Re: [libvirt] [PATCH 2/3] New utility functions virFileCreate and virDirCreate

Quoting Laine Stump (laine(a)laine.org): > These functions create a new file or directory with the given > uid/gid. If the flag VIR_FILE_CREATE_AS_UID is given, they do this by > forking a new process, calling setuid/setgid in the new process, and > then creating the file. This is better than simply calling open then > fchown, because in the latter case, a root-squashing nfs server would > create the new file as user nobody, then refuse to allow fchown. > > If VIR_FILE_CREATE_AS_UID is not specified, the simpler tactic of > creating the file/dir, then chowning is is used. This gives better > results in cases where the parent directory isn't on a root-squashing > NFS server, but doesn't give permission for the specified uid/gid to > create files. (Note that if the fork/setuid method fails to create the > file due to access privileges, the parent process will make a second > attempt using this simpler method.) > > Return from both of these functions is 0 on success, or the value of > errno if there was a failure. > --- > src/util/util.c | 247 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ > src/util/util.h | 9 ++ > 2 files changed, 256 insertions(+), 0 deletions(-) > > diff --git a/src/util/util.c b/src/util/util.c > index 1d493de..1cb29f4 100644 > --- a/src/util/util.c > +++ b/src/util/util.c > @@ -1126,6 +1126,253 @@ int virFileExists(const char *path) > return(0); > } > > + > +static int virFileCreateSimple(const char *path, mode_t mode, uid_t uid, gid_t gid) { > + int fd = -1; > + int ret = 0; > + > + if ((fd = open(path, O_RDWR | O_CREAT | O_EXCL, mode)) < 0) { > + ret = errno; > + virReportSystemError(NULL, errno, _("failed to create file '%s'"), > + path); > + goto error; > + } > + if ((getuid() == 0) && ((uid != 0) || (gid != 0))) { How about checking for CAP_CHOWN instead of getuid()==0? Otherwise if I try installing this certain ways, virFileCreateSimple() will refuse to try the chown even though it could succeed.