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cbortojson: adapt to work with picolibc's variant of funopen #341

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Merged
thiagomacieira merged 1 commit into from
Oct 19, 2026
+42 −5
Merged

cbortojson: adapt to work with picolibc's variant of funopen #341

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35 changes: 32 additions & 3 deletions CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,7 @@ include(GNUInstallDirs)
include(GenerateExportHeader)
include(CheckLinkerFlag)
include(CheckSymbolExists)
include(CheckCSourceCompiles)

add_library(tinycbor
src/cborencoder.c
Expand Down Expand Up @@ -131,13 +132,41 @@ configure_file(tinycbor.pc.in tinycbor.pc @ONLY)

# Check for open_memstream and store the result in HAVE_OPEN_MEMSTREAM
check_symbol_exists(open_memstream stdio.h HAVE_OPEN_MEMSTREAM)
check_symbol_exists(funopen stdio.h HAVE_OPEN_FUNOPEN)
# Check for funopen - try traditional BSD signature first (int/const char*/int),
# then the POSIX-like variant used by picolibc (ssize_t/const void*/size_t).
set(_saved_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
if(MSVC)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} /we4028 /we4113")
else()
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror=incompatible-pointer-types")
endif()
check_c_source_compiles("
#include <stdio.h>
static int write_fn(void *c, const char *b, int n) { (void)c; (void)b; return n; }
static int close_fn(void *c) { (void)c; return 0; }
int main(void) { funopen(NULL, NULL, write_fn, NULL, close_fn); return 0; }
" HAVE_OPEN_FUNOPEN)
if(NOT HAVE_OPEN_FUNOPEN)
check_c_source_compiles("
#include <stdio.h>
#include <sys/types.h>
static ssize_t write_fn(void *c, const void *b, size_t n) { (void)c; (void)b; return (ssize_t)n; }
static int close_fn(void *c) { (void)c; return 0; }
int main(void) { funopen(NULL, NULL, write_fn, NULL, close_fn); return 0; }
" HAVE_OPEN_FUNOPEN_SSIZE)
endif()
set(CMAKE_REQUIRED_FLAGS "${_saved_CMAKE_REQUIRED_FLAGS}")
unset(_saved_CMAKE_REQUIRED_FLAGS)
check_symbol_exists(fopencookie stdio.h HAVE_OPEN_FOPENCOOKIE)

if(NOT HAVE_OPEN_MEMSTREAM)
if (HAVE_OPEN_FUNOPEN)
if (HAVE_OPEN_FUNOPEN OR HAVE_OPEN_FUNOPEN_SSIZE)
message(STATUS "implementing open_memstream using funopen()")
target_compile_definitions(tinycbor PRIVATE HAVE_OPEN_FUNOPEN)
if(HAVE_OPEN_FUNOPEN_SSIZE)
target_compile_definitions(tinycbor PRIVATE HAVE_OPEN_FUNOPEN_SSIZE)
else()
target_compile_definitions(tinycbor PRIVATE HAVE_OPEN_FUNOPEN)
endif()
target_sources(tinycbor PRIVATE src/open_memstream.c)
elseif (HAVE_OPEN_FOPENCOOKIE)
message(STATUS "implementing open_memstream using fopencookie()")
Expand Down
12 changes: 10 additions & 2 deletions src/open_memstream.c
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Original file line number Diff line number Diff line change
Expand Up @@ -35,12 +35,20 @@
#if defined(__unix__) || defined(__APPLE__)
# include <unistd.h>
#endif
#if defined(HAVE_OPEN_FUNOPEN)
#if defined(HAVE_OPEN_FUNOPEN) || defined(HAVE_OPEN_FUNOPEN_SSIZE)
# if defined(HAVE_OPEN_FUNOPEN_SSIZE)
typedef ssize_t RetType;
typedef size_t LenType;
typedef const void *WriteBufType;
# else
typedef int RetType;
typedef int LenType;
typedef const char *WriteBufType;
# endif
#elif defined(HAVE_OPEN_FOPENCOOKIE)
typedef ssize_t RetType;
typedef size_t LenType;
typedef const char *WriteBufType;
#else
# error "Cannot implement open_memstream!"
#endif
Expand All @@ -54,7 +62,7 @@ struct Buffer
size_t alloc;
};

static RetType write_to_buffer(void *cookie, const char *data, LenType len)
static RetType write_to_buffer(void *cookie, WriteBufType data, LenType len)
{
struct Buffer *b = (struct Buffer *)cookie;
char *ptr = *b->ptr;
Expand Down
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