initial commit

src/device_discovery.cpp

@@ -0,0 +1,93 @@
+#include "adc_sweep/device_discovery.hpp"
+
+#include <algorithm>
+#include <filesystem>
+#include <fstream>
+#include <sstream>
+#include <string>
+#include <vector>
+
+namespace adc_sweep {
+namespace fs = std::filesystem;
+
+namespace {
+
+std::string trim(std::string s) {
+    while (!s.empty() && (s.back() == '\n' || s.back() == '\r' || s.back() == ' ' || s.back() == '\t')) {
+        s.pop_back();
+    }
+    size_t i = 0;
+    while (i < s.size() && (s[i] == ' ' || s[i] == '\t')) {
+        ++i;
+    }
+    return s.substr(i);
+}
+
+std::string read_file_trim(const fs::path& p) {
+    std::ifstream f(p);
+    if (!f.is_open()) {
+        return {};
+    }
+    std::ostringstream ss;
+    ss << f.rdbuf();
+    return trim(ss.str());
+}
+
+std::string hex4(uint16_t v) {
+    constexpr char kHex[] = "0123456789abcdef";
+    std::string out(4, '0');
+    out[0] = kHex[(v >> 12U) & 0xFU];
+    out[1] = kHex[(v >> 8U) & 0xFU];
+    out[2] = kHex[(v >> 4U) & 0xFU];
+    out[3] = kHex[v & 0xFU];
+    return out;
+}
+
+bool tty_name_ok(const std::string& name) {
+    return (name.rfind("ttyACM", 0) == 0) || (name.rfind("ttyUSB", 0) == 0);
+}
+
+}  // namespace
+
+std::optional<std::string> find_tty_by_vid_pid(uint16_t vid, uint16_t pid) {
+    const fs::path usb_root("/sys/bus/usb/devices");
+    if (!fs::exists(usb_root)) {
+        return std::nullopt;
+    }
+
+    const std::string vid_s = hex4(vid);
+    const std::string pid_s = hex4(pid);
+    std::vector<std::string> candidates;
+
+    for (const auto& entry : fs::directory_iterator(usb_root)) {
+        if (!entry.is_directory()) {
+            continue;
+        }
+        const fs::path devdir = entry.path();
+        const std::string v = read_file_trim(devdir / "idVendor");
+        const std::string p = read_file_trim(devdir / "idProduct");
+        if (v != vid_s || p != pid_s) {
+            continue;
+        }
+
+        for (const auto& sub : fs::recursive_directory_iterator(devdir, fs::directory_options::skip_permission_denied)) {
+            const std::string name = sub.path().filename().string();
+            if (!tty_name_ok(name)) {
+                continue;
+            }
+            const std::string devnode = "/dev/" + name;
+            if (fs::exists(devnode)) {
+                candidates.push_back(devnode);
+            }
+        }
+    }
+
+    if (candidates.empty()) {
+        return std::nullopt;
+    }
+    std::sort(candidates.begin(), candidates.end());
+    candidates.erase(std::unique(candidates.begin(), candidates.end()), candidates.end());
+    return candidates.front();
+}
+
+}  // namespace adc_sweep