setarch: fix personality syscall return code check

Depending on architecture and kernel version, personality
syscall is either capable or incapable of returning an error.
If the return value is not an error, then it's the previous
personality value, which can be an arbitrary value
undistinguishable from an error value.
To make things clear, a second call is needed.

For more details about personality syscall peculiarities see
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=glibc-2.22-637-ge0043e17dfc5

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>

diff --git a/sys-utils/setarch.c b/sys-utils/setarch.c
index b6159c5b468abe53337ca13c2a65058c851b7af0..b5e401c81cbcd71723b21e9f5dfd1fcd465cf3aa 100644 (file)
--- a/sys-utils/setarch.c
+++ b/sys-utils/setarch.c
@@ -236,8 +236,18 @@ static int set_arch(const char *pers, unsigned long options, int list)
        if (transitions[i].perval < 0)
                errx(EXIT_FAILURE, _("%s: Unrecognized architecture"), pers);
        pers_value = transitions[i].perval | options;
-       if (personality(pers_value) == -EINVAL)
-               return 1;
+       if (personality(pers_value) < 0) {
+               /*
+                * Depending on architecture and kernel version, personality
+                * syscall is either capable or incapable of returning an error.
+                * If the return value is not an error, then it's the previous
+                * personality value, which can be an arbitrary value
+                * undistinguishable from an error value.
+                * To make things clear, a second call is needed.
+                */
+               if (personality(pers_value) < 0)
+                       return 1;
+       }
        uname(&un);
        if (transitions[i].result_arch && strcmp(un.machine, transitions[i].result_arch)) {
                if (strcmp(transitions[i].result_arch, "i386")