readwrite.c

Apache 2.0.63 is the current stable version of the 2.0 series, and is recommended over any previous

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "apr_arch_file_io.h"
#include "apr_strings.h"
#include "apr_thread_mutex.h"
#include "apr_support.h"

/* The only case where we don't use wait_for_io_or_timeout is on
 * pre-BONE BeOS, so this check should be sufficient and simpler */
#if !BEOS_R5
#define USE_WAIT_FOR_IO
#endif

/* problems: 
 * 1) ungetchar not used for buffered files
 */
APR_DECLARE(apr_status_t) apr_file_read(apr_file_t *thefile, void *buf, apr_size_t *nbytes)
{
    apr_ssize_t rv;
    apr_size_t bytes_read;

    if (*nbytes <= 0) {
        *nbytes = 0;
        return APR_SUCCESS;
    }

    if (thefile->buffered) {
        char *pos = (char *)buf;
        apr_uint64_t blocksize;
        apr_uint64_t size = *nbytes;

        file_lock(thefile);

        if (thefile->direction == 1) {
            rv = apr_file_flush_locked(thefile);
            if (rv) {
                file_unlock(thefile);
                return rv;
            }
            thefile->bufpos = 0;
            thefile->direction = 0;
            thefile->dataRead = 0;
        }

        rv = 0;
        if (thefile->ungetchar != -1) {
            *pos = (char)thefile->ungetchar;
            ++pos;
            --size;
            thefile->ungetchar = -1;
        }
        while (rv == 0 && size > 0) {
            if (thefile->bufpos >= thefile->dataRead) {
                int bytesread = read(thefile->filedes, thefile->buffer, APR_FILE_BUFSIZE);
                if (bytesread == 0) {
                    thefile->eof_hit = TRUE;
                    rv = APR_EOF;
                    break;
                }
                else if (bytesread == -1) {
                    rv = errno;
                    break;
                }
                thefile->dataRead = bytesread;
                thefile->filePtr += thefile->dataRead;
                thefile->bufpos = 0;
            }

            blocksize = size > thefile->dataRead - thefile->bufpos ? thefile->dataRead - thefile->bufpos : size;
            memcpy(pos, thefile->buffer + thefile->bufpos, blocksize);
            thefile->bufpos += blocksize;
            pos += blocksize;
            size -= blocksize;
        }

        *nbytes = pos - (char *)buf;
        if (*nbytes) {
            rv = 0;
        }

        file_unlock(thefile);

        return rv;
    }
    else {
        bytes_read = 0;
        if (thefile->ungetchar != -1) {
            bytes_read = 1;
            *(char *)buf = (char)thefile->ungetchar;
            buf = (char *)buf + 1;
            (*nbytes)--;
            thefile->ungetchar = -1;
            if (*nbytes == 0) {
                *nbytes = bytes_read;
                return APR_SUCCESS;
            }
        }

        do {
            rv = read(thefile->filedes, buf, *nbytes);
        } while (rv == -1 && errno == EINTR);
#ifdef USE_WAIT_FOR_IO
        if (rv == -1 && 
            (errno == EAGAIN || errno == EWOULDBLOCK) && 
            thefile->timeout != 0) {
            apr_status_t arv = apr_wait_for_io_or_timeout(thefile, NULL, 1);
            if (arv != APR_SUCCESS) {
                *nbytes = bytes_read;
                return arv;
            }
            else {
                do {
                    rv = read(thefile->filedes, buf, *nbytes);
                } while (rv == -1 && errno == EINTR);
            }
        }  
#endif
        *nbytes = bytes_read;
        if (rv == 0) {
            thefile->eof_hit = TRUE;
            return APR_EOF;
        }
        if (rv > 0) {
            *nbytes += rv;
            return APR_SUCCESS;
        }
        return errno;
    }
}

APR_DECLARE(apr_status_t) apr_file_write(apr_file_t *thefile, const void *buf, apr_size_t *nbytes)
{
    apr_size_t rv;

    if (thefile->buffered) {
        char *pos = (char *)buf;
        int blocksize;
        int size = *nbytes;

        file_lock(thefile);

        if ( thefile->direction == 0 ) {
            /* Position file pointer for writing at the offset we are 
             * logically reading from
             */
            apr_int64_t offset = thefile->filePtr - thefile->dataRead + thefile->bufpos;
            if (offset != thefile->filePtr)
                lseek(thefile->filedes, offset, SEEK_SET);
            thefile->bufpos = thefile->dataRead = 0;
            thefile->direction = 1;
        }

        rv = 0;
        while (rv == 0 && size > 0) {
            if (thefile->bufpos == APR_FILE_BUFSIZE)   /* write buffer is full*/
                rv = apr_file_flush_locked(thefile);

            blocksize = size > APR_FILE_BUFSIZE - thefile->bufpos ? 
                        APR_FILE_BUFSIZE - thefile->bufpos : size;
            memcpy(thefile->buffer + thefile->bufpos, pos, blocksize);                      
            thefile->bufpos += blocksize;
            pos += blocksize;
            size -= blocksize;
        }

        file_unlock(thefile);

        return rv;
    }
    else {
        do {
            rv = write(thefile->filedes, buf, *nbytes);
        } while (rv == (apr_size_t)-1 && errno == EINTR);
#ifdef USE_WAIT_FOR_IO
        if (rv == (apr_size_t)-1 &&
            (errno == EAGAIN || errno == EWOULDBLOCK) && 
            thefile->timeout != 0) {
            apr_status_t arv = apr_wait_for_io_or_timeout(thefile, NULL, 0);
            if (arv != APR_SUCCESS) {
                *nbytes = 0;
                return arv;
            }
            else {
                do {
                    do {
                        rv = write(thefile->filedes, buf, *nbytes);
                    } while (rv == (apr_size_t)-1 && errno == EINTR);
                    if (rv == (apr_size_t)-1 &&
                        (errno == EAGAIN || errno == EWOULDBLOCK)) {
                        *nbytes /= 2; /* yes, we'll loop if kernel lied
                                       * and we can't even write 1 byte
                                       */
                    }
                    else {
                        break;
                    }
                } while (1);
            }
        }  
#endif
        if (rv == (apr_size_t)-1) {
            (*nbytes) = 0;
            return errno;
        }
        *nbytes = rv;
        return APR_SUCCESS;
    }
}

APR_DECLARE(apr_status_t) apr_file_writev(apr_file_t *thefile, const struct iovec *vec,
                                          apr_size_t nvec, apr_size_t *nbytes)
{
#ifdef HAVE_WRITEV
    apr_status_t rv;
    int bytes;

    if (thefile->buffered) {
        file_lock(thefile);

        rv = apr_file_flush_locked(thefile);
        if (rv != APR_SUCCESS) {
            file_unlock(thefile);
            return rv;
        }
        if (thefile->direction == 0) {
            /* Position file pointer for writing at the offset we are
             * logically reading from
             */
            apr_int64_t offset = thefile->filePtr - thefile->dataRead +
                                 thefile->bufpos;
            if (offset != thefile->filePtr)
                lseek(thefile->filedes, offset, SEEK_SET);
            thefile->bufpos = thefile->dataRead = 0;
        }

        file_unlock(thefile);
    }

    if ((bytes = writev(thefile->filedes, vec, nvec)) < 0) {
        *nbytes = 0;
        rv = errno;
    }
    else {
        *nbytes = bytes;
        rv = APR_SUCCESS;
    }
    return rv;
#else
    *nbytes = vec[0].iov_len;
    return apr_file_write(thefile, vec[0].iov_base, nbytes);
#endif
}

APR_DECLARE(apr_status_t) apr_file_putc(char ch, apr_file_t *thefile)
{
    apr_size_t nbytes = 1;

    return apr_file_write(thefile, &ch, &nbytes);
}

APR_DECLARE(apr_status_t) apr_file_ungetc(char ch, apr_file_t *thefile)
{
    thefile->ungetchar = (unsigned char)ch;
    return APR_SUCCESS; 
}

APR_DECLARE(apr_status_t) apr_file_getc(char *ch, apr_file_t *thefile)
{
    apr_size_t nbytes = 1;

    return apr_file_read(thefile, ch, &nbytes);
}

APR_DECLARE(apr_status_t) apr_file_puts(const char *str, apr_file_t *thefile)
{
    apr_size_t nbytes = strlen(str);

    return apr_file_write(thefile, str, &nbytes);
}

apr_status_t apr_file_flush_locked(apr_file_t *thefile)
{
    apr_status_t rv = APR_SUCCESS;

    if (thefile->direction == 1 && thefile->bufpos) {
        apr_ssize_t written;

        do {
            written = write(thefile->filedes, thefile->buffer, thefile->bufpos);
        } while (written == -1 && errno == EINTR);
        if (written == -1) {
            rv = errno;
        } else {
            thefile->filePtr += written;
            thefile->bufpos = 0;
        }
    }

    return rv;
}

APR_DECLARE(apr_status_t) apr_file_flush(apr_file_t *thefile)
{
    apr_status_t rv = APR_SUCCESS;

    if (thefile->buffered) {
        file_lock(thefile);
        rv = apr_file_flush_locked(thefile);
        file_unlock(thefile);
    }
    /* There isn't anything to do if we aren't buffering the output
     * so just return success.
     */
    return rv; 
}

APR_DECLARE(apr_status_t) apr_file_gets(char *str, int len, apr_file_t *thefile)
{
    apr_status_t rv = APR_SUCCESS; /* get rid of gcc warning */
    apr_size_t nbytes;
    const char *str_start = str;
    char *final = str + len - 1;

    if (len <= 1) {  
        /* sort of like fgets(), which returns NULL and stores no bytes 
         */
        return APR_SUCCESS;
    }

    while (str < final) { /* leave room for trailing '\0' */
        nbytes = 1;
        rv = apr_file_read(thefile, str, &nbytes);
        if (rv != APR_SUCCESS) {
            break;
        }
        if (*str == '\n') {
            ++str;
            break;
        }
        ++str;
    }
    /* We must store a terminating '\0' if we've stored any chars. We can
     * get away with storing it if we hit an error first. 
     */
    *str = '\0';
    if (str > str_start) {
        /* we stored chars; don't report EOF or any other errors;
         * the app will find out about that on the next call
         */
        return APR_SUCCESS;
    }
    return rv;
}

APR_DECLARE_NONSTD(int) apr_file_printf(apr_file_t *fptr, 
                                        const char *format, ...)
{
    apr_status_t cc;
    va_list ap;
    char *buf;
    int len;

    buf = malloc(HUGE_STRING_LEN);
    if (buf == NULL) {
        return 0;
    }
    va_start(ap, format);
    len = apr_vsnprintf(buf, HUGE_STRING_LEN, format, ap);
    cc = apr_file_puts(buf, fptr);
    va_end(ap);
    free(buf);
    return (cc == APR_SUCCESS) ? len : -1;
}