tpm_emulator: drop direct use of errno variable

The code tends to include errno into error messages after
tpm_util_test_tpmdev() and tpm_emulator_ctrlcmd() calls.

Both has error paths, where errno is not set, examples:

tpm_emulator_ctrlcmd()
  qemu_chr_fe_write_all()
    qemu_chr_write()
      replay_char_write_event_load()
        ...
        *res = replay_get_dword();
        ...

tpm_util_test_tpmdev()
  tpm_util_test()
    tpm_util_request()
      ...
      if (n != requestlen) {
          return -EFAULT;
      }
      ...

Both doesn't document that they set errno.

Let's drop these explicit usage of errno. If we need this information,
it should be added to errp deeper in the stack.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

backends/tpm/tpm_emulator.c

@@ -225,7 +225,7 @@ static int tpm_emulator_set_locality(TPMEmulator *tpm_emu, uint8_t locty_number,
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_LOCALITY, &loc,
                              sizeof(loc), sizeof(loc.u.resp.tpm_result),
                              sizeof(loc)) < 0) {
-        error_setg_errno(errp, errno, "tpm-emulator: could not set locality");
+        error_setg(errp, "tpm-emulator: could not set locality");
         return -1;
     }
 
@@ -263,7 +263,7 @@ static int tpm_emulator_probe_caps(TPMEmulator *tpm_emu)
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_GET_CAPABILITY, &cap_n, 0,
                              sizeof(cap_n.u.resp.tpm_result),
                              sizeof(cap_n)) < 0) {
-        error_report("tpm-emulator: probing failed : %s", strerror(errno));
+        error_report("tpm-emulator: probing failed");
         return -1;
     }
 
@@ -314,7 +314,7 @@ static int tpm_emulator_stop_tpm(TPMBackend *tb, Error **errp)
 
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_STOP, &res, 0,
                              sizeof(ptm_res), sizeof(res)) < 0) {
-        error_setg_errno(errp, errno, "tpm-emulator: Could not stop TPM");
+        error_setg(errp, "tpm-emulator: Could not stop TPM");
         return -1;
     }
 
@@ -342,8 +342,7 @@ static int tpm_emulator_lock_storage(TPMEmulator *tpm_emu)
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_LOCK_STORAGE, &pls, sizeof(pls.u.req),
                              sizeof(pls.u.resp.tpm_result),
                              sizeof(pls.u.resp)) < 0) {
-        error_report("tpm-emulator: Could not lock storage within 3 seconds: "
-                     "%s", strerror(errno));
+        error_report("tpm-emulator: Could not lock storage within 3 seconds");
         return -1;
     }
 
@@ -375,8 +374,7 @@ static int tpm_emulator_set_buffer_size(TPMBackend *tb,
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_BUFFERSIZE, &psbs,
                              sizeof(psbs.u.req), sizeof(psbs.u.resp.tpm_result),
                              sizeof(psbs.u.resp)) < 0) {
-        error_setg_errno(errp, errno,
-                         "tpm-emulator: Could not set buffer size");
+        error_setg(errp, "tpm-emulator: Could not set buffer size");
         return -1;
     }
 
@@ -424,7 +422,7 @@ static int tpm_emulator_startup_tpm_resume(TPMBackend *tb, size_t buffersize,
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_INIT, &init, sizeof(init),
                              sizeof(init.u.resp.tpm_result),
                              sizeof(init)) < 0) {
-        error_setg_errno(errp, errno, "tpm-emulator: could not send INIT");
+        error_setg(errp, "tpm-emulator: could not send INIT");
         goto err_exit;
     }
 
@@ -479,8 +477,7 @@ static bool tpm_emulator_get_tpm_established_flag(TPMBackend *tb)
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_GET_TPMESTABLISHED, &est, 0,
                              sizeof(est) /* always returns resp.bit */,
                              sizeof(est)) < 0) {
-        error_report("tpm-emulator: Could not get the TPM established flag: %s",
-                     strerror(errno));
+        error_report("tpm-emulator: Could not get the TPM established flag");
         return false;
     }
     trace_tpm_emulator_get_tpm_established_flag(est.u.resp.bit);
@@ -508,8 +505,7 @@ static int tpm_emulator_reset_tpm_established_flag(TPMBackend *tb,
                              &reset_est, sizeof(reset_est),
                              sizeof(reset_est.u.resp.tpm_result),
                              sizeof(reset_est)) < 0) {
-        error_report("tpm-emulator: Could not reset the establishment bit: %s",
-                     strerror(errno));
+        error_report("tpm-emulator: Could not reset the establishment bit");
         return -1;
     }
 
@@ -539,8 +535,7 @@ static void tpm_emulator_cancel_cmd(TPMBackend *tb)
     /* FIXME: make the function non-blocking, or it may block a VCPU */
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_CANCEL_TPM_CMD, &res, 0,
                              sizeof(ptm_res), sizeof(res)) < 0) {
-        error_report("tpm-emulator: Could not cancel command: %s",
-                     strerror(errno));
+        error_report("tpm-emulator: Could not cancel command");
     } else if (res != 0) {
         error_report("tpm-emulator: Failed to cancel TPM: 0x%x",
                      be32_to_cpu(res));
@@ -601,8 +596,7 @@ static int tpm_emulator_prepare_data_fd(TPMEmulator *tpm_emu)
 
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_DATAFD, &res, 0,
                              sizeof(ptm_res), sizeof(res)) < 0 || res != 0) {
-        error_report("tpm-emulator: Failed to send CMD_SET_DATAFD: %s",
-                     strerror(errno));
+        error_report("tpm-emulator: Failed to send CMD_SET_DATAFD");
         goto err_exit;
     }
 
@@ -659,8 +653,8 @@ static int tpm_emulator_handle_device_opts(TPMEmulator *tpm_emu, QemuOpts *opts)
      */
     if (tpm_util_test_tpmdev(QIO_CHANNEL_SOCKET(tpm_emu->data_ioc)->fd,
                              &tpm_emu->tpm_version)) {
-        error_report("'%s' is not emulating TPM device. Error: %s",
-                      tpm_emu->options->chardev, strerror(errno));
+        error_report("'%s' is not emulating TPM device.",
+                      tpm_emu->options->chardev);
         goto err;
     }
 
@@ -750,8 +744,7 @@ static int tpm_emulator_get_state_blob(TPMEmulator *tpm_emu,
                              /* always returns up to resp.data */
                              offsetof(ptm_getstate, u.resp.data),
                              offsetof(ptm_getstate, u.resp.data)) < 0) {
-        error_report("tpm-emulator: could not get state blob type %d : %s",
-                     type, strerror(errno));
+        error_report("tpm-emulator: could not get state blob type %d", type);
         return -1;
     }
 
@@ -853,9 +846,8 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
     /* write the header only */
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_STATEBLOB, &pss,
                              offsetof(ptm_setstate, u.req.data), 0, 0) < 0) {
-        error_setg_errno(errp, errno,
-                         "tpm-emulator: could not set state blob type %d",
-                         type);
+        error_setg(errp, "tpm-emulator: could not set state blob type %d",
+                   type);
         return -1;
     }
 
@@ -1037,8 +1029,7 @@ static void tpm_emulator_shutdown(TPMEmulator *tpm_emu)
 
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SHUTDOWN, &res, 0,
                              sizeof(ptm_res), sizeof(res)) < 0) {
-        error_report("tpm-emulator: Could not cleanly shutdown the TPM: %s",
-                     strerror(errno));
+        error_report("tpm-emulator: Could not cleanly shutdown the TPM");
     } else if (res != 0) {
         error_report("tpm-emulator: TPM result for shutdown: 0x%x %s",
                      be32_to_cpu(res), tpm_emulator_strerror(be32_to_cpu(res)));