[libc] Add printf error handling

libc/include/llvm-libc-macros/generic-error-number-macros.h

@@ -43,6 +43,7 @@
 #define EPIPE 32
 #define EDOM 33
 #define ERANGE 34
+#define EOVERFLOW 75
 #define EILSEQ 84
 
 #endif // LLVM_LIBC_MACROS_GENERIC_ERROR_NUMBER_MACROS_H

libc/src/stdio/CMakeLists.txt

@@ -125,6 +125,9 @@ add_entrypoint_object(
   DEPENDS
     libc.src.stdio.printf_core.printf_main
     libc.src.stdio.printf_core.writer
+    libc.src.stdio.printf_core.core_structs
+    libc.src.__support.libc_errno
+    libc.hdr.errno_macros
 )
 
 add_entrypoint_object(
@@ -136,6 +139,9 @@ add_entrypoint_object(
   DEPENDS
     libc.src.stdio.printf_core.printf_main
     libc.src.stdio.printf_core.writer
+    libc.src.stdio.printf_core.core_structs
+    libc.src.__support.libc_errno
+    libc.hdr.errno_macros
 )
 
 add_entrypoint_object(
@@ -146,6 +152,9 @@ add_entrypoint_object(
     asprintf.h
   DEPENDS
     libc.src.stdio.printf_core.vasprintf_internal
+    libc.src.stdio.printf_core.core_structs
+    libc.src.__support.libc_errno
+    libc.hdr.errno_macros
 )
 
 add_entrypoint_object(
@@ -157,6 +166,7 @@ add_entrypoint_object(
   DEPENDS
     libc.src.stdio.printf_core.printf_main
     libc.src.stdio.printf_core.writer
+    libc.src.stdio.printf_core.core_structs
 )
 
 add_entrypoint_object(
@@ -168,6 +178,9 @@ add_entrypoint_object(
   DEPENDS
     libc.src.stdio.printf_core.printf_main
     libc.src.stdio.printf_core.writer
+    libc.src.stdio.printf_core.core_structs
+    libc.src.__support.libc_errno
+    libc.hdr.errno_macros
 )
 
 add_entrypoint_object(
@@ -178,6 +191,9 @@ add_entrypoint_object(
     vasprintf.h
   DEPENDS
     libc.src.stdio.printf_core.vasprintf_internal
+    libc.src.stdio.printf_core.core_structs
+    libc.src.__support.libc_errno
+    libc.hdr.errno_macros
 )
 
 add_subdirectory(printf_core)

libc/src/stdio/asprintf.cpp

@@ -7,7 +7,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/stdio/asprintf.h"
+#include "hdr/errno_macros.h"
 #include "src/__support/arg_list.h"
+#include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
 #include "src/stdio/printf_core/vasprintf_internal.h"
 
@@ -22,8 +24,17 @@ LLVM_LIBC_FUNCTION(int, asprintf,
                                  // and pointer semantics, as well as handling
                                  // destruction automatically.
   va_end(vlist);
-  int ret = printf_core::vasprintf_internal(buffer, format, args);
-  return ret;
+  auto ret_val = printf_core::vasprintf_internal(buffer, format, args);
+  if (!ret_val.has_value()) {
+    libc_errno = printf_core::internal_error_to_errno(ret_val.error());
+    return -1;
+  }
+  if (ret_val.value() > cpp::numeric_limits<int>::max()) {
+    libc_errno = EOVERFLOW;
+    return -1;
+  }
+
+  return static_cast<int>(ret_val.value());
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/stdio/baremetal/CMakeLists.txt

@@ -31,6 +31,7 @@ add_entrypoint_object(
     libc.src.stdio.printf_core.writer
     libc.src.__support.arg_list
     libc.src.__support.OSUtil.osutil
+    libc.src.__support.libc_errno
 )
 
 add_entrypoint_object(
@@ -89,6 +90,7 @@ add_entrypoint_object(
     libc.src.stdio.printf_core.writer
     libc.src.__support.arg_list
     libc.src.__support.OSUtil.osutil
+    libc.src.__support.libc_errno
 )
 
 add_entrypoint_object(

libc/src/stdio/baremetal/printf.cpp

@@ -9,6 +9,7 @@
 #include "src/stdio/printf.h"
 #include "src/__support/OSUtil/io.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/printf_main.h"
@@ -42,13 +43,24 @@ LLVM_LIBC_FUNCTION(int, printf, (const char *__restrict format, ...)) {
       buffer, BUFF_SIZE, &stdout_write_hook, nullptr);
   printf_core::Writer<printf_core::WriteMode::FLUSH_TO_STREAM> writer(wb);
 
-  int retval = printf_core::printf_main(&writer, format, args);
+  auto retval = printf_core::printf_main(&writer, format, args);
+  if (!retval.has_value()) {
+    libc_errno = printf_core::internal_error_to_errno(retval.error());
+    return -1;
+  }
 
   int flushval = wb.overflow_write("");
-  if (flushval != printf_core::WRITE_OK)
-    retval = flushval;
+  if (flushval != printf_core::WRITE_OK) {
+    libc_errno = printf_core::internal_error_to_errno(-flushval);
+    return -1;
+  }
 
-  return retval;
+  if (retval.value() > cpp::numeric_limits<int>::max()) {
+    libc_errno = EOVERFLOW;
+    return -1;
+  }
+
+  return static_cast<int>(retval.value());
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/stdio/baremetal/vprintf.cpp

@@ -7,8 +7,10 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/stdio/vprintf.h"
+#include "hdr/errno_macros.h"
 #include "src/__support/OSUtil/io.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/printf_main.h"
@@ -40,13 +42,24 @@ LLVM_LIBC_FUNCTION(int, vprintf,
       buffer, BUFF_SIZE, &stdout_write_hook, nullptr);
   printf_core::Writer<printf_core::WriteMode::FLUSH_TO_STREAM> writer(wb);
 
-  int retval = printf_core::printf_main(&writer, format, args);
+  auto retval = printf_core::printf_main(&writer, format, args);
+  if (!retval.has_value()) {
+    libc_errno = printf_core::internal_error_to_errno(retval.error());
+    return -1;
+  }
 
   int flushval = wb.overflow_write("");
-  if (flushval != printf_core::WRITE_OK)
-    retval = flushval;
+  if (flushval != printf_core::WRITE_OK) {
+    libc_errno = printf_core::internal_error_to_errno(-flushval);
+    return -1;
+  }
 
-  return retval;
+  if (retval.value() > cpp::numeric_limits<int>::max()) {
+    libc_errno = EOVERFLOW;
+    return -1;
+  }
+
+  return static_cast<int>(retval.value());
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/stdio/generic/CMakeLists.txt

@@ -394,6 +394,7 @@ list(APPEND fprintf_deps
       libc.hdr.types.FILE
       libc.src.__support.arg_list
       libc.src.stdio.printf_core.vfprintf_internal
+      libc.src.stdio.printf_core.core_structs
 )
 
 if(LLVM_LIBC_FULL_BUILD)

libc/src/stdio/generic/fprintf.cpp

@@ -27,8 +27,17 @@ LLVM_LIBC_FUNCTION(int, fprintf,
                                  // and pointer semantics, as well as handling
                                  // destruction automatically.
   va_end(vlist);
-  int ret_val = printf_core::vfprintf_internal(stream, format, args);
-  return ret_val;
+  auto ret_val = printf_core::vfprintf_internal(stream, format, args);
+  if (!ret_val.has_value()) {
+    libc_errno = printf_core::internal_error_to_errno(ret_val.error());
+    return -1;
+  }
+  if (ret_val.value() > cpp::numeric_limits<int>::max()) {
+    libc_errno = EOVERFLOW;
+    return -1;
+  }
+
+  return static_cast<int>(ret_val.value());
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/stdio/generic/printf.cpp

@@ -11,6 +11,7 @@
 #include "src/__support/File/file.h"
 #include "src/__support/arg_list.h"
 #include "src/__support/macros/config.h"
+#include "src/stdio/printf_core/core_structs.h"
 #include "src/stdio/printf_core/vfprintf_internal.h"
 
 #include "hdr/types/FILE.h"
@@ -31,9 +32,18 @@ LLVM_LIBC_FUNCTION(int, printf, (const char *__restrict format, ...)) {
                                  // and pointer semantics, as well as handling
                                  // destruction automatically.
   va_end(vlist);
-  int ret_val = printf_core::vfprintf_internal(
+  auto ret_val = printf_core::vfprintf_internal(
       reinterpret_cast<::FILE *>(PRINTF_STDOUT), format, args);
-  return ret_val;
+  if (!ret_val.has_value()) {
+    libc_errno = printf_core::internal_error_to_errno(ret_val.error());
+    return -1;
+  }
+  if (ret_val.value() > cpp::numeric_limits<int>::max()) {
+    libc_errno = EOVERFLOW;
+    return -1;
+  }
+
+  return static_cast<int>(ret_val.value());
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/stdio/generic/vfprintf.cpp

@@ -11,6 +11,7 @@
 #include "src/__support/File/file.h"
 #include "src/__support/arg_list.h"
 #include "src/__support/macros/config.h"
+#include "src/stdio/printf_core/core_structs.h"
 #include "src/stdio/printf_core/vfprintf_internal.h"
 
 #include "hdr/types/FILE.h"
@@ -24,8 +25,17 @@ LLVM_LIBC_FUNCTION(int, vfprintf,
   internal::ArgList args(vlist); // This holder class allows for easier copying
                                  // and pointer semantics, as well as handling
                                  // destruction automatically.
-  int ret_val = printf_core::vfprintf_internal(stream, format, args);
-  return ret_val;
+  auto ret_val = printf_core::vfprintf_internal(stream, format, args);
+  if (!ret_val.has_value()) {
+    libc_errno = printf_core::internal_error_to_errno(ret_val.error());
+    return -1;
+  }
+  if (ret_val.value() > cpp::numeric_limits<int>::max()) {
+    libc_errno = EOVERFLOW;
+    return -1;
+  }
+
+  return static_cast<int>(ret_val.value());
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/stdio/generic/vprintf.cpp

@@ -29,9 +29,18 @@ LLVM_LIBC_FUNCTION(int, vprintf,
   internal::ArgList args(vlist); // This holder class allows for easier copying
                                  // and pointer semantics, as well as handling
                                  // destruction automatically.
-  int ret_val = printf_core::vfprintf_internal(
+  auto ret_val = printf_core::vfprintf_internal(
       reinterpret_cast<::FILE *>(PRINTF_STDOUT), format, args);
-  return ret_val;
+  if (!ret_val.has_value()) {
+    libc_errno = printf_core::internal_error_to_errno(ret_val.error());
+    return -1;
+  }
+  if (ret_val.value() > cpp::numeric_limits<int>::max()) {
+    libc_errno = EOVERFLOW;
+    return -1;
+  }
+
+  return static_cast<int>(ret_val.value());
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/stdio/printf_core/CMakeLists.txt

@@ -47,6 +47,7 @@ add_header_library(
     libc.include.inttypes
     libc.src.__support.CPP.string_view
     libc.src.__support.FPUtil.fp_bits
+    libc.hdr.errno_macros
 )
 
 add_header_library(
@@ -125,6 +126,7 @@ add_header_library(
     .writer
     .core_structs
     libc.src.__support.arg_list
+    libc.src.__support.error_or
 )
 
 add_header_library(
@@ -136,6 +138,7 @@ add_header_library(
     libc.hdr.func.free
     libc.hdr.func.realloc
     libc.src.__support.arg_list
+    libc.src.__support.error_or
     libc.src.stdio.printf_core.printf_main
     libc.src.stdio.printf_core.writer
 )
@@ -152,6 +155,7 @@ add_header_library(
     vfprintf_internal.h
   DEPENDS
     libc.src.__support.File.file
+    libc.src.__support.error_or
     libc.src.__support.arg_list
     libc.src.stdio.printf_core.printf_main
     libc.src.stdio.printf_core.writer

libc/src/stdio/printf_core/core_structs.h

@@ -11,6 +11,7 @@
 
 #include "src/__support/macros/config.h"
 
+#include "hdr/errno_macros.h"
 #include "src/__support/CPP/string_view.h"
 #include "src/__support/CPP/type_traits.h"
 #include "src/__support/FPUtil/FPBits.h"
@@ -132,14 +133,46 @@ template <typename T> LIBC_INLINE constexpr TypeDesc type_desc_from_type() {
 
 // This is the value to be returned by conversions when no error has occurred.
 constexpr int WRITE_OK = 0;
-// These are the printf return values for when an error has occurred. They are
-// all negative, and should be distinct.
-constexpr int FILE_WRITE_ERROR = -1;
-constexpr int FILE_STATUS_ERROR = -2;
-constexpr int NULLPTR_WRITE_ERROR = -3;
-constexpr int INT_CONVERSION_ERROR = -4;
-constexpr int FIXED_POINT_CONVERSION_ERROR = -5;
-constexpr int ALLOCATION_ERROR = -6;
+// These are the error return values used by the printf engine when an
+// error has occurred. They are all large negative, distinct values starting
+// from -1000 to not overlap with system errors.
+constexpr int FILE_WRITE_ERROR = -1001;
+constexpr int FILE_STATUS_ERROR = -1002;
+constexpr int NULLPTR_WRITE_ERROR = -1003;
+constexpr int INT_CONVERSION_ERROR = -1004;
+constexpr int FIXED_POINT_CONVERSION_ERROR = -1005;
+constexpr int ALLOCATION_ERROR = -1006;
+
+LIBC_INLINE static int internal_error_to_errno(int internal_error) {
+  // System error occured, return error as is.
+  if (internal_error < 1001) {
+    return internal_error;
+  }
+
+  // Map internal error to errno.
+  switch (-internal_error) {
+  case WRITE_OK:
+    return 0;
+  case FILE_WRITE_ERROR:
+    return EIO;
+  case FILE_STATUS_ERROR:
+    return EIO;
+  case NULLPTR_WRITE_ERROR:
+    return EINVAL;
+  case INT_CONVERSION_ERROR:
+    return ERANGE;
+  case FIXED_POINT_CONVERSION_ERROR:
+    return EINVAL;
+  case ALLOCATION_ERROR:
+    return ENOMEM;
+  default:
+    LIBC_ASSERT(
+        false &&
+        "Invalid internal printf error code passed to internal_error_to_errno");
+    return EINVAL;
+  }
+}
+
 } // namespace printf_core
 } // namespace LIBC_NAMESPACE_DECL
 

libc/src/stdio/printf_core/int_converter.h

@@ -9,6 +9,7 @@
 #ifndef LLVM_LIBC_SRC_STDIO_PRINTF_CORE_INT_CONVERTER_H
 #define LLVM_LIBC_SRC_STDIO_PRINTF_CORE_INT_CONVERTER_H
 
+#include "hdr/errno_macros.h"
 #include "src/__support/CPP/span.h"
 #include "src/__support/CPP/string_view.h"
 #include "src/__support/ctype_utils.h"