--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dep/animia/src/fd/proc.cc	Sun Nov 19 04:21:56 2023 -0500
@@ -0,0 +1,151 @@
+#include "animia/fd/proc.h"
+#include "animia.h"
+#include "animia/util.h"
+
+#include <algorithm>
+#include <cstring>
+#include <filesystem>
+#include <fstream>
+#include <sstream>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include <dirent.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#ifdef FREEBSD
+#	include <sys/types.h>
+#	include <sys/user.h>
+#	include <libutil.h>
+#endif
+
+#define PROC_LOCATION "/proc"
+
+namespace animia::internal::proc {
+
+/* this uses dirent instead of std::filesystem; it would make a bit
+   more sense to use the latter, but this is platform dependent already :) */
+static std::vector<std::string> GetAllFilesInDir(const std::string& _dir) {
+	std::vector<std::string> ret;
+
+	DIR* dir = opendir(_dir.c_str());
+	if (!dir)
+		return ret;
+
+	struct dirent* dp;
+	while ((dp = readdir(dir)) != NULL) {
+		if (!(!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, "..")))
+			ret.push_back(_dir + "/" + dp->d_name);
+	}
+
+	closedir(dir);
+	return ret;
+}
+
+static std::string Basename(const std::string& path) {
+	return path.substr(path.find_last_of("/") + 1, path.length());
+}
+
+static bool IsRegularFile(std::string link) {
+	struct stat sb;
+	if (stat(link.c_str(), &sb) == -1)
+		return false;
+	return S_ISREG(sb.st_mode);
+}
+
+static bool AreFlagsOk(pid_t pid, int fd) {
+	const std::string path = PROC_LOCATION "/" + std::to_string(pid) + "/fdinfo/" + std::to_string(fd);
+
+	std::ifstream file(path.c_str());
+	if (!file)
+		return false;
+
+	int flags = 0;
+	for (std::string line; std::getline(file, line); )
+		if (line.find("flags:", 0) == 0)
+			flags = std::stoi(line.substr(line.find_last_not_of("0123456789") + 1));
+
+	if (flags & O_WRONLY || flags & O_RDWR)
+		return false;
+	return true;
+}
+
+static bool GetFilenameFromFd(std::string link, std::string& out) {
+	/* gets around stupid linux limitation where /proc doesn't
+	   give actual filesize readings */
+	constexpr size_t OUT_MAX = (1 << 15); // 32KiB
+	out.resize(1024);
+
+	for (ssize_t exe_used = 0;
+	     out.length() < OUT_MAX && exe_used >= (ssize_t)(out.length() - 1);
+		 out.resize(out.length() * 2)) {
+		exe_used = readlink(link.c_str(), &out.front(), out.length());
+		if (exe_used == (ssize_t)-1 || exe_used < (ssize_t)1)
+			return false;
+	}
+}
+
+static std::string GetProcessName(pid_t pid) {
+	std::string result;
+
+#ifdef FREEBSD
+	struct kinfo_proc* proc = kinfo_getproc(pid);
+	if (!proc)
+		return "";
+	result = proc->ki_comm;
+	free(proc);
+#elif defined(LINUX)
+	const std::string path = PROC_LOCATION "/" + std::to_string(pid) + "/comm";
+
+	if (!util::ReadFile(path, result))
+		return "";
+
+	result.erase(std::remove(result.begin(), result.end(), '\n'), result.end());
+#endif
+
+	return result;
+}
+
+bool ProcFdTools::EnumerateOpenProcesses(process_proc_t process_proc) {
+	bool success = false;
+	for (const auto& dir : GetAllFilesInDir(PROC_LOCATION)) {
+		pid_t pid;
+		try {
+			pid = std::stoul(Basename(dir));
+			success = true;
+		} catch (std::invalid_argument) {
+			continue;
+		}
+		if (!process_proc({pid, GetProcessName(pid)}))
+			return false;
+	}
+	return success;
+}
+
+bool ProcFdTools::EnumerateOpenFiles(const std::set<pid_t>& pids, open_file_proc_t open_file_proc) {
+	if (!open_file_proc)
+		return false;
+
+	for (const auto& pid : pids) {
+		const std::string path = PROC_LOCATION "/" + std::to_string(pid) + "/fd";
+
+		for (const auto& dir : GetAllFilesInDir(path)) {
+			if (!AreFlagsOk(pid, std::stoi(Basename(dir))))
+				continue;
+
+			std::string name = GetFilenameFromFd(dir);
+
+			if (!IsRegularFile(name))
+				continue;
+
+			if (!open_file_proc({pid, name}))
+				return false;
+		}
+	}
+	return true;
+}
+
+} // namespace animia::internal::linux