cdrom_id: open non-mounted optical media with O_EXCL

This should prevent confusing drives during CD burning sessions. Based
on a patch from Harald Hoyer.

diff --git a/extras/cdrom_id/cdrom_id.c b/extras/cdrom_id/cdrom_id.c
index 2380b158a07ece9cb076b3fb82434fd1c9f5b2ff..e485768de41154488a3b4d659dbfb8fd47e629bd 100644 (file)
--- a/extras/cdrom_id/cdrom_id.c
+++ b/extras/cdrom_id/cdrom_id.c
@@ -112,6 +112,30 @@ static unsigned long long int cd_media_session_last_offset;
 #define ASC(errcode)   (((errcode) >> 8) & 0xFF)
 #define ASCQ(errcode)  ((errcode) & 0xFF)
 
+static int is_mounted(const char *device)
+{
+       struct stat statbuf;
+       FILE *fp;
+       int maj, min;
+       int mounted = 0;
+
+       if (stat(device, &statbuf) < 0)
+               return -ENODEV;
+
+       fp = fopen("/proc/self/mountinfo", "r");
+       if (fp == NULL)
+               return -ENOSYS;
+       while (fscanf(fp, "%*s %*s %i:%i %*[^\n]", &maj, &min) == 2) {
+               printf("got %u %u\n", maj, min);
+               if (makedev(maj, min) == statbuf.st_rdev) {
+                       mounted = 1;
+                       break;
+               }
+       }
+       fclose(fp);
+       return mounted;
+}
+
 static void info_scsi_cmd_err(struct udev *udev, char *cmd, int err)
 {
        if (err == -1) {
@@ -568,7 +592,7 @@ int main(int argc, char *argv[])
                goto exit;
        }
 
-       fd = open(node, O_RDONLY | O_NONBLOCK);
+       fd = open(node, O_RDONLY|O_NONBLOCK|(is_mounted(node) ? 0 : O_EXCL));
        if (fd < 0) {
                info(udev, "unable to open '%s'\n", node);
                fprintf(stderr, "unable to open '%s'\n", node);