[libc] Add printf error handling (with fixes #2) (#166517)

https://github.com/llvm/llvm-project/issues/159474

Another try of trying to land
https://github.com/llvm/llvm-project/pull/166382
- Fix some leftover tests checking for specific  errnos
- Guard errno checking tests to not run on the GPU

@michaelrj-google

1 files changed, 15 insertions, 2 deletions

diff --git a/libc/src/stdio/vsprintf.cpp b/libc/src/stdio/vsprintf.cpp
index 26d497be4212..f9cf8118534f 100644
--- a/libc/src/stdio/vsprintf.cpp
+++ b/libc/src/stdio/vsprintf.cpp
@@ -10,7 +10,10 @@
 
 #include "src/__support/CPP/limits.h"
 #include "src/__support/arg_list.h"
+#include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
+#include "src/stdio/printf_core/core_structs.h"
+#include "src/stdio/printf_core/error_mapper.h"
 #include "src/stdio/printf_core/printf_main.h"
 #include "src/stdio/printf_core/writer.h"
 
@@ -30,9 +33,19 @@ LLVM_LIBC_FUNCTION(int, vsprintf,
       wb(buffer, cpp::numeric_limits<size_t>::max());
   printf_core::Writer writer(wb);
 
-  int ret_val = printf_core::printf_main(&writer, format, args);
+  auto ret_val = printf_core::printf_main(&writer, format, args);
+  if (!ret_val.has_value()) {
+    libc_errno = printf_core::internal_error_to_errno(ret_val.error());
+    return -1;
+  }
   wb.buff[wb.buff_cur] = '\0';
-  return ret_val;
+
+  if (ret_val.value() > static_cast<size_t>(cpp::numeric_limits<int>::max())) {
+    libc_errno =
+        printf_core::internal_error_to_errno(-printf_core::OVERFLOW_ERROR);
+    return -1;
+  }
+  return static_cast<int>(ret_val.value());
 }
 
 } // namespace LIBC_NAMESPACE_DECL