Assume mutex locking cannot fail

Locking and unlocking a non-recursive mutex is a simple memory
operation and should not fail on any reasonable platform with correct
usage.  A pthread mutex can return EDEADLK on lock or EPERM on unlock,
or EINVAL if the mutex is uninitialized, but all of these conditions
would reflect serious bugs in the calling code.

Change the k5_mutex_lock and k5_mutex_unlock wrappers to return void
and adjust all call sites.  Propagate this change through
k5_cc_mutex_lock and k5_cc_mutex_unlock as well.

src/include/k5-thread.h

@@ -378,17 +378,17 @@ static inline int k5_mutex_finish_init(k5_mutex_t *m)
 #define k5_mutex_destroy(M)                     \
     (k5_os_mutex_destroy(M))
 
-#if __GNUC__ >= 4
-static int k5_mutex_lock(k5_mutex_t *)
-    __attribute__((warn_unused_result));
-#endif
-static inline int k5_mutex_lock(k5_mutex_t *m)
+static inline void k5_mutex_lock(k5_mutex_t *m)
 {
-    return k5_os_mutex_lock(m);
+    int r = k5_os_mutex_lock(m);
+    assert(r == 0);
 }
 
-#define k5_mutex_unlock(M)                      \
-    (k5_os_mutex_unlock(M))
+static inline void k5_mutex_unlock(k5_mutex_t *m)
+{
+    int r = k5_os_mutex_unlock(m);
+    assert(r == 0);
+}
 
 #define k5_mutex_assert_locked(M)       ((void)(M))
 #define k5_mutex_assert_unlocked(M)     ((void)(M))
@@ -423,12 +423,8 @@ extern int k5_key_delete(k5_key_t);
 
 extern int  KRB5_CALLCONV krb5int_mutex_alloc  (k5_mutex_t **);
 extern void KRB5_CALLCONV krb5int_mutex_free   (k5_mutex_t *);
-extern int  KRB5_CALLCONV krb5int_mutex_lock   (k5_mutex_t *)
-#if __GNUC__ >= 4
-    __attribute__((warn_unused_result))
-#endif
-    ;
-extern int  KRB5_CALLCONV krb5int_mutex_unlock (k5_mutex_t *);
+extern void KRB5_CALLCONV krb5int_mutex_lock   (k5_mutex_t *);
+extern void KRB5_CALLCONV krb5int_mutex_unlock (k5_mutex_t *);
 
 /* In time, many of the definitions above should move into the support
    library, and this file should be greatly simplified.  For type

src/lib/crypto/krb/prng_fortuna.c

@@ -391,9 +391,7 @@ krb5_c_random_add_entropy(krb5_context context, unsigned int randsource,
     ret = krb5int_crypto_init();
     if (ret)
         return ret;
-    ret = k5_mutex_lock(&fortuna_lock);
-    if (ret)
-        return ret;
+    k5_mutex_lock(&fortuna_lock);
     if (randsource == KRB5_C_RANDSOURCE_OSRAND ||
         randsource == KRB5_C_RANDSOURCE_TRUSTEDPARTY) {
         /* These sources contain enough entropy that we should use them
@@ -414,17 +412,14 @@ krb5_c_random_add_entropy(krb5_context context, unsigned int randsource,
 krb5_error_code KRB5_CALLCONV
 krb5_c_random_make_octets(krb5_context context, krb5_data *outdata)
 {
-    krb5_error_code ret;
 #ifdef _WIN32
     DWORD pid = GetCurrentProcessId();
 #else
     pid_t pid = getpid();
 #endif
     unsigned char pidbuf[4];
 
-    ret = k5_mutex_lock(&fortuna_lock);
-    if (ret)
-        return ret;
+    k5_mutex_lock(&fortuna_lock);
 
     if (!have_entropy) {
         k5_mutex_unlock(&fortuna_lock);

src/lib/gssapi/generic/util_errmap.c

@@ -183,13 +183,7 @@ OM_uint32 gssint_mecherrmap_map(OM_uint32 minor, const gss_OID_desc * oid)
 
     me.code = minor;
     me.mech = *oid;
-    err = k5_mutex_lock(&mutex);
-    if (err) {
-#ifdef DEBUG
-        if (f != stderr) fclose(f);
-#endif
-        return 0;
-    }
+    k5_mutex_lock(&mutex);
 
     /* Is this status+oid already mapped?  */
     p = mecherrmap_findright(&m, me);
@@ -254,14 +248,11 @@ int gssint_mecherrmap_get(OM_uint32 minor, gss_OID mech_oid,
                           OM_uint32 *mech_minor)
 {
     const struct mecherror *p;
-    int err;
 
     if (minor == 0) {
         return EINVAL;
     }
-    err = k5_mutex_lock(&mutex);
-    if (err)
-        return err;
+    k5_mutex_lock(&mutex);
     p = mecherrmap_findleft(&m, minor);
     k5_mutex_unlock(&mutex);
     if (!p) {

src/lib/gssapi/krb5/acquire_cred.c

@@ -112,11 +112,7 @@ gss_krb5int_register_acceptor_identity(OM_uint32 *minor_status,
             return GSS_S_FAILURE;
     }
 
-    err = k5_mutex_lock(&gssint_krb5_keytab_lock);
-    if (err) {
-        free(new);
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&gssint_krb5_keytab_lock);
     old = krb5_gss_keytab;
     krb5_gss_keytab = new;
     k5_mutex_unlock(&gssint_krb5_keytab_lock);
@@ -196,11 +192,7 @@ acquire_accept_cred(krb5_context context,
     if (req_keytab != NULL) {
         code = krb5_kt_dup(context, req_keytab, &kt);
     } else {
-        code = k5_mutex_lock(&gssint_krb5_keytab_lock);
-        if (code) {
-            *minor_status = code;
-            return GSS_S_FAILURE;
-        }
+        k5_mutex_lock(&gssint_krb5_keytab_lock);
         if (krb5_gss_keytab != NULL) {
             code = krb5_kt_resolve(context, krb5_gss_keytab, &kt);
             k5_mutex_unlock(&gssint_krb5_keytab_lock);

src/lib/gssapi/krb5/copy_ccache.c

@@ -23,11 +23,7 @@ gss_krb5int_copy_ccache(OM_uint32 *minor_status,
 
     /* cred handle will have been validated by gssspi_set_cred_option() */
     k5creds = (krb5_gss_cred_id_t) *cred_handle;
-    code = k5_mutex_lock(&k5creds->lock);
-    if (code) {
-        *minor_status = code;
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&k5creds->lock);
     if (k5creds->usage == GSS_C_ACCEPT) {
         k5_mutex_unlock(&k5creds->lock);
         *minor_status = (OM_uint32) G_BAD_USAGE;

src/lib/gssapi/krb5/init_sec_context.c

@@ -1014,9 +1014,7 @@ krb5_gss_init_context (krb5_context *ctxp)
     if (err)
         return err;
 #ifndef _WIN32
-    err = k5_mutex_lock(&kg_kdc_flag_mutex);
-    if (err)
-        return err;
+    k5_mutex_lock(&kg_kdc_flag_mutex);
     is_kdc = kdc_flag;
     k5_mutex_unlock(&kg_kdc_flag_mutex);
 
@@ -1041,10 +1039,7 @@ krb5int_gss_use_kdc_context(OM_uint32 *minor_status,
     err = gss_krb5int_initialize_library();
     if (err)
         return err;
-    *minor_status = k5_mutex_lock(&kg_kdc_flag_mutex);
-    if (*minor_status) {
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&kg_kdc_flag_mutex);
     kdc_flag = 1;
     k5_mutex_unlock(&kg_kdc_flag_mutex);
     return GSS_S_COMPLETE;

src/lib/gssapi/krb5/naming_exts.c

@@ -119,15 +119,10 @@ kg_duplicate_name(krb5_context context,
 {
     krb5_error_code code;
 
-    code = k5_mutex_lock(&src->lock);
-    if (code != 0)
-        return code;
-
+    k5_mutex_lock(&src->lock);
     code = kg_init_name(context, src->princ, src->service, src->host,
                         src->ad_context, 0, dst);
-
     k5_mutex_unlock(&src->lock);
-
     return code;
 }
 
@@ -282,11 +277,7 @@ krb5_gss_inquire_name(OM_uint32 *minor_status,
 
     kname = (krb5_gss_name_t)name;
 
-    code = k5_mutex_lock(&kname->lock);
-    if (code != 0) {
-        *minor_status = code;
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&kname->lock);
 
     if (kname->ad_context == NULL) {
         code = krb5_authdata_context_init(context, &kname->ad_context);
@@ -343,13 +334,7 @@ krb5_gss_get_name_attribute(OM_uint32 *minor_status,
     }
 
     kname = (krb5_gss_name_t)name;
-
-    code = k5_mutex_lock(&kname->lock);
-    if (code != 0) {
-        *minor_status = code;
-        krb5_free_context(context);
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&kname->lock);
 
     if (kname->ad_context == NULL) {
         code = krb5_authdata_context_init(context, &kname->ad_context);
@@ -421,12 +406,7 @@ krb5_gss_set_name_attribute(OM_uint32 *minor_status,
     }
 
     kname = (krb5_gss_name_t)name;
-
-    code = k5_mutex_lock(&kname->lock);
-    if (code != 0) {
-        *minor_status = code;
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&kname->lock);
 
     if (kname->ad_context == NULL) {
         code = krb5_authdata_context_init(context, &kname->ad_context);
@@ -476,12 +456,7 @@ krb5_gss_delete_name_attribute(OM_uint32 *minor_status,
     }
 
     kname = (krb5_gss_name_t)name;
-
-    code = k5_mutex_lock(&kname->lock);
-    if (code != 0) {
-        *minor_status = code;
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&kname->lock);
 
     if (kname->ad_context == NULL) {
         code = krb5_authdata_context_init(context, &kname->ad_context);
@@ -528,12 +503,7 @@ krb5_gss_map_name_to_any(OM_uint32 *minor_status,
     }
 
     kname = (krb5_gss_name_t)name;
-
-    code = k5_mutex_lock(&kname->lock);
-    if (code != 0) {
-        *minor_status = code;
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&kname->lock);
 
     if (kname->ad_context == NULL) {
         code = krb5_authdata_context_init(context, &kname->ad_context);
@@ -585,12 +555,7 @@ krb5_gss_release_any_name_mapping(OM_uint32 *minor_status,
     }
 
     kname = (krb5_gss_name_t)name;
-
-    code = k5_mutex_lock(&kname->lock);
-    if (code != 0) {
-        *minor_status = code;
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&kname->lock);
 
     if (kname->ad_context == NULL) {
         code = krb5_authdata_context_init(context, &kname->ad_context);
@@ -646,12 +611,7 @@ krb5_gss_export_name_composite(OM_uint32 *minor_status,
     }
 
     kname = (krb5_gss_name_t)name;
-
-    code = k5_mutex_lock(&kname->lock);
-    if (code != 0) {
-        *minor_status = code;
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&kname->lock);
 
     code = krb5_unparse_name(context, kname->princ, &princstr);
     if (code != 0)

src/lib/gssapi/krb5/s4u_gss_glue.c

@@ -58,11 +58,7 @@ kg_impersonate_name(OM_uint32 *minor_status,
     if (impersonator_cred->req_enctypes != NULL)
         in_creds.keyblock.enctype = impersonator_cred->req_enctypes[0];
 
-    code = k5_mutex_lock(&user->lock);
-    if (code != 0) {
-        *minor_status = code;
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&user->lock);
 
     if (user->ad_context != NULL) {
         code = krb5_authdata_export_authdata(context,

src/lib/gssapi/krb5/set_allowable_enctypes.c

@@ -91,9 +91,7 @@ gss_krb5int_set_allowable_enctypes(OM_uint32 *minor_status,
             }
         }
     } else {
-        kerr = k5_mutex_lock(&cred->lock);
-        if (kerr)
-            goto error_out;
+        k5_mutex_lock(&cred->lock);
         if (cred->req_enctypes)
             free(cred->req_enctypes);
         cred->req_enctypes = NULL;
@@ -110,11 +108,7 @@ gss_krb5int_set_allowable_enctypes(OM_uint32 *minor_status,
         kerr = ENOMEM;
         goto error_out;
     }
-    kerr = k5_mutex_lock(&cred->lock);
-    if (kerr) {
-        free(new_ktypes);
-        goto error_out;
-    }
+    k5_mutex_lock(&cred->lock);
     if (cred->req_enctypes)
         free(cred->req_enctypes);
     cred->req_enctypes = new_ktypes;

src/lib/gssapi/krb5/val_cred.c

@@ -37,12 +37,7 @@ krb5_gss_validate_cred_1(OM_uint32 *minor_status, gss_cred_id_t cred_handle,
     krb5_principal princ;
 
     cred = (krb5_gss_cred_id_t) cred_handle;
-
-    code = k5_mutex_lock(&cred->lock);
-    if (code) {
-        *minor_status = code;
-        return GSS_S_FAILURE;
-    }
+    k5_mutex_lock(&cred->lock);
 
     if (cred->ccache && cred->expire != 0) {
         if ((code = krb5_cc_get_principal(context, cred->ccache, &princ))) {