libubi: improve errors handling

Improve comments about what is returned if UBI device or node
does not exist.

Better check for ENODEV error code.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

7 files changed, 71 insertions, 22 deletions

diff --git a/ubi-utils/include/libubi.h b/ubi-utils/include/libubi.h
index bc3404c..7ff0934 100644
--- a/ubi-utils/include/libubi.h
+++ b/ubi-utils/include/libubi.h
@@ -295,8 +295,8 @@ int ubi_rsvol(libubi_t desc, const char *node, int vol_id, long long bytes);
  *
  * This function tests whether @node is a UBI device or volume node and returns
  * %1 if this is an UBI device node, %2 if this is a volume node, and %-1 if
- * this is not an UBI node or if an error occurred (the latter is indicated by
- * a non-zero errno).
+ * this is not an UBI device or volume node (errno is ENODEV in this case) or
+ * if an error occurred.
  */
 int ubi_probe_node(libubi_t desc, const char *node);
 
@@ -307,7 +307,8 @@ int ubi_probe_node(libubi_t desc, const char *node);
  * @info: pointer to the &struct ubi_dev_info object to fill
  *
  * This function fills the passed @info object with UBI device information and
- * returns %0 in case of success and %-1 in case of failure.
+ * returns %0 in case of success and %-1 in case of failure. If the UBI device
+ * corresponding to @node does not exist, errno is set to @ENODEV.
  */
 int ubi_get_dev_info(libubi_t desc, const char *node,
 		     struct ubi_dev_info *info);
@@ -319,7 +320,8 @@ int ubi_get_dev_info(libubi_t desc, const char *node,
  * @info: pointer to the &struct ubi_dev_info object to fill
  *
  * This function is identical to 'ubi_get_dev_info()' except that it accepts UBI
- * device number, not UBI character device.
+ * device number, not UBI character device. If the UBI device @dev_num does not
+ * exist, errno is set to @ENODEV.
  */
 int ubi_get_dev_info1(libubi_t desc, int dev_num, struct ubi_dev_info *info);
 
@@ -330,7 +332,8 @@ int ubi_get_dev_info1(libubi_t desc, int dev_num, struct ubi_dev_info *info);
  * @info: pointer to the &struct ubi_vol_info object to fill
  *
  * This function fills the passed @info object with UBI volume information and
- * returns %0 in case of success and %-1 in case of failure.
+ * returns %0 in case of success and %-1 in case of failure. If the UBI volume
+ * corresponding to @node does not exist, errno is set to @ENODEV.
  */
 int ubi_get_vol_info(libubi_t desc, const char *node,
 		     struct ubi_vol_info *info);
@@ -343,7 +346,9 @@ int ubi_get_vol_info(libubi_t desc, const char *node,
  * @info: pointer to the &struct ubi_vol_info object to fill
  *
  * This function is identical to 'ubi_get_vol_info()' except that it accepts UBI
- * volume ID, not UBI volume character device.
+ * volume ID, not UBI volume character device. If the UBI device @dev_num does
+ * not exist, or if the UBI volume @vol_id does not exist, errno is set to
+ * @ENODEV.
  */
 int ubi_get_vol_info1(libubi_t desc, int dev_num, int vol_id,
 		      struct ubi_vol_info *info);
@@ -352,11 +357,12 @@ int ubi_get_vol_info1(libubi_t desc, int dev_num, int vol_id,
  * ubi_get_vol_info1_nm - get UBI volume information by volume name.
  * @desc: UBI library descriptor
  * @dev_num: UBI device number
- * @vol_id: ID of the UBI volume to fetch information about
+ * @name: name of the UBI volume to fetch information about
  * @info: pointer to the &struct ubi_vol_info object to fill
  *
  * This function is identical to 'ubi_get_vol_info()' except that it accepts UBI
- * volume name, not UBI volume ID.
+ * volume name, not UBI volume ID. If the UBI device @dev_num does not exist,
+ * or if the UBI volume @name does not exist, errno is set to @ENODEV.
  */
 int ubi_get_vol_info1_nm(libubi_t desc, int dev_num, const char *name,
 			 struct ubi_vol_info *info);
diff --git a/ubi-utils/src/libubi.c b/ubi-utils/src/libubi.c
index d4b29b9..067f17e 100644
--- a/ubi-utils/src/libubi.c
+++ b/ubi-utils/src/libubi.c
@@ -787,17 +787,15 @@ int ubi_probe_node(libubi_t desc, const char *node)
 	/* This is supposdely an UBI volume device node */
 	sprintf(file, lib->ubi_vol, i, minor - 1);
 	fd = open(file, O_RDONLY);
-	if (fd == -1) {
-		sys_errmsg("cannot open \"%s\"", node);
-		return -1;
-	}
+	if (fd == -1)
+		goto out_not_ubi;
 
 	return 2;
 
 out_not_ubi:
 	errmsg("\"%s\" has major:minor %d:%d, but this does not correspond to "
-	       "any UBI device or volume", node, major, minor);
-	errno = 0;
+	       "any existing UBI device or volume", node, major, minor);
+	errno = ENODEV;
 	return -1;
 }
 
@@ -1002,6 +1000,22 @@ int ubi_leb_change_start(libubi_t desc, int fd, int lnum, int bytes, int dtype)
 	return 0;
 }
 
+/**
+ * dev_present - check whether an UBI device is present.
+ * @lib: libubi descriptor
+ * @dev_num: UBI device number to check
+ *
+ * This function returns %1 if UBI device is present and %0 if not.
+ */
+static int dev_present(struct libubi *lib, int dev_num)
+{
+	struct stat st;
+	char file[strlen(lib->ubi_dev) + 50];
+
+	sprintf(file, lib->ubi_dev, dev_num);
+	return !stat(file, &st);
+}
+
 int ubi_get_dev_info1(libubi_t desc, int dev_num, struct ubi_dev_info *info)
 {
 	DIR *sysfs_ubi;
@@ -1011,6 +1025,11 @@ int ubi_get_dev_info1(libubi_t desc, int dev_num, struct ubi_dev_info *info)
 	memset(info, '\0', sizeof(struct ubi_dev_info));
 	info->dev_num = dev_num;
 
+	if (!dev_present(lib, dev_num)) {
+		errno = ENODEV;
+		return -1;
+	}
+
 	sysfs_ubi = opendir(lib->sysfs_ubi);
 	if (!sysfs_ubi)
 		return -1;
@@ -1085,9 +1104,15 @@ out_close:
 
 int ubi_get_dev_info(libubi_t desc, const char *node, struct ubi_dev_info *info)
 {
-	int dev_num;
+	int err, dev_num;
 	struct libubi *lib = (struct libubi *)desc;
 
+	err = ubi_probe_node(desc, node);
+	if (err != 1) {
+		errno = ENODEV;
+		return -1;
+	}
+
 	if (dev_node2num(lib, node, &dev_num))
 		return -1;
 
@@ -1155,9 +1180,15 @@ int ubi_get_vol_info1(libubi_t desc, int dev_num, int vol_id,
 
 int ubi_get_vol_info(libubi_t desc, const char *node, struct ubi_vol_info *info)
 {
-	int vol_id, dev_num;
+	int err, vol_id, dev_num;
 	struct libubi *lib = (struct libubi *)desc;
 
+	err = ubi_probe_node(desc, node);
+	if (err != 2) {
+		errno = ENODEV;
+		return -1;
+	}
+
 	if (vol_node2nums(lib, node, &dev_num, &vol_id))
 		return -1;
 
diff --git a/ubi-utils/src/ubimkvol.c b/ubi-utils/src/ubimkvol.c
index dba7133..b5805a4 100644
--- a/ubi-utils/src/ubimkvol.c
+++ b/ubi-utils/src/ubimkvol.c
@@ -251,7 +251,10 @@ int main(int argc, char * const argv[])
 		       args.node);
 		goto out_libubi;
 	} else if (err < 0) {
-		errmsg("\"%s\" is not an UBI device node", args.node);
+		if (errno == ENODEV)
+			errmsg("\"%s\" is not an UBI device node", args.node);
+		else
+			sys_errmsg("error while probing \"%s\"", args.node);
 		goto out_libubi;
 	}
 
diff --git a/ubi-utils/src/ubinfo.c b/ubi-utils/src/ubinfo.c
index 025ac62..036ed6c 100644
--- a/ubi-utils/src/ubinfo.c
+++ b/ubi-utils/src/ubinfo.c
@@ -142,8 +142,8 @@ static int translate_dev(libubi_t libubi, const char *node)
 
 	err = ubi_probe_node(libubi, node);
 	if (err == -1) {
-		if (errno)
-			return errmsg("unrecognized device node \"%s\"", node);
+		if (errno != ENODEV)
+			return sys_errmsg("error while probing \"%s\"", node);
 		return errmsg("\"%s\" does not correspond to any UBI device or volume", node);
 	}
 
diff --git a/ubi-utils/src/ubirename.c b/ubi-utils/src/ubirename.c
index 08b3cd5..00c53e4 100644
--- a/ubi-utils/src/ubirename.c
+++ b/ubi-utils/src/ubirename.c
@@ -105,7 +105,10 @@ int main(int argc, char * const argv[])
 		       node);
 		goto out_libubi;
 	} else if (err < 0) {
-		errmsg("\"%s\" is not an UBI device node", node);
+		if (errno == ENODEV)
+			errmsg("\"%s\" is not an UBI device node", node);
+		else
+			sys_errmsg("error while probing \"%s\"", node);
 		goto out_libubi;
 	}
 
diff --git a/ubi-utils/src/ubirmvol.c b/ubi-utils/src/ubirmvol.c
index 17aece4..f7a3820 100644
--- a/ubi-utils/src/ubirmvol.c
+++ b/ubi-utils/src/ubirmvol.c
@@ -193,7 +193,10 @@ int main(int argc, char * const argv[])
 		       args.node);
 		goto out_libubi;
 	} else if (err < 0) {
-		errmsg("\"%s\" is not an UBI device node", args.node);
+		if (errno == ENODEV)
+			errmsg("\"%s\" is not an UBI device node", args.node);
+		else
+			sys_errmsg("error while probing \"%s\"", args.node);
 		goto out_libubi;
 	}
 
diff --git a/ubi-utils/src/ubiupdatevol.c b/ubi-utils/src/ubiupdatevol.c
index b160461..df424d2 100644
--- a/ubi-utils/src/ubiupdatevol.c
+++ b/ubi-utils/src/ubiupdatevol.c
@@ -331,7 +331,10 @@ int main(int argc, char * const argv[])
 		       args.node);
 		goto out_libubi;
 	} else if (err < 0) {
-		errmsg("\"%s\" is not an UBI volume node", args.node);
+		if (errno == ENODEV)
+			errmsg("\"%s\" is not an UBI volume node", args.node);
+		else
+			sys_errmsg("error while probing \"%s\"", args.node);
 		goto out_libubi;
 	}