src/lib/istream-file.c

	istream-file.c revision 411d6baa37f31d90730e90c4a28c43e1974bbe58
/* Copyright (c) 2002-2003 Timo Sirainen */

/* @UNSAFE: whole file */

#include "lib.h"
#include "istream-internal.h"
#include "network.h"

#include <time.h>
#include <unistd.h>
#include <sys/stat.h>

#define I_STREAM_MIN_SIZE 4096

struct file_istream {
    struct _istream istream;

    size_t max_buffer_size;
    uoff_t skip_left;

    unsigned int file:1;
    unsigned int autoclose_fd:1;
};

static void _close(struct _iostream *stream)
{
    struct file_istream *fstream = (struct file_istream *) stream;
    struct _istream *_stream = (struct _istream *) stream;

    if (fstream->autoclose_fd && _stream->fd != -1) {
        if (close(_stream->fd) < 0)
            i_error("file_istream.close() failed: %m");
        _stream->fd = -1;
    }
}

static void _destroy(struct _iostream *stream)
{
    struct _istream *_stream = (struct _istream *) stream;

    p_free(_stream->iostream.pool, _stream->w_buffer);
}

static void _set_max_buffer_size(struct _iostream *stream, size_t max_size)
{
    struct file_istream *fstream = (struct file_istream *) stream;

    fstream->max_buffer_size = max_size;
}

static void i_stream_grow_buffer(struct _istream *stream, size_t bytes)
{
    struct file_istream *fstream = (struct file_istream *) stream;
    size_t old_size;

    old_size = stream->buffer_size;

    stream->buffer_size = stream->pos + bytes;
    if (stream->buffer_size <= I_STREAM_MIN_SIZE)
        stream->buffer_size = I_STREAM_MIN_SIZE;
    else {
        stream->buffer_size =
            pool_get_exp_grown_size(stream->iostream.pool,
                        old_size, stream->buffer_size);
    }

    if (fstream->max_buffer_size > 0 &&
        stream->buffer_size > fstream->max_buffer_size)
        stream->buffer_size = fstream->max_buffer_size;

    stream->buffer = stream->w_buffer =
        p_realloc(stream->iostream.pool, stream->w_buffer,
              old_size, stream->buffer_size);
}

static void i_stream_compress(struct _istream *stream)
{
    memmove(stream->w_buffer, stream->w_buffer + stream->skip,
        stream->pos - stream->skip);
    stream->pos -= stream->skip;

    stream->skip = 0;
}

static ssize_t _read(struct _istream *stream)
{
    struct file_istream *fstream = (struct file_istream *) stream;
    size_t size;
    ssize_t ret;

    if (stream->istream.closed)
        return -1;

    stream->istream.stream_errno = 0;

    if (stream->pos == stream->buffer_size) {
        if (stream->skip > 0) {
            /* remove the unused bytes from beginning of buffer */
                        i_stream_compress(stream);
        } else if (fstream->max_buffer_size == 0 ||
               stream->buffer_size < fstream->max_buffer_size) {
            /* buffer is full - grow it */
            i_stream_grow_buffer(stream, I_STREAM_MIN_SIZE);
        }

        if (stream->pos == stream->buffer_size)
            return -2; /* buffer full */
    }

    size = stream->buffer_size - stream->pos;

    ret = -1;

    if (fstream->file) {
        do {
            ret = pread(stream->fd, stream->w_buffer + stream->pos,
                    size, stream->istream.v_offset +
                    (stream->pos - stream->skip));
        } while (ret < 0 && errno == EINTR);
    } else {
        ret = read(stream->fd, stream->w_buffer + stream->pos, size);
    }
    if (ret == 0) {
        /* EOF */
        stream->istream.eof = TRUE;
        return -1;
    }

    if (ret < 0) {
        if (errno == EINTR || errno == EAGAIN)
            ret = 0;
        else {
            stream->istream.eof = TRUE;
            stream->istream.stream_errno = errno;
            return -1;
        }
    }

    if (ret > 0 && fstream->skip_left > 0) {
        i_assert(!fstream->file);
        i_assert(stream->skip == stream->pos);

        if (fstream->skip_left >= (size_t)ret) {
            fstream->skip_left -= ret;
            ret = 0;
        } else {
            ret -= fstream->skip_left;
            stream->pos += fstream->skip_left;
            stream->skip += fstream->skip_left;
            fstream->skip_left = 0;
        }
    }

    stream->pos += ret;
    i_assert(ret != 0 || !fstream->file);
    return ret;
}

static void _seek(struct _istream *stream, uoff_t v_offset)
{
    struct file_istream *fstream = (struct file_istream *) stream;

    if (!stream->istream.seekable) {
        if (v_offset < stream->istream.v_offset) {
            stream->istream.stream_errno = ESPIPE;
            return;
        }
        fstream->skip_left += v_offset - stream->istream.v_offset;
    }

    stream->istream.stream_errno = 0;
    stream->istream.v_offset = v_offset;
    stream->skip = stream->pos = 0;
}

static uoff_t _get_size(struct _istream *stream)
{
    struct file_istream *fstream = (struct file_istream *) stream;
    struct stat st;

    if (fstream->file && fstat(stream->fd, &st) == 0 && S_ISREG(st.st_mode))
        return (uoff_t)st.st_size;
    else
        return (uoff_t)-1;
}

struct istream *i_stream_create_file(int fd, pool_t pool,
                     size_t max_buffer_size, int autoclose_fd)
{
    struct file_istream *fstream;
    struct stat st;

    fstream = p_new(pool, struct file_istream, 1);
    fstream->max_buffer_size = max_buffer_size;
    fstream->autoclose_fd = autoclose_fd;

    fstream->istream.iostream.close = _close;
    fstream->istream.iostream.destroy = _destroy;
    fstream->istream.iostream.set_max_buffer_size = _set_max_buffer_size;

    fstream->istream.read = _read;
    fstream->istream.seek = _seek;
    fstream->istream.get_size = _get_size;

    /* get size of fd if it's a file */
    if (fstat(fd, &st) == 0 && S_ISREG(st.st_mode)) {
        fstream->file = TRUE;
        fstream->istream.istream.seekable = TRUE;
    }

    return _i_stream_create(&fstream->istream, pool, fd, 0);
}