1 files changed, 72 insertions, 0 deletions
diff --git a/src/core/lib/gpr/string_posix.cc b/src/core/lib/gpr/string_posix.cc
new file mode 100644
index 0000000000..8b818e39b9
--- /dev/null
+++ b/src/core/lib/gpr/string_posix.cc
@@ -0,0 +1,72 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#ifdef GPR_POSIX_STRING
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/string_util.h>
+
+int gpr_asprintf(char** strp, const char* format, ...) {
+  va_list args;
+  int ret;
+  char buf[64];
+  size_t strp_buflen;
+
+  /* Use a constant-sized buffer to determine the length. */
+  va_start(args, format);
+  ret = vsnprintf(buf, sizeof(buf), format, args);
+  va_end(args);
+  if (ret < 0) {
+    *strp = nullptr;
+    return -1;
+  }
+
+  /* Allocate a new buffer, with space for the NUL terminator. */
+  strp_buflen = (size_t)ret + 1;
+  if ((*strp = (char*)gpr_malloc(strp_buflen)) == nullptr) {
+    /* This shouldn't happen, because gpr_malloc() calls abort(). */
+    return -1;
+  }
+
+  /* Return early if we have all the bytes. */
+  if (strp_buflen <= sizeof(buf)) {
+    memcpy(*strp, buf, strp_buflen);
+    return ret;
+  }
+
+  /* Try again using the larger buffer. */
+  va_start(args, format);
+  ret = vsnprintf(*strp, strp_buflen, format, args);
+  va_end(args);
+  if ((size_t)ret == strp_buflen - 1) {
+    return ret;
+  }
+
+  /* This should never happen. */
+  gpr_free(*strp);
+  *strp = nullptr;
+  return -1;
+}
+
+#endif /* GPR_POSIX_STRING */