[libc-commits] [libc] [libc] Support for scanf on baremetal (PR #131043)
Petr Hosek via libc-commits
libc-commits at lists.llvm.org
Tue Mar 18 00:08:15 PDT 2025
https://github.com/petrhosek updated https://github.com/llvm/llvm-project/pull/131043
>From dee82741b51822fb0780b030b4f747e07d76e527 Mon Sep 17 00:00:00 2001
From: Petr Hosek <phosek at google.com>
Date: Wed, 12 Mar 2025 16:08:42 -0700
Subject: [PATCH 1/2] [libc] Support for scanf on baremetal
This uses the templatized scanf Reader interface introduced in #131037.
---
libc/config/baremetal/aarch64/entrypoints.txt | 6 +-
libc/config/baremetal/arm/entrypoints.txt | 6 +-
libc/config/baremetal/riscv/entrypoints.txt | 6 +-
libc/src/stdio/CMakeLists.txt | 58 ++-----------------
libc/src/stdio/baremetal/CMakeLists.txt | 26 +++++++++
libc/src/stdio/baremetal/scanf.cpp | 52 +++++++++++++++++
libc/src/stdio/baremetal/vscanf.cpp | 51 ++++++++++++++++
libc/src/stdio/generic/CMakeLists.txt | 54 +++++++++++++++++
libc/src/stdio/{ => generic}/fscanf.cpp | 0
libc/src/stdio/{ => generic}/scanf.cpp | 0
libc/src/stdio/{ => generic}/vfscanf.cpp | 0
libc/src/stdio/{ => generic}/vscanf.cpp | 0
libc/src/stdio/scanf_core/CMakeLists.txt | 9 +--
13 files changed, 201 insertions(+), 67 deletions(-)
create mode 100644 libc/src/stdio/baremetal/scanf.cpp
create mode 100644 libc/src/stdio/baremetal/vscanf.cpp
rename libc/src/stdio/{ => generic}/fscanf.cpp (100%)
rename libc/src/stdio/{ => generic}/scanf.cpp (100%)
rename libc/src/stdio/{ => generic}/vfscanf.cpp (100%)
rename libc/src/stdio/{ => generic}/vscanf.cpp (100%)
diff --git a/libc/config/baremetal/aarch64/entrypoints.txt b/libc/config/baremetal/aarch64/entrypoints.txt
index 2c226ef176c08..ffe7e622279a0 100644
--- a/libc/config/baremetal/aarch64/entrypoints.txt
+++ b/libc/config/baremetal/aarch64/entrypoints.txt
@@ -128,13 +128,15 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.stdio.putchar
libc.src.stdio.puts
libc.src.stdio.remove
+ libc.src.stdio.scanf
libc.src.stdio.snprintf
libc.src.stdio.sprintf
- libc.src.stdio.asprintf
+ libc.src.stdio.sscanf
libc.src.stdio.vprintf
+ libc.src.stdio.vscanf
libc.src.stdio.vsnprintf
libc.src.stdio.vsprintf
- libc.src.stdio.vasprintf
+ libc.src.stdio.vsscanf
# stdbit.h entrypoints
libc.src.stdbit.stdc_bit_ceil_uc
diff --git a/libc/config/baremetal/arm/entrypoints.txt b/libc/config/baremetal/arm/entrypoints.txt
index d7a01bdf90b3f..a6628d1c56219 100644
--- a/libc/config/baremetal/arm/entrypoints.txt
+++ b/libc/config/baremetal/arm/entrypoints.txt
@@ -128,13 +128,15 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.stdio.putchar
libc.src.stdio.puts
libc.src.stdio.remove
+ libc.src.stdio.scanf
libc.src.stdio.snprintf
libc.src.stdio.sprintf
- libc.src.stdio.asprintf
+ libc.src.stdio.sscanf
libc.src.stdio.vprintf
+ libc.src.stdio.vscanf
libc.src.stdio.vsnprintf
libc.src.stdio.vsprintf
- libc.src.stdio.vasprintf
+ libc.src.stdio.vsscanf
# stdbit.h entrypoints
libc.src.stdbit.stdc_bit_ceil_uc
diff --git a/libc/config/baremetal/riscv/entrypoints.txt b/libc/config/baremetal/riscv/entrypoints.txt
index ae00803dd0def..ccbcb85a216a8 100644
--- a/libc/config/baremetal/riscv/entrypoints.txt
+++ b/libc/config/baremetal/riscv/entrypoints.txt
@@ -124,13 +124,15 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.stdio.putchar
libc.src.stdio.puts
libc.src.stdio.remove
+ libc.src.stdio.scanf
libc.src.stdio.snprintf
libc.src.stdio.sprintf
- libc.src.stdio.asprintf
+ libc.src.stdio.sscanf
libc.src.stdio.vprintf
+ libc.src.stdio.vscanf
libc.src.stdio.vsnprintf
libc.src.stdio.vsprintf
- libc.src.stdio.vasprintf
+ libc.src.stdio.vsscanf
# stdbit.h entrypoints
libc.src.stdbit.stdc_bit_ceil_uc
diff --git a/libc/src/stdio/CMakeLists.txt b/libc/src/stdio/CMakeLists.txt
index b9bc904471df9..23c103c1d6465 100644
--- a/libc/src/stdio/CMakeLists.txt
+++ b/libc/src/stdio/CMakeLists.txt
@@ -95,20 +95,6 @@ add_entrypoint_object(
libc.src.__support.File.platform_file
)
-list(APPEND scanf_deps
- libc.src.__support.arg_list
- libc.src.stdio.scanf_core.vfscanf_internal
- libc.hdr.types.FILE
-)
-
-if(LLVM_LIBC_FULL_BUILD AND NOT LIBC_TARGET_OS_IS_GPU)
- list(APPEND scanf_deps
- libc.src.__support.File.file
- libc.src.__support.File.platform_file
- libc.src.__support.File.platform_stdin
- )
-endif()
-
add_entrypoint_object(
sscanf
SRCS
@@ -133,46 +119,6 @@ add_entrypoint_object(
libc.src.stdio.scanf_core.scanf_main
)
-add_entrypoint_object(
- fscanf
- SRCS
- fscanf.cpp
- HDRS
- fscanf.h
- DEPENDS
- ${scanf_deps}
-)
-
-add_entrypoint_object(
- vfscanf
- SRCS
- vfscanf.cpp
- HDRS
- vfscanf.h
- DEPENDS
- ${scanf_deps}
-)
-
-add_entrypoint_object(
- scanf
- SRCS
- scanf.cpp
- HDRS
- scanf.h
- DEPENDS
- ${scanf_deps}
-)
-
-add_entrypoint_object(
- vscanf
- SRCS
- vscanf.cpp
- HDRS
- vscanf.h
- DEPENDS
- ${scanf_deps}
-)
-
add_entrypoint_object(
sprintf
SRCS
@@ -295,8 +241,12 @@ add_stdio_entrypoint_object(getchar)
add_stdio_entrypoint_object(getchar_unlocked)
add_stdio_entrypoint_object(fgets)
add_stdio_entrypoint_object(ungetc)
+add_stdio_entrypoint_object(scanf)
+add_stdio_entrypoint_object(fscanf)
add_stdio_entrypoint_object(stdin)
add_stdio_entrypoint_object(stdout)
add_stdio_entrypoint_object(stderr)
add_stdio_entrypoint_object(vprintf)
add_stdio_entrypoint_object(vfprintf)
+add_stdio_entrypoint_object(vscanf)
+add_stdio_entrypoint_object(vfscanf)
diff --git a/libc/src/stdio/baremetal/CMakeLists.txt b/libc/src/stdio/baremetal/CMakeLists.txt
index c5cf4a8e0e5b5..4abe8bc66b25b 100644
--- a/libc/src/stdio/baremetal/CMakeLists.txt
+++ b/libc/src/stdio/baremetal/CMakeLists.txt
@@ -55,6 +55,19 @@ add_entrypoint_object(
libc.src.__support.CPP.string_view
)
+add_entrypoint_object(
+ scanf
+ SRCS
+ scanf.cpp
+ HDRS
+ ../scanf.h
+ DEPENDS
+ libc.src.stdio.scanf_core.scanf_main
+ libc.src.stdio.scanf_core.reader
+ libc.src.__support.arg_list
+ libc.src.__support.OSUtil.osutil
+)
+
add_entrypoint_object(
vprintf
SRCS
@@ -67,3 +80,16 @@ add_entrypoint_object(
libc.src.__support.arg_list
libc.src.__support.OSUtil.osutil
)
+
+add_entrypoint_object(
+ vscanf
+ SRCS
+ vscanf.cpp
+ HDRS
+ ../vscanf.h
+ DEPENDS
+ libc.src.stdio.scanf_core.scanf_main
+ libc.src.stdio.scanf_core.reader
+ libc.src.__support.arg_list
+ libc.src.__support.OSUtil.osutil
+)
diff --git a/libc/src/stdio/baremetal/scanf.cpp b/libc/src/stdio/baremetal/scanf.cpp
new file mode 100644
index 0000000000000..1b0bf3e3afd54
--- /dev/null
+++ b/libc/src/stdio/baremetal/scanf.cpp
@@ -0,0 +1,52 @@
+//===-- Implementation of scanf ---------------------------------*- 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/scanf.h"
+
+#include "hdr/stdio_macros.h"
+#include "src/__support/OSUtil/io.h"
+#include "src/__support/arg_list.h"
+#include "src/__support/macros/config.h"
+#include "src/stdio/scanf_core/reader.h"
+#include "src/stdio/scanf_core/scanf_main.h"
+
+#include <stdarg.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace {
+
+struct StreamBuffer : scanf_core::ReadBuffer<StreamBuffer> {
+ LIBC_INLINE char getc() {
+ char buf[1];
+ read_from_stdin(buf, sizeof(buf));
+ return buf[0];
+ }
+ LIBC_INLINE void ungetc(int) {}
+};
+
+} // namespace
+
+LLVM_LIBC_FUNCTION(int, scanf, (const char *__restrict format, ...)) {
+ va_list vlist;
+ va_start(vlist, format);
+ internal::ArgList args(vlist); // This holder class allows for easier copying
+ // and pointer semantics, as well as handling
+ // destruction automatically.
+ va_end(vlist);
+
+ StreamBuffer buffer;
+ scanf_core::Reader<StreamBuffer> reader(&buffer);
+
+ int retval = scanf_core::scanf_main(&reader, format, args);
+ // This is done to avoid including stdio.h in the internals. On most systems
+ // EOF is -1, so this will be transformed into just "return retval".
+ return (retval == -1) ? EOF : retval;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/stdio/baremetal/vscanf.cpp b/libc/src/stdio/baremetal/vscanf.cpp
new file mode 100644
index 0000000000000..e0119d6146d89
--- /dev/null
+++ b/libc/src/stdio/baremetal/vscanf.cpp
@@ -0,0 +1,51 @@
+//===-- Implementation of vscanf --------------------------------*- 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/vscanf.h"
+
+#include "hdr/stdio_macros.h"
+#include "src/__support/OSUtil/io.h"
+#include "src/__support/arg_list.h"
+#include "src/__support/macros/config.h"
+#include "src/stdio/scanf_core/reader.h"
+#include "src/stdio/scanf_core/scanf_main.h"
+
+#include <stdarg.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace {
+
+struct StreamBuffer : scanf_core::ReadBuffer<StreamBuffer> {
+ LIBC_INLINE char getc() {
+ char buf[1];
+ read_from_stdin(buf, sizeof(buf));
+ return buf[0];
+ }
+ LIBC_INLINE void ungetc(int) {}
+};
+
+} // namespace
+
+LLVM_LIBC_FUNCTION(int, vscanf,
+ (const char *__restrict format, va_list vlist)) {
+ internal::ArgList args(vlist); // This holder class allows for easier copying
+ // and pointer semantics, as well as handling
+ // destruction automatically.
+ va_end(vlist);
+
+ StreamBuffer buffer;
+ scanf_core::Reader<StreamBuffer> reader(&buffer);
+
+ int retval = scanf_core::scanf_main(&reader, format, args);
+ // This is done to avoid including stdio.h in the internals. On most systems
+ // EOF is -1, so this will be transformed into just "return retval".
+ return (retval == -1) ? EOF : retval;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/stdio/generic/CMakeLists.txt b/libc/src/stdio/generic/CMakeLists.txt
index bf301a6b0cb3c..9f568c5ab8d3a 100644
--- a/libc/src/stdio/generic/CMakeLists.txt
+++ b/libc/src/stdio/generic/CMakeLists.txt
@@ -425,6 +425,60 @@ add_entrypoint_object(
${fprintf_deps}
)
+list(APPEND scanf_deps
+ libc.src.__support.arg_list
+ libc.src.stdio.scanf_core.vfscanf_internal
+ libc.hdr.types.FILE
+)
+
+if(LLVM_LIBC_FULL_BUILD AND NOT LIBC_TARGET_OS_IS_GPU)
+ list(APPEND scanf_deps
+ libc.src.__support.File.file
+ libc.src.__support.File.platform_file
+ libc.src.__support.File.platform_stdin
+ )
+endif()
+
+add_entrypoint_object(
+ fscanf
+ SRCS
+ fscanf.cpp
+ HDRS
+ ../fscanf.h
+ DEPENDS
+ ${scanf_deps}
+)
+
+add_entrypoint_object(
+ vfscanf
+ SRCS
+ vfscanf.cpp
+ HDRS
+ ../vfscanf.h
+ DEPENDS
+ ${scanf_deps}
+)
+
+add_entrypoint_object(
+ scanf
+ SRCS
+ scanf.cpp
+ HDRS
+ ../scanf.h
+ DEPENDS
+ ${scanf_deps}
+)
+
+add_entrypoint_object(
+ vscanf
+ SRCS
+ vscanf.cpp
+ HDRS
+ ../vscanf.h
+ DEPENDS
+ ${scanf_deps}
+)
+
add_entrypoint_object(
fgets
SRCS
diff --git a/libc/src/stdio/fscanf.cpp b/libc/src/stdio/generic/fscanf.cpp
similarity index 100%
rename from libc/src/stdio/fscanf.cpp
rename to libc/src/stdio/generic/fscanf.cpp
diff --git a/libc/src/stdio/scanf.cpp b/libc/src/stdio/generic/scanf.cpp
similarity index 100%
rename from libc/src/stdio/scanf.cpp
rename to libc/src/stdio/generic/scanf.cpp
diff --git a/libc/src/stdio/vfscanf.cpp b/libc/src/stdio/generic/vfscanf.cpp
similarity index 100%
rename from libc/src/stdio/vfscanf.cpp
rename to libc/src/stdio/generic/vfscanf.cpp
diff --git a/libc/src/stdio/vscanf.cpp b/libc/src/stdio/generic/vscanf.cpp
similarity index 100%
rename from libc/src/stdio/vscanf.cpp
rename to libc/src/stdio/generic/vscanf.cpp
diff --git a/libc/src/stdio/scanf_core/CMakeLists.txt b/libc/src/stdio/scanf_core/CMakeLists.txt
index 014413ccaa8da..714b174892504 100644
--- a/libc/src/stdio/scanf_core/CMakeLists.txt
+++ b/libc/src/stdio/scanf_core/CMakeLists.txt
@@ -16,6 +16,8 @@ if(LIBC_TARGET_OS_IS_GPU)
libc.src.stdio.ungetc
libc.src.stdio.ferror
)
+elseif(LIBC_TARGET_OS_IS_BAREMETAL)
+ # There's no FILE* for baremetal.
elseif(LLVM_LIBC_FULL_BUILD)
list(APPEND file_deps
libc.src.__support.File.file
@@ -54,13 +56,6 @@ add_header_library(
libc.src.__support.CPP.string_view
)
-if(NOT(TARGET libc.src.__support.File.file) AND LLVM_LIBC_FULL_BUILD AND
- (NOT LIBC_TARGET_OS_IS_GPU))
- # Not all platforms have a file implementation. If file is unvailable, and a
- # full build is requested, then we must skip all file based scanf sections.
- return()
-endif()
-
add_object_library(
scanf_main
SRCS
>From cdad78efba3b4f07bed2741cf732d69c876abb4f Mon Sep 17 00:00:00 2001
From: Petr Hosek <phosek at google.com>
Date: Mon, 17 Mar 2025 23:57:00 -0700
Subject: [PATCH 2/2] Update the implementation
---
libc/src/stdio/baremetal/getchar.cpp | 2 +-
libc/src/stdio/baremetal/scanf.cpp | 10 +++++-----
libc/src/stdio/baremetal/vscanf.cpp | 10 +++++-----
3 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/libc/src/stdio/baremetal/getchar.cpp b/libc/src/stdio/baremetal/getchar.cpp
index 0a78a1ff8adf1..8fb7bc32537e7 100644
--- a/libc/src/stdio/baremetal/getchar.cpp
+++ b/libc/src/stdio/baremetal/getchar.cpp
@@ -17,7 +17,7 @@ namespace LIBC_NAMESPACE_DECL {
LLVM_LIBC_FUNCTION(int, getchar, ()) {
char buf[1];
auto result = read_from_stdin(buf, sizeof(buf));
- if (result < 0)
+ if (result <= 0)
return EOF;
return buf[0];
}
diff --git a/libc/src/stdio/baremetal/scanf.cpp b/libc/src/stdio/baremetal/scanf.cpp
index 1b0bf3e3afd54..d2ce36c9be733 100644
--- a/libc/src/stdio/baremetal/scanf.cpp
+++ b/libc/src/stdio/baremetal/scanf.cpp
@@ -21,10 +21,12 @@ namespace LIBC_NAMESPACE_DECL {
namespace {
-struct StreamBuffer : scanf_core::ReadBuffer<StreamBuffer> {
+struct StreamReader : scanf_core::Reader<StreamReader> {
LIBC_INLINE char getc() {
char buf[1];
- read_from_stdin(buf, sizeof(buf));
+ auto result = read_from_stdin(buf, sizeof(buf));
+ if (result <= 0)
+ return EOF;
return buf[0];
}
LIBC_INLINE void ungetc(int) {}
@@ -40,9 +42,7 @@ LLVM_LIBC_FUNCTION(int, scanf, (const char *__restrict format, ...)) {
// destruction automatically.
va_end(vlist);
- StreamBuffer buffer;
- scanf_core::Reader<StreamBuffer> reader(&buffer);
-
+ StreamReader reader;
int retval = scanf_core::scanf_main(&reader, format, args);
// This is done to avoid including stdio.h in the internals. On most systems
// EOF is -1, so this will be transformed into just "return retval".
diff --git a/libc/src/stdio/baremetal/vscanf.cpp b/libc/src/stdio/baremetal/vscanf.cpp
index e0119d6146d89..a3aee63711a8e 100644
--- a/libc/src/stdio/baremetal/vscanf.cpp
+++ b/libc/src/stdio/baremetal/vscanf.cpp
@@ -21,10 +21,12 @@ namespace LIBC_NAMESPACE_DECL {
namespace {
-struct StreamBuffer : scanf_core::ReadBuffer<StreamBuffer> {
+struct StreamReader : scanf_core::Reader<StreamReader> {
LIBC_INLINE char getc() {
char buf[1];
- read_from_stdin(buf, sizeof(buf));
+ auto result = read_from_stdin(buf, sizeof(buf));
+ if (result <= 0)
+ return EOF;
return buf[0];
}
LIBC_INLINE void ungetc(int) {}
@@ -39,9 +41,7 @@ LLVM_LIBC_FUNCTION(int, vscanf,
// destruction automatically.
va_end(vlist);
- StreamBuffer buffer;
- scanf_core::Reader<StreamBuffer> reader(&buffer);
-
+ StreamReader reader;
int retval = scanf_core::scanf_main(&reader, format, args);
// This is done to avoid including stdio.h in the internals. On most systems
// EOF is -1, so this will be transformed into just "return retval".
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