syscall: simplify execve handling on libc platforms

Rather than providing three different execve variables for different
platforms, use a single variable. Provide a small wrapper that handles
conversion to uintptr for the AIX/Solaris case.

Note that this removes special handling for openbsd/mips64, which is
now a dead port.

Updates #61546

Change-Id: I3d6387c31669f64bfb61639536803e595f478647
Reviewed-on: https://go-review.googlesource.com/c/go/+/693880
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/src/syscall/exec_libc.go b/src/syscall/exec_libc.go
index 0e88650873..2e7e33d9ef 100644
--- a/src/syscall/exec_libc.go
+++ b/src/syscall/exec_libc.go
@@ -61,7 +61,13 @@ func write1(fd uintptr, buf uintptr, nbyte uintptr) (n uintptr, err Errno)
 
 // syscall defines this global on our behalf to avoid a build dependency on other platforms
 func init() {
-	execveLibc = execve
+	execveLibc = execveLibcWrapper
+}
+
+func execveLibcWrapper(path *byte, argv **byte, envp **byte) error {
+	return execve(uintptr(unsafe.Pointer(path)),
+		uintptr(unsafe.Pointer(argv)),
+		uintptr(unsafe.Pointer(envp)))
 }
 
 // Fork, dup fd onto 0..len(fd), and exec(argv0, argvv, envv) in child.