SD card manager from microreader

libs/hardware/SDCardManager/include/SDCardManager.h

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+#ifndef SDCARD_MANAGER_H
+#define SDCARD_MANAGER_H
+
+#include <Arduino.h>
+
+#include <vector>
+
+class SDCardManager {
+ public:
+  SDCardManager(uint8_t epd_sclk, uint8_t sd_miso, uint8_t epd_mosi, uint8_t sd_cs, uint8_t eink_cs);
+  bool begin();
+  bool ready() const;
+  std::vector<String> listFiles(const char* path = "/", int maxFiles = 200);
+  // Read the entire file at `path` into a String. Returns empty string on failure.
+  String readFile(const char* path);
+  // Low-memory helpers:
+  // Stream the file contents to a `Print` (e.g. `Serial`, or any `Print`-derived object).
+  // Returns true on success, false on failure.
+  bool readFileToStream(const char* path, Print& out, size_t chunkSize = 256);
+  // Read up to `bufferSize-1` bytes into `buffer`, null-terminating it. Returns bytes read.
+  size_t readFileToBuffer(const char* path, char* buffer, size_t bufferSize, size_t maxBytes = 0);
+  // Write a string to `path` on the SD card. Overwrites existing file.
+  // Returns true on success.
+  bool writeFile(const char* path, const String& content);
+  // Ensure a directory exists, creating it if necessary. Returns true on success.
+  bool ensureDirectoryExists(const char* path);
+
+ private:
+  uint8_t epd_sclk;
+  uint8_t sd_miso;
+  uint8_t epd_mosi;
+  uint8_t sd_cs;
+  uint8_t eink_cs;
+  bool initialized = false;
+};
+
+#endif

libs/hardware/SDCardManager/library.json

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+{
+  "name": "SDCardManager",
+  "version": "1.0.0",
+  "description": "SD card file system utilities",
+  "authors": [
+    {
+      "name": "CidVonHighwind",
+      "url": "https://github.com/CidVonHighwind"
+    }
+  ],
+  "dependencies": {},
+  "platforms": "espressif32",
+  "frameworks": ["arduino", "espidf"]
+}

libs/hardware/SDCardManager/src/SDCardManager.cpp

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+#include "SDCardManager.h"
+
+#include <SD.h>
+#include <SPI.h>
+
+SDCardManager::SDCardManager(uint8_t epd_sclk, uint8_t sd_miso, uint8_t epd_mosi, uint8_t sd_cs, uint8_t eink_cs)
+    : epd_sclk(epd_sclk), sd_miso(sd_miso), epd_mosi(epd_mosi), sd_cs(sd_cs), eink_cs(eink_cs), initialized(false) {}
+
+bool SDCardManager::begin() {
+  pinMode(eink_cs, OUTPUT);
+  digitalWrite(eink_cs, HIGH);
+
+  pinMode(sd_cs, OUTPUT);
+  digitalWrite(sd_cs, HIGH);
+
+  SPI.begin(epd_sclk, sd_miso, epd_mosi, sd_cs);
+  if (!SD.begin(sd_cs, SPI, 40000000)) {
+    Serial.print("\n SD card not detected\n");
+    initialized = false;
+  } else {
+    Serial.print("\n SD card detected\n");
+    initialized = true;
+  }
+
+  return initialized;
+}
+
+bool SDCardManager::ready() const {
+  return initialized;
+}
+
+std::vector<String> SDCardManager::listFiles(const char* path, int maxFiles) {
+  std::vector<String> ret;
+  if (!initialized) {
+    Serial.println("SDCardManager: not initialized, returning empty list");
+    return ret;
+  }
+
+  File root = SD.open(path);
+  if (!root) {
+    Serial.println("Failed to open directory.");
+    return ret;
+  }
+  if (!root.isDirectory()) {
+    Serial.println("Path is not a directory.");
+    root.close();
+    return ret;
+  }
+
+  int count = 0;
+  for (File f = root.openNextFile(); f && count < maxFiles; f = root.openNextFile()) {
+    if (f.isDirectory()) {
+      f.close();
+      continue;
+    }
+    ret.push_back(String(f.name()));
+    f.close();
+    count++;
+  }
+  root.close();
+  return ret;
+}
+
+String SDCardManager::readFile(const char* path) {
+  if (!initialized) {
+    Serial.println("SDCardManager: not initialized; cannot read file");
+    return String("");
+  }
+
+  File f = SD.open(path);
+  if (!f) {
+    Serial.printf("Failed to open file: %s\n", path);
+    return String("");
+  }
+
+  String content = "";
+  size_t maxSize = 50000;  // Limit to 50KB
+  size_t readSize = 0;
+  while (f.available() && readSize < maxSize) {
+    char c = (char)f.read();
+    content += c;
+    readSize++;
+  }
+  f.close();
+  return content;
+}
+
+bool SDCardManager::readFileToStream(const char* path, Print& out, size_t chunkSize) {
+  if (!initialized) {
+    Serial.println("SDCardManager: not initialized; cannot read file");
+    return false;
+  }
+
+  File f = SD.open(path);
+  if (!f) {
+    Serial.printf("Failed to open file: %s\n", path);
+    return false;
+  }
+
+  const size_t localBufSize = 256;
+  uint8_t buf[localBufSize];
+  size_t toRead = (chunkSize == 0) ? localBufSize : (chunkSize < localBufSize ? chunkSize : localBufSize);
+
+  while (f.available()) {
+    int r = f.read(buf, toRead);
+    if (r > 0) {
+      out.write(buf, (size_t)r);
+    } else {
+      break;
+    }
+  }
+
+  f.close();
+  return true;
+}
+
+size_t SDCardManager::readFileToBuffer(const char* path, char* buffer, size_t bufferSize, size_t maxBytes) {
+  if (!buffer || bufferSize == 0)
+    return 0;
+  if (!initialized) {
+    Serial.println("SDCardManager: not initialized; cannot read file");
+    buffer[0] = '\0';
+    return 0;
+  }
+
+  File f = SD.open(path);
+  if (!f) {
+    Serial.printf("Failed to open file: %s\n", path);
+    buffer[0] = '\0';
+    return 0;
+  }
+
+  size_t maxToRead = (maxBytes == 0) ? (bufferSize - 1) : min(maxBytes, bufferSize - 1);
+  size_t total = 0;
+  const size_t chunk = 64;
+
+  while (f.available() && total < maxToRead) {
+    size_t want = maxToRead - total;
+    size_t readLen = (want < chunk) ? want : chunk;
+    int r = f.read((uint8_t*)(buffer + total), readLen);
+    if (r > 0) {
+      total += (size_t)r;
+    } else {
+      break;
+    }
+  }
+
+  buffer[total] = '\0';
+  f.close();
+  return total;
+}
+
+bool SDCardManager::writeFile(const char* path, const String& content) {
+  if (!initialized) {
+    Serial.println("SDCardManager: not initialized; cannot write file");
+    return false;
+  }
+
+  // Remove existing file so we perform an overwrite rather than append
+  if (SD.exists(path)) {
+    SD.remove(path);
+  }
+
+  File f = SD.open(path, FILE_WRITE);
+  if (!f) {
+    Serial.printf("Failed to open file for write: %s\n", path);
+    return false;
+  }
+
+  size_t written = f.print(content);
+  f.close();
+  return (written == content.length());
+}
+
+bool SDCardManager::ensureDirectoryExists(const char* path) {
+  if (!initialized) {
+    Serial.println("SDCardManager: not initialized; cannot create directory");
+    return false;
+  }
+
+  // Check if directory already exists
+  if (SD.exists(path)) {
+    File dir = SD.open(path);
+    if (dir && dir.isDirectory()) {
+      dir.close();
+      Serial.printf("Directory already exists: %s\n", path);
+      return true;
+    }
+    dir.close();
+  }
+
+  // Create the directory
+  if (SD.mkdir(path)) {
+    Serial.printf("Created directory: %s\n", path);
+    return true;
+  } else {
+    Serial.printf("Failed to create directory: %s\n", path);
+    return false;
+  }
+}