i2c-tools: only try /dev/i2c/* if opening /dev/i2c-* fails with ENOENT

Trying to access /dev/i2c/* on every error after opening /dev/i2c-* can
mislead users who e.g. don't have root access. Instead of bailing-out
with "permission denied" we currently print "no such file or directory".

Fix it by trying open("/dev/i2c/%d") only if we got ENOENT.

Upstream i2cdetect tries to get any info it can from /sys and /proc even
when invoked by an unprivileged user, but we don't want to add unnecessary
bloat.

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/miscutils/i2c_tools.c b/miscutils/i2c_tools.c
index 2805cf3b0..7034dc9a8 100644
--- a/miscutils/i2c_tools.c
+++ b/miscutils/i2c_tools.c
@@ -379,8 +379,12 @@ static int i2c_dev_open(int i2cbus)
         sprintf(filename, "/dev/i2c-%d", i2cbus);
         fd = open(filename, O_RDWR);
         if (fd < 0) {
-                filename[8] = '/'; /* change to "/dev/i2c/%d" */
-                fd = xopen(filename, O_RDWR);
+                if (errno == ENOENT) {
+                        filename[8] = '/'; /* change to "/dev/i2c/%d" */
+                        fd = xopen(filename, O_RDWR);
+                } else {
+                        bb_perror_msg_and_die("can't open '%s'", filename);
+                }
         }
 
         return fd;