5e63167965
There are three flavors of WriteBuffer currently, all of which could be passed into `printf_core::Writer` class. It's a tricky class, since it chooses a flavor-specific logic either based on runtime dispatch (to save code size and prevent generating three versions of the entirety of printf_core), or based on template arguments (to avoid dealing with function pointers in codegen for `FILL_BUFF_AND_DROP_OVERFLOW` path). Refactor this somewhat convoluted logic to have three concrete subclasses inheriting from the templated base class, and use static polymorphism with `reinterpret_cast` to implement dispatching above. Now we can actually have flavor-specific fields, constructors, and methods (e.g. `flush_to_stream` is now a method of `FlushingBuffer`), and the code on the user side is cleaner: the complexity of enabling/disabling runtime-dispatch and using proper template arguments is now localized in `writer.h`. This code will need to be further templatized to support buffers of type `wchar_t` to implement `swprintf()` and friends. This change would make it (ever so slightly) easier.
55 lines
1.9 KiB
C++
55 lines
1.9 KiB
C++
//===-- Implementation of snprintf ------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/stdio/snprintf.h"
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#include "src/__support/CPP/limits.h"
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#include "src/__support/arg_list.h"
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#include "src/__support/libc_errno.h"
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#include "src/__support/macros/config.h"
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#include "src/stdio/printf_core/core_structs.h"
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#include "src/stdio/printf_core/error_mapper.h"
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#include "src/stdio/printf_core/printf_main.h"
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#include "src/stdio/printf_core/writer.h"
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#include <stdarg.h>
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#include <stddef.h>
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namespace LIBC_NAMESPACE_DECL {
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LLVM_LIBC_FUNCTION(int, snprintf,
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(char *__restrict buffer, size_t buffsz,
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const char *__restrict format, ...)) {
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va_list vlist;
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va_start(vlist, format);
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internal::ArgList args(vlist); // This holder class allows for easier copying
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// and pointer semantics, as well as handling
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// destruction automatically.
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va_end(vlist);
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printf_core::DropOverflowBuffer wb(buffer, (buffsz > 0 ? buffsz - 1 : 0));
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printf_core::Writer writer(wb);
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auto ret_val = printf_core::printf_main(&writer, format, args);
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if (!ret_val.has_value()) {
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libc_errno = printf_core::internal_error_to_errno(ret_val.error());
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return -1;
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}
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if (buffsz > 0) // if the buffsz is 0 the buffer may be a null pointer.
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wb.buff[wb.buff_cur] = '\0';
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if (ret_val.value() > static_cast<size_t>(cpp::numeric_limits<int>::max())) {
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libc_errno =
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printf_core::internal_error_to_errno(-printf_core::OVERFLOW_ERROR);
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return -1;
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}
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return static_cast<int>(ret_val.value());
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}
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} // namespace LIBC_NAMESPACE_DECL
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