From 691e94c0c1542a3cdbe6f683e42e8854b5485bbc Mon Sep 17 00:00:00 2001
From: DTB <trinity@trinity.moe>
Date: Sun, 7 Jul 2024 20:33:54 -0600
Subject: [PATCH] dj(1): error reporting more of the time

---
 src/dj.c | 49 +++++++++++++++++++++++++++++--------------------
 1 file changed, 29 insertions(+), 20 deletions(-)

diff --git a/src/dj.c b/src/dj.c
index 4dc4842..88c3979 100644
--- a/src/dj.c
+++ b/src/dj.c
@@ -37,17 +37,18 @@ char *program_name = "dj";
  * writing ends of its jockeyed "pipe". User-configurable members are noted
  * with their relevant options. */
 struct Io{
-	int bs;       	/* buffer size (-bB) */
+	char *buf;	  	/* buffer */
+	char *fn;	  	/* file name (-io) */
+	size_t bs;    	/* buffer size (-bB) */
 	size_t bufuse;	/* buffer usage */
-	char *buf;		/* buffer */
-	size_t bytes;	/* bytes processed */
-	int fd;			/* file descriptor */
-	int fl;			/* file opening flags */
-	char *fn;		/* file name (may be stdin_name or stdout_name) (-io) */
-	size_t prec;	/* partial records processed */
-	size_t rec; 	/* records processed */
-	long seek;		/* bytes to seek/skip (will be 0 after skippage) (-sS) */
-}; 
+	size_t bytes; 	/* bytes processed */
+	size_t prec;  	/* partial records processed */
+	size_t rec;   	/* records processed */
+	long seek;  	/* remaining bytes to seek/skip (-sS) */
+	int fd;		  	/* file descriptor */
+	int fl;		  	/* file opening flags */
+	char error: 1;	/* (bool) error status */
+};
 
 /* To be assigned to main:fmt and used with printio(). */
 static char *fmt_asv   = "%d\037%d\036%d\037%d\035%d\036%d\034";
@@ -73,8 +74,10 @@ Io_read(struct Io *io){
 	assert(io->bs > 0);
 	assert(io->bufuse < io->bs);
 
-	if((t = read(io->fd, &(io->buf)[io->bufuse], io->bs - io->bufuse)) < 0)
+	if((t = read(io->fd, &(io->buf)[io->bufuse], io->bs - io->bufuse)) < 0){
+		io->error = 1;
 		t = 0;
+	}
 
 	io->bufuse += t;
 	io->bytes  += t;
@@ -93,9 +96,10 @@ Io_write(struct Io *io){
 	assert(io->bufuse > 0);
 	assert(io->bufuse <= io->bs);
 
-	if((t = write(io->fd, io->buf, io->bufuse)) < 0)
+	if((t = write(io->fd, io->buf, io->bufuse)) < 0){
+		io->error = 1;
 		t = 0;
-	else if(t > 0)
+	}else if(t > 0)
 		memmove(io->buf, &(io->buf)[t], (io->bufuse -= t));
 
 	io->bytes += t;
@@ -158,20 +162,21 @@ int main(int argc, char *argv[]){
 	char *fmt;    /* == fmt_asv (default) or fmt_human (-H) */
 	size_t i;     /* side of io being modified */
 	char noerror; /* 0=exits (default) 1=retries on partial reads or writes */
-	struct Io io[2];
+	struct Io io[2 /* { in, out } */];
 
 	/* Set defaults. */
 	align = -1;
 	count = 0;
 	fmt = fmt_asv;
 	noerror = 0;
-	for(i = 0; i < 2; ++i){
+	for(i = 0; i < (sizeof io) / (sizeof *io); ++i){
 		io[i].bs = 1024 /* 1 KiB */; /* GNU dd(1) default; POSIX says 512B */
 		io[i].bufuse = 0;
 		io[i].bytes = 0;
 		io[i].fd = i == 0 ? STDIN_FILENO : STDOUT_FILENO;
 		io[i].fn = i == 0 ? stdin_name   : stdout_name;
 		io[i].fl = i == 0 ? read_flags   : write_flags;
+		io[i].error = 0;
 		io[i].prec = 0;
 		io[i].rec = 0;
 		io[i].seek = 0;
@@ -227,10 +232,10 @@ int main(int argc, char *argv[]){
 	if(argc > optind)
 		return usage(program_name);
 
-	for(i = 0; i < 2; ++i){
+	for(i = 0; i < (sizeof io) / (sizeof *io); ++i){
 		/* buffer allocation */
 		if((io[i].buf = malloc(io[i].bs * (sizeof *(io[i].buf)))) == NULL){
-			fprintf(stderr, "%s: Failed to allocate %d bytes\n",
+			fprintf(stderr, "%s: Failed to allocate %zd bytes\n",
 				program_name, io[i].bs);
 			return EX_OSERR;
 		}
@@ -245,7 +250,7 @@ int main(int argc, char *argv[]){
 		do{
 			memset(io[1].buf, '\0',
 				(t = io[1].bufuse = MIN(io[1].bs, io[1].seek)));
-			if(Io_write(&io[1])->bufuse == t && !noerror)
+			if(Io_write(&io[1])->bufuse == t && !noerror && !io[1].error)
 				Io_write(&io[1]); /* second chance */
 		}while((io[1].seek -= (t - io[1].bufuse)) > 0 && io[1].bufuse != t);
 		io[1].bufuse = 0;
@@ -268,7 +273,7 @@ int main(int argc, char *argv[]){
 				io[0].bufuse = io[0].bs - io[0].seek;
 
 			t = io[0].bufuse;
-			if(Io_read(&io[0])->bufuse == t && !noerror)
+			if(Io_read(&io[0])->bufuse == t && !noerror && io[0].error)
 				Io_read(&io[0]); /* second chance */
 			assert(io[0].bufuse >= t);
 			if(io[0].bufuse == t) /* that's all she wrote */
@@ -322,7 +327,7 @@ int main(int argc, char *argv[]){
 			}
 
 			t = io[1].bufuse;
-			if(Io_write(&io[1])->bufuse == t && !noerror)
+			if(Io_write(&io[1])->bufuse == t && !noerror && !io[1].error)
 				Io_write(&io[1]); /* second chance */
 			assert(io[1].bufuse <= t);
 			if(io[1].bufuse == t){ /* no more love */
@@ -341,5 +346,9 @@ int main(int argc, char *argv[]){
 
 	fprintio(stderr, fmt, io);
 
+	for(i = 0; i < (sizeof io) / (sizeof *io); ++i)
+		if(io[i].error)
+			return oserr(io[i].fn);
+
 	return EX_OK;
 }