On Wed, 2015-11-25 at 16:56 -0500, Boris Ostrovsky wrote: > getpwnam_r() has fairly complicated return rules. From man pages: > > RETURN VALUE > ... > On success, getpwnam_r() and getpwuid_r() return zero, and set > *result to pwd. If no matching password record was found, these > functions return 0 and store NULL in *result. In case of error, > an error number is returned, and NULL is stored in *result. > ERRORS > 0 or ENOENT or ESRCH or EBADF or EPERM or ... > The given name or uid was not found.
My reference when reviewing this is the (IMHO more canonical) http://pubs.o pengroup.org/onlinepubs/9699919799/functions/getpwnam.html . I suppose you are looking at the Linux and/or glibc man pages? > While it's not clear what ellipses are meant to be, the way we currently > treat return values from getpwnam_r() is no sufficient. In fact, two of > my systems behave differently when username is not found: one returns > ENOENT and the other returns 0. Which two systems are these? When you say "returns" do you mean "returns 0 and sets errno to XXX" or literally returns ENOENT? > Both set *result to NULL. > > This patch adjusts return value management to be more in line with man > pages. > > While at it, also make sure we don't get stuck on ERANGE. > > Signed-off-by: Boris Ostrovsky <boris.ostrov...@oracle.com> > --- > tools/libxl/libxl_dm.c | 23 ++++++++++++++--------- > 1 file changed, 14 insertions(+), 9 deletions(-) > > diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c > index a4934df..bd3daeb 100644 > --- a/tools/libxl/libxl_dm.c > +++ b/tools/libxl/libxl_dm.c > @@ -726,7 +726,7 @@ static int libxl__dm_runas_helper(libxl__gc *gc, > const char *username) > struct passwd pwd, *user = NULL; > char *buf = NULL; > long buf_size; > - int ret; > + int ret, retry_cnt = 0; > > buf_size = sysconf(_SC_GETPW_R_SIZE_MAX); > if (buf_size < 0) { > @@ -740,12 +740,17 @@ static int libxl__dm_runas_helper(libxl__gc *gc, > const char *username) > ret = getpwnam_r(username, &pwd, buf, buf_size, &user); > if (ret == ERANGE) { > buf_size += 128; > + if (retry_cnt++ > 10) > + return ERROR_FAIL; > continue; > } > - if (ret != 0) > - return ERROR_FAIL; > - if (user != NULL) > - return 1; > + if (user == NULL) { > + if (!ret || (ret == ENOENT) || (ret == ESRCH) || > + (ret == EBADF) || (ret == EPERM)) > + return ERROR_NOTFOUND; > + else > + return ERROR_FAIL; > + } > return 0; > } > } > @@ -1261,16 +1266,16 @@ static int > libxl__build_device_model_args_new(libxl__gc *gc, > > user = GCSPRINTF("%s%d", LIBXL_QEMU_USER_BASE, guest_domid); > ret = libxl__dm_runas_helper(gc, user); > - if (ret < 0) > + if (ret && (ret != ERROR_NOTFOUND)) > return ret; > - if (ret > 0) > + if (!ret) > goto end_search; > > user = LIBXL_QEMU_USER_SHARED; > ret = libxl__dm_runas_helper(gc, user); > - if (ret < 0) > + if (ret && (ret != ERROR_NOTFOUND)) > return ret; > - if (ret > 0) { > + if (!ret) { > LOG(WARN, "Could not find user %s%d, falling back to %s", > LIBXL_QEMU_USER_BASE, guest_domid, > LIBXL_QEMU_USER_SHARED); > goto end_search; _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
