1 files changed, 86 insertions, 0 deletions
diff --git a/src/core/lib/support/string_posix.c b/src/core/lib/support/string_posix.c
new file mode 100644
index 0000000000..a73b3106a5
--- /dev/null
+++ b/src/core/lib/support/string_posix.c
@@ -0,0 +1,86 @@
+/*
+ *
+ * Copyright 2015-2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#ifdef GPR_POSIX_STRING
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <grpc/support/alloc.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 = NULL;
+    return -1;
+  }
+
+  /* Allocate a new buffer, with space for the NUL terminator. */
+  strp_buflen = (size_t)ret + 1;
+  if ((*strp = gpr_malloc(strp_buflen)) == NULL) {
+    /* 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 = NULL;
+  return -1;
+}
+
+#endif /* GPR_POSIX_STRING */