util: A generic function to convert error to string for windows.

More users will be added in an upcoming commit. Signed-off-by: Gurucharan Shetty <[email protected]> Acked-by: Ben Pfaff <[email protected]>
dkarhi · Jan 28, 2014 · 06f14c9 · 06f14c9
1 parent 9d0581f
commit 06f14c9
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Showing 3 changed files with 22 additions and 11 deletions.
diff --git a/lib/entropy.c b/lib/entropy.c
@@ -56,22 +56,12 @@ get_entropy(void *buffer, size_t n)
 #else
     int error = 0;
     HCRYPTPROV   crypt_prov = 0;
-    LPVOID msg_buf;
 
     CryptAcquireContext(&crypt_prov, NULL, NULL,
                         PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
     if (!CryptGenRandom(crypt_prov, n, buffer)) {
+        char *msg_buf = ovs_lasterror_to_string();
         error = EINVAL;
-        FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER
-                      | FORMAT_MESSAGE_FROM_SYSTEM
-                      | FORMAT_MESSAGE_IGNORE_INSERTS,
-                      NULL,
-                      GetLastError(),
-                      0,
-                      (LPTSTR)&msg_buf,
-                      0,
-                      NULL
-            );
         VLOG_ERR("CryptGenRandom: read error (%s)", msg_buf);
         LocalFree(msg_buf);
     }

diff --git a/lib/util.c b/lib/util.c
@@ -1649,3 +1649,19 @@ ovs_scan(const char *s, const char *format, ...)
     return ok;
 }
 
+#ifdef _WIN32
+
+/* Calls FormatMessage() with GetLastError() as an argument. Returns
+ * pointer to a buffer that receives the null-terminated string that specifies
+ * the formatted message and that has to be freed by the caller with
+ * LocalFree(). */
+char *
+ovs_lasterror_to_string(void)
+{
+    char *buffer;
+    FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM
+                  | FORMAT_MESSAGE_IGNORE_INSERTS, NULL, GetLastError(), 0,
+                  (char *)&buffer, 0, NULL);
+    return buffer;
+}
+#endif
diff --git a/lib/util.h b/lib/util.h
@@ -490,6 +490,11 @@ void bitwise_put(uint64_t value,
 uint64_t bitwise_get(const void *src, unsigned int src_len,
                      unsigned int src_ofs, unsigned int n_bits);
 
+#ifdef _WIN32
+
+char *ovs_lasterror_to_string(void);
+#endif
+
 #ifdef  __cplusplus
 }
 #endif