[libc] Add vasprintf function

[izaakschroeder]

Needs proper implementation, but the stubs are here.

See:

• https://linux.die.net/man/3/vasprintf
• https://android.googlesource.com/platform/bionic/+/froyo-release/libc/stdio/vasprintf.c

[llvmbot]

@llvm/pr-subscribers-libc

Author: Izaak Schroeder (izaakschroeder)

Changes

Needs proper implementation, but the stubs are here.

---

Full diff: https://github.com/llvm/llvm-project/pull/97528.diff

4 Files Affected:

• (modified) libc/spec/stdc.td (+7)
• (modified) libc/src/stdio/CMakeLists.txt (+10)
• (added) libc/src/stdio/vasprintf.cpp (+27)
• (added) libc/src/stdio/vasprintf.h (+22)

diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
index 9ff40bf76700c..6902bbfe14417 100644
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -968,6 +968,13 @@ def StdC : StandardSpec<"stdc"> {
               RetValSpec<IntType>,
               [ArgSpec<IntType>, ArgSpec<FILEPtr>]
           >,
+          FunctionSpec<
+              "vasprintf",
+              RetValSpec<IntType>,
+              [ArgSpec<CharRestrictedPtrPtr>,
+               ArgSpec<ConstCharPtr>,
+               ArgSpec<VaListType>]
+          >,
       ],
       [
           ObjectSpec<
diff --git a/libc/src/stdio/CMakeLists.txt b/libc/src/stdio/CMakeLists.txt
index a659d9e847a9e..300a97ca4377a 100644
--- a/libc/src/stdio/CMakeLists.txt
+++ b/libc/src/stdio/CMakeLists.txt
@@ -203,6 +203,16 @@ add_entrypoint_object(
     libc.src.stdio.printf_core.vfprintf_internal
 )
 
+add_entrypoint_object(
+  vasprintf
+  SRCS
+    vasprintf.cpp
+  HDRS
+    vasprintf.h
+  DEPENDS
+    libc.src.__support.arg_list
+)
+
 add_stdio_entrypoint_object(
   fileno
   SRCS
diff --git a/libc/src/stdio/vasprintf.cpp b/libc/src/stdio/vasprintf.cpp
new file mode 100644
index 0000000000000..d625d98e83706
--- /dev/null
+++ b/libc/src/stdio/vasprintf.cpp
@@ -0,0 +1,27 @@
+//===-- Implementation of vasprintf -----------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdio/vasprintf.h"
+
+#include "src/__support/arg_list.h"
+
+#include <stdarg.h>
+#include <stdio.h>
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(int, vasprintf,
+                   (char **__restrict, const char *,
+                    va_list vlist)) {
+  internal::ArgList args(vlist); // This holder class allows for easier copying
+                                 // and pointer semantics, as well as handling
+                                 // destruction automatically.
+  return -1;
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdio/vasprintf.h b/libc/src/stdio/vasprintf.h
new file mode 100644
index 0000000000000..f9b1d85ef81fb
--- /dev/null
+++ b/libc/src/stdio/vasprintf.h
@@ -0,0 +1,22 @@
+//===-- Implementation header of vasprintf ----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STDIO_VASPRINTF_H
+#define LLVM_LIBC_SRC_STDIO_VASPRINTF_H
+
+#include <stdarg.h>
+#include <stdio.h>
+
+namespace LIBC_NAMESPACE {
+
+int vasprintf(char **__restrict s, const char * format,
+             va_list vlist);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDIO_VASPRINTF_H

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[nickdesaulniers]

Thanks for the patch! Sorry we missed code reviewing this (I was on paternity leave).

Looks like vasprintf got implemented in a5e67fb, so closing this PR.