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[libc] Support for scanf on baremetal #131043

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merged 7 commits into from
Mar 20, 2025
Merged

[libc] Support for scanf on baremetal #131043

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dee8274
[libc] Support for scanf on baremetal
petrhosek Mar 12, 2025
4ebcb48
Merge remote-tracking branch 'origin/main' into libc-baremetal-scanf
petrhosek Mar 18, 2025
cdad78e
Update the implementation
petrhosek Mar 18, 2025
c9d8ccc
Remove the unnecessary file_deps
petrhosek Mar 18, 2025
8f461ff
Reintroduce an accidentally dropped asprintf and vasprinf
petrhosek Mar 18, 2025
3cffce6
Extract `StdinReader` into a shared header
petrhosek Mar 20, 2025
062804f
Include `scanf_internal.h`
petrhosek Mar 20, 2025
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8 changes: 6 additions & 2 deletions libc/config/baremetal/aarch64/entrypoints.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -123,18 +123,22 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.inttypes.strtoumax

# stdio.h entrypoints
libc.src.stdio.asprintf
libc.src.stdio.getchar
libc.src.stdio.printf
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.vasprintf
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
Expand Down
8 changes: 6 additions & 2 deletions libc/config/baremetal/arm/entrypoints.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -123,18 +123,22 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.inttypes.strtoumax

# stdio.h entrypoints
libc.src.stdio.asprintf
libc.src.stdio.getchar
libc.src.stdio.printf
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.vasprintf
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
Expand Down
8 changes: 6 additions & 2 deletions libc/config/baremetal/riscv/entrypoints.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -119,18 +119,22 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.inttypes.strtoumax

# stdio.h entrypoints
libc.src.stdio.asprintf
libc.src.stdio.getchar
libc.src.stdio.printf
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.vasprintf
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
Expand Down
58 changes: 4 additions & 54 deletions libc/src/stdio/CMakeLists.txt
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Expand Up @@ -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)
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Is this not needed anymore?

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It was moved to libc/src/stdio/generic/CMakeLists.txt.

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
Expand All @@ -133,46 +119,6 @@ add_entrypoint_object(
libc.src.stdio.scanf_core.string_reader
)

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
Expand Down Expand Up @@ -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)
35 changes: 35 additions & 0 deletions libc/src/stdio/baremetal/CMakeLists.txt
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Expand Up @@ -55,6 +55,28 @@ add_entrypoint_object(
libc.src.__support.CPP.string_view
)

add_header_library(
scanf_internal
HDRS
scanf_internal.h
DEPENDS
libc.src.stdio.scanf_core.reader
libc.src.__support.OSUtil.osutil
)

add_entrypoint_object(
scanf
SRCS
scanf.cpp
HDRS
../scanf.h
DEPENDS
.scanf_internal
libc.src.stdio.scanf_core.scanf_main
libc.src.__support.arg_list
libc.src.__support.OSUtil.osutil
)

add_entrypoint_object(
vprintf
SRCS
Expand All @@ -67,3 +89,16 @@ add_entrypoint_object(
libc.src.__support.arg_list
libc.src.__support.OSUtil.osutil
)

add_entrypoint_object(
vscanf
SRCS
vscanf.cpp
HDRS
../vscanf.h
DEPENDS
.scanf_internal
libc.src.stdio.scanf_core.scanf_main
libc.src.__support.arg_list
libc.src.__support.OSUtil.osutil
)
2 changes: 1 addition & 1 deletion libc/src/stdio/baremetal/getchar.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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];
}
Expand Down
37 changes: 37 additions & 0 deletions libc/src/stdio/baremetal/scanf.cpp
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Original file line number Diff line number Diff line change
@@ -0,0 +1,37 @@
//===-- 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/baremetal/scanf_internal.h"
#include "src/stdio/scanf_core/scanf_main.h"

#include <stdarg.h>

namespace LIBC_NAMESPACE_DECL {

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);

scanf_core::StdinReader 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".
return (retval == -1) ? EOF : retval;
}

} // namespace LIBC_NAMESPACE_DECL
30 changes: 30 additions & 0 deletions libc/src/stdio/baremetal/scanf_internal.h
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Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
//===-- Internal implementation header 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/__support/OSUtil/io.h"
#include "src/__support/macros/config.h"
#include "src/stdio/scanf_core/reader.h"

namespace LIBC_NAMESPACE_DECL {

namespace scanf_core {

struct StdinReader : public Reader<StdinReader> {
LIBC_INLINE char getc() {
char buf[1];
auto result = read_from_stdin(buf, sizeof(buf));
if (result <= 0)
return EOF;
return buf[0];
}
LIBC_INLINE void ungetc(int) {}
};

} // namespace scanf_core

} // namespace LIBC_NAMESPACE_DECL
36 changes: 36 additions & 0 deletions libc/src/stdio/baremetal/vscanf.cpp
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@@ -0,0 +1,36 @@
//===-- 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/baremetal/scanf_internal.h"
#include "src/stdio/scanf_core/scanf_main.h"

#include <stdarg.h>

namespace LIBC_NAMESPACE_DECL {

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);

scanf_core::StdinReader 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".
return (retval == -1) ? EOF : retval;
}

} // namespace LIBC_NAMESPACE_DECL
54 changes: 54 additions & 0 deletions libc/src/stdio/generic/CMakeLists.txt
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Expand Up @@ -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
Expand Down
0 libc/src/stdio/fscanf.cpp → libc/src/stdio/generic/fscanf.cpp
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File renamed without changes.
0 libc/src/stdio/scanf.cpp → libc/src/stdio/generic/scanf.cpp
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File renamed without changes.
0 libc/src/stdio/vfscanf.cpp → libc/src/stdio/generic/vfscanf.cpp
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File renamed without changes.
0 libc/src/stdio/vscanf.cpp → libc/src/stdio/generic/vscanf.cpp
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File renamed without changes.
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