diff --git a/lib/Makefile.am b/lib/Makefile.am
index 224ce970..1fcc7c71 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -15,6 +15,8 @@ libuasync_a_SOURCES = \
 	socket_compat.h \
 	platform_compat.c \
 	platform_compat.h \
+	file_io.c \
+	file_io.h \
 	getmyip.c \
 	getmyip.h \
 	swm_min.c \
diff --git a/src/video/video.c b/src/video/video.c
index 69a0dacc..043eb28b 100644
--- a/src/video/video.c
+++ b/src/video/video.c
@@ -5,6 +5,7 @@
 #include "../../lib/mem.h"
 #include "../../lib/u_async.h"
 #include "../../lib/platform_compat.h"
+#include "../../lib/file_io.h"
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -232,148 +233,6 @@ int video_needs_transcode(const struct video_info* info) {
     return 0;
 }
 
-struct vc_file {
-    char temporary[VIDEO_PATH_MAX + 64];
-    FILE* file;
-};
-
-#ifdef _WIN32
-static int vc_wide(const char* path, wchar_t* wide) {
-    if (MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, path, -1, wide, VIDEO_PATH_MAX + 64)) return 0;
-    DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video invalid UTF-8 path=%s winerr=%lu", path, GetLastError());
-    return -1;
-}
-#endif
-
-/* Проверить обычные файлы и их идентичность до записи; повторить перед публикацией. */
-static int vc_paths(const char* source, const char* destination) {
-    if (!source || !destination || !*source || !*destination ||
-        strlen(source) >= VIDEO_PATH_MAX || strlen(destination) >= VIDEO_PATH_MAX) {
-        DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video invalid/oversized source or destination");
-        return -1;
-    }
-#ifdef _WIN32
-    wchar_t from[VIDEO_PATH_MAX + 64], to[VIDEO_PATH_MAX + 64];
-    if (vc_wide(source, from) || vc_wide(destination, to)) return -1;
-    HANDLE input = CreateFileW(from, GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
-                              NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
-    BY_HANDLE_FILE_INFORMATION a, b;
-    int valid = input != INVALID_HANDLE_VALUE && GetFileInformationByHandle(input, &a) &&
-        GetFileType(input) == FILE_TYPE_DISK && !(a.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY);
-    if (input != INVALID_HANDLE_VALUE) CloseHandle(input);
-    if (!valid) { DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video invalid source=%s winerr=%lu", source, GetLastError()); return -1; }
-    DWORD attributes = GetFileAttributesW(to);
-    if (attributes == INVALID_FILE_ATTRIBUTES) {
-        DWORD error = GetLastError();
-        if (error == ERROR_FILE_NOT_FOUND) return 0;
-        DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video destination inspection failed path=%s winerr=%lu", destination, error);
-        return -1;
-    }
-    if (attributes & (FILE_ATTRIBUTE_DIRECTORY | FILE_ATTRIBUTE_REPARSE_POINT)) {
-        DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video destination is directory/reparse point path=%s", destination); return -1;
-    }
-    HANDLE output = CreateFileW(to, GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
-                               NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
-    valid = output != INVALID_HANDLE_VALUE && GetFileInformationByHandle(output, &b) && GetFileType(output) == FILE_TYPE_DISK;
-    if (output != INVALID_HANDLE_VALUE) CloseHandle(output);
-    if (!valid || (a.dwVolumeSerialNumber == b.dwVolumeSerialNumber &&
-        a.nFileIndexHigh == b.nFileIndexHigh && a.nFileIndexLow == b.nFileIndexLow)) {
-        DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video destination aliases source or cannot be inspected path=%s", destination); return -1;
-    }
-#else
-    struct stat input, output;
-    if (stat(source, &input) || !S_ISREG(input.st_mode)) {
-        DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video source is not readable regular file path=%s errno=%d", source, errno); return -1;
-    }
-    if (lstat(destination, &output)) {
-        if (errno == ENOENT) return 0;
-        DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video destination stat failed path=%s errno=%d", destination, errno); return -1;
-    }
-    if (!S_ISREG(output.st_mode) || (input.st_dev == output.st_dev && input.st_ino == output.st_ino)) {
-        DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video destination is not distinct regular file source=%s destination=%s", source, destination);
-        return -1;
-    }
-#endif
-    return 0;
-}
-
-/* Создать уникальный соседний файл эксклюзивно; FILE остаётся у задачи до finish/discard. */
-static int vc_file_open(struct vc_file* output, const char* destination) {
-    for (int attempt = 0; attempt < 8; attempt++) {
-        uint8_t random[16]; char suffix[33];
-        if (random_bytes(random, sizeof(random))) { DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video temp randomness failed"); return -1; }
-        for (unsigned i = 0; i < sizeof(random); i++) snprintf(suffix + i * 2, 3, "%02x", random[i]);
-        snprintf(output->temporary, sizeof(output->temporary), "%s.tmp.%s", destination, suffix);
-#ifdef _WIN32
-        wchar_t wide[VIDEO_PATH_MAX + 64];
-        if (vc_wide(output->temporary, wide)) { output->temporary[0] = 0; return -1; }
-        int fd = _wopen(wide, _O_CREAT | _O_EXCL | _O_RDWR | _O_BINARY, _S_IREAD | _S_IWRITE);
-#else
-        int fd = open(output->temporary, O_CREAT | O_EXCL | O_RDWR, 0600);
-#endif
-        if (fd < 0) {
-            output->temporary[0] = 0;
-            if (errno == EEXIST) continue;
-            DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video temporary creation failed destination=%s errno=%d", destination, errno);
-            return -1;
-        }
-#ifdef _WIN32
-        output->file = _fdopen(fd, "wb+");
-        if (!output->file) _close(fd);
-#else
-        output->file = fdopen(fd, "wb+");
-        if (!output->file) close(fd);
-#endif
-        if (!output->file) { DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video fdopen failed errno=%d", errno); return -1; }
-        DEBUG_DEBUG(DEBUG_CATEGORY_VIDEO, "video temporary opened path=%s", output->temporary);
-        return 0;
-    }
-    DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video temporary collision limit destination=%s", destination);
-    return -1;
-}
-
-static int vc_file_finish(struct vc_file* output) {
-    int error = fflush(output->file) ? errno : 0;
-    if (fclose(output->file) && !error) error = errno;
-    output->file = NULL;
-    if (error) { DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video flush/close failed path=%s errno=%d", output->temporary, error); return -1; }
-    return 0;
-}
-
-static void vc_file_discard(struct vc_file* output) {
-    if (output->file) {
-        if (fclose(output->file)) DEBUG_WARN(DEBUG_CATEGORY_VIDEO, "video cleanup close failed errno=%d", errno);
-        output->file = NULL;
-    }
-    if (!output->temporary[0]) return;
-#ifdef _WIN32
-    wchar_t wide[VIDEO_PATH_MAX + 64];
-    int error = vc_wide(output->temporary, wide) ? -1 : _wremove(wide);
-#else
-    int error = remove(output->temporary);
-#endif
-    if (error && errno != ENOENT) DEBUG_WARN(DEBUG_CATEGORY_VIDEO, "video temporary cleanup failed path=%s errno=%d", output->temporary, errno);
-    output->temporary[0] = 0;
-}
-
-/* Последняя способная отказать операция: после rename результат уже опубликован. */
-static int vc_file_publish(struct vc_file* output, const char* source, const char* destination) {
-    if (vc_paths(source, destination)) return -1;
-#ifdef _WIN32
-    wchar_t from[VIDEO_PATH_MAX + 64], to[VIDEO_PATH_MAX + 64];
-    if (vc_wide(output->temporary, from) || vc_wide(destination, to)) return -1;
-    if (!MoveFileExW(from, to, MOVEFILE_REPLACE_EXISTING)) {
-        DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video publish failed destination=%s winerr=%lu", destination, GetLastError()); return -1;
-    }
-#else
-    if (rename(output->temporary, destination)) {
-        DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video publish failed destination=%s errno=%d", destination, errno); return -1;
-    }
-#endif
-    output->temporary[0] = 0;
-    DEBUG_INFO(DEBUG_CATEGORY_VIDEO, "video published destination=%s", destination);
-    return 0;
-}
 
 struct vc_stream {
     int index;
@@ -391,7 +250,7 @@ struct vc_stream {
 
 struct vc_ctx {
     char source[VIDEO_PATH_MAX], destination[VIDEO_PATH_MAX];
-    struct vc_file file;
+    struct file_io_temp file;
     void (*done)(void*, int, const struct video_info*);
     void* arg;
     int error, remux;
@@ -409,7 +268,7 @@ static int vc_io_write(void* opaque, const uint8_t* bytes, int length) {
 #else
 static int vc_io_write(void* opaque, uint8_t* bytes, int length) {
 #endif
-    struct vc_file* file = opaque;
+    struct file_io_temp* file = opaque;
     if (fwrite(bytes, 1, length, file->file) == (size_t)length) return length;
     int error = errno ? errno : EIO;
     DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video MP4 write failed path=%s requested=%d errno=%d", file->temporary, length, error);
@@ -417,7 +276,7 @@ static int vc_io_write(void* opaque, uint8_t* bytes, int length) {
 }
 
 static int64_t vc_io_seek(void* opaque, int64_t offset, int whence) {
-    struct vc_file* file = opaque;
+    struct file_io_temp* file = opaque;
     if (whence == AVSEEK_SIZE) {
 #ifdef _WIN32
         struct _stat64 info;
@@ -459,7 +318,7 @@ static int vc_output_close(struct vc_ctx* ctx) {
         avio_context_free(&ctx->output->pb);
         if (error < 0) DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video MP4 buffered output failed error=%s", vc_errstr(error));
     }
-    if (ctx->file.file && vc_file_finish(&ctx->file)) error = -1;
+    if (ctx->file.file && file_io_temp_finish(&ctx->file)) error = -1;
     return error < 0 ? -1 : 0;
 }
 
@@ -854,7 +713,7 @@ static int vc_run(struct vc_ctx* ctx) {
 static void vc_thread_entry(void* raw) {
     struct vc_ctx* ctx = raw;
     video_ffmpeg_init();
-    if (vc_paths(ctx->source, ctx->destination) || vc_file_open(&ctx->file, ctx->destination)) { ctx->error = -1; return; }
+    if (file_io_paths(ctx->source, ctx->destination) || file_io_temp_open(&ctx->file, ctx->destination)) { ctx->error = -1; return; }
     struct stat info;
     if (!stat(ctx->source, &info)) ctx->source_size = info.st_size;
     int error = vc_run(ctx);
@@ -873,8 +732,8 @@ static void vc_thread_entry(void* raw) {
 static void vc_done_trampoline(void* raw, int error) {
     struct vc_ctx* ctx = raw;
     if (!error) error = ctx->error;
-    if (!error && vc_file_publish(&ctx->file, ctx->source, ctx->destination)) error = -1;
-    vc_file_discard(&ctx->file);
+    if (!error && file_io_temp_publish(&ctx->file, ctx->source, ctx->destination)) error = -1;
+    file_io_temp_discard(&ctx->file);
     vc_progress_set(-1);
     vc_active_set(0);
     DEBUG_DEBUG(DEBUG_CATEGORY_VIDEO, "video completion destination=%s error=%d", ctx->destination, error);
@@ -929,11 +788,11 @@ static int vc_first_frame(AVFormatContext* format, AVCodecContext* decoder, int
 }
 
 int video_extract_thumbnail(const char* src, const char* dst, int max_w) {
-    if (vc_paths(src, dst)) return -1;
+    if (file_io_paths(src, dst)) return -1;
     if (max_w <= 0) max_w = 320;
     if (max_w < 2) { DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video thumbnail width must be >=2"); return -1; }
     video_ffmpeg_init();
-    struct vc_file output = {0};
+    struct file_io_temp output = {0};
     AVFormatContext* format = NULL;
     AVCodecContext* decoder = NULL; AVCodecContext* encoder = NULL;
     AVFrame* input = NULL; AVFrame* frame = NULL; AVPacket* packet = NULL;
@@ -983,17 +842,17 @@ int video_extract_thumbnail(const char* src, const char* dst, int max_w) {
     }
     if (error < 0) goto done;
     phase = "write JPEG";
-    if (vc_file_open(&output, dst)) { error = AVERROR(EIO); goto done; }
+    if (file_io_temp_open(&output, dst)) { error = AVERROR(EIO); goto done; }
     if (fwrite(packet->data, 1, packet->size, output.file) != (size_t)packet->size) {
         error = AVERROR(errno ? errno : EIO); goto done;
     }
-    if (vc_file_finish(&output)) { error = AVERROR(EIO); goto done; }
+    if (file_io_temp_finish(&output)) { error = AVERROR(EIO); goto done; }
     phase = "publish JPEG";
-    error = vc_file_publish(&output, src, dst) ? AVERROR(EIO) : 0;
+    error = file_io_temp_publish(&output, src, dst) ? AVERROR(EIO) : 0;
 done:
     if (error < 0) DEBUG_ERROR(DEBUG_CATEGORY_VIDEO, "video thumbnail failed phase=%s source=%s destination=%s error=%s",
                               phase, src, dst, vc_errstr(error));
-    vc_file_discard(&output);
+    file_io_temp_discard(&output);
     sws_freeContext(scale); av_frame_free(&input); av_frame_free(&frame); av_packet_free(&packet);
     avcodec_free_context(&decoder); avcodec_free_context(&encoder); avformat_close_input(&format);
     return error < 0 ? -1 : 0;