[libc-commits] [libc] [libc] improve error handling and compiler hints (PR #109026)

[Michael Jones via libc-commits]

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@@ -9,17 +9,72 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_IO_H
 #define LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_IO_H
 
+#include "hdr/errno_macros.h"
 #include "src/__support/CPP/string_view.h"
 #include "src/__support/macros/config.h"
-#include "syscall.h" // For internal syscall function.
-
+#include "syscall.h"     // For internal syscall function.
 #include <sys/syscall.h> // For syscall numbers.
 
 namespace LIBC_NAMESPACE_DECL {
 
 LIBC_INLINE void write_to_stderr(cpp::string_view msg) {
-  LIBC_NAMESPACE::syscall_impl<long>(SYS_write, 2 /* stderr */, msg.data(),
-                                     msg.size());
+  size_t written = 0;
+  const char *msg_data = msg.data();
+  while (written != msg.size()) {
+    auto delta = LIBC_NAMESPACE::syscall_impl<long>(SYS_write, 2 /* stderr */,
+                                                    msg_data, msg.size());
+    // If the write syscall was interrupted, try again. Otherwise, this is an
+    // error routine, we do not handle further errors.
+    if (delta == -EINTR)
+      continue;
+    if (delta < 0)
+      return;
+    written += delta;
+    msg_data += delta;
+  }
+}
+
+template <size_t N>
+LIBC_INLINE void write_all_to_stderr(const cpp::string_view (&msgs)[N]) {
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michaelrj-google wrote:

I think we should consider this design carefully. If we add this function, then it needs to be added for every platform we support.

https://github.com/llvm/llvm-project/pull/109026