diff options
Diffstat (limited to 'lib/mlibc/options/ansi/generic/file-io.cpp')
| -rw-r--r-- | lib/mlibc/options/ansi/generic/file-io.cpp | 745 |
1 files changed, 745 insertions, 0 deletions
diff --git a/lib/mlibc/options/ansi/generic/file-io.cpp b/lib/mlibc/options/ansi/generic/file-io.cpp new file mode 100644 index 0000000..e59b109 --- /dev/null +++ b/lib/mlibc/options/ansi/generic/file-io.cpp @@ -0,0 +1,745 @@ + +#include <errno.h> +#include <stdlib.h> +#include <stdint.h> +#include <string.h> +#include <stdio.h> +#if __MLIBC_GLIBC_OPTION +#include <stdio_ext.h> +#endif + +#include <bits/ensure.h> + +#include <mlibc/debug.hpp> + +#include <abi-bits/fcntl.h> +#include <frg/allocation.hpp> +#include <frg/mutex.hpp> +#include <mlibc/allocator.hpp> +#include <mlibc/file-io.hpp> +#include <mlibc/ansi-sysdeps.hpp> +#include <mlibc/lock.hpp> + +namespace mlibc { + +// -------------------------------------------------------------------------------------- +// abstract_file implementation. +// -------------------------------------------------------------------------------------- + +namespace { + using file_list = frg::intrusive_list< + abstract_file, + frg::locate_member< + abstract_file, + frg::default_list_hook<abstract_file>, + &abstract_file::_list_hook + > + >; + + // Useful when debugging the FILE implementation. + constexpr bool globallyDisableBuffering = false; + + // The maximum number of characters we permit the user to ungetc. + constexpr size_t ungetBufferSize = 8; + + // List of files that will be flushed before exit(). + file_list &global_file_list() { + static frg::eternal<file_list> list; + return list.get(); + }; +} + +// For pipe-like streams (seek returns ESPIPE), we need to make sure +// that the buffer only ever contains all-dirty or all-clean data. +// Regarding _type and _bufmode: +// As we might construct FILE objects for FDs that are not actually +// open (e.g. for std{in,out,err}), we defer the type determination and cache the result. + +abstract_file::abstract_file(void (*do_dispose)(abstract_file *)) +: _type{stream_type::unknown}, _bufmode{buffer_mode::unknown}, _do_dispose{do_dispose} { + // TODO: For __fwriting to work correctly, set the __io_mode to 1 if the write is write-only. + __buffer_ptr = nullptr; + __unget_ptr = nullptr; + __buffer_size = 4096; + __offset = 0; + __io_offset = 0; + __valid_limit = 0; + __dirty_begin = 0; + __dirty_end = 0; + __io_mode = 0; + __status_bits = 0; + + global_file_list().push_back(this); +} + +abstract_file::~abstract_file() { + if(__dirty_begin != __dirty_end) + mlibc::infoLogger() << "mlibc warning: File is not flushed before destruction" + << frg::endlog; + + if(__buffer_ptr) + getAllocator().free(__buffer_ptr - ungetBufferSize); + + auto it = global_file_list().iterator_to(this); + global_file_list().erase(it); +} + +void abstract_file::dispose() { + if(!_do_dispose) + return; + _do_dispose(this); +} + +// Note that read() and write() are asymmetric: +// While read() can trigger a write-back, write() can never trigger a read-ahead(). +// This peculiarity is reflected in their code. + +int abstract_file::read(char *buffer, size_t max_size, size_t *actual_size) { + __ensure(max_size); + + if(_init_bufmode()) + return -1; + + size_t unget_length = 0; + if (__unget_ptr != __buffer_ptr) { + unget_length = frg::min(max_size, (size_t)(__buffer_ptr - __unget_ptr)); + memcpy(buffer, __unget_ptr, unget_length); + + __unget_ptr += unget_length; + buffer += unget_length; + max_size -= unget_length; + + if (max_size == 0) { + *actual_size = unget_length; + return 0; + } + } + + if(globallyDisableBuffering || _bufmode == buffer_mode::no_buffer) { + size_t io_size; + if(int e = io_read(buffer, max_size, &io_size); e) { + __status_bits |= __MLIBC_ERROR_BIT; + return e; + } + if(!io_size) + __status_bits |= __MLIBC_EOF_BIT; + *actual_size = io_size + unget_length; + return 0; + } + + // Ensure correct buffer type for pipe-like streams. + // TODO: In order to support pipe-like streams we need to write-back the buffer. + if(__io_mode && __valid_limit) + mlibc::panicLogger() << "mlibc: Cannot read-write to same pipe-like stream" + << frg::endlog; + __io_mode = 0; + + // Clear the buffer, then buffer new data. + if(__offset == __valid_limit) { + // TODO: We only have to write-back/reset if __valid_limit reaches the buffer end. + if(int e = _write_back(); e) + return e; + if(int e = _reset(); e) + return e; + + // Perform a read-ahead. + _ensure_allocation(); + size_t io_size; + if(int e = io_read(__buffer_ptr, __buffer_size, &io_size); e) { + __status_bits |= __MLIBC_ERROR_BIT; + return e; + } + if(!io_size) { + __status_bits |= __MLIBC_EOF_BIT; + *actual_size = 0; + return 0; + } + + __io_offset = io_size; + __valid_limit = io_size; + } + + // Return data from the buffer. + __ensure(__offset < __valid_limit); + + auto chunk = frg::min(size_t(__valid_limit - __offset), max_size); + memcpy(buffer, __buffer_ptr + __offset, chunk); + __offset += chunk; + + *actual_size = chunk + unget_length; + return 0; +} + +int abstract_file::write(const char *buffer, size_t max_size, size_t *actual_size) { + __ensure(max_size); + + if(_init_bufmode()) + return -1; + if(globallyDisableBuffering || _bufmode == buffer_mode::no_buffer) { + // As we do not buffer, nothing can be dirty. + __ensure(__dirty_begin == __dirty_end); + size_t io_size; + if(int e = io_write(buffer, max_size, &io_size); e) { + __status_bits |= __MLIBC_ERROR_BIT; + return e; + } + *actual_size = io_size; + return 0; + } + + // Flush the buffer if necessary. + if(__offset == __buffer_size) { + if(int e = _write_back(); e) + return e; + if(int e = _reset(); e) + return e; + } + + // Ensure correct buffer type for pipe-like streams. + // TODO: We could full support pipe-like files + // by ungetc()ing all data before a write happens, + // however, for now we just report an error. + if(!__io_mode && __valid_limit) // TODO: Only check this for pipe-like streams. + mlibc::panicLogger() << "mlibc: Cannot read-write to same pipe-like stream" + << frg::endlog; + __io_mode = 1; + + __ensure(__offset < __buffer_size); + auto chunk = frg::min(__buffer_size - __offset, max_size); + + // Line-buffered streams perform I/O on full lines. + bool flush_line = false; + if(_bufmode == buffer_mode::line_buffer) { + auto nl = reinterpret_cast<char *>(memchr(buffer, '\n', chunk)); + if(nl) { + chunk = nl + 1 - buffer; + flush_line = true; + } + } + __ensure(chunk); + + // Buffer data (without necessarily performing I/O). + _ensure_allocation(); + memcpy(__buffer_ptr + __offset, buffer, chunk); + + if(__dirty_begin != __dirty_end) { + __dirty_begin = frg::min(__dirty_begin, __offset); + __dirty_end = frg::max(__dirty_end, __offset + chunk); + }else{ + __dirty_begin = __offset; + __dirty_end = __offset + chunk; + } + __valid_limit = frg::max(__offset + chunk, __valid_limit); + __offset += chunk; + + // Flush line-buffered streams. + if(flush_line) { + if(_write_back()) + return -1; + } + + *actual_size = chunk; + return 0; +} + +int abstract_file::unget(char c) { + if (!__unget_ptr) { + // This can happen if the file is unbuffered, but we still need + // a space to store ungetc'd data. + __ensure(!__buffer_ptr); + _ensure_allocation(); + __ensure(__unget_ptr); + } + + if ((size_t)(__buffer_ptr - __unget_ptr) + 1 > ungetBufferSize) + return EOF; + else { + *(--__unget_ptr) = c; + return c; + } +} + +int abstract_file::update_bufmode(buffer_mode mode) { + // setvbuf() has undefined behavior if I/O has been performed. + __ensure(__dirty_begin == __dirty_end + && "update_bufmode() must only be called before performing I/O"); + _bufmode = mode; + return 0; +} + +void abstract_file::purge() { + __offset = 0; + __io_offset = 0; + __valid_limit = 0; + __dirty_end = __dirty_begin; + __unget_ptr = __buffer_ptr; +} + +int abstract_file::flush() { + if (__dirty_end != __dirty_begin) { + if (int e = _write_back(); e) + return e; + } + + if (int e = _save_pos(); e) + return e; + purge(); + return 0; +} + +int abstract_file::tell(off_t *current_offset) { + off_t seek_offset; + if(int e = io_seek(0, SEEK_CUR, &seek_offset); e) + return e; + + *current_offset = seek_offset + (off_t(__offset) - off_t(__io_offset)); + return 0; +} + +int abstract_file::seek(off_t offset, int whence) { + if(int e = _write_back(); e) + return e; + + off_t new_offset; + if(whence == SEEK_CUR) { + auto seek_offset = offset + (off_t(__offset) - off_t(__io_offset)); + if(int e = io_seek(seek_offset, whence, &new_offset); e) { + __status_bits |= __MLIBC_ERROR_BIT; + return e; + } + }else{ + __ensure(whence == SEEK_SET || whence == SEEK_END); + if(int e = io_seek(offset, whence, &new_offset); e) { + __status_bits |= __MLIBC_ERROR_BIT; + return e; + } + } + + // We just forget the current buffer. + // TODO: If the seek is "small", we can just modify our internal offset. + purge(); + + return 0; +} + +int abstract_file::_init_type() { + if(_type != stream_type::unknown) + return 0; + + if(int e = determine_type(&_type); e) + return e; + __ensure(_type != stream_type::unknown); + return 0; +} + +int abstract_file::_init_bufmode() { + if(_bufmode != buffer_mode::unknown) + return 0; + + if(determine_bufmode(&_bufmode)) + return -1; + __ensure(_bufmode != buffer_mode::unknown); + return 0; +} + +int abstract_file::_write_back() { + if(int e = _init_type(); e) + return e; + + if(__dirty_begin == __dirty_end) + return 0; + + // For non-pipe streams, first do a seek to reset the + // I/O position to zero, then do a write(). + if(_type == stream_type::file_like) { + if(__io_offset != __dirty_begin) { + __ensure(__dirty_begin - __io_offset > 0); + off_t new_offset; + if(int e = io_seek(off_t(__dirty_begin) - off_t(__io_offset), SEEK_CUR, &new_offset); e) + return e; + __io_offset = __dirty_begin; + } + }else{ + __ensure(_type == stream_type::pipe_like); + __ensure(__io_offset == __dirty_begin); + } + + // Now, we are in the correct position to write-back everything. + while(__io_offset < __dirty_end) { + size_t io_size; + if(int e = io_write(__buffer_ptr + __io_offset, __dirty_end - __io_offset, &io_size); e) { + __status_bits |= __MLIBC_ERROR_BIT; + return e; + } + __ensure(io_size > 0 && "io_write() is expected to always write at least one byte"); + __io_offset += io_size; + __dirty_begin += io_size; + } + + return 0; +} + +int abstract_file::_save_pos() { + if (int e = _init_type(); e) + return e; + if (int e = _init_bufmode(); e) + return e; + + if (_type == stream_type::file_like && _bufmode != buffer_mode::no_buffer) { + off_t new_offset; + auto seek_offset = (off_t(__offset) - off_t(__io_offset)); + if (int e = io_seek(seek_offset, SEEK_CUR, &new_offset); e) { + __status_bits |= __MLIBC_ERROR_BIT; + mlibc::infoLogger() << "hit io_seek() error " << e << frg::endlog; + return e; + } + return 0; + } + return 0; // nothing to do for the rest +} + +int abstract_file::_reset() { + if(int e = _init_type(); e) + return e; + + // For pipe-like files, we must not forget already read data. + // TODO: Report this error to the user. + if(_type == stream_type::pipe_like) + __ensure(__offset == __valid_limit); + + __ensure(__dirty_begin == __dirty_end); + __offset = 0; + __io_offset = 0; + __valid_limit = 0; + + return 0; +} + +// This may still be called when buffering is disabled, for ungetc. +void abstract_file::_ensure_allocation() { + if(__buffer_ptr) + return; + + auto ptr = getAllocator().allocate(__buffer_size + ungetBufferSize); + __buffer_ptr = reinterpret_cast<char *>(ptr) + ungetBufferSize; + __unget_ptr = __buffer_ptr; +} + +// -------------------------------------------------------------------------------------- +// fd_file implementation. +// -------------------------------------------------------------------------------------- + +fd_file::fd_file(int fd, void (*do_dispose)(abstract_file *), bool force_unbuffered) +: abstract_file{do_dispose}, _fd{fd}, _force_unbuffered{force_unbuffered} { } + +int fd_file::fd() { + return _fd; +} + +int fd_file::close() { + if(__dirty_begin != __dirty_end) + mlibc::infoLogger() << "mlibc warning: File is not flushed before closing" + << frg::endlog; + if(int e = mlibc::sys_close(_fd); e) + return e; + return 0; +} + +int fd_file::reopen(const char *path, const char *mode) { + int mode_flags = parse_modestring(mode); + + int fd; + if(int e = sys_open(path, mode_flags, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH, &fd); e) { + return e; + } + + flush(); + close(); + getAllocator().deallocate(__buffer_ptr, __buffer_size + ungetBufferSize); + + __buffer_ptr = nullptr; + __unget_ptr = nullptr; + __buffer_size = 4096; + _reset(); + _fd = fd; + + if(mode_flags & O_APPEND) { + seek(0, SEEK_END); + } + + return 0; +} + +int fd_file::determine_type(stream_type *type) { + off_t offset; + int e = mlibc::sys_seek(_fd, 0, SEEK_CUR, &offset); + if(!e) { + *type = stream_type::file_like; + return 0; + }else if(e == ESPIPE) { + *type = stream_type::pipe_like; + return 0; + }else{ + return e; + } +} + +int fd_file::determine_bufmode(buffer_mode *mode) { + // When isatty() is not implemented, we fall back to the safest default (no buffering). + if(!mlibc::sys_isatty) { + MLIBC_MISSING_SYSDEP(); + *mode = buffer_mode::no_buffer; + return 0; + } + if(_force_unbuffered) { + *mode = buffer_mode::no_buffer; + return 0; + } + + if(int e = mlibc::sys_isatty(_fd); !e) { + *mode = buffer_mode::line_buffer; + return 0; + }else if(e == ENOTTY) { + *mode = buffer_mode::full_buffer; + return 0; + }else{ + mlibc::infoLogger() << "mlibc: sys_isatty() failed while determining whether" + " stream is interactive" << frg::endlog; + return -1; + } +} + +int fd_file::io_read(char *buffer, size_t max_size, size_t *actual_size) { + ssize_t s; + if(int e = mlibc::sys_read(_fd, buffer, max_size, &s); e) + return e; + *actual_size = s; + return 0; +} + +int fd_file::io_write(const char *buffer, size_t max_size, size_t *actual_size) { + ssize_t s; + if(int e = mlibc::sys_write(_fd, buffer, max_size, &s); e) + return e; + *actual_size = s; + return 0; +} + +int fd_file::io_seek(off_t offset, int whence, off_t *new_offset) { + if(int e = mlibc::sys_seek(_fd, offset, whence, new_offset); e) + return e; + return 0; +} + +int fd_file::parse_modestring(const char *mode) { + // Consume the first char; this must be 'r', 'w' or 'a'. + int flags = 0; + bool has_plus = strchr(mode, '+'); + if(*mode == 'r') { + if(has_plus) { + flags = O_RDWR; + }else{ + flags = O_RDONLY; + } + }else if(*mode == 'w') { + if(has_plus) { + flags = O_RDWR; + }else{ + flags = O_WRONLY; + } + flags |= O_CREAT | O_TRUNC; + }else if(*mode == 'a') { + if(has_plus) { + flags = O_APPEND | O_RDWR; + }else{ + flags = O_APPEND | O_WRONLY; + } + flags |= O_CREAT; + }else{ + mlibc::infoLogger() << "Illegal fopen() mode '" << *mode << "'" << frg::endlog; + } + mode += 1; + + // Consume additional flags. + while(*mode) { + if(*mode == '+') { + mode++; // This is already handled above. + }else if(*mode == 'b') { + mode++; // mlibc assumes that there is no distinction between text and binary. + }else if(*mode == 'e') { + flags |= O_CLOEXEC; + mode++; + }else{ + mlibc::infoLogger() << "Illegal fopen() flag '" << mode << "'" << frg::endlog; + mode++; + } + } + + return flags; +} + +} // namespace mlibc + +namespace { + mlibc::fd_file stdin_file{0}; + mlibc::fd_file stdout_file{1}; + mlibc::fd_file stderr_file{2, nullptr, true}; + + struct stdio_guard { + stdio_guard() { } + + ~stdio_guard() { + // Only flush the files but do not close them. + for(auto it : mlibc::global_file_list()) { + if(int e = it->flush(); e) + mlibc::infoLogger() << "mlibc warning: Failed to flush file before exit()" + << frg::endlog; + } + } + } global_stdio_guard; +} + +FILE *stderr = &stderr_file; +FILE *stdin = &stdin_file; +FILE *stdout = &stdout_file; + +int fileno_unlocked(FILE *file_base) { + auto file = static_cast<mlibc::fd_file *>(file_base); + return file->fd(); +} + +int fileno(FILE *file_base) { + auto file = static_cast<mlibc::fd_file *>(file_base); + frg::unique_lock lock(file->_lock); + return fileno_unlocked(file_base); +} + +FILE *fopen(const char *path, const char *mode) { + int flags = mlibc::fd_file::parse_modestring(mode); + + int fd; + if(int e = mlibc::sys_open(path, flags, 0666, &fd); e) { + errno = e; + return nullptr; + } + + return frg::construct<mlibc::fd_file>(getAllocator(), fd, + mlibc::file_dispose_cb<mlibc::fd_file>); +} + +int fclose(FILE *file_base) { + auto file = static_cast<mlibc::abstract_file *>(file_base); + int e = 0; + if(file->flush()) + e = EOF; + if(file->close()) + e = EOF; + file->dispose(); + return e; +} + +int fseek(FILE *file_base, long offset, int whence) { + auto file = static_cast<mlibc::abstract_file *>(file_base); + frg::unique_lock lock(file->_lock); + if(int e = file->seek(offset, whence); e) { + errno = e; + return -1; + } + return 0; +} + +long ftell(FILE *file_base) { + auto file = static_cast<mlibc::abstract_file *>(file_base); + frg::unique_lock lock(file->_lock); + off_t current_offset; + if(int e = file->tell(¤t_offset); e) { + errno = e; + return -1; + } + return current_offset; +} + +int fflush_unlocked(FILE *file_base) { + if(file_base == NULL) { + // Only flush the files but do not close them. + for(auto it : mlibc::global_file_list()) { + if(int e = it->flush(); e) + mlibc::infoLogger() << "mlibc warning: Failed to flush file" + << frg::endlog; + } + return 0; + } + auto file = static_cast<mlibc::abstract_file *>(file_base); + if(file->flush()) + return EOF; + return 0; +} +int fflush(FILE *file_base) { + if(file_base == NULL) { + // Only flush the files but do not close them. + for(auto it : mlibc::global_file_list()) { + frg::unique_lock lock(it->_lock); + if(int e = it->flush(); e) + mlibc::infoLogger() << "mlibc warning: Failed to flush file" + << frg::endlog; + } + return 0; + } + + auto file = static_cast<mlibc::abstract_file *>(file_base); + frg::unique_lock lock(file->_lock); + if (file->flush()) + return EOF; + return 0; +} + +int setvbuf(FILE *file_base, char *, int mode, size_t) { + // TODO: We could also honor the buffer, but for now use just set the mode. + auto file = static_cast<mlibc::abstract_file *>(file_base); + if(mode == _IONBF) { + if(int e = file->update_bufmode(mlibc::buffer_mode::no_buffer); e) { + errno = e; + return -1; + } + }else if(mode == _IOLBF) { + if(int e = file->update_bufmode(mlibc::buffer_mode::line_buffer); e) { + errno = e; + return -1; + } + }else if(mode == _IOFBF) { + if(int e = file->update_bufmode(mlibc::buffer_mode::full_buffer); e) { + errno = e; + return -1; + } + }else{ + errno = EINVAL; + return -1; + } + + return 0; +} + +void rewind(FILE *file_base) { + auto file = static_cast<mlibc::abstract_file *>(file_base); + frg::unique_lock lock(file->_lock); + file->seek(0, SEEK_SET); + file_base->__status_bits &= ~(__MLIBC_EOF_BIT | __MLIBC_ERROR_BIT); +} + +int ungetc(int c, FILE *file_base) { + if (c == EOF) + return EOF; + + auto file = static_cast<mlibc::abstract_file *>(file_base); + frg::unique_lock lock(file->_lock); + return file->unget(c); +} + +#if __MLIBC_GLIBC_OPTION +void __fpurge(FILE *file_base) { + auto file = static_cast<mlibc::abstract_file *>(file_base); + frg::unique_lock lock(file->_lock); + file->purge(); +} +#endif + |