bacio.c

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#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
 
#include "clib.h"
 
int
baciol(int mode, long int start, int size, long int no,
       long int *nactual, int *fdes, const char *fname, void *datary)
{
    /* Initialization. */
    *nactual = 0;
 
    /* Check for illegal combinations of options */
    if ((BAOPEN_RONLY & mode) &&
        ((BAOPEN_WONLY & mode) || (BAOPEN_WONLY_TRUNC & mode) || (BAOPEN_WONLY_APPEND & mode)))
        return BA_EROANDWO;
 
    if ((BAREAD & mode) && (BAWRITE & mode)) 
        return BA_ERANDW;
 
    /* Open files with correct read/write and file permission. */
    if (BAOPEN_RONLY & mode)
    {
        *fdes = open(fname, O_RDONLY , S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR | S_IWGRP);
    }
    else if (BAOPEN_WONLY & mode)
    {
        *fdes = open(fname, O_WRONLY | O_CREAT , S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR | S_IWGRP);
    }
    else if (BAOPEN_WONLY_TRUNC & mode)
    {
        *fdes = open(fname, O_WRONLY | O_CREAT | O_TRUNC , S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR | S_IWGRP);
    }
    else if (BAOPEN_WONLY_APPEND & mode)
    {
        *fdes = open(fname, O_WRONLY | O_CREAT | O_APPEND , S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR | S_IWGRP);
    }
    else if (BAOPEN_RW & mode)
    {
        *fdes = open(fname, O_RDWR | O_CREAT , S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR | S_IWGRP);
    }
 
    /* If the file open didn't work, or a bad fdes was passed in,
     * return error. */
    if (*fdes < 0)
        return BA_EFILEOPEN;
 
    /* Check for bad mode flags. */
    if (BAREAD & mode &&
        ((BAOPEN_WONLY & mode) || (BAOPEN_WONLY_TRUNC & mode) || (BAOPEN_WONLY_APPEND & mode)))
        return BA_ERONWO;
 
    /* Read data as requested. */
    if (BAREAD & mode )
    {
        /* Seek the right part of the file. */
        if (!(mode & NOSEEK))
            if (lseek(*fdes, start, SEEK_SET) == -1)
                return BA_ERNOSTART;
 
        if (datary == NULL)
        {
            printf("Massive catastrophe -- datary pointer is NULL\n");
            return BA_EDATANULL;
        }
        *nactual = read(*fdes, (void *)datary, (size_t)no);
    }
 
    /* Check for bad mode flag. */
    if (BAWRITE & mode && BAOPEN_RONLY & mode) 
        return BA_EWANDRO;
    
    /* See if we should be writing. */
    if (BAWRITE & mode)
    {
        if (!(mode & NOSEEK))
            if (lseek(*fdes, start, SEEK_SET) == -1)
                return BA_EWNOSTART;
 
        if (datary == NULL)
        {
            printf("Massive catastrophe -- datary pointer is NULL\n");
            return BA_EDATANULL;
        }
        *nactual = write(*fdes, (void *) datary, (size_t)no);
    }
 
    /* Close file if requested */
    if (BACLOSE & mode )
        if (close(*fdes) != 0)
            return BA_ECLOSE;
 
    /* Check that if we were reading or writing, that we actually got
       what we expected. Return 0 (success) if we're here and weren't
       reading or writing. */
    if ((mode & BAREAD || mode & BAWRITE) && (*nactual != no))
        return BA_EFEWDATA;
    else 
        return BA_NOERROR;
}