+ * Internal wrapper function which must be called for _all_ output
+ * to the log file. It takes care of opening the log file if it
+ * isn't open, buffering data if it's in the process of being
+ * opened asynchronously, etc.
+ */
+static void logwrite(struct LogContext *ctx, void *data, int len)
+{
+ /*
+ * In state L_CLOSED, we call logfopen, which will set the state
+ * to one of L_OPENING, L_OPEN or L_ERROR. Hence we process all of
+ * those three _after_ processing L_CLOSED.
+ */
+ if (ctx->state == L_CLOSED)
+ logfopen(ctx);
+
+ if (ctx->state == L_OPENING) {
+ bufchain_add(&ctx->queue, data, len);
+ } else if (ctx->state == L_OPEN) {
+ assert(ctx->lgfp);
+ fwrite(data, 1, len, ctx->lgfp);
+ } /* else L_ERROR, so ignore the write */
+}
+
+/*
+ * Convenience wrapper on logwrite() which printf-formats the
+ * string.
+ */
+static void logprintf(struct LogContext *ctx, const char *fmt, ...)
+{
+ va_list ap;
+ char *data;
+
+ va_start(ap, fmt);
+ data = dupvprintf(fmt, ap);
+ va_end(ap);
+
+ logwrite(ctx, data, strlen(data));
+ sfree(data);
+}
+
+/*
+ * Flush any open log file.
+ */
+void logflush(void *handle) {
+ struct LogContext *ctx = (struct LogContext *)handle;
+ if (ctx->cfg.logtype > 0)
+ if (ctx->state == L_OPEN)
+ fflush(ctx->lgfp);
+}
+
+static void logfopen_callback(void *handle, int mode)
+{
+ struct LogContext *ctx = (struct LogContext *)handle;
+ char buf[256], *event;
+ struct tm tm;
+ const char *fmode;
+
+ if (mode == 0) {
+ ctx->state = L_ERROR; /* disable logging */
+ } else {
+ fmode = (mode == 1 ? "ab" : "wb");
+ ctx->lgfp = f_open(ctx->currlogfilename, fmode);
+ if (ctx->lgfp)
+ ctx->state = L_OPEN;
+ else
+ ctx->state = L_ERROR;
+ }
+
+ if (ctx->state == L_OPEN) {
+ /* Write header line into log file. */
+ tm = ltime();
+ strftime(buf, 24, "%Y.%m.%d %H:%M:%S", &tm);
+ logprintf(ctx, "=~=~=~=~=~=~=~=~=~=~=~= PuTTY log %s"
+ " =~=~=~=~=~=~=~=~=~=~=~=\r\n", buf);
+ }
+
+ event = dupprintf("%s session log (%s mode) to file: %s",
+ (mode == 0 ? "Disabled writing" :
+ mode == 1 ? "Appending" : "Writing new"),
+ (ctx->cfg.logtype == LGTYP_ASCII ? "ASCII" :
+ ctx->cfg.logtype == LGTYP_DEBUG ? "raw" :
+ ctx->cfg.logtype == LGTYP_PACKETS ? "SSH packets" :
+ "unknown"),
+ filename_to_str(&ctx->currlogfilename));
+ logevent(ctx->frontend, event);
+ sfree(event);
+
+ /*
+ * Having either succeeded or failed in opening the log file,
+ * we should write any queued data out.
+ */
+ assert(ctx->state != L_OPENING); /* make _sure_ it won't be requeued */
+ while (bufchain_size(&ctx->queue)) {
+ void *data;
+ int len;
+ bufchain_prefix(&ctx->queue, &data, &len);
+ logwrite(ctx, data, len);
+ bufchain_consume(&ctx->queue, len);
+ }
+}
+
+/*
+ * Open the log file. Takes care of detecting an already-existing
+ * file and asking the user whether they want to append, overwrite
+ * or cancel logging.
+ */
+void logfopen(void *handle)
+{
+ struct LogContext *ctx = (struct LogContext *)handle;
+ struct tm tm;
+ int mode;
+
+ /* Prevent repeat calls */
+ if (ctx->state != L_CLOSED)
+ return;
+
+ if (!ctx->cfg.logtype)
+ return;
+
+ tm = ltime();
+
+ /* substitute special codes in file name */
+ xlatlognam(&ctx->currlogfilename, ctx->cfg.logfilename,ctx->cfg.host, &tm);
+
+ ctx->lgfp = f_open(ctx->currlogfilename, "r"); /* file already present? */
+ if (ctx->lgfp) {
+ fclose(ctx->lgfp);
+ if (ctx->cfg.logxfovr != LGXF_ASK) {
+ mode = ((ctx->cfg.logxfovr == LGXF_OVR) ? 2 : 1);
+ } else
+ mode = askappend(ctx->frontend, ctx->currlogfilename,
+ logfopen_callback, ctx);
+ } else
+ mode = 2; /* create == overwrite */
+
+ if (mode < 0)
+ ctx->state = L_OPENING;
+ else
+ logfopen_callback(ctx, mode); /* open the file */
+}
+
+void logfclose(void *handle)
+{
+ struct LogContext *ctx = (struct LogContext *)handle;
+ if (ctx->lgfp) {
+ fclose(ctx->lgfp);
+ ctx->lgfp = NULL;
+ }
+ ctx->state = L_CLOSED;
+}
+
+/*