miniffs/miniffs.c

/******************************************************************************
 * MiniFFS : Mini Flat File System
 * miniffs.c: Shared code for all platforms.
 *
 * Copyright (c) 2008-2022 986-Studio. All rights reserved.
 *
 ******************************************************************************/

#include <stdlib.h>
#include <string.h>

#define __miniffs_internal
#include <miniffs.h>

static miniffs_error_t last_error = MINIFFS_NOERROR;

/* Public API */

file_t *miniffs_open(miniffs_t *fs, const char *filename)
{
    file_t *ret = (file_t *)calloc(1, sizeof(file_t));
    if (ret == NULL)
    {
        miniffs_seterror(MINIFFS_ALLOCATION_ERROR);
        goto exit;
    }

    ret->private_data = fs;
    ret->fent = miniffs_findfile(fs, filename);
    if (!ret->fent)
    {
        if (miniffs_geterror() != MINIFFS_INVALID_NAME)
        {
            miniffs_seterror(MINIFFS_FILE_NOT_FOUND);
        }
        goto free_and_exit;
    }

    ret->offset = 0;
    miniffs_seterror(MINIFFS_NOERROR);
    goto exit;

free_and_exit:
    free(ret);
    ret = NULL;

exit:
    return ret;
}

int miniffs_close(file_t *file)
{
    /* Let's poison the struct */
    file->private_data = NULL;
    file->offset = 0;
    file->fent = NULL;

    free(file);

    miniffs_seterror(MINIFFS_NOERROR);
}

void *miniffs_map(file_t *file)
{
    miniffs_t *fs = (miniffs_t *)file->private_data;

    miniffs_seterror(MINIFFS_NOERROR);

    return miniffs_getfileaddr(fs, file->fent);
}

uint8_t miniffs_read(file_t *file)
{
    miniffs_t *fs = (miniffs_t *) file->private_data;
    uint8_t *filePtr = miniffs_getfileaddr(fs, file->fent);
    uint8_t ret = filePtr[file->offset];

    file->offset++;

    if (file->offset >= file->fent->size)
    {
        miniffs_seterror(MINIFFS_END_OF_FILE);
        file->offset = file->fent->size - 1;
    }
    else
    {
        miniffs_seterror(MINIFFS_NOERROR);
    }

    return ret;
}

int miniffs_read_blocks(void *ptr, size_t size, size_t nmemb, file_t *file)
{
    int i;
    miniffs_t *fs = (miniffs_t *) file->private_data;
    uint8_t *filePtr = miniffs_getfileaddr(fs, file->fent);
    size_t fileOffset = file->offset;
    size_t bufferOffset = 0;
    int blockCount = 0;

    for(i = 0; i < nmemb; i++)
    {
        if (file->fent->size >= (fileOffset + size))
        {
            memcpy(ptr + bufferOffset, &filePtr[fileOffset], size);
            bufferOffset += size;
            fileOffset += size;
            blockCount++;
        }
    }
    file->offset = fileOffset;
    miniffs_seterror(MINIFFS_NOERROR);
    return blockCount;
}

int miniffs_seek(file_t *file, size_t offset, int whence)
{
    bool noError = true;
    switch(whence) {
        default:
            miniffs_seterror(MINIFFS_INVALID_PARAMS);
            return -1;

        case MFFS_SEEK_SET:
            file->offset = offset;
            break;
        case MFFS_SEEK_CUR:
            file->offset += offset;
            break;
        case MFFS_SEEK_END:
            if (file->fent->size <= offset)
            {
                /* Negative boundary check */
                noError = false;
                miniffs_seterror(MINIFFS_SEEK_OUT_OF_BOUNDARIES);
                file->offset = 0;
            }
            else
            {
                file->offset = file->fent->size - 1 - offset;
            }
        break;
    }

    if (file->offset >= file->fent->size)
    {
        /* Positive Boundary check */
        noError = false;
        miniffs_seterror(MINIFFS_SEEK_OUT_OF_BOUNDARIES);
        file->offset = file->fent->size - 1;
    }

    if (noError)
    {
        miniffs_seterror(MINIFFS_NOERROR);
    }
}

size_t miniffs_tell(file_t *file)
{
    miniffs_seterror(MINIFFS_NOERROR);
    return file->offset;
}

miniffs_error_t miniffs_geterror()
{
    return last_error;
}

/* Private API */
bool miniffs_isvalidfs(miniffs_t *fs)
{
    return (fs->header->magic == MINIFFS_MAGIC) &&
           (fs->header->fs_version_major == MINIFFS_VERSION_MAJOR) &&
           (fs->header->fs_version_minor == MINIFFS_VERSION_MINOR) &&
           (fs->header->fs_filename_len == MINIFFS_FILENAME_LENGTH) &&
           (fs->header->fs_extention_len == MINIFFS_EXTENSION_LENGTH);
}

static void make_fullname(char *name, char *ext, char *out)
{
    uint8_t nameLen = strnlen(name, MINIFFS_FILENAME_LENGTH);
    uint8_t extLen = strnlen(ext, MINIFFS_EXTENSION_LENGTH);

    memcpy(out, name, nameLen);
    memcpy(out + nameLen, ".", 1);
    memcpy(out + nameLen + 1, ext, extLen);
}

fileentry_t *miniffs_findfile(miniffs_t *fs, const char *filename)
{
    int i;
    char entryFullName[MINIFFS_FULLNAME_LENGTH];
    uint8_t filenameLength = strlen(filename);
    fileentry_t *ret = NULL;
    if (filenameLength > MINIFFS_FULLNAME_LENGTH)
    {
        miniffs_seterror(MINIFFS_INVALID_NAME);
        goto exit;
    }

    for(i = 0; i < fs->header->entry_count; i++)
    {
        fileentry_t *cur = &fs->header->fent[i];
        make_fullname(cur->name, cur->ext, entryFullName);

        if (memcmp(filename, entryFullName, filenameLength) == 0)
        {
            /* File found! */
            ret = cur;
            break;
        }
    }

exit:
    return ret;
}

void miniffs_seterror(miniffs_error_t err)
{
    last_error = err;
}