path: root/package/makedevs
diff options
authorGravatar Arnout Vandecappelle <arnout@mind.be>2016-11-05 14:38:12 +0100
committerGravatar Thomas Petazzoni <thomas.petazzoni@free-electrons.com>2016-11-05 23:32:59 +0100
commitc85cd189dc1ded92b78c5968860ff447ec9815ad (patch)
tree458a1bb56afb3453d17ab6e37e631d708e2b76d9 /package/makedevs
parentab1b6f7df4355244dfc54b877889ff7a3cde02a0 (diff)
makedevs: make device node creation idempotent
We use makedevs to create device nodes in the target rootfs. However, this can be called several times, e.g. when building several filesystem images or when rebuilding. When makedevs is called the second time, the device node already exists so mknod() errors out. This wasn't noticed before because fakeroot's mknod() wrapper (incorrectly) does _not_ error out when the file exists already. Now we switched from fakeroot to pseudo, the problem becomes apparent. Before creating the device node, check if it already exists and if so, if it has the correct device type and number. Change of mode and ownership is still done. This approach was preferred over removing the target files before creating them, which would be simpler. However, when e.g. a file exists as a normal file and makedevs specifies it as a device node, that really is an error so we should detect it. The other types don't have to be changed. The 'd' (directory) type is already OK because it already only creates directories if they don't exist yet. The 'f' (file mode) and 'r' (recursive) types only operate on files and directories that exist already. Patch also sent upstream to busybox. Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> Reported-by: Fabio Estevam <festevam@gmail.com> Tested-by: Fabio Estevam <festevam@gmail.com> Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr> Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Diffstat (limited to 'package/makedevs')
1 files changed, 16 insertions, 2 deletions
diff --git a/package/makedevs/makedevs.c b/package/makedevs/makedevs.c
index 7092b1475e..bcf0e0f000 100644
--- a/package/makedevs/makedevs.c
+++ b/package/makedevs/makedevs.c
@@ -601,6 +601,7 @@ int main(int argc, char **argv)
dev_t rdev;
unsigned i;
char *full_name_inc;
+ struct stat st;
if (type == 'p') {
mode |= S_IFIFO;
@@ -622,10 +623,23 @@ int main(int argc, char **argv)
for (i = start; i <= start + count; i++) {
sprintf(full_name_inc, count ? "%s%u" : "%s", full_name, i);
rdev = makedev(major, minor + (i - start) * increment);
- if (mknod(full_name_inc, mode, rdev) < 0) {
+ if (stat(full_name_inc, &st) == 0) {
+ if ((mode & S_IFMT) != (st.st_mode & S_IFMT)) {
+ bb_error_msg("line %d: node %s exists but is of wrong file type", linenum, full_name_inc);
+ continue;
+ }
+ if (st.st_rdev != rdev) {
+ bb_error_msg("line %d: node %s exists but is wrong device number", linenum, full_name_inc);
+ continue;
+ }
+ } else if (mknod(full_name_inc, mode, rdev) < 0) {
bb_perror_msg("line %d: can't create node %s", linenum, full_name_inc);
- } else if (chown(full_name_inc, uid, gid) < 0) {
+ continue;
+ }
+ if (chown(full_name_inc, uid, gid) < 0) {
bb_perror_msg("line %d: can't chown %s", linenum, full_name_inc);
} else if (chmod(full_name_inc, mode) < 0) {