Quoting Laine Stump (laine@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. -serge