libmocha/source/devoptab/devoptab_fsa_open.cpp

#include "devoptab_fsa.h"
#include "logger.h"
#include <mutex>

// Extended "magic" value that allows opening files with FS_OPEN_FLAG_UNENCRYPTED in underlying FSOpenFileEx() call similar to O_DIRECTORY
#ifndef O_UNENCRYPTED
#define O_UNENCRYPTED 0x4000000
#endif

int __fsa_open(struct _reent *r,
               void *fileStruct,
               const char *path,
               int flags,
               int mode) {
    FSAFileHandle fd;
    FSError status;
    const char *fsMode;

    if (!fileStruct || !path) {
        r->_errno = EINVAL;
        return -1;
    }

    bool createFileIfNotFound = false;
    bool failIfFileNotFound   = false;
    // Map flags to open modes
    int commonFlagMask = O_CREAT | O_TRUNC | O_APPEND;
    if (((flags & O_ACCMODE) == O_RDONLY) && !(flags & commonFlagMask)) {
        fsMode = "r";
    } else if (((flags & O_ACCMODE) == O_RDWR) && !(flags & commonFlagMask)) {
        fsMode = "r+";
    } else if (((flags & O_ACCMODE) == O_WRONLY) && ((flags & commonFlagMask) == (O_CREAT | O_TRUNC))) {
        fsMode = "w";
    } else if (((flags & O_ACCMODE) == O_RDWR) && ((flags & commonFlagMask) == (O_CREAT | O_TRUNC))) {
        fsMode = "w+";
    } else if (((flags & O_ACCMODE) == O_WRONLY) && ((flags & commonFlagMask) == (O_CREAT | O_APPEND))) {
        fsMode = "a";
    } else if (((flags & O_ACCMODE) == O_RDWR) && ((flags & commonFlagMask) == (O_CREAT | O_APPEND))) {
        fsMode = "a+";
    } else if (((flags & O_ACCMODE) == O_WRONLY) && ((flags & commonFlagMask) == (O_CREAT))) {
        // Cafe OS doesn't have a matching mode for this, so we have to be creative and create the file.
        createFileIfNotFound = true;
        // It's not possible to open a file with write only mode which doesn't truncate the file
        // Technically we could read from the file, but our read implementation is blocking this.
        fsMode = "r+";
    } else if (((flags & O_ACCMODE) == O_WRONLY) && ((flags & commonFlagMask) == (O_APPEND))) {
        // Cafe OS doesn't have a matching mode for this, so we have to check if the file exists.
        failIfFileNotFound = true;
        fsMode             = "a";
    } else if (((flags & O_ACCMODE) == O_WRONLY) && ((flags & commonFlagMask) == (O_TRUNC))) {
        // As above
        failIfFileNotFound = true;
        fsMode             = "w";
    } else {
        r->_errno = EINVAL;
        return -1;
    }

    char *fixedPath = __fsa_fixpath(r, path);
    if (!fixedPath) {
        r->_errno = ENOMEM;
        return -1;
    }

    auto *file = (__fsa_file_t *) fileStruct;
    strncpy(file->fullPath, fixedPath, sizeof(file->fullPath) - 1);
    free(fixedPath);

    // Prepare flags
    FSOpenFileFlags openFlags = (flags & O_UNENCRYPTED) ? FS_OPEN_FLAG_UNENCRYPTED : FS_OPEN_FLAG_NONE;
    FSMode translatedMode     = __fsa_translate_permission_mode(mode);
    uint32_t preAllocSize     = 0;

    // Init mutex and lock
    file->mutex.init(file->fullPath);
    std::lock_guard<MutexWrapper> lock(file->mutex);

    auto *deviceData = (FSADeviceData *) r->deviceData;

    if (createFileIfNotFound || failIfFileNotFound || (flags & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) {
        // Check if file exists
        FSAStat stat;
        status = FSAGetStat(deviceData->clientHandle, file->fullPath, &stat);
        if (status == FS_ERROR_NOT_FOUND) {
            if (createFileIfNotFound) { // Create new file if needed
                status = FSAOpenFileEx(deviceData->clientHandle, file->fullPath, "w", translatedMode,
                                       openFlags, preAllocSize, &fd);
                if (status == FS_ERROR_OK) {
                    if (FSACloseFile(deviceData->clientHandle, fd) != FS_ERROR_OK) {
                        DEBUG_FUNCTION_LINE_ERR("FSACloseFile(0x%08X, 0x%08X) (%s) failed: %s",
                                                deviceData->clientHandle, fd, file->fullPath, FSAGetStatusStr(status));
                    }
                    fd = -1;
                } else {
                    DEBUG_FUNCTION_LINE_ERR("FSAOpenFileEx(0x%08X, %s, %s, 0x%X, 0x%08X, 0x%08X, 0x%08X) failed: %s",
                                            deviceData->clientHandle, file->fullPath, "w", translatedMode, openFlags, preAllocSize, &fd,
                                            FSAGetStatusStr(status));
                    r->_errno = __fsa_translate_error(status);
                    return -1;
                }
            } else if (failIfFileNotFound) { // Return an error if we don't we create new files
                r->_errno = __fsa_translate_error(status);
                return -1;
            }
        } else if (status == FS_ERROR_OK) {
            // If O_CREAT and O_EXCL are set, open() shall fail if the file exists.
            if ((flags & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) {
                r->_errno = EEXIST;
                return -1;
            }
        }
    }

    status = FSAOpenFileEx(deviceData->clientHandle, file->fullPath, fsMode, translatedMode, openFlags, preAllocSize, &fd);
    if (status < 0) {
        DEBUG_FUNCTION_LINE_ERR("FSAOpenFileEx(0x%08X, %s, %s, 0x%X, 0x%08X, 0x%08X, 0x%08X) failed: %s",
                                deviceData->clientHandle, file->fullPath, fsMode, translatedMode, openFlags, preAllocSize, &fd,
                                FSAGetStatusStr(status));
        r->_errno = __fsa_translate_error(status);
        return -1;
    }

    file->fd    = fd;
    file->flags = (flags & (O_ACCMODE | O_APPEND | O_SYNC));
    // Is always 0, even if O_APPEND is set.
    file->offset = 0;

    if (flags & O_APPEND) {
        FSAStat stat;
        status = FSAGetStatFile(deviceData->clientHandle, fd, &stat);
        if (status < 0) {
            DEBUG_FUNCTION_LINE_ERR("FSAGetStatFile(0x%08X, 0x%08X, 0x%08X) (%s) failed: %s",
                                    deviceData->clientHandle, fd, &stat, file->fullPath, FSAGetStatusStr(status));
            r->_errno = __fsa_translate_error(status);
            if (FSACloseFile(deviceData->clientHandle, fd) < 0) {
                DEBUG_FUNCTION_LINE_ERR("FSACloseFile(0x%08X, 0x%08X) (%d) failed: %s",
                                        deviceData->clientHandle, fd, file->fullPath, FSAGetStatusStr(status));
            }
            return -1;
        }
        file->appendOffset = stat.size;
    }
    return 0;
}