Exploring compilation issues on 32-bit architectures.

Notably, arm and x86 have to use a setgroups32 syscall.

Signed-off-by: Andrew G. Morgan <morgan@kernel.org>

4 files changed, 25 insertions, 3 deletions

diff --git a/cap/convenience.go b/cap/convenience.go
index d60b2d6..9dd9d07 100644
--- a/cap/convenience.go
+++ b/cap/convenience.go
@@ -236,7 +236,7 @@ func SetGroups(gid int, suppl ...int) error {
 		return err
 	}
 	if len(suppl) == 0 {
-		if _, _, err := callWKernel(syscall.SYS_SETGROUPS, 0, 0, 0); err != 0 {
+		if _, _, err := callWKernel(sys_setgroups_variant, 0, 0, 0); err != 0 {
 			return err
 		}
 		return nil
@@ -247,7 +247,7 @@ func SetGroups(gid int, suppl ...int) error {
 	for i, g := range suppl {
 		gs[i] = uint32(g)
 	}
-	if _, _, err := callWKernel(syscall.SYS_SETGROUPS, uintptr(len(suppl)), uintptr(unsafe.Pointer(&gs[0])), 0); err != 0 {
+	if _, _, err := callWKernel(sys_setgroups_variant, uintptr(len(suppl)), uintptr(unsafe.Pointer(&gs[0])), 0); err != 0 {
 		return err
 	}
 	return nil
diff --git a/cap/legacy.go b/cap/legacy.go
new file mode 100644
index 0000000..7bdf9b4
--- /dev/null
+++ b/cap/legacy.go
@@ -0,0 +1,7 @@
+// +build linux,arm linux,386
+
+package cap
+
+import "syscall"
+
+var sys_setgroups_variant = uintptr(syscall.SYS_SETGROUPS32)
diff --git a/cap/modern.go b/cap/modern.go
new file mode 100644
index 0000000..04a4919
--- /dev/null
+++ b/cap/modern.go
@@ -0,0 +1,8 @@
+// +build linux,!arm
+// +build linux,!386
+
+package cap
+
+import "syscall"
+
+var sys_setgroups_variant = uintptr(syscall.SYS_SETGROUPS)
diff --git a/libcap/cap_proc.c b/libcap/cap_proc.c
index 28fca22..310922c 100644
--- a/libcap/cap_proc.c
+++ b/libcap/cap_proc.c
@@ -477,6 +477,13 @@ int cap_setuid(uid_t uid)
     return ret;
 }
 
+#if defined(__arm__) || defined(__i386__) || \
+    defined(__i486__) || defined(__i586__) || defined(__i686__)
+#define sys_setgroups_variant  SYS_setgroups32
+#else
+#define sys_setgroups_variant  SYS_setgroups
+#endif
+
 /*
  * cap_setgroups combines setting the gid with changing the set of
  * supplemental groups for a user into one call that raises the needed
@@ -503,7 +510,7 @@ int cap_setgroups(gid_t gid, size_t ngroups, const gid_t groups[])
 	    ret = _libcap_syscall(SYS_setgid, (long int) gid, 0, 0);
 	}
 	if (ret == 0) {
-	    ret = _libcap_syscall(SYS_setgroups, (long int) ngroups,
+	    ret = _libcap_syscall(sys_setgroups_variant, (long int) ngroups,
 				  (long int) groups, 0);
 	}
 	if (ret < 0) {