From 71f4a411b69356772ee90466586670f4c194b6c7 Mon Sep 17 00:00:00 2001
From: DTB <trinity@trinity.moe>
Date: Fri, 19 Jul 2024 18:40:24 -0600
Subject: [PATCH] dj(1): replace do/while in write loop

---
 src/dj.c | 44 ++++++++++++++++++++++++++------------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/src/dj.c b/src/dj.c
index 4af59ff..593ae31 100644
--- a/src/dj.c
+++ b/src/dj.c
@@ -157,7 +157,7 @@ usage(char *s) {
 }
 
 int main(int argc, char *argv[]) {
- 	int align;    /* low 8b used, negative if no alignment is being done */
+   	int align;    /* low 8b used, negative if no alignment is being done */
 	int count;    /* 0 if dj(1) runs until no more reads are possible */
 	char *fmt;    /* == fmt_asv (default) or fmt_human (-H) */
 	size_t i;     /* side of io being modified */
@@ -331,21 +331,20 @@ int main(int argc, char *argv[]) {
 			}
 		}
 
-		/* write */
-		do { /* while(io[0].bufuse > 0); */
-			int t;
+		assert(io[0].bufuse > 0);
 
+		while (io[0].bufuse > 0) { /* write */
 			if (io[0].bs <= io[1].bs) {
 				int n;
 
-				/* saturate obuf */
-				memcpy(
+				memcpy( /* saturate obuf */
 					io[1].buf, io[0].buf,
 				   (io[1].bufuse = (n = MIN(io[0].bufuse, io[1].bs)))
 				);
+
 				/* permute the copied units out of ibuf */
 				memmove(io[0].buf, &(io[0].buf)[n], (io[0].bufuse -= n));
-			} else /* if(io[0].bs < io[1].bs) */ {
+			} else /* if(io[0].bs > io[1].bs) */ {
 				int n;
 
 				/* drain what we can from ibuf */
@@ -353,12 +352,10 @@ int main(int argc, char *argv[]) {
 					&(io[1].buf)[io[1].bufuse], io[0].buf,
 				    (n = MIN(io[0].bufuse, io[1].bs - io[1].bufuse))
 				);
-
 				io[1].bufuse += n;
 
 				/* permute out the copied units */
 				memmove(io[0].buf, &(io[0].buf)[n], io[0].bs - n);
-
 				io[0].bufuse -= n;
 
 				if(io[0].bs + io[1].bufuse <= io[1].bs && count != 1) {
@@ -366,16 +363,27 @@ int main(int argc, char *argv[]) {
 				}
 			}
 
-			t = io[1].bufuse;
-			if (Io_write(&io[1])->bufuse == t && !noerror && io[1].error == 0) {
-				Io_write(&io[1]); /* second chance */
-			}
+			{ /* writes actually happen, or die */
+				size_t t;
 
-			assert(io[1].bufuse <= t);
+				t = io[1].bufuse;
+				if (Io_write(&io[1])->bufuse == t
+						&& !noerror
+						&& io[1].error == 0) {
+					Io_write(&io[1]); /* second chance */
+				}
 
-			if (io[1].bufuse == t) { /* no more love */
-				count = 1;
-				break;
+				assert(io[1].error == 0 || io[1].bufuse == t);
+				/* if the Io_writes errored, bufuse wouldn't have changed, and
+				 * the error will be reported at the end of the read/write
+				 * loop */
+
+				assert(io[1].bufuse <= t);
+
+				if (io[1].bufuse == t) { /* no more love */
+					count = 1;
+					break;
+				}
 			}
 
 			if (0 < io[1].bufuse /* && io[1].bufuse < t */) {
@@ -384,7 +392,7 @@ int main(int argc, char *argv[]) {
 
 				if(!noerror) { count = 1; }
 			}
-		} while(io[0].bufuse > 0);
+		}
 	} while(count == 0 || --count > 0);
 
 	fprintio(stderr, fmt, io);