| //======================================================================== |
| // |
| // InMemoryFile.cc |
| // |
| // Represents a file in-memory with GNU's stdio wrappers. |
| // NOTE as of this writing, open() depends on the glibc 'fopencookie' |
| // extension and is not supported on other platforms. The |
| // HAVE_IN_MEMORY_FILE macro is intended to reflect whether this class is |
| // usable. |
| // |
| // This file is licensed under the GPLv2 or later |
| // |
| // Copyright (C) 2018, 2019 Greg Knight <lyngvi@gmail.com> |
| // Copyright (C) 2020 Albert Astals Cid <aacid@kde.org> |
| // |
| //======================================================================== |
| |
| #include "InMemoryFile.h" |
| |
| #include <cstring> |
| #include <sstream> |
| |
| InMemoryFile::InMemoryFile() = default; |
| |
| #ifdef HAVE_IN_MEMORY_FILE_FOPENCOOKIE |
| ssize_t InMemoryFile::_read(char *buf, size_t sz) |
| { |
| auto toRead = std::min<size_t>(data.size() - iohead, sz); |
| memcpy(&buf[0], &data[iohead], toRead); |
| iohead += toRead; |
| return toRead; |
| } |
| |
| ssize_t InMemoryFile::_write(const char *buf, size_t sz) |
| { |
| if (iohead + sz > data.size()) { |
| data.resize(iohead + sz); |
| } |
| memcpy(&data[iohead], buf, sz); |
| iohead += sz; |
| return sz; |
| } |
| |
| int InMemoryFile::_seek(off64_t *offset, int whence) |
| { |
| switch (whence) { |
| case SEEK_SET: |
| iohead = (*offset); |
| break; |
| case SEEK_CUR: |
| iohead += (*offset); |
| break; |
| case SEEK_END: |
| iohead -= (*offset); |
| break; |
| } |
| (*offset) = std::min<off64_t>(std::max<off64_t>(iohead, 0l), data.size()); |
| iohead = static_cast<size_t>(*offset); |
| return 0; |
| } |
| #endif // def HAVE_IN_MEMORY_FILE_FOPENCOOKIE |
| |
| FILE *InMemoryFile::open(const char *mode) |
| { |
| #ifdef HAVE_IN_MEMORY_FILE_FOPENCOOKIE |
| if (fptr != nullptr) { |
| fprintf(stderr, "InMemoryFile: BUG: Why is this opened more than once?"); |
| return nullptr; // maybe there's some legit reason for it, whoever comes up with one can remove this line |
| } |
| static const cookie_io_functions_t methods = { |
| /* .read = */ [](void *self, char *buf, size_t sz) { return ((InMemoryFile *)self)->_read(buf, sz); }, |
| /* .write = */ [](void *self, const char *buf, size_t sz) { return ((InMemoryFile *)self)->_write(buf, sz); }, |
| /* .seek = */ [](void *self, off64_t *offset, int whence) { return ((InMemoryFile *)self)->_seek(offset, whence); }, |
| /* .close = */ |
| [](void *self) { |
| ((InMemoryFile *)self)->fptr = nullptr; |
| return 0; |
| }, |
| }; |
| return fptr = fopencookie(this, mode, methods); |
| #else |
| fprintf(stderr, "If you can read this, your platform does not support the features necessary to achieve your goals."); |
| return nullptr; |
| #endif |
| } |