[libc] Support _IONBF buffering for read_unlocked #120677
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- Add the functions read_unlocked_nbf and read_unlocked_fbf.
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@llvm/pr-subscribers-libc Author: Jack Huang (jackhong12) ChangesSupport _IONBF buffering for read_unlocked. Add the functions read_unlocked_nbf() and read_unlocked_fbf(). Fixes: #120155 Full diff: https://github.com/llvm/llvm-project/pull/120677.diff 2 Files Affected:
diff --git a/libc/src/__support/File/file.cpp b/libc/src/__support/File/file.cpp
index 972249fef96bcf..cb8e1dff9fe96e 100644
--- a/libc/src/__support/File/file.cpp
+++ b/libc/src/__support/File/file.cpp
@@ -190,6 +190,17 @@ FileIOResult File::read_unlocked(void *data, size_t len) {
prev_op = FileOp::READ;
+ if (bufmode == _IONBF) { // unbuffered.
+ return read_unlocked_nbf(static_cast<uint8_t *>(data), len);
+ } else if (bufmode == _IOFBF) { // fully buffered
+ return read_unlocked_fbf(static_cast<uint8_t *>(data), len);
+ } else /*if (bufmode == _IOLBF) */ { // line buffered
+ // There is no line buffered mode for read. Use fully buffer instead.
+ return read_unlocked_fbf(static_cast<uint8_t *>(data), len);
+ }
+}
+
+FileIOResult File::read_unlocked_fbf(uint8_t *data, size_t len) {
cpp::span<uint8_t> bufref(static_cast<uint8_t *>(buf), bufsize);
cpp::span<uint8_t> dataref(static_cast<uint8_t *>(data), len);
@@ -245,6 +256,18 @@ FileIOResult File::read_unlocked(void *data, size_t len) {
return {transfer_size + available_data, result.error};
}
+FileIOResult File::read_unlocked_nbf(uint8_t *data, size_t len) {
+ auto result = platform_read(this, data, len);
+
+ if (result.has_error() || result < len) {
+ if (!result.has_error())
+ eof = true;
+ else
+ err = true;
+ }
+ return result;
+}
+
int File::ungetc_unlocked(int c) {
// There is no meaning to unget if:
// 1. You are trying to push back EOF.
diff --git a/libc/src/__support/File/file.h b/libc/src/__support/File/file.h
index 42e1d11b4ab1a0..548f051a1b9f5c 100644
--- a/libc/src/__support/File/file.h
+++ b/libc/src/__support/File/file.h
@@ -280,6 +280,9 @@ class File {
FileIOResult write_unlocked_fbf(const uint8_t *data, size_t len);
FileIOResult write_unlocked_nbf(const uint8_t *data, size_t len);
+ FileIOResult read_unlocked_fbf(uint8_t *data, size_t len);
+ FileIOResult read_unlocked_nbf(uint8_t *data, size_t len);
+
constexpr void adjust_buf() {
if (read_allowed() && (buf == nullptr || bufsize == 0)) {
// We should allow atleast one ungetc operation.
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✅ With the latest revision this PR passed the C/C++ code formatter. |
For read_unlocked() with the _IONBUF mode, there is still an one-character buffer which is used to store the data inserted by ungetc(), so we always need to check the buffer first.
jackhong12
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Sorry for the delays in code review, most of us have been off for the holidays in the US. @michaelrj-google should be back online this week to review. |
- The function copy_data_from_buf returns size_t. - Fix the spelling error. - Fix the incorrect data, error, in FileIOResult.
michaelrj-google
approved these changes
Jan 7, 2025
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I can submit the code by myself. Let me check how to merge it. Thanks for your reviews! |
nickdesaulniers
approved these changes
Jan 8, 2025
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/73/builds/11402 Here is the relevant piece of the build log for the reference |
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Support _IONBF buffering for read_unlocked. Add the functions read_unlocked_nbf() and read_unlocked_fbf().
Fixes: #120155