From 16379362c02a2472f00fac49cad62788547c9519 Mon Sep 17 00:00:00 2001
From: Dominick Allen <djallen@librehumanitas.org>
Date: Wed, 1 Jan 2025 17:41:17 -0600
Subject: Add CSV parsing, printing, fix buffered file reading.

---
 source/fud_file.cpp | 76 ++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 55 insertions(+), 21 deletions(-)

(limited to 'source/fud_file.cpp')

diff --git a/source/fud_file.cpp b/source/fud_file.cpp
index 55f8dbc..caf0f5a 100644
--- a/source/fud_file.cpp
+++ b/source/fud_file.cpp
@@ -17,6 +17,8 @@
 
 #include "fud_file.hpp"
 
+#include "fud_algorithm.hpp"
+
 #include <cerrno>
 #include <fcntl.h>
 #include <linux/openat2.h>
@@ -625,6 +627,7 @@ DrainResult BufferedRegularFile::write(const std::byte* source, size_t length, O
 
 DrainResult BufferedRegularFile::read(std::byte* sink, size_t length, Option<size_t> maxExtraAttempts)
 {
+    auto extraAttempts = maxExtraAttempts.valueOr(0);
     DrainResult result{0, FudStatus::Success};
 
     if (sink == nullptr) {
@@ -637,15 +640,6 @@ DrainResult BufferedRegularFile::read(std::byte* sink, size_t length, Option<siz
         return result;
     }
 
-    if (m_lastOperation != Operation::Write) {
-        m_bufferLength = 0;
-        m_lastOperation = Operation::Write;
-    }
-
-    if (length == 0) {
-        return result;
-    }
-
     if (m_lastOperation == Operation::Write && m_bufferLength > 0) {
         result.status = FudStatus::OperationInvalid;
         return result;
@@ -653,13 +647,18 @@ DrainResult BufferedRegularFile::read(std::byte* sink, size_t length, Option<siz
 
     if (m_lastOperation != Operation::Read) {
         m_lastOperation = Operation::Read;
+        m_bufferPosition = 0;
+        m_bufferLength = 0;
+    }
+
+    if (length == 0) {
+        return result;
     }
 
     if (m_bufferLength > 0 && m_bufferPosition < m_bufferLength) {
-        auto count = m_bufferLength - m_bufferPosition;
-        if (count > length) {
-            count = length;
-        }
+        auto remainingLength = m_bufferLength - m_bufferPosition;
+        auto count = min(length, remainingLength);
+
         auto copyStatus = copyMem(sink, length, m_buffer.data() + m_bufferPosition, count);
         fudAssert(copyStatus == FudStatus::Success);
 
@@ -677,23 +676,52 @@ DrainResult BufferedRegularFile::read(std::byte* sink, size_t length, Option<siz
         m_bufferLength = 0;
     }
 
+    if (length == 0) {
+        return result;
+    }
+
+    fudAssert(m_bufferLength == 0);
+    fudAssert(m_bufferPosition == 0);
+
     if (length > m_buffer.size()) {
-        auto drainResult = m_file.read(sink, length, maxExtraAttempts.valueOr(0));
+        auto drainResult = m_file.read(sink, length, extraAttempts);
+
+        sink += drainResult.bytesDrained;
+        length -= drainResult.bytesDrained;
+
         result.status = drainResult.status;
         result.bytesDrained += drainResult.bytesDrained;
+        return result;
     }
 
-    if (length == 0 || result.status != FudStatus::Success) {
+    fudAssert(length > 0);
+
+    if (result.status != FudStatus::Success) {
         return result;
     }
 
-    fudAssert(m_bufferLength == 0 && m_bufferPosition == 0);
-    auto drainResult = m_file.read(m_buffer.data(), m_buffer.size(), maxExtraAttempts.valueOr(0));
-    if (drainResult.status != FudStatus::Success && drainResult.status != FudStatus::Partial) {
-        result.status = drainResult.status;
-    } else {
-        result.status = FudStatus::Success;
+    fudAssert(m_bufferLength == 0);
+    fudAssert(m_bufferPosition == 0);
+
+    auto drainResult = m_file.read(m_buffer.data(), m_buffer.size(), extraAttempts);
+    result.status = drainResult.status;
+    if (drainResult.status == FudStatus::Success || drainResult.status == FudStatus::Partial) {
         m_bufferLength = drainResult.bytesDrained;
+
+        auto count = min(length, m_bufferLength);
+
+        auto copyStatus = copyMem(sink, count, m_buffer.data(), count);
+        fudAssert(copyStatus == FudStatus::Success);
+
+        sink += count;
+        length -= count;
+
+        if (drainResult.status == FudStatus::Partial && length == 0) {
+            drainResult.status = FudStatus::Success;
+        }
+
+        m_bufferPosition = count;
+        result.bytesDrained += count;
     }
 
     return result;
@@ -713,6 +741,12 @@ DrainResult BufferedRegularFile::flush(size_t maxExtraAttempts)
         return {0, FudStatus::Success};
     }
 
+    if (m_lastOperation != Operation::Write) {
+        m_bufferLength = 0;
+        m_bufferPosition = 0;
+        return {0, FudStatus::Success};
+    }
+
     auto drainResult = m_file.write(m_buffer.data(), m_bufferLength, maxExtraAttempts);
     if (drainResult.status == FudStatus::Success) {
         m_bufferLength = 0;
-- 
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