Merge pull request #292 from tbzatek/errno-fixes-1

tree: nvme_configure_ctrl(): Set errno to zero on success

Author: dwsuse

src/nvme/linux.c

@@ -433,21 +433,22 @@ static char *__nvme_get_attr(const char *path)
 {
 	char value[4096] = { 0 };
 	int ret, fd;
+	int saved_errno;
 
 	fd = open(path, O_RDONLY);
-	if (fd < 0) {
-#if 0
-		nvme_msg(LOG_DEBUG, "Failed to open %s: %s\n", path,
-			 strerror(errno));
-#endif
+	if (fd < 0)
 		return NULL;
-	}
 
 	ret = read(fd, value, sizeof(value) - 1);
+	saved_errno = errno;
 	close(fd);
-	if (ret < 0 || !strlen(value)) {
+	if (ret < 0) {
+		errno = saved_errno;
 		return NULL;
 	}
+	errno = 0;
+	if (!strlen(value))
+		return NULL;
 
 	if (value[strlen(value) - 1] == '\n')
 		value[strlen(value) - 1] = '\0';
@@ -463,8 +464,10 @@ char *nvme_get_attr(const char *dir, const char *attr)
 	int ret;
 
 	ret = asprintf(&path, "%s/%s", dir, attr);
-	if (ret < 0)
+	if (ret < 0) {
+		errno = ENOMEM;
 		return NULL;
+	}
 
 	value = __nvme_get_attr(path);
 	free(path);

src/nvme/tree.c

@@ -1144,6 +1144,7 @@ static int nvme_configure_ctrl(nvme_root_t r, nvme_ctrl_t c, const char *path,
 	c->cntrltype = nvme_get_ctrl_attr(c, "cntrltype");
 	c->dctype = nvme_get_ctrl_attr(c, "dctype");
 
+	errno = 0; /* cleanup after nvme_get_ctrl_attr() */
 	return 0;
 }
 

src/nvme/tree.h

@@ -1118,7 +1118,8 @@ int nvme_dump_tree(nvme_root_t r);
  * @d:		sysfs directory
  * @attr:	sysfs attribute name
  *
- * Return: String with the contents of @attr
+ * Return: String with the contents of @attr or %NULL in case of an empty value
+ * 	   or in case of an error (indicated by non-zero errno code).
  */
 char *nvme_get_attr(const char *d, const char *attr);
 
@@ -1127,7 +1128,8 @@ char *nvme_get_attr(const char *d, const char *attr);
  * @s:		nvme_subsystem_t object
  * @attr:	sysfs attribute name
  *
- * Return: String with the contents of @attr
+ * Return: String with the contents of @attr or %NULL in case of an empty value
+ * 	   or in case of an error (indicated by non-zero errno code).
  */
 char *nvme_get_subsys_attr(nvme_subsystem_t s, const char *attr);
 
@@ -1136,7 +1138,8 @@ char *nvme_get_subsys_attr(nvme_subsystem_t s, const char *attr);
  * @c:		Controller instance
  * @attr:	sysfs attribute name
  *
- * Return: String with the contents of @attr
+ * Return: String with the contents of @attr or %NULL in case of an empty value
+ * 	   or in case of an error (indicated by non-zero errno code).
  */
 char *nvme_get_ctrl_attr(nvme_ctrl_t c, const char *attr);
 
@@ -1145,7 +1148,8 @@ char *nvme_get_ctrl_attr(nvme_ctrl_t c, const char *attr);
  * @n:		nvme_ns_t object
  * @attr:	sysfs attribute name
  *
- * Return: String with the contents of @attr
+ * Return: String with the contents of @attr or %NULL in case of an empty value
+ * 	   or in case of an error (indicated by non-zero errno code).
  */
 char *nvme_get_ns_attr(nvme_ns_t n, const char *attr);
 
@@ -1164,7 +1168,8 @@ nvme_ns_t nvme_subsystem_lookup_namespace(struct nvme_subsystem *s,
  * @p:		nvme_path_t object
  * @attr:	sysfs attribute name
  *
- * Return:  String with the contents of @attr
+ * Return: String with the contents of @attr or %NULL in case of an empty value
+ * 	   or in case of an error (indicated by non-zero errno code).
  */
 char *nvme_get_path_attr(nvme_path_t p, const char *attr);