From e766015d60c927aae03b8e43d956c6976c16b2ba Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Sat, 13 Jan 2024 15:54:46 -0500
Subject: ioq: Use the negative errno convention

---
 src/bfstd.c |  9 +++++++++
 src/bfstd.h | 10 ++++++++++
 src/bftw.c  |  2 +-
 src/ioq.c   | 32 +++++++++++---------------------
 src/ioq.h   |  6 ++----
 5 files changed, 33 insertions(+), 26 deletions(-)

(limited to 'src')

diff --git a/src/bfstd.c b/src/bfstd.c
index 15e8667..0a9b87c 100644
--- a/src/bfstd.c
+++ b/src/bfstd.c
@@ -59,6 +59,15 @@ bool errno_is_like(int category) {
 	return error_is_like(errno, category);
 }
 
+int try(int ret) {
+	if (ret >= 0) {
+		return ret;
+	} else {
+		bfs_assert(errno > 0, "errno should be positive, was %d\n", errno);
+		return -errno;
+	}
+}
+
 char *xdirname(const char *path) {
 	size_t i = xbaseoff(path);
 
diff --git a/src/bfstd.h b/src/bfstd.h
index 8953b9b..d160c88 100644
--- a/src/bfstd.h
+++ b/src/bfstd.h
@@ -63,6 +63,16 @@ bool error_is_like(int error, int category);
  */
 bool errno_is_like(int category);
 
+/**
+ * Apply the "negative errno" convention.
+ *
+ * @param ret
+ *         The return value of the attempted operation.
+ * @return
+ *         ret, if non-negative, otherwise -errno.
+ */
+int try(int ret);
+
 #include <fcntl.h>
 
 #ifndef O_EXEC
diff --git a/src/bftw.c b/src/bftw.c
index 49f07df..952b090 100644
--- a/src/bftw.c
+++ b/src/bftw.c
@@ -621,7 +621,7 @@ static int bftw_ioq_pop(struct bftw_state *state, bool block) {
 		}
 
 		dir = ent->opendir.dir;
-		if (ent->ret == 0) {
+		if (ent->result >= 0) {
 			bftw_file_set_dir(cache, file, dir);
 		} else {
 			bftw_freedir(cache, dir);
diff --git a/src/ioq.c b/src/ioq.c
index 2739338..89ebb3e 100644
--- a/src/ioq.c
+++ b/src/ioq.c
@@ -455,42 +455,35 @@ static bool ioq_check_cancel(struct ioq *ioq, struct ioq_ent *ent) {
 		return false;
 	}
 
-	ent->ret = -1;
-	ent->error = EINTR;
+	ent->result = -EINTR;
 	ioqq_push(ioq->ready, ent);
 	return true;
 }
 
 /** Handle a single request synchronously. */
 static void ioq_handle(struct ioq *ioq, struct ioq_ent *ent) {
-	int ret;
-
 	switch (ent->op) {
 	case IOQ_CLOSE:
-		ret = xclose(ent->close.fd);
+		ent->result = try(xclose(ent->close.fd));
 		break;
 
 	case IOQ_OPENDIR:
-		ret = bfs_opendir(ent->opendir.dir, ent->opendir.dfd, ent->opendir.path, ent->opendir.flags);
-		if (ret == 0) {
+		ent->result = try(bfs_opendir(ent->opendir.dir, ent->opendir.dfd, ent->opendir.path, ent->opendir.flags));
+		if (ent->result >= 0) {
 			bfs_polldir(ent->opendir.dir);
 		}
 		break;
 
 	case IOQ_CLOSEDIR:
-		ret = bfs_closedir(ent->closedir.dir);
+		ent->result = try(bfs_closedir(ent->closedir.dir));
 		break;
 
 	default:
 		bfs_bug("Unknown ioq_op %d", (int)ent->op);
-		ret = -1;
-		errno = ENOSYS;
+		ent->result = -ENOSYS;
 		break;
 	}
 
-	ent->ret = ret;
-	ent->error = ret == 0 ? 0 : errno;
-
 	ioqq_push(ioq->ready, ent);
 }
 
@@ -603,24 +596,21 @@ static void ioq_ring_reap(struct ioq_ring_state *state) {
 		}
 
 		struct ioq_ent *ent = io_uring_cqe_get_data(cqe);
-		ent->ret = cqe->res >= 0 ? cqe->res : -1;
-		ent->error = cqe->res < 0 ? -cqe->res : 0;
+		ent->result = cqe->res;
 		io_uring_cqe_seen(ring, cqe);
 		--state->submitted;
 
-		if (ent->op == IOQ_OPENDIR && ent->ret >= 0) {
-			int fd = ent->ret;
+		if (ent->op == IOQ_OPENDIR && ent->result >= 0) {
+			int fd = ent->result;
 			if (ioq_check_cancel(ioq, ent)) {
 				xclose(fd);
 				continue;
 			}
 
-			ent->ret = bfs_opendir(ent->opendir.dir, fd, NULL, ent->opendir.flags);
-			if (ent->ret == 0) {
+			ent->result = try(bfs_opendir(ent->opendir.dir, fd, NULL, ent->opendir.flags));
+			if (ent->result >= 0) {
 				// TODO: io_uring_prep_getdents()
 				bfs_polldir(ent->opendir.dir);
-			} else {
-				ent->error = errno;
 			}
 		}
 
diff --git a/src/ioq.h b/src/ioq.h
index 87727cb..e1e5052 100644
--- a/src/ioq.h
+++ b/src/ioq.h
@@ -36,10 +36,8 @@ struct ioq_ent {
 	/** The I/O operation. */
 	enum ioq_op op;
 
-	/** The return value of the operation. */
-	int ret;
-	/** The error code, if the operation failed. */
-	int error;
+	/** The return value (on success) or negative error code (on failure). */
+	int result;
 
 	/** Arbitrary user data. */
 	void *ptr;
-- 
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