[PATCH 7/9] pkeys.7: Update the example to match glibc

[Stephen Kitt <steve@xxxxxxx>]

glibc 2.27 introduced support for the pkeys functions, but the glibc
versions don't match those declared in the example. Update the example
to match glibc, and avoid declaring the functions if glibc is new
enough.

Signed-off-by: Stephen Kitt <steve@xxxxxxx>
---
 man7/pkeys.7 | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/man7/pkeys.7 b/man7/pkeys.7
index 73ddcdc43..480ff21d4 100644
--- a/man7/pkeys.7
+++ b/man7/pkeys.7
@@ -186,8 +186,10 @@ Segmentation fault (core dumped)
 #include <unistd.h>
 #include <sys/syscall.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <sys/mman.h>
 
+#if __GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 27)
 static inline void
 wrpkru(unsigned int pkru)
 {
@@ -200,7 +202,7 @@ wrpkru(unsigned int pkru)
 }
 
 int
-pkey_set(int pkey, unsigned long rights, unsigned long flags)
+pkey_set(int pkey, unsigned long rights)
 {
     unsigned int pkru = (rights << (2 * pkey));
     return wrpkru(pkru);
@@ -214,9 +216,9 @@ pkey_mprotect(void *ptr, size_t size, unsigned long orig_prot,
 }
 
 int
-pkey_alloc(void)
+pkey_alloc(unsigned int flags, unsigned int rights)
 {
-    return syscall(SYS_pkey_alloc, 0, 0);
+    return syscall(SYS_pkey_alloc, flags, rights);
 }
 
 int
@@ -224,6 +226,7 @@ pkey_free(unsigned long pkey)
 {
     return syscall(SYS_pkey_free, pkey);
 }
+#endif
 
 #define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \e
                            } while (0)
@@ -252,7 +255,7 @@ main(void)
     /*
      * Allocate a protection key:
      */
-    pkey = pkey_alloc();
+    pkey = pkey_alloc(0, 0);
     if (pkey == \-1)
         errExit("pkey_alloc");
 
@@ -260,7 +263,7 @@ main(void)
      * Disable access to any memory with "pkey" set,
      * even though there is none right now.
      */
-    status = pkey_set(pkey, PKEY_DISABLE_ACCESS, 0);
+    status = pkey_set(pkey, PKEY_DISABLE_ACCESS);
     if (status)
         errExit("pkey_set");
 
-- 
2.30.2