Fixes error and exit paths in rsa sample programs
diff --git a/programs/pkey/rsa_decrypt.c b/programs/pkey/rsa_decrypt.c
index 37227e8..5bfe332 100644
--- a/programs/pkey/rsa_decrypt.c
+++ b/programs/pkey/rsa_decrypt.c
@@ -30,6 +30,9 @@
 #else
 #include <stdio.h>
 #define mbedtls_printf     printf
+#define mbedtls_exit       exit
+#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
+#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
 #endif
 
 #if defined(MBEDTLS_BIGNUM_C) && defined(MBEDTLS_RSA_C) && \
@@ -39,8 +42,8 @@
 #include "mbedtls/entropy.h"
 #include "mbedtls/ctr_drbg.h"
 
-#include <stdio.h>
 #include <string.h>
+
 #endif
 
 #if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_RSA_C) ||  \
@@ -57,7 +60,7 @@
 int main( int argc, char *argv[] )
 {
     FILE *f;
-    int ret, c;
+    int return_val, exit_val, c;
     size_t i;
     mbedtls_rsa_context rsa;
     mbedtls_entropy_context entropy;
@@ -68,10 +71,7 @@
     ((void) argv);
 
     memset(result, 0, sizeof( result ) );
-    mbedtls_ctr_drbg_init( &ctr_drbg );
-    mbedtls_entropy_init( &entropy );
-    mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 );
-    ret = 1;
+    exit_val = MBEDTLS_EXIT_SUCCESS;
 
     if( argc != 1 )
     {
@@ -81,17 +81,23 @@
         mbedtls_printf( "\n" );
 #endif
 
-        goto exit;
+        mbedtls_exit( MBEDTLS_EXIT_FAILURE );
     }
 
     mbedtls_printf( "\n  . Seeding the random number generator..." );
     fflush( stdout );
 
-    if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
-                               (const unsigned char *) pers,
-                               strlen( pers ) ) ) != 0 )
+    mbedtls_ctr_drbg_init( &ctr_drbg );
+    mbedtls_entropy_init( &entropy );
+
+    return_val = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func,
+                                        &entropy, (const unsigned char *) pers,
+                                        strlen( pers ) );
+    if( return_val != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_ctr_drbg_seed returned %d\n", ret );
+        exit_val = MBEDTLS_EXIT_FAILURE;
+        mbedtls_printf( " failed\n  ! mbedtls_ctr_drbg_seed returned %d\n",
+                        return_val );
         goto exit;
     }
 
@@ -100,21 +106,24 @@
 
     if( ( f = fopen( "rsa_priv.txt", "rb" ) ) == NULL )
     {
+        exit_val = MBEDTLS_EXIT_FAILURE;
         mbedtls_printf( " failed\n  ! Could not open rsa_priv.txt\n" \
                 "  ! Please run rsa_genkey first\n\n" );
         goto exit;
     }
 
-    if( ( ret = mbedtls_mpi_read_file( &rsa.N , 16, f ) ) != 0 ||
-        ( ret = mbedtls_mpi_read_file( &rsa.E , 16, f ) ) != 0 ||
-        ( ret = mbedtls_mpi_read_file( &rsa.D , 16, f ) ) != 0 ||
-        ( ret = mbedtls_mpi_read_file( &rsa.P , 16, f ) ) != 0 ||
-        ( ret = mbedtls_mpi_read_file( &rsa.Q , 16, f ) ) != 0 ||
-        ( ret = mbedtls_mpi_read_file( &rsa.DP, 16, f ) ) != 0 ||
-        ( ret = mbedtls_mpi_read_file( &rsa.DQ, 16, f ) ) != 0 ||
-        ( ret = mbedtls_mpi_read_file( &rsa.QP, 16, f ) ) != 0 )
+    if( ( return_val = mbedtls_mpi_read_file( &rsa.N , 16, f ) ) != 0 ||
+        ( return_val = mbedtls_mpi_read_file( &rsa.E , 16, f ) ) != 0 ||
+        ( return_val = mbedtls_mpi_read_file( &rsa.D , 16, f ) ) != 0 ||
+        ( return_val = mbedtls_mpi_read_file( &rsa.P , 16, f ) ) != 0 ||
+        ( return_val = mbedtls_mpi_read_file( &rsa.Q , 16, f ) ) != 0 ||
+        ( return_val = mbedtls_mpi_read_file( &rsa.DP, 16, f ) ) != 0 ||
+        ( return_val = mbedtls_mpi_read_file( &rsa.DQ, 16, f ) ) != 0 ||
+        ( return_val = mbedtls_mpi_read_file( &rsa.QP, 16, f ) ) != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_mpi_read_file returned %d\n\n", ret );
+        exit_val = MBEDTLS_EXIT_FAILURE;
+        mbedtls_printf( " failed\n  ! mbedtls_mpi_read_file returned %d\n\n",
+                        return_val );
         goto exit;
     }
 
@@ -125,10 +134,9 @@
     /*
      * Extract the RSA encrypted value from the text file
      */
-    ret = 1;
-
     if( ( f = fopen( "result-enc.txt", "rb" ) ) == NULL )
     {
+        exit_val = MBEDTLS_EXIT_FAILURE;
         mbedtls_printf( "\n  ! Could not open %s\n\n", "result-enc.txt" );
         goto exit;
     }
@@ -143,6 +151,7 @@
 
     if( i != rsa.len )
     {
+        exit_val = MBEDTLS_EXIT_FAILURE;
         mbedtls_printf( "\n  ! Invalid RSA signature format\n\n" );
         goto exit;
     }
@@ -153,11 +162,14 @@
     mbedtls_printf( "\n  . Decrypting the encrypted data" );
     fflush( stdout );
 
-    if( ( ret = mbedtls_rsa_pkcs1_decrypt( &rsa, mbedtls_ctr_drbg_random, &ctr_drbg,
-                                   MBEDTLS_RSA_PRIVATE, &i, buf, result,
-                                   1024 ) ) != 0 )
+    return_val = mbedtls_rsa_pkcs1_decrypt( &rsa, mbedtls_ctr_drbg_random,
+                                            &ctr_drbg, MBEDTLS_RSA_PRIVATE, &i,
+                                            buf, result, 1024 );
+    if( return_val != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_rsa_pkcs1_decrypt returned %d\n\n", ret );
+        exit_val = MBEDTLS_EXIT_FAILURE;
+        mbedtls_printf( " failed\n  ! mbedtls_rsa_pkcs1_decrypt returned %d\n\n",
+                        return_val );
         goto exit;
     }
 
@@ -165,8 +177,6 @@
 
     mbedtls_printf( "The decrypted result is: '%s'\n\n", result );
 
-    ret = 0;
-
 exit:
     mbedtls_ctr_drbg_free( &ctr_drbg );
     mbedtls_entropy_free( &entropy );
@@ -177,6 +187,7 @@
     fflush( stdout ); getchar();
 #endif
 
-    return( ret );
+    return( exit_val );
 }
 #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_FS_IO */
+