same buffer
/*      and file descriptor, or it can have separate read/write
/*      buffers and/or file descriptors.
/* .IP \(bu
/*      No automatic flushing of VSTREAM_OUT upon program exit, or of
/*      VSTREAM_ERR at any time. No unbuffered or line buffered modes.
/*      This functionality may be added when it is really needed.
/* .PP
/*      vstream_fopen() opens the named file and associates a buffered
/*      stream with it.  The \fIpath\fR, \fIflags\fR and \fImode\fR
/*      arguments are passed on to the open(2) routine. The result is
/*      a null pointer in case of problems. The \fIpath\fR argument is
/*      copied and can be looked up with VSTREAM_PATH().
/*
/*      vstream_fdopen() takes an open file and associates a buffered
/*      stream with it. The \fIflags\fR argument specifies how the file
/*      was opened. vstream_fdopen() either succeeds or never returns.
/*
/*      vstream_fclose() closes the named buffered stream. The result
/*      is 0 in case of success, VSTREAM_EOF in case of problems.
/*      vstream_fclose() reports the same errors as vstream_ferror().
/*
/*      vstream_fdclose() leaves the file(s) open but is otherwise
/*      identical to vstream_fclose().
/*
/*      vstream_fprintf() formats its arguments according to the
/*      \fIformat\fR argument and writes the result to the named stream.
/*      The result is the stream argument. It understands the s, c, d, u,
/*      o, x, X, e, f and g format types, the l modifier, field width and
/*      precision, sign, and padding with zeros or spaces. In addition,
/*      vstream_fprintf() recognizes the %m format specifier and expands
/*      it to the error message corresponding to the current value of the
/*      global \fIerrno\fR variable.
/*
/*      vstream_printf() performs formatted output to the standard output
/*      stream.
/*
/*      VSTREAM_GETC() reads the next character from the named stream.
/*      The result is VSTREAM_EOF when end-of-file is reached or if a read
/*      error was detected. VSTREAM_GETC() is an unsafe macro that
/*      evaluates some arguments more than once.
/*
/*      VSTREAM_GETCHAR() is an alias for VSTREAM_GETC(VSTREAM_IN).
/*
/*      VSTREAM_PUTC() appends the specified character to the specified
/*      stream. The result is the stored character, or VSTREAM_EOF in
/*      case of problems. VSTREAM_PUTC() is an unsafe macro that
/*      evaluates some arguments more than once.
/*
/*      VSTREAM_PUTCHAR(c) is an alias for VSTREAM_PUTC(c, VSTREAM_OUT).
/*
/*      vstream_ungetc() pushes back a character onto the specified stream
/*      and returns the character, or VSTREAM_EOF in case of problems.
/*      It is an error to push back before reading (or immediately after
/*      changing the stream offset via vstream_fseek()). Upon successful
/*      return, vstream_ungetc() clears the end-of-file stream flag.
/*
/*      vstream_fputs() appends the given null-terminated string to the
/*      specified buffered stream. The result is 0 in case of success,
/*      VSTREAM_EOF in case of problems.
/*
/*      vstream_ftell() returns the file offset for the specified stream,
/*      -1 if the stream is connected to a non-seekable file.
/*
/*      vstream_fseek() changes the file position for the next read or write
/*      operation. Unwritten output is flushed. With unidirectional streams,
/*      unread input is discarded. The \fIoffset\fR argument specifies the file
/*      position from the beginning of the file (\fIwhence\fR is SEEK_SET),
/*      from the current file position (\fIwhence\fR is SEEK_CUR), or from
/*      the file end (SEEK_END). The result value is the file offset
/*      from the beginning of the file, -1 in case of problems.
/*
/*      vstream_fflush() flushes unwritten data to a file that was
/*      opened in read-write or write-only mode.
/*      vstream_fflush() returns 0 in case of success, VSTREAM_EOF in
/*      case of problems. It is an error to flush a read-only stream.
/*      vstream_fflush() reports the same errors as vstream_ferror().
/*
/*      vstream_fpurge() discards the contents of the stream buffer.
/*      If direction is VSTREAM_PURGE_READ, it discards unread data,
/*      else if direction is VSTREAM_PURGE_WRITE, it discards unwritten
/*      data. In the case of a double-buffered stream, if direction is
/*      VSTREAM_PURGE_BOTH, it discards the content of both the read
/*      and write buffers. vstream_fpurge() returns 0 in case of success,
/*      VSTREAM_EOF in case of problems.
/*
/*      vstream_fread() and vstream_fwrite() perform unformatted I/O
/*      on the named stream. The result value is the number of bytes
/*      transferred. A short count is returned in case of end-of-file
/*      or error conditions.
/*
/*      vstream_control() allows the user to fine tune the behavior of
/*      the specified stream.  The arguments are a list of (name,
/*      value) pairs, terminated with VSTREAM_CTL_END.
/*      The following lists the names and the types of the corresponding
/*      value arguments.
/* .IP "VSTREAM_CTL_READ_FN (ssize_t (*)(int, void *, size_t, int, void *))"
/*      The argument specifies an alternative for the timed_read(3) function,
/*      for example, a read function that performs decryption.
/* .IP "VSTREAM_CTL_WRITE_FN (ssize_t (*)(int, void *, size_t, int, void *))"
/*      The argument specifies an alternative for the timed_write(3) function,
/*      for example, a write function that performs encryption.
/* .IP "VSTREAM_CTL_CONTEXT (char *)"
/*      The argument specifies application context that is passed on to
/*      the application-specified read/write routines. No copy is made.
/* .IP "VSTREAM_CTL_PATH (char *)"
/*      Updates the stored pathname of the specified stream. The pathname
/*      is copied.
/* .IP "VSTREAM_CTL_DOUBLE (no value)"
/*      Use separate buffers for reading and for writing.  This prevents
/*      unread input from being discarded upon change of I/O direction.
/* .IP "VSTREAM_CTL_READ_FD (int)
/*      The argument specifies the file descriptor to be used for reading.
/*      This feature is limited to double-buffered streams, and makes the
/*      stream non-seekable.
/* .IP "VSTREAM_CTL_WRITE_FD (int)
/*      The argument specifies the file descriptor to be used for writing.
/*      This feature is limited to double-buffered streams, and makes the
/*      stream non-seekable.
/* .IP "VSTREAM_CTL_DUPFD (int)"
/*      The argument specifies a minimum file descriptor value. If
/*      the actual stream's file descriptors are below the minimum,
/*      reallocate the descriptors to the first free value greater
/*      than or equal to the minimum. The VSTREAM_CTL_DUPFD macro
/*      is defined only on systems with fcntl() F_DUPFD support.
/* .IP "VSTREAM_CTL_WAITPID_FN (int (*)(pid_t, WAIT_STATUS_T *, int))"
/*      A pointer to function that behaves like waitpid(). This information
/*      is used by the vstream_pclose() routine.
/* .IP "VSTREAM_CTL_TIMEOUT (int)
/*      The deadline for a descriptor to become readable in case of a read
/*      request, or writable in case of a write request. Specify a value
/*      <= 0 to disable deadlines.
/* .IP "VSTREAM_CTL_EXCEPT (no value)"
/*      Enable exception handling with vstream_setjmp() and vstream_longjmp().
/*      This involves allocation of additional memory that normally isn't
/*      used.
/* .IP "VSTREAM_CTL_BUFSIZE (ssize_t)"
/*      Specify a non-default write buffer size, or zero to implement
/*      a no-op. Requests to shrink an existing buffer size are
/*      ignored. Requests to change a fixed-size buffer (stdin,
/*      stdout, stderr) are not allowed.
/*
/*      NOTE: the VSTREAM_CTL_BUFSIZE argument type is ssize_t, not
/*      int. Use an explicit cast to avoid problems on LP64
/*      environments and other environments where ssize_t is larger
/*      than int.
/* .PP
/*      vstream_fileno() gives access to the file handle associated with
/*      a buffered stream. With streams that have separate read/write
/*      file descriptors, the result is the current descriptor.
/*
/*      vstream_context() returns the application context that is passed on to
/*      the application-specified read/write routines.
/*
/*      VSTREAM_PATH() is an unsafe macro that returns the name stored
/*      with vstream_fopen() or with vstream_control(). The macro is
/*      unsafe because it evaluates some arguments more than once.
/*
/*      vstream_feof() returns non-zero when a previous operation on the
/*      specified stream caused an end-of-file condition.
/*      Although further read requests after EOF may complete
/*      succesfully, vstream_feof() will keep returning non-zero
/*      until vstream_clearerr() is called for that stream.
/*
/*      vstream_ferror() returns non-zero when a previous operation on the
/*      specified stream caused a non-EOF error condition, including timeout.
/*      After a non-EOF error on a stream, no I/O request will
/*      complete until after vstream_clearerr() is called for that stream.
/*
/*      vstream_ftimeout() returns non-zero when a previous operation on the
/*      specified stream caused a timeout error condition. See
/*      vstream_ferror() for error persistence details.
/*
/*      vstream_clearerr() resets the timeout, error and end-of-file indication
/*      of the specified stream, and returns no useful result.
/*
/*      vstream_vfprintf() provides an alternate interface
/*      for formatting an argument list according to a format string.
/*
/*      vstream_bufstat() provides input and output buffer status
/*      information.  The command is one of the following:
/* .IP VSTREAM_BST_IN_PEND
/*      Return the number of characters that can be read without
/*      refilling the read buffer.
/* .IP VSTREAM_BST_OUT_PEND
/*      Return the number of characters that are waiting in the
/*      write buffer.
/* .PP
/*      vstream_peek() returns the number of characters that can be
/*      read from the named stream without refilling the read buffer.
/*      This is an alias for vstream_bufstat(stream, VSTREAM_BST_IN_PEND).
/*
/*      vstream_setjmp() saves processing context and makes that context
/*      available for use with vstream_longjmp().  Normally, vstream_setjmp()
/*      returns zero.  A non-zero result means that vstream_setjmp() returned
/*      through a vstream_longjmp() call; the result is the \fIval\fR argment
/*      given to vstream_longjmp().
/*
/*      NB: non-local jumps such as vstream_longjmp() are not safe
/*      for jumping out of any routine that manipulates VSTREAM data.
/*      longjmp() like calls are best avoided in signal handlers.
/*
/*      vstream_ftime() returns the time of initialization, the last buffer
/*      fill operation, or the last buffer flush operation for the specified
/*      stream. This information is maintained only when stream timeouts are
/*      enabled.
/*
/*      vstream_ftimeval() is like vstream_ftime() but returns more
/*      detail.
/* DIAGNOSTICS
/*      Panics: interface violations. Fatal errors: out of memory.
/* SEE ALSO
/*      timed_read(3) default read routine
/*      timed_write(3) default write routine
/*      vbuf_print(3) formatting engine
/*      setjmp(3) non-local jumps
/* BUGS
/*      Should use mmap() on reasonable systems.
/* LICENSE
/* .ad
/* .fi
/*      The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*      Wietse Venema
/*      IBM T.J. Watson Research
/*      P.O. Box 704
/*      Yorktown Heights, NY 10598, USA
/*--*/

/* System library. */

#include <sys_defs.h>
#include <stdlib.h>                     /* 44BSD stdarg.h uses abort() */
#include <stdarg.h>
#include <stddef.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <errno.h>
#include <string.h>

/* Utility library. */

#include "mymalloc.h"
#include "msg.h"
#include "vbuf_print.h"
#include "iostuff.h"
#include "vstring.h"
#include "vstream.h"

/* Application-specific. */

 /*
  * Forward declarations.
  */
static int vstream_buf_get_ready(VBUF *);
static int vstream_buf_put_ready(VBUF *);
static int vstream_buf_space(VBUF *, ssize_t);

 /*
  * Initialization of the three pre-defined streams. Pre-allocate a static
  * I/O buffer for the standard error stream, so that the error handler can
  * produce a diagnostic even when memory allocation fails.
  * 
  * XXX We don't (yet) statically initialize the req_bufsize field: it is the
  * last VSTREAM member so we don't break Postfix 2.4 binary compatibility,
  * and Wietse doesn't know how to specify an initializer for the jmp_buf
  * VSTREAM member (which can be a struct or an array) without collateral
  * damage to the source code. We can fix the initialization later in the
  * Postfix 2.5 development cycle.
  */
static unsigned char vstream_fstd_buf[VSTREAM_BUFSIZE];

VSTREAM vstream_fstd[] = {
    {{
            0,                          /* flags */
            0, 0, 0, 0,                 /* buffer */
            vstream_buf_get_ready, vstream_buf_put_ready, vstream_buf_space,
    }, STDIN_FILENO, (VSTREAM_FN) timed_read, (VSTREAM_FN) timed_write,},
    {{
            0,                          /* flags */
            0, 0, 0, 0,                 /* buffer */
            vstream_buf_get_ready, vstream_buf_put_ready, vstream_buf_space,
    }, STDOUT_FILENO, (VSTREAM_FN) timed_read, (VSTREAM_FN) timed_write,},
    {{
            VBUF_FLAG_FIXED | VSTREAM_FLAG_WRITE,
            vstream_fstd_buf, VSTREAM_BUFSIZE, VSTREAM_BUFSIZE, vstream_fstd_buf,
            vstream_buf_get_ready, vstream_buf_put_ready, vstream_buf_space,
    }, STDERR_FILENO, (VSTREAM_FN) timed_read, (VSTREAM_FN) timed_write,},
};

#define VSTREAM_STATIC(v) ((v) >= VSTREAM_IN && (v) <= VSTREAM_ERR)

 /*
  * A bunch of macros to make some expressions more readable. XXX We're
  * assuming that O_RDONLY == 0, O_WRONLY == 1, O_RDWR == 2.
  */
#define VSTREAM_ACC_MASK(f)     ((f) & (O_APPEND | O_WRONLY | O_RDWR))

#define VSTREAM_CAN_READ(f)     (VSTREAM_ACC_MASK(f) == O_RDONLY \
                                || VSTREAM_ACC_MASK(f) == O_RDWR)
#define VSTREAM_CAN_WRITE(f)    (VSTREAM_ACC_MASK(f) & O_WRONLY \
                                || VSTREAM_ACC_MASK(f) & O_RDWR \
                                || VSTREAM_ACC_MASK(f) & O_APPEND)

#define VSTREAM_BUF_COUNT(bp, n) \
        ((bp)->flags & VSTREAM_FLAG_READ ? -(n) : (n))

#define VSTREAM_BUF_AT_START(bp) { \
        (bp)->cnt = VSTREAM_BUF_COUNT((bp), (bp)->len); \
        (bp)->ptr = (bp)->data; \
    }

#define VSTREAM_BUF_AT_OFFSET(bp, offset) { \
        (bp)->ptr = (bp)->data + (offset); \
        (bp)->cnt = VSTREAM_BUF_COUNT(bp, (bp)->len - (offset)); \
    }

#define VSTREAM_BUF_AT_END(bp) { \
        (bp)->cnt = 0; \
        (bp)->ptr = (bp)->data + (bp)->len; \
    }

#define VSTREAM_BUF_ZERO(bp) { \
        (bp)->flags = 0; \
        (bp)->data = (bp)->ptr = 0; \
        (bp)->len = (bp)->cnt = 0; \
    }

#define VSTREAM_BUF_ACTIONS(bp, get_action, put_action, space_action) { \
        (bp)->get_ready = (get_action); \
        (bp)->put_ready = (put_action); \
        (bp)->space = (space_action); \
    }

#define VSTREAM_SAVE_STATE(stream, buffer, filedes) { \
        stream->buffer = stream->buf; \
        stream->filedes = stream->fd; \
    }

#define VSTREAM_RESTORE_STATE(stream, buffer, filedes) do { \
        stream->buffer.flags = stream->buf.flags; \
        stream->buf = stream->buffer; \
        stream->fd = stream->filedes; \
    } while(0)

#define VSTREAM_FORK_STATE(stream, buffer, filedes) { \
        stream->buffer = stream->buf; \
        stream->filedes = stream->fd; \
        stream->buffer.data = stream->buffer.ptr = 0; \
        stream->buffer.len = stream->buffer.cnt = 0; \
        stream->buffer.flags &= ~VSTREAM_FLAG_FIXED; \
    };

#define VSTREAM_FLAG_READ_DOUBLE (VSTREAM_FLAG_READ | VSTREAM_FLAG_DOUBLE)
#define VSTREAM_FLAG_WRITE_DOUBLE (VSTREAM_FLAG_WRITE | VSTREAM_FLAG_DOUBLE)

#define VSTREAM_FFLUSH_SOME(stream) \
        vstream_fflush_some((stream), (stream)->buf.len - (stream)->buf.cnt)

/* vstream_buf_init - initialize buffer */

static void vstream_buf_init(VBUF *bp, int flags)
{

    /*
     * Initialize the buffer such that the first data access triggers a
     * buffer boundary action.
     */
    VSTREAM_BUF_ZERO(bp);
    VSTREAM_BUF_ACTIONS(bp,
                        VSTREAM_CAN_READ(flags) ? vstream_buf_get_ready : 0,
                        VSTREAM_CAN_WRITE(flags) ? vstream_buf_put_ready : 0,
                        vstream_buf_space);
}

/* vstream_buf_alloc - allocate buffer memory */

static void vstream_buf_alloc(VBUF *bp, ssize_t len)
{
    VSTREAM *stream = VBUF_TO_APPL(bp, VSTREAM, buf);
    ssize_t used = bp->ptr - bp->data;
    const char *myname = "vstream_buf_alloc";

    if (len < bp->len)
        msg_panic("%s: attempt to shrink buffer", myname);
    if (bp->flags & VSTREAM_FLAG_FIXED)
        msg_panic("%s: unable to extend fixed-size buffer", myname);

    /*
     * Late buffer allocation allows the user to override the default policy.
     * If a buffer already exists, allow for the presence of (output) data.
     */
    bp->data = (unsigned char *)
        (bp->data ? myrealloc((char *) bp->data, len) : mymalloc(len));
    bp->len = len;
    if (bp->flags & VSTREAM_FLAG_READ) {
        bp->ptr = bp->data + used;
        if (bp->flags & VSTREAM_FLAG_DOUBLE)
            VSTREAM_SAVE_STATE(stream, read_buf, read_fd);
    } else {
        VSTREAM_BUF_AT_OFFSET(bp, used);
        if (bp->flags & VSTREAM_FLAG_DOUBLE)
            VSTREAM_SAVE_STATE(stream, write_buf, write_fd);
    }
}

/* vstream_buf_wipe - reset buffer to initial state */

static void vstream_buf_wipe(VBUF *bp)
{
    if ((bp->flags & VBUF_FLAG_FIXED) == 0 && bp->data)
        myfree((char *) bp->data);
    VSTREAM_BUF_ZERO(bp);
    VSTREAM_BUF_ACTIONS(bp, 0, 0, 0);
}

/* vstream_fflush_some - flush some buffered data */

static int vstream_fflush_some(VSTREAM *stream, ssize_t to_flush)
{
    const char *myname = "vstream_fflush_some";
    VBUF   *bp = &stream->buf;
    ssize_t used;
    ssize_t left_over;
    char   *data;
    ssize_t len;
    ssize_t n;

    /*
     * Sanity checks. It is illegal to flush a read-only stream. Otherwise,
     * if there is buffered input, discard the input. If there is buffered
     * output, require that the amount to flush is larger than the amount to
     * keep, so that we can memcpy() the residue.
     */
    if (bp->put_ready == 0)
        msg_panic("%s: read-only stream", myname);
    switch (bp->flags & (VSTREAM_FLAG_WRITE | VSTREAM_FLAG_READ)) {
    case VSTREAM_FLAG_READ:                     /* discard input */
        VSTREAM_BUF_AT_END(bp);
        /* FALLTHROUGH */
    case 0:                                     /* flush after seek? */
        return ((bp->flags & VSTREAM_FLAG_ERR) ? VSTREAM_EOF : 0);
    case VSTREAM_FLAG_WRITE:                    /* output buffered */
        break;
    case VSTREAM_FLAG_WRITE | VSTREAM_FLAG_READ:
        msg_panic("%s: read/write stream", myname);
    }
    used = bp->len - bp->cnt;
    left_over = used - to_flush;

    if (msg_verbose > 2 && stream != VSTREAM_ERR)
        msg_info("%s: fd %d flush %ld", myname, stream->fd, (long) to_flush);
    if (to_flush < 0 || left_over < 0)
        msg_panic("%s: bad to_flush %ld", myname, (long) to_flush);
    if (to_flush < left_over)
        msg_panic("%s: to_flush < left_over", myname);
    if (to_flush == 0)
        return ((bp->flags & VSTREAM_FLAG_ERR) ? VSTREAM_EOF : 0);
    if (bp->flags & VSTREAM_FLAG_ERR)
        return (VSTREAM_EOF);

    /*
     * When flushing a buffer, allow for partial writes. These can happen
     * while talking to a network. Update the cached file seek position, if
     * any.
     */
    for (data = (char *) bp->data, len = to_flush; len > 0; len -= n, data += n) {
        if ((n = stream->write_fn(stream->fd, data, len, stream->timeout, stream->context)) <= 0) {
            bp->flags |= VSTREAM_FLAG_ERR;
            if (errno == ETIMEDOUT)
                bp->flags |= VSTREAM_FLAG_TIMEOUT;
            return (VSTREAM_EOF);
        }
        if (stream->timeout)
            GETTIMEOFDAY(&stream->iotime);
        if (msg_verbose > 2 && stream != VSTREAM_ERR && n != to_flush)
            msg_info("%s: %d flushed %ld/%ld", myname, stream->fd,
                     (long) n, (long) to_flush);
    }
    if (bp->flags & VSTREAM_FLAG_SEEK)
        stream->offset += to_flush;

    /*
     * Allow for partial buffer flush requests. We use memcpy() for reasons
     * of portability to pre-ANSI environments (SunOS 4.x or Ultrix 4.x :-).
     * This is OK because we have already verified that the to_flush count is
     * larger than the left_over count.
     */
    if (left_over > 0)
        memcpy(bp->data, bp->data + to_flush, left_over);
    bp->cnt += to_flush;
    bp->ptr -= to_flush;
    return ((bp->flags & VSTREAM_FLAG_ERR) ? VSTREAM_EOF : 0);
}

/* vstream_fflush_delayed - delayed stream flush for double-buffered stream */

static int vstream_fflush_delayed(VSTREAM *stream)
{
    int     status;

    /*
     * Sanity check.
     */
    if ((stream->buf.flags & VSTREAM_FLAG_READ_DOUBLE) != VSTREAM_FLAG_READ_DOUBLE)
        msg_panic("vstream_fflush_delayed: bad flags");

    /*
     * Temporarily swap buffers and flush unwritten data. This may seem like
     * a lot of work, but it's peanuts compared to the write(2) call that we
     * already have avoided. For example, delayed flush is never used on a
     * non-pipelined SMTP connection.
     */
    stream->buf.flags &= ~VSTREAM_FLAG_READ;
    VSTREAM_SAVE_STATE(stream, read_buf, read_fd);
    stream->buf.flags |= VSTREAM_FLAG_WRITE;
    VSTREAM_RESTORE_STATE(stream, write_buf, write_fd);

    status = VSTREAM_FFLUSH_SOME(stream);

    stream->buf.flags &= ~VSTREAM_FLAG_WRITE;
    VSTREAM_SAVE_STATE(stream, write_buf, write_fd);
    stream->buf.flags |= VSTREAM_FLAG_READ;
    VSTREAM_RESTORE_STATE(stream, read_buf, read_fd);

    return (status);
}

/* vstream_buf_get_ready - vbuf callback to make buffer ready for reading */

static int vstream_buf_get_ready(VBUF *bp)
{
    VSTREAM *stream = VBUF_TO_APPL(bp, VSTREAM, buf);
    const char *myname = "vstream_buf_get_ready";
    ssize_t n;

    /*
     * Detect a change of I/O direction or position. If so, flush any
     * unwritten output immediately when the stream is single-buffered, or
     * when the stream is double-buffered and the read buffer is empty.
     */
    switch (bp->flags & (VSTREAM_FLAG_WRITE | VSTREAM_FLAG_READ)) {
    case VSTREAM_FLAG_WRITE:                    /* change direction */
        if (bp->ptr > bp->data)
            if ((bp->flags & VSTREAM_FLAG_DOUBLE) == 0
                || stream->read_buf.cnt >= 0)
                if (VSTREAM_FFLUSH_SOME(stream))
                    return (VSTREAM_EOF);
        bp->flags &= ~VSTREAM_FLAG_WRITE;
        if (bp->flags & VSTREAM_FLAG_DOUBLE)
            VSTREAM_SAVE_STATE(stream, write_buf, write_fd);
        /* FALLTHROUGH */
    case 0:                                     /* change position */
        bp->flags |= VSTREAM_FLAG_READ;
        if (bp->flags & VSTREAM_FLAG_DOUBLE) {
            VSTREAM_RESTORE_STATE(stream, read_buf, read_fd);
            if (bp->cnt < 0)
                return (0);
        }
        /* FALLTHROUGH */
    case VSTREAM_FLAG_READ:                     /* no change */
        break;
    case VSTREAM_FLAG_WRITE | VSTREAM_FLAG_READ:
        msg_panic("%s: read/write stream", myname);
    }

    /*
     * If this is the first GET operation, allocate a buffer. Late buffer
     * allocation gives the application a chance to override the default
     * buffering policy.
     */
    if (stream->req_bufsize == 0)
        stream->req_bufsize = VSTREAM_BUFSIZE;
    if (bp->len < stream->req_bufsize)
        vstream_buf_alloc(bp, stream->req_bufsize);

    /*
     * If the stream is double-buffered and the write buffer is not empty,
     * this is the time to flush the write buffer. Delayed flushes reduce
     * system call overhead, and on TCP sockets, avoid triggering Nagle's
     * algorithm.
     */
    if ((bp->flags & VSTREAM_FLAG_DOUBLE)
        && stream->write_buf.len > stream->write_buf.cnt)
        if (vstream_fflush_delayed(stream))
            return (VSTREAM_EOF);

    /*
     * Did we receive an EOF indication?
     */
    if (bp->flags & VSTREAM_FLAG_EOF)
        return (VSTREAM_EOF);

    /*
     * Fill the buffer with as much data as we can handle, or with as much
     * data as is available right now, whichever is less. Update the cached
     * file seek position, if any.
     */
    switch (n = stream->read_fn(stream->fd, bp->data, bp->len, stream->timeout, stream->context)) {
    case -1:
        bp->flags |= VSTREAM_FLAG_ERR;
        if (errno == ETIMEDOUT)
            bp->flags |= VSTREAM_FLAG_TIMEOUT;
        return (VSTREAM_EOF);
    case 0:
        bp->flags |= VSTREAM_FLAG_EOF;
        return (VSTREAM_EOF);
    default:
        if (stream->timeout)
            GETTIMEOFDAY(&stream->iotime);
        if (msg_verbose > 2)
            msg_info("%s: fd %d got %ld", myname, stream->fd, (long) n);
        bp->cnt = -n;
        bp->ptr = bp->data;
        if (bp->flags & VSTREAM_FLAG_SEEK)
            stream->offset += n;
        return (0);
    }
}

/* vstream_buf_put_ready - vbuf callback to make buffer ready for writing */

static int vstream_buf_put_ready(VBUF *bp)
{
    VSTREAM *stream = VBUF_TO_APPL(bp, VSTREAM, buf);
    const char *myname = "vstream_buf_put_ready";

    /*
     * Sanity checks. Detect a change of I/O direction or position. If so,
     * discard unread input, and reset the buffer to the beginning.
     */
    switch (bp->flags & (VSTREAM_FLAG_WRITE | VSTREAM_FLAG_READ)) {
    case VSTREAM_FLAG_READ:                     /* change direction */
        bp->flags &= ~VSTREAM_FLAG_READ;
        if (bp->flags & VSTREAM_FLAG_DOUBLE)
            VSTREAM_SAVE_STATE(stream, read_buf, read_fd);
        /* FALLTHROUGH */
    case 0:                                     /* change position */
        bp->flags |= VSTREAM_FLAG_WRITE;
        if (bp->flags & VSTREAM_FLAG_DOUBLE)
            VSTREAM_RESTORE_STATE(stream, write_buf, write_fd);
        else
            VSTREAM_BUF_AT_START(bp);
        /* FALLTHROUGH */
    case VSTREAM_FLAG_WRITE:                    /* no change */
        break;
    case VSTREAM_FLAG_WRITE | VSTREAM_FLAG_READ:
        msg_panic("%s: read/write stream", myname);
    }

    /*
     * Remember the direction. If this is the first PUT operation for this
     * stream or if the buffer is smaller than the requested size, allocate a
     * new buffer; obviously there is no data to be flushed yet. Otherwise,
     * flush the buffer.
     */
    if (stream->req_bufsize == 0)
        stream->req_bufsize = VSTREAM_BUFSIZE;  /* Postfix 2.4 binary compat. */
    if (bp->len < stream->req_bufsize) {
        vstream_buf_alloc(bp, stream->req_bufsize);
    } else if (bp->cnt <= 0) {
        if (VSTREAM_FFLUSH_SOME(stream))
            return (VSTREAM_EOF);
    }
    return (0);
}

/* vstream_buf_space - reserve space ahead of time */

static int vstream_buf_space(VBUF *bp, ssize_t want)
{
    VSTREAM *stream = VBUF_TO_APPL(bp, VSTREAM, buf);
    ssize_t used;
    ssize_t incr;
    ssize_t shortage;
    const char *myname = "vstream_buf_space";

    /*
     * Sanity checks. Reserving space implies writing. It is illegal to write
     * to a read-only stream. Detect a change of I/O direction or position.
     * If so, reset the buffer to the beginning.
     */
    if (bp->put_ready == 0)
        msg_panic("%s: read-only stream", myname);
    switch (bp->flags & (VSTREAM_FLAG_READ | VSTREAM_FLAG_WRITE)) {
    case VSTREAM_FLAG_READ:                     /* change direction */
        bp->flags &= ~VSTREAM_FLAG_READ;
        if (bp->flags & VSTREAM_FLAG_DOUBLE)
            VSTREAM_SAVE_STATE(stream, read_buf, read_fd);
        /* FALLTHROUGH */
    case 0:                                     /* change position */
        bp->flags |= VSTREAM_FLAG_WRITE;
        if (bp->flags & VSTREAM_FLAG_DOUBLE)
            VSTREAM_RESTORE_STATE(stream, write_buf, write_fd);
        else
            VSTREAM_BUF_AT_START(bp);
        /* FALLTHROUGH */
    case VSTREAM_FLAG_WRITE:                    /* no change */
        break;
    case VSTREAM_FLAG_READ | VSTREAM_FLAG_WRITE:
        msg_panic("%s: read/write stream", myname);
    }

    /*
     * See if enough space is available. If not, flush a multiple of
     * VSTREAM_BUFSIZE bytes and resize the buffer to a multiple of
     * VSTREAM_BUFSIZE. We flush multiples of VSTREAM_BUFSIZE in an attempt
     * to keep file updates block-aligned for better performance.
     */
#define VSTREAM_TRUNCATE(count, base)   (((count) / (base)) * (base))
#define VSTREAM_ROUNDUP(count, base)    VSTREAM_TRUNCATE(count + base - 1, base)

    if (want > bp->cnt) {
        if (stream->req_bufsize == 0)
            stream->req_bufsize = VSTREAM_BUFSIZE;      /* 2.4 binary compat. */
        if ((used = bp->len - bp->cnt) > stream->req_bufsize)
            if (vstream_fflush_some(stream, VSTREAM_TRUNCATE(used, stream->req_bufsize)))
                return (VSTREAM_EOF);
        if ((shortage = (want - bp->cnt)) > 0) {
            if ((bp->flags & VSTREAM_FLAG_FIXED)
                || shortage > __MAXINT__(ssize_t) -bp->len - stream->req_bufsize) {
                bp->flags |= VSTREAM_FLAG_ERR;
            } else {
                incr = VSTREAM_ROUNDUP(shortage, stream->req_bufsize);
                vstream_buf_alloc(bp, bp->len + incr);
            }
        }
    }
    return (vstream_ferror(stream) ? VSTREAM_EOF : 0);  /* mmap() may fail */
}

/* vstream_fpurge - discard unread or unwritten content */

int     vstream_fpurge(VSTREAM *stream, int direction)
{
    const char *myname = "vstream_fpurge";
    VBUF   *bp = &stream->buf;

#define VSTREAM_MAYBE_PURGE_WRITE(d, b) if ((d) & VSTREAM_PURGE_WRITE) \
        VSTREAM_BUF_AT_START((b))
#define VSTREAM_MAYBE_PURGE_READ(d, b) if ((d) & VSTREAM_PURGE_READ) \
        VSTREAM_BUF_AT_END((b))

    /*
     * To discard all unread contents, position the read buffer at its end,
     * so that we skip over any unread data, and so that the next read
     * operation will refill the buffer.
     * 
     * To discard all unwritten content, position the write buffer at its
     * beginning, so that the next write operation clobbers any unwritten
     * data.
     */
    switch (bp->flags & (VSTREAM_FLAG_READ_DOUBLE | VSTREAM_FLAG_WRITE)) {
    case VSTREAM_FLAG_READ_DOUBLE:
        VSTREAM_MAYBE_PURGE_WRITE(direction, &stream->write_buf);
        /* FALLTHROUGH */
    case VSTREAM_FLAG_READ:
        VSTREAM_MAYBE_PURGE_READ(direction, bp);
        break;
    case VSTREAM_FLAG_DOUBLE:
        VSTREAM_MAYBE_PURGE_WRITE(direction, &stream->write_buf);
        VSTREAM_MAYBE_PURGE_READ(direction, &stream->read_buf);
        break;
    case VSTREAM_FLAG_WRITE_DOUBLE:
        VSTREAM_MAYBE_PURGE_READ(direction, &stream->read_buf);
        /* FALLTHROUGH */
    case VSTREAM_FLAG_WRITE:
        VSTREAM_MAYBE_PURGE_WRITE(direction, bp);
        break;
    case VSTREAM_FLAG_READ_DOUBLE | VSTREAM_FLAG_WRITE:
    case VSTREAM_FLAG_READ | VSTREAM_FLAG_WRITE:
        msg_panic("%s: read/write stream", myname);
    }

    /*
     * Invalidate the cached file seek position.
     */
    bp->flags &= ~VSTREAM_FLAG_SEEK;
    stream->offset = 0;

    return (0);
}

/* vstream_fseek - change I/O position */

off_t   vstream_fseek(VSTREAM *stream, off_t offset, int whence)
{
    const char *myname = "vstream_fseek";
    VBUF   *bp = &stream->buf;

    /*
     * Flush any unwritten output. Discard any unread input. Position the
     * buffer at the end, so that the next GET or PUT operation triggers a
     * buffer boundary action.
     */
    switch (bp->flags & (VSTREAM_FLAG_READ | VSTREAM_FLAG_WRITE)) {
    case VSTREAM_FLAG_WRITE:
        if (bp->ptr > bp->data) {
            if (whence == SEEK_CUR)
                offset += (bp->ptr - bp->data); /* add unwritten data */
            else if (whence == SEEK_END)
                bp->flags &= ~VSTREAM_FLAG_SEEK;
            if (VSTREAM_FFLUSH_SOME(stream))
                return (-1);
        }
        VSTREAM_BUF_AT_END(bp);
        break;
    case VSTREAM_FLAG_READ:
        if (whence == SEEK_CUR)
            offset += bp->cnt;                  /* subtract unread data */
        else if (whence == SEEK_END)
            bp->flags &= ~VSTREAM_FLAG_SEEK;
        /* FALLTHROUGH */
    case 0:
        VSTREAM_BUF_AT_END(bp);
        break;
    case VSTREAM_FLAG_READ | VSTREAM_FLAG_WRITE:
        msg_panic("%s: read/write stream", myname);
    }

    /*
     * Clear the read/write flags to inform the buffer boundary action
     * routines that we may have changed I/O position.
     */
    bp->flags &= ~(VSTREAM_FLAG_READ | VSTREAM_FLAG_WRITE);

    /*
     * Shave an unnecessary system call.
     */
    if (bp->flags & VSTREAM_FLAG_NSEEK) {
        errno = ESPIPE;
        return (-1);
    }

    /*
     * Update the cached file seek position.
     */
    if ((stream->offset = lseek(stream->fd, offset, whence)) < 0) {
        bp->flags |= VSTREAM_FLAG_NSEEK;
    } else {
        bp->flags |= VSTREAM_FLAG_SEEK;
    }
    bp->flags &= ~VSTREAM_FLAG_EOF;
    return (stream->offset);
}

/* vstream_ftell - return file offset */

off_t   vstream_ftell(VSTREAM *stream)
{
    VBUF   *bp = &stream->buf;

    /*
     * Shave an unnecessary syscall.
     */
    if (bp->flags & VSTREAM_FLAG_NSEEK) {
        errno = ESPIPE;
        return (-1);
    }

    /*
     * Use the cached file offset when available. This is the offset after
     * the last read, write or seek operation.
     */
    if ((bp->flags & VSTREAM_FLAG_SEEK) == 0) {
        if ((stream->offset = lseek(stream->fd, (off_t) 0, SEEK_CUR)) < 0) {
            bp->flags |= VSTREAM_FLAG_NSEEK;
            return (-1);
        }
        bp->flags |= VSTREAM_FLAG_SEEK;
    }

    /*
     * If this is a read buffer, subtract the number of unread bytes from the
     * cached offset. Remember that read counts are negative.
     */
    if (bp->flags & VSTREAM_FLAG_READ)
        return (stream->offset + bp->cnt);

    /*
     * If this is a write buffer, add the number of unwritten bytes to the
     * cached offset.
     */
    if (bp->flags & VSTREAM_FLAG_WRITE)
        return (stream->offset + (bp->ptr - bp->data));

    /*
     * Apparently, this is a new buffer, or a buffer after seek, so there is
     * no need to account for unread or unwritten data.
     */
    return (stream->offset);
}

/* vstream_fdopen - add buffering to pre-opened stream */

VSTREAM *vstream_fdopen(int fd, int flags)
{
    VSTREAM *stream;

    /*
     * Sanity check.
     */
    if (fd < 0)
        msg_panic("vstream_fdopen: bad file %d", fd);

    /*
     * Initialize buffers etc. but do as little as possible. Late buffer
     * allocation etc. gives the application a chance to override default
     * policies. Either this, or the vstream*open() routines would have to
     * have a really ugly interface with lots of mostly-unused arguments (can
     * you say VMS?).
     */
    stream = (VSTREAM *) mymalloc(sizeof(*stream));
    stream->fd = fd;
    stream->read_fn = VSTREAM_CAN_READ(flags) ? (VSTREAM_FN) timed_read : 0;
    stream->write_fn = VSTREAM_CAN_WRITE(flags) ? (VSTREAM_FN) timed_write : 0;
    vstream_buf_init(&stream->buf, flags);
    stream->offset = 0;
    stream->path = 0;
    stream->pid = 0;
    stream->waitpid_fn = 0;
    stream->timeout = 0;
    stream->context = 0;
    stream->jbuf = 0;
    stream->iotime.tv_sec = stream->iotime.tv_usec = 0;
    stream->req_bufsize = VSTREAM_BUFSIZE;
    return (stream);
}

/* vstream_fopen - open buffered file stream */

VSTREAM *vstream_fopen(const char *path, int flags, mode_t mode)
{
    VSTREAM *stream;
    int     fd;

    if ((fd = open(path, flags, mode)) < 0) {
        return (0);
    } else {
        stream = vstream_fdopen(fd, flags);
        stream->path = mystrdup(path);
        return (stream);
    }
}

/* vstream_fflush - flush write buffer */

int     vstream_fflush(VSTREAM *stream)
{
    if ((stream->buf.flags & VSTREAM_FLAG_READ_DOUBLE)
        == VSTREAM_FLAG_READ_DOUBLE
        && stream->write_buf.len > stream->write_buf.cnt)
        vstream_fflush_delayed(stream);
    return (VSTREAM_FFLUSH_SOME(stream));
}

/* vstream_fclose - close buffered stream */

int     vstream_fclose(VSTREAM *stream)
{
    int     err;

    /*
     * NOTE: Negative file descriptors are not part of the external
     * interface. They are for internal use only, in order to support
     * vstream_fdclose() without a lot of code duplication. Applications that
     * rely on negative VSTREAM file descriptors will break without warning.
     */
    if (stream->pid != 0)
        msg_panic("vstream_fclose: stream has process");
    if ((stream->buf.flags & VSTREAM_FLAG_WRITE_DOUBLE) != 0 && stream->fd >= 0)
        vstream_fflush(stream);
    /* Do not remove: vstream_fdclose() depends on this error test. */
    err = vstream_ferror(stream);
    if (stream->buf.flags & VSTREAM_FLAG_DOUBLE) {
        if (stream->read_fd >= 0)
            err |= close(stream->read_fd);
        if (stream->write_fd != stream->read_fd)
            if (stream->write_fd >= 0)
                err |= close(stream->write_fd);
        vstream_buf_wipe(&stream->read_buf);
        vstream_buf_wipe(&stream->write_buf);
        stream->buf = stream->read_buf;
    } else {
        if (stream->fd >= 0)
            err |= close(stream->fd);
        vstream_buf_wipe(&stream->buf);
    }
    if (stream->path)
        myfree(stream->path);
    if (stream->jbuf)
        myfree((char *) stream->jbuf);
    if (!VSTREAM_STATIC(stream))
        myfree((char *) stream);
    return (err ? VSTREAM_EOF : 0);
}

/* vstream_fdclose - close stream, leave file(s) open */

int     vstream_fdclose(VSTREAM *stream)
{

    /*
     * Flush unwritten output, just like vstream_fclose(). Errors are
     * reported by vstream_fclose().
     */
    if ((stream->buf.flags & VSTREAM_FLAG_WRITE_DOUBLE) != 0)
        (void) vstream_fflush(stream);

    /*
     * NOTE: Negative file descriptors are not part of the external
     * interface. They are for internal use only, in order to support
     * vstream_fdclose() without a lot of code duplication. Applications that
     * rely on negative VSTREAM file descriptors will break without warning.
     */
    if (stream->buf.flags & VSTREAM_FLAG_DOUBLE) {
        stream->fd = stream->read_fd = stream->write_fd = -1;
    } else {
        stream->fd = -1;
    }
    return (vstream_fclose(stream));
}

/* vstream_printf - formatted print to stdout */

VSTREAM *vstream_printf(const char *fmt,...)
{
    VSTREAM *stream = VSTREAM_OUT;
    va_list ap;

    va_start(ap, fmt);
    vbuf_print(&stream->buf, fmt, ap);
    va_end(ap);
    return (stream);
}

/* vstream_fprintf - formatted print to buffered stream */

VSTREAM *vstream_fprintf(VSTREAM *stream, const char *fmt,...)
{
    va_list ap;

    va_start(ap, fmt);
    vbuf_print(&stream->buf, fmt, ap);
    va_end(ap);
    return (stream);
}

/* vstream_fputs - write string to stream */

int     vstream_fputs(const char *str, VSTREAM *stream)
{
    int     ch;

    while ((ch = *str++) != 0)
        if (VSTREAM_PUTC(ch, stream) == VSTREAM_EOF)
            return (VSTREAM_EOF);
    return (0);
}

/* vstream_control - fine control */

void    vstream_control(VSTREAM *stream, int name,...)
{
    const char *myname = "vstream_control";
    va_list ap;
    int     floor;
    int     old_fd;
    ssize_t req_bufsize = 0;

    for (va_start(ap, name); name != VSTREAM_CTL_END; name = va_arg(ap, int)) {
        switch (name) {
        case VSTREAM_CTL_READ_FN:
            stream->read_fn = va_arg(ap, VSTREAM_FN);
            break;
        case VSTREAM_CTL_WRITE_FN:
            stream->write_fn = va_arg(ap, VSTREAM_FN);
            break;
        case VSTREAM_CTL_CONTEXT:
            stream->context = va_arg(ap, char *);
            break;
        case VSTREAM_CTL_PATH:
            if (stream->path)
                myfree(stream->path);
            stream->path = mystrdup(va_arg(ap, char *));
            break;
        case VSTREAM_CTL_DOUBLE:
            if ((stream->buf.flags & VSTREAM_FLAG_DOUBLE) == 0) {
                stream->buf.flags |= VSTREAM_FLAG_DOUBLE;
                if (stream->buf.flags & VSTREAM_FLAG_READ) {
                    VSTREAM_SAVE_STATE(stream, read_buf, read_fd);
                    VSTREAM_FORK_STATE(stream, write_buf, write_fd);
                } else {
                    VSTREAM_SAVE_STATE(stream, write_buf, write_fd);
                    VSTREAM_FORK_STATE(stream, read_buf, read_fd);
                }
            }
            break;
        case VSTREAM_CTL_READ_FD:
            if ((stream->buf.flags & VSTREAM_FLAG_DOUBLE) == 0)
                msg_panic("VSTREAM_CTL_READ_FD requires double buffering");
            stream->read_fd = va_arg(ap, int);
            stream->buf.flags |= VSTREAM_FLAG_NSEEK;
            break;
        case VSTREAM_CTL_WRITE_FD:
            if ((stream->buf.flags & VSTREAM_FLAG_DOUBLE) == 0)
                msg_panic("VSTREAM_CTL_WRITE_FD requires double buffering");
            stream->write_fd = va_arg(ap, int);
            stream->buf.flags |= VSTREAM_FLAG_NSEEK;
            break;
        case VSTREAM_CTL_WAITPID_FN:
            stream->waitpid_fn = va_arg(ap, VSTREAM_WAITPID_FN);
            break;
        case VSTREAM_CTL_TIMEOUT:
            if (stream->timeout == 0)
                GETTIMEOFDAY(&stream->iotime);
            stream->timeout = va_arg(ap, int);
            break;
        case VSTREAM_CTL_EXCEPT:
            if (stream->jbuf == 0)
                stream->jbuf =
                    (VSTREAM_JMP_BUF *) mymalloc(sizeof(VSTREAM_JMP_BUF));
            break;

#ifdef VSTREAM_CTL_DUPFD

#define VSTREAM_TRY_DUPFD(backup, fd, floor) do { \
        if (((backup) = (fd)) < floor) { \
            if (((fd) = fcntl((backup), F_DUPFD, (floor))) < 0) \
                msg_fatal("fcntl F_DUPFD %d: %m", (floor)); \
            (void) close(backup); \
        } \
    } while (0)

        case VSTREAM_CTL_DUPFD:
            floor = va_arg(ap, int);
            if (stream->buf.flags & VSTREAM_FLAG_DOUBLE) {
                VSTREAM_TRY_DUPFD(old_fd, stream->read_fd, floor);
                if (stream->write_fd == old_fd)
                    stream->write_fd = stream->read_fd;
                else
                    VSTREAM_TRY_DUPFD(old_fd, stream->write_fd, floor);
                stream->fd = (stream->buf.flags & VSTREAM_FLAG_READ) ?
                    stream->read_fd : stream->write_fd;
            } else {
                VSTREAM_TRY_DUPFD(old_fd, stream->fd, floor);
            }
            break;
#endif

            /*
             * Postpone memory (re)allocation until the space is needed.
             */
        case VSTREAM_CTL_BUFSIZE:
            req_bufsize = va_arg(ap, ssize_t);
            if (req_bufsize < 0)
                msg_panic("VSTREAM_CTL_BUFSIZE with negative size: %ld",
                          (long) req_bufsize);
            if (stream->req_bufsize == 0)
                stream->req_bufsize = VSTREAM_BUFSIZE;  /* 2.4 binary compat. */
            if (stream != VSTREAM_ERR
                && req_bufsize > stream->req_bufsize)
                stream->req_bufsize = req_bufsize;
            break;
        default:
            msg_panic("%s: bad name %d", myname, name);
        }
    }
    va_end(ap);
}

/* vstream_vfprintf - formatted print engine */

VSTREAM *vstream_vfprintf(VSTREAM *vp, const char *format, va_list ap)
{
    vbuf_print(&vp->buf, format, ap);
    return (vp);
}

/* vstream_bufstat - get stream buffer status */

ssize_t vstream_bufstat(VSTREAM *vp, int command)
{
    VBUF   *bp;

    switch (command & VSTREAM_BST_MASK_DIR) {
    case VSTREAM_BST_FLAG_IN:
        if (vp->buf.flags & VSTREAM_FLAG_READ) {
            bp = &vp->buf;
        } else if (vp->buf.flags & VSTREAM_FLAG_DOUBLE) {
            bp = &vp->read_buf;
        } else {
            bp = 0;
        }
        switch (command & ~VSTREAM_BST_MASK_DIR) {
        case VSTREAM_BST_FLAG_PEND:
            return (bp ? -bp->cnt : 0);
            /* Add other requests below. */
        }
        break;
    case VSTREAM_BST_FLAG_OUT:
        if (vp->buf.flags & VSTREAM_FLAG_WRITE) {
            bp = &vp->buf;
        } else if (vp->buf.flags & VSTREAM_FLAG_DOUBLE) {
            bp = &vp->write_buf;
        } else {
            bp = 0;
        }
        switch (command & ~VSTREAM_BST_MASK_DIR) {
        case VSTREAM_BST_FLAG_PEND:
            return (bp ? bp->len - bp->cnt : 0);
            /* Add other requests below. */
        }
        break;
    }
    msg_panic("vstream_bufstat: unknown command: %d", command);
}

#undef vstream_peek                     /* API binary compatibility. */

/* vstream_peek - peek at a stream */

ssize_t vstream_peek(VSTREAM *vp)
{
    if (vp->buf.flags & VSTREAM_FLAG_READ) {
        return (-vp->buf.cnt);
    } else if (vp->buf.flags & VSTREAM_FLAG_DOUBLE) {
        return (-vp->read_buf.cnt);
    } else {
        return (0);
    }
}