From 58245c9484ca74ad2d71d0dbe63b861820c65db9 Mon Sep 17 00:00:00 2001
From: DTB <trinity@trinity.moe>
Date: Thu, 22 Feb 2024 19:27:14 -0700
Subject: [PATCH] dj(1): remove function pointer hijinks (fixes #66)

---
 src/dj.c | 42 +++++++++++++++++++++---------------------
 1 file changed, 21 insertions(+), 21 deletions(-)

diff --git a/src/dj.c b/src/dj.c
index d5bd59c..8a6732c 100644
--- a/src/dj.c
+++ b/src/dj.c
@@ -203,28 +203,28 @@ Io_fdseek(struct Io *io){
 	
 	if(!fdisstd(io->fd) && lseek(io->fd, io->seek, SEEK_SET) != -1)
 		return -1;
-	else if(io->fl == write_flags){
-		memset(io->buf, '\0', io->bs);
-		/* This is a dirty trick; rather than testing conditions and operating
-		 * likewise, because the parameters to read or write are going to be
-		 * the same either way, just use a function pointer to keep track of
-		 * the intended operation. */
-		op = (int (*)(int, void *, size_t))&write;
-		/* Function pointer casts are risky; this works because the difference
-		 * is in the second parameter and only that write(2) makes the buffer
-		 * const whereas read(2) does not. To avoid even the slightest
-		 * undefined behavior comment out the cast, just be ready for a
-		 * -Wincompatible-function-pointer-types if your compiler notices it.
-		 */
-	}else
-		op = &read;
 
-	/* We're going to cheat and use bufuse as the retval for write(2), which is
-	 * fine because it'll be zeroed as this function returns anyway. */
-	do{	if(	(io->bufuse = (*op)(io->fd, io->buf, MIN(io->bs, io->seek))) == 0)
-			/* second chance */
-			io->bufuse = (*op)(io->fd, io->buf, MIN(io->bs, io->seek));
-	}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
+	/* repeated code to get the condition out of the loop */
+	if(io->fl == write_flags){
+		memset(io->buf, '\0', io->bs);
+		/* We're going to cheat and use bufuse as the retval for write(2),
+		 * which is fine because it'll be zeroed as this function returns
+		 * anyway. */
+		do{
+			if((io->bufuse = write(io->fd, io->buf, MIN(io->bs, io->seek)))
+					== 0)
+				/* second chance */
+				io->bufuse = write(io->fd, io->buf, MIN(io->bs, io->seek));
+		}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
+	}else if(io->fl == read_flags){
+		do{
+			if((io->bufuse = read(io->fd, io->buf, MIN(io->bs, io->seek)))
+					== 0)
+				/* second chance */
+				io->bufuse = read(io->fd, io->buf, MIN(io->bs, io->seek));
+		}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
+	}else
+		return EX_SOFTWARE;
 
 	io->bufuse = 0;