[PATCH v2 10/12] bsd-user: do_freebsd_sysctl helper for sysctl(2)

[Warner Losh <imp@bsdimp.com>]

From: Kyle Evans <kevans@FreeBSD.org>

Implement the wrapper function for sysctl(2). This puts the oid
arguments into a standard form and calls the common
do_freebsd_sysctl_oid.

Signed-off-by: Kyle Evans <kevans@FreeBSD.org>
Co-Authored-by: Juergen Lock <nox@jelal.kn-bremen.de>
Signed-off-by: Juergen Lock <nox@jelal.kn-bremen.de>
Co-Authored-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Stacey Son <sson@FreeBSD.org>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Signed-off-by: Warner Losh <imp@bsdimp.com>
---
 bsd-user/freebsd/os-sys.c     | 57 ++++++++++++++++++++++++++++++++++-
 bsd-user/freebsd/os-syscall.c |  4 +++
 bsd-user/qemu.h               |  2 ++
 3 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/bsd-user/freebsd/os-sys.c b/bsd-user/freebsd/os-sys.c
index cbaa70958b9..e70f8f21c52 100644
--- a/bsd-user/freebsd/os-sys.c
+++ b/bsd-user/freebsd/os-sys.c
@@ -258,7 +258,7 @@ static inline void sysctl_oidfmt(uint32_t *holdp)
     holdp[0] = tswap32(holdp[0]);
 }
 
-static abi_long G_GNUC_UNUSED do_freebsd_sysctl_oid(CPUArchState *env, int32_t *snamep,
+static abi_long do_freebsd_sysctl_oid(CPUArchState *env, int32_t *snamep,
         int32_t namelen, void *holdp, size_t *holdlenp, void *hnewp,
         size_t newlen)
 {
@@ -481,6 +481,61 @@ out:
     return ret;
 }
 
+abi_long do_freebsd_sysctl(CPUArchState *env, abi_ulong namep, int32_t namelen,
+        abi_ulong oldp, abi_ulong oldlenp, abi_ulong newp, abi_ulong newlen)
+{
+    abi_long ret = -TARGET_EFAULT;
+    void *hnamep, *holdp = NULL, *hnewp = NULL;
+    size_t holdlen;
+    abi_ulong oldlen = 0;
+    int32_t *snamep = g_malloc(sizeof(int32_t) * namelen), *p, *q, i;
+
+    /* oldlenp is read/write, pre-check here for write */
+    if (oldlenp) {
+        if (!access_ok(VERIFY_WRITE, oldlenp, sizeof(abi_ulong)) ||
+            get_user_ual(oldlen, oldlenp)) {
+            goto out;
+        }
+    }
+    hnamep = lock_user(VERIFY_READ, namep, namelen, 1);
+    if (hnamep == NULL) {
+        goto out;
+    }
+    if (newp) {
+        hnewp = lock_user(VERIFY_READ, newp, newlen, 1);
+        if (hnewp == NULL) {
+            goto out;
+        }
+    }
+    if (oldp) {
+        holdp = lock_user(VERIFY_WRITE, oldp, oldlen, 0);
+        if (holdp == NULL) {
+            goto out;
+        }
+    }
+    holdlen = oldlen;
+    for (p = hnamep, q = snamep, i = 0; i < namelen; p++, i++, q++) {
+        *q = tswap32(*p);
+    }
+
+    ret = do_freebsd_sysctl_oid(env, snamep, namelen, holdp, &holdlen, hnewp,
+        newlen);
+
+    /*
+     * writeability pre-checked above. __sysctl(2) returns ENOMEM and updates
+     * oldlenp for the proper size to use.
+     */
+    if (oldlenp && (ret == 0 || ret == -TARGET_ENOMEM)) {
+        put_user_ual(holdlen, oldlenp);
+    }
+    unlock_user(hnamep, namep, 0);
+    unlock_user(holdp, oldp, holdlen);
+    unlock_user(holdp, oldp, ret == 0 ? holdlen : 0);
+out:
+    g_free(snamep);
+    return ret;
+}
+
 /* sysarch() is architecture dependent. */
 abi_long do_freebsd_sysarch(void *cpu_env, abi_long arg1, abi_long arg2)
 {
diff --git a/bsd-user/freebsd/os-syscall.c b/bsd-user/freebsd/os-syscall.c
index e00997a818c..20ab3d4d9a1 100644
--- a/bsd-user/freebsd/os-syscall.c
+++ b/bsd-user/freebsd/os-syscall.c
@@ -494,6 +494,10 @@ static abi_long freebsd_syscall(void *cpu_env, int num, abi_long arg1,
         /*
          * sys{ctl, arch, call}
          */
+    case TARGET_FREEBSD_NR___sysctl: /* sysctl(3) */
+        ret = do_freebsd_sysctl(cpu_env, arg1, arg2, arg3, arg4, arg5, arg6);
+        break;
+
     case TARGET_FREEBSD_NR_sysarch: /* sysarch(2) */
         ret = do_freebsd_sysarch(cpu_env, arg1, arg2);
         break;
diff --git a/bsd-user/qemu.h b/bsd-user/qemu.h
index 0ceecfb6dfa..c7248cfde6f 100644
--- a/bsd-user/qemu.h
+++ b/bsd-user/qemu.h
@@ -252,6 +252,8 @@ bool is_error(abi_long ret);
 int host_to_target_errno(int err);
 
 /* os-sys.c */
+abi_long do_freebsd_sysctl(CPUArchState *env, abi_ulong namep, int32_t namelen,
+        abi_ulong oldp, abi_ulong oldlenp, abi_ulong newp, abi_ulong newlen);
 abi_long do_freebsd_sysarch(void *cpu_env, abi_long arg1, abi_long arg2);
 
 /* user access */
-- 
2.39.1