treewide: add errno_set helper for returning positive error code in errno

We have this sequence at multiple places: Check a return value for being
below zero and if so, turn it positive and store into errno.

Instead of opencoding it everywhere, add a helper to encapsulate this.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20240304190038.3486881-4-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

2 files changed, 13 insertions, 24 deletions

diff --git a/lib/libfile.c b/lib/libfile.c
index 72a2fc79c7..185c7af721 100644
--- a/lib/libfile.c
+++ b/lib/libfile.c
@@ -33,10 +33,8 @@ int pwrite_full(int fd, const void *buf, size_t size, loff_t offset)
 
 	while (size) {
 		now = pwrite(fd, buf, size, offset);
-		if (now == 0) {
-			errno = ENOSPC;
-			return -errno;
-		}
+		if (now == 0)
+			return errno_set(-ENOSPC);
 		if (now < 0)
 			return now;
 		size -= now;
@@ -61,10 +59,8 @@ int write_full(int fd, const void *buf, size_t size)
 
 	while (size) {
 		now = write(fd, buf, size);
-		if (now == 0) {
-			errno = ENOSPC;
-			return -errno;
-		}
+		if (now == 0)
+			return errno_set(-ENOSPC);
 		if (now < 0)
 			return now;
 		size -= now;
@@ -240,8 +236,7 @@ again:
 	/* ensure wchar_t nul termination */
 	buf = calloc(ALIGN(read_size, 2) + 2, 1);
 	if (!buf) {
-		ret = -ENOMEM;
-		errno = ENOMEM;
+		ret = errno_set(-ENOMEM);
 		goto err_out;
 	}
 
diff --git a/lib/parameter.c b/lib/parameter.c
index dc80f3f858..c587d10eab 100644
--- a/lib/parameter.c
+++ b/lib/parameter.c
@@ -90,28 +90,22 @@ int dev_set_param(struct device *dev, const char *name, const char *val)
 	struct param_d *param;
 	int ret;
 
-	if (!dev) {
-		errno = ENODEV;
-		return -ENODEV;
-	}
+	if (!dev)
+		return errno_set(-ENODEV);
 
 	param = get_param_by_name(dev, name);
 
-	if (!param) {
-		errno = EINVAL;
-		return -EINVAL;
-	}
+	if (!param)
+		return errno_set(-EINVAL);
 
-	if (param->flags & PARAM_FLAG_RO) {
-		errno = EACCES;
-		return -EACCES;
-	}
+	if (param->flags & PARAM_FLAG_RO)
+		return errno_set(-EACCES);
 
 	ret = param->set(dev, param, val);
 	if (ret)
-		errno = -ret;
+		return errno_set(ret);
 
-	return ret;
+	return 0;
 }
 
 /**