source: mainline/uspace/lib/libc/generic/io/stdio.c@ 04b687b

/*
 * Copyright (c) 2008 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libc
 * @{
 */
/**
 * @file
 * @brief ANSI C Stream I/O.
 */ 

#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <bool.h>
#include <stdio.h>

/**
 * Open a stream.
 *
 * @param file_name     Name of the file to open.
 * @param mode          Mode string, (r|w|a)[b|t][+].
 */
FILE *fopen(const char *file_name, const char *mode)
{
        FILE *f;
        int flags;
        bool plus;
        const char *mp;

        /* Parse mode except first character. */

        mp = mode;
        if (*mp++ == '\0') {
                errno = EINVAL;
                return NULL;
        }

        if (*mp == 'b' || *mp == 't') ++mp;

        if (*mp == '+') {
                ++mp;
                plus = true;
        } else {
                plus = false;
        }

        if (*mp != '\0') {
                errno = EINVAL;
                return NULL;
        }

        /* Parse first character of mode and determine flags for open(). */

        switch (mode[0]) {
        case 'r':
                flags = plus ? O_RDWR : O_RDONLY;
                break;
        case 'w':
                flags = (O_TRUNC | O_CREAT) | (plus ? O_RDWR : O_WRONLY);
                break;
        case 'a':
                /* TODO: a+ must read from beginning, append to the end. */
                if (plus) {
                        errno = ENOTSUP;
                        return NULL;
                }
                flags = (O_APPEND | O_CREAT) | (plus ? O_RDWR : O_WRONLY);
        default:
                errno = EINVAL;
                return NULL;
        }

        /* Open file. */
        
        f = malloc(sizeof(FILE));
        if (f == NULL) {
                errno = ENOMEM;
                return NULL;
        }

        f->fd = open(file_name, flags, 0666);
        if (f->fd < 0) {
                free(f);
                return NULL; /* errno was set by open() */
        }

        f->error = 0;
        f->eof = 0;

        return f;
}

/** Close a stream.
 *
 * @param f     Pointer to stream.
 * @return      0 on success, EOF on error.
 */
int fclose(FILE *f)
{
        int rc;

        rc = close(f->fd);
        free(f);

        if (rc != 0)
                return EOF; /* errno was set by close() */

        return 0;
}

/** Read from a stream.
 *
 * @param buf   Destination buffer.
 * @param size  Size of each record.
 * @param nmemb Number of records to read.
 * @param f     Pointer to the stream.
 */
size_t fread(void *buf, size_t size, size_t nmemb, FILE *f)
{
        size_t left, done, n;

        left = size * nmemb;
        done = 0;

        while (left > 0 && !f->error && !f->eof) {
                n = read(f->fd, buf + done, left);

                if (n < 0) {
                        f->error = 1;
                } else if (n == 0) {
                        f->eof = 1;
                } else {
                        left -= n;
                        done += n;
                }
        }

        return done / size;
}


/** Write to a stream.
 *
 * @param buf   Source buffer.
 * @param size  Size of each record.
 * @param nmemb Number of records to write.
 * @param f     Pointer to the stream.
 */
size_t fwrite(const void *buf, size_t size, size_t nmemb, FILE *f)
{
        size_t left, done, n;

        left = size * nmemb;
        done = 0;

        while (left > 0 && !f->error) {
                n = write(f->fd, buf + done, left);

                if (n <= 0) {
                        f->error = 1;
                } else {
                        left -= n;
                        done += n;
                }
        } 

        return done / size;
}

/** Return the end-of-file indicator of a stream. */
int feof(FILE *f)
{
        return f->eof;
}

/** Return the error indicator of a stream. */
int ferror(FILE *f)
{
        return f->error;
}

/** Clear the error and end-of-file indicators of a stream. */
void clearerr(FILE *f)
{
        f->eof = 0;
        f->error = 0;
}

/** @}
 */