From c0d678824537239f5e17822cd8473ac32f1ed251 Mon Sep 17 00:00:00 2001
From: Andrey Rys <rys@lynxlynx.ru>
Date: Sun, 16 Jan 2022 12:21:54 +0100
Subject: [PATCH] -O nobuf: disable IO buffering

useful for online "as user types" encrypting
cannot use CTR here because CTR increases counter each time message continuation appears
---
 VERSION     |  2 +-
 tfc_error.c |  2 ++
 tfc_misc.c  |  3 +--
 tfcrypt.c   | 11 +++++++++--
 tfcrypt.h   |  2 +-
 5 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/VERSION b/VERSION
index 4b9026d..900731f 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-63
+64
diff --git a/tfc_error.c b/tfc_error.c
index a00b070..2b50807 100644
--- a/tfc_error.c
+++ b/tfc_error.c
@@ -162,6 +162,7 @@ void usage(void)
 		tfc_say("    when the whole status line width is smaller than tty width.");
 		tfc_say("    statless: emit less information in status line (only processed data).");
 		tfc_say("    iobs=val: set IO block size value. Must not exceed %u bytes.", TFC_U(TFC_BLKSIZE));
+		tfc_say("    nobuf: disable IO buffering, write as soon as data received (only for stream ciphers!)");
 		tfc_say("    iseek=val: seek source file/device by these val bytes.");
 		tfc_say("    oseek=val: seek destination file/device by these val bytes.");
 		tfc_say("    ioseek=val: seek both source and destination.");
@@ -341,6 +342,7 @@ void usage(void)
 	tfc_say("    shorthex: with -H, do not print printable characters, dump only hex string.");
 	tfc_say("    logfile: (same as -o) redirect all messages to logfile instead of stderr.");
 	tfc_say("    iobs=val: set IO block size value. Must not exceed %u bytes.", TFC_U(TFC_BLKSIZE));
+	tfc_say("    nobuf: disable IO buffering, write as soon as data received (only for stream ciphers!)");
 	tfc_say("    xtsblocks=val: use these nr of TF blocks per XTS block. Default is %u.", TFC_U(TFC_XTSBLOCKS));
 	tfc_say("    iseek=val: seek source file/device by these val bytes.");
 	tfc_say("    Initial counter is adjusted automatically.");
diff --git a/tfc_misc.c b/tfc_misc.c
index b140a82..01998f2 100644
--- a/tfc_misc.c
+++ b/tfc_misc.c
@@ -102,11 +102,10 @@ const char *tfc_modename(int mode)
 	return NULL;
 }
 
-tfc_yesno tfc_is_stream(int mode)
+tfc_yesno tfc_is_freestream(int mode)
 {
 	switch (mode) {
 		case TFC_MODE_PLAIN:
-		case TFC_MODE_CTR:
 		case TFC_MODE_STREAM: return YES;
 	}
 
diff --git a/tfcrypt.c b/tfcrypt.c
index 2b2a26f..bad1d43 100644
--- a/tfcrypt.c
+++ b/tfcrypt.c
@@ -30,6 +30,7 @@
 
 static tfc_byte svctr[TF_BLOCK_SIZE];
 static tfc_fsize rwd, do_read_loops, loopcnt;
+static tfc_yesno unbuffered;
 
 static void open_log(const char *logfile)
 {
@@ -346,6 +347,12 @@ _baddfname:
 						show_when_done = YES;
 					else if (!strcmp(s, "pid"))
 						show_pid = YES;
+					else if (!strcmp(s, "nobuf")) {
+						if (!tfc_is_freestream(ctr_mode)) xerror(NO, YES, YES,
+							"cannot activate unbuffered mode for non-stream cipher mode %s!",
+							tfc_modename(ctr_mode));
+						else unbuffered = YES;
+					}
 					else if (!strncmp(s, "readloops", 9) && *(s+9) == '=') {
 						do_read_loops = tfc_humanfsize(s+10, &stoi);
 						if (!str_empty(stoi)) do_read_loops = NOSIZE;
@@ -362,7 +369,7 @@ _baddfname:
 							"%s: invalid block size value", s);
 						}
 						else blksize = (size_t)tfc_modifysize((tfc_fsize)blksize, strchr(s, ':'));
-						if (!tfc_is_stream(ctr_mode) && blksize < TF_BLOCK_SIZE) xerror(NO, YES, YES,
+						if (!tfc_is_freestream(ctr_mode) && blksize < TF_BLOCK_SIZE) xerror(NO, YES, YES,
 							"%s: block size is lesser than TF_BLOCK_SIZE (%u bytes)", s, TFC_U(TF_BLOCK_SIZE));
 						if (blksize > TFC_BLKSIZE) xerror(NO, YES, YES,
 							"%s: block size exceeds %u bytes",
@@ -1209,7 +1216,7 @@ _ragain:	lio = xread(sfd, pblk, lrem);
 				default: xerror(NO, NO, NO, "%s", srcfname); break;
 			}
 		}
-		if (lio && lio < lrem) {
+		if (unbuffered == NO && lio && lio < lrem) {
 			pblk += lio;
 			lrem -= lio;
 			goto _ragain;
diff --git a/tfcrypt.h b/tfcrypt.h
index 42088a1..2806614 100644
--- a/tfcrypt.h
+++ b/tfcrypt.h
@@ -193,7 +193,7 @@ int xxopen(tfc_yesno noerr, const char *pathname, int flags);
 int xopen(const char *pathname, int flags);
 void xclose(int fd);
 const char *tfc_modename(int mode);
-tfc_yesno tfc_is_stream(int mode);
+tfc_yesno tfc_is_freestream(int mode);
 void tfc_getcurtime(tfc_useconds *tx);
 char *tfc_format_time(tfc_useconds t);
 char *tfc_format_pid(const char *str);
-- 
2.31.1