scd:p15: Improve support for some CardOS based cards.

* scd/iso7816.c (iso7816_read_binary_ext): Add optional arg r_sw and
change callers.
(iso7816_read_record): Factor all code out to ...
(iso7816_read_record_ext): new.
* scd/app-p15.c (select_and_read_binary): Fallback to record reading.
(read_ef_aodf): Clear EOF error.

3 files changed, 68 insertions, 14 deletions

diff --git a/scd/app-p15.c b/scd/app-p15.c
index 602e97e2c..3737b85ca 100644
--- a/scd/app-p15.c
+++ b/scd/app-p15.c
@@ -466,6 +466,7 @@ select_and_read_binary (int slot, unsigned short efid, const char *efid_desc,
                         unsigned char **buffer, size_t *buflen)
 {
   gpg_error_t err;
+  int sw;
 
   err = iso7816_select_file (slot, efid, 0);
   if (err)
@@ -474,11 +475,33 @@ select_and_read_binary (int slot, unsigned short efid, const char *efid_desc,
                  efid_desc, efid, gpg_strerror (err));
       return err;
     }
-  err = iso7816_read_binary (slot, 0, 0, buffer, buflen);
-  if (err)
+
+  err = iso7816_read_binary_ext (slot, 0, 0, 0, buffer, buflen, &sw);
+  if (err && sw == 0x6981)
     {
-      log_error ("p15: error reading %s (0x%04X): %s\n",
-                 efid_desc, efid, gpg_strerror (err));
+      /* Command was not possible for file structure.  Try to read the
+       * first record instead.  */
+      err = iso7816_read_record_ext (slot, 1, 1, 0, buffer, buflen, &sw);
+      if (err)
+        {
+          log_error ("p15: error reading %s (0x%04X)"
+                     " after fallback to record mode: %s (sw=%04X)\n",
+                     efid_desc, efid, gpg_strerror (err), sw);
+          return err;
+        }
+      /* On a CardOS based card I noticed that the record started with
+       * a byte 0x01 followed by another byte with the length of the
+       * record.  Detect this here and remove this prefix.  */
+      if (*buflen > 2 && (*buffer)[0] == 1 && (*buffer)[1] == *buflen - 2)
+        {
+          memmove (*buffer, *buffer + 2, *buflen - 2);
+          *buflen = *buflen - 2;
+        }
+    }
+  else if (err)
+    {
+      log_error ("p15: error reading %s (0x%04X): %s (sw=%04X)\n",
+                 efid_desc, efid, gpg_strerror (err), sw);
       return err;
     }
   return 0;
@@ -2180,6 +2203,8 @@ read_ef_aodf (app_t app, unsigned short fid, aodf_object_t *result)
          extensions of pkcs#15. */
 
     ready:
+      if (gpg_err_code (err) == GPG_ERR_EOF)
+        err = 0;
       if (opt.verbose)
         {
           log_info ("p15: AODF %04hX: id=", fid);
@@ -2922,7 +2947,7 @@ readcert_by_cdf (app_t app, cdf_object_t cdf,
     goto leave;
 
   err = iso7816_read_binary_ext (app_get_slot (app), 1, cdf->off, cdf->len,
-                                 &buffer, &buflen);
+                                 &buffer, &buflen, NULL);
   if (!err && (!buflen || *buffer == 0xff))
     err = gpg_error (GPG_ERR_NOT_FOUND);
   if (err)
diff --git a/scd/iso7816.c b/scd/iso7816.c
index 5316d0b3b..ef02d64cc 100644
--- a/scd/iso7816.c
+++ b/scd/iso7816.c
@@ -875,13 +875,15 @@ iso7816_get_challenge (int slot, int length, unsigned char *buffer)
 }
 
 /* Perform a READ BINARY command requesting a maximum of NMAX bytes
-   from OFFSET.  With NMAX = 0 the entire file is read. The result is
-   stored in a newly allocated buffer at the address passed by RESULT.
-   Returns the length of this data at the address of RESULTLEN. */
+ * from OFFSET.  With NMAX = 0 the entire file is read. The result is
+ * stored in a newly allocated buffer at the address passed by RESULT.
+ * Returns the length of this data at the address of RESULTLEN.  If
+ * R_SW is not NULL the last status word is stored there. */
 gpg_error_t
 iso7816_read_binary_ext (int slot, int extended_mode,
                          size_t offset, size_t nmax,
-                         unsigned char **result, size_t *resultlen)
+                         unsigned char **result, size_t *resultlen,
+                         int *r_sw)
 {
   int sw;
   unsigned char *buffer;
@@ -889,6 +891,9 @@ iso7816_read_binary_ext (int slot, int extended_mode,
   int read_all = !nmax;
   size_t n;
 
+  if (r_sw)
+    *r_sw = 0;
+
   if (!result || !resultlen)
     return gpg_error (GPG_ERR_INV_VALUE);
   *result = NULL;
@@ -914,6 +919,8 @@ iso7816_read_binary_ext (int slot, int extended_mode,
                              ((offset>>8) & 0xff), (offset & 0xff) , -1, NULL,
                              n, &buffer, &bufferlen);
         }
+      if (r_sw)
+        *r_sw = sw;
 
       if (*result && sw == SW_BAD_P0_P1)
         {
@@ -974,7 +981,8 @@ gpg_error_t
 iso7816_read_binary (int slot, size_t offset, size_t nmax,
                      unsigned char **result, size_t *resultlen)
 {
-  return iso7816_read_binary_ext (slot, 0, offset, nmax, result, resultlen);
+  return iso7816_read_binary_ext (slot, 0, offset, nmax,
+                                  result, resultlen, NULL);
 }
 
 
@@ -984,15 +992,20 @@ iso7816_read_binary (int slot, size_t offset, size_t nmax,
    should be 0 to read the current EF or contain a short EF. The
    result is stored in a newly allocated buffer at the address passed
    by RESULT.  Returns the length of this data at the address of
-   RESULTLEN. */
+   RESULTLEN.  If R_SW is not NULL the last status word is stored
+   there.  */
 gpg_error_t
-iso7816_read_record (int slot, int recno, int reccount, int short_ef,
-                     unsigned char **result, size_t *resultlen)
+iso7816_read_record_ext (int slot, int recno, int reccount, int short_ef,
+                         unsigned char **result, size_t *resultlen,
+                         int *r_sw)
 {
   int sw;
   unsigned char *buffer;
   size_t bufferlen;
 
+  if (r_sw)
+    *r_sw = 0;
+
   if (!result || !resultlen)
     return gpg_error (GPG_ERR_INV_VALUE);
   *result = NULL;
@@ -1011,6 +1024,8 @@ iso7816_read_record (int slot, int recno, int reccount, int short_ef,
                      short_ef? short_ef : 0x04,
                      -1, NULL,
                      0, &buffer, &bufferlen);
+  if (r_sw)
+    *r_sw = sw;
 
   if (sw != SW_SUCCESS && sw != SW_EOF_REACHED)
     {
@@ -1028,6 +1043,15 @@ iso7816_read_record (int slot, int recno, int reccount, int short_ef,
 }
 
 
+gpg_error_t
+iso7816_read_record (int slot, int recno, int reccount, int short_ef,
+                     unsigned char **result, size_t *resultlen)
+{
+  return iso7816_read_record_ext (slot, recno, reccount, short_ef,
+                                  result, resultlen, NULL);
+}
+
+
 /* Perform an UPDATE BINARY command on card in SLOT.  Write DATA of
  * length DATALEN to a transparent file at OFFSET.  */
 gpg_error_t
diff --git a/scd/iso7816.h b/scd/iso7816.h
index 10a1aa8d1..d68ee57f2 100644
--- a/scd/iso7816.h
+++ b/scd/iso7816.h
@@ -142,9 +142,14 @@ gpg_error_t iso7816_get_challenge (int slot,
 
 gpg_error_t iso7816_read_binary_ext (int slot, int extended_mode,
                                      size_t offset, size_t nmax,
-                                     unsigned char **result, size_t *resultlen);
+                                     unsigned char **result, size_t *resultlen,
+                                     int *r_sw);
 gpg_error_t iso7816_read_binary (int slot, size_t offset, size_t nmax,
                                  unsigned char **result, size_t *resultlen);
+gpg_error_t iso7816_read_record_ext (int slot, int recno, int reccount,
+                                     int short_ef,
+                                     unsigned char **result, size_t *resultlen,
+                                     int *r_sw);
 gpg_error_t iso7816_read_record (int slot, int recno, int reccount,
                                  int short_ef,
                                  unsigned char **result, size_t *resultlen);