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https://github.com/esphome/esphome.git
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J. Nick Koston
76a35df85a
Apply the same linker wrap technique used on ESP32 (PR #14362) to RP2040. ESPHome logging uses snprintf/vsnprintf, not libc printf, so the FILE*-based printf path (_vfprintf_r) is dead code at runtime. The stubs redirect printf/vprintf/fprintf through vsnprintf + fwrite, allowing the linker to GC _vfprintf_r (~8.9 KB).
72 lines
2.1 KiB
C++
72 lines
2.1 KiB
C++
/*
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* Linker wrap stubs for FILE*-based printf functions.
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*
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* The RP2040 Arduino framework and libraries may reference printf(),
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* vprintf(), and fprintf() which pull in newlib's _vfprintf_r (~8.9 KB).
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* ESPHome never uses these — all logging goes through the logger component
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* which uses snprintf/vsnprintf, so the libc FILE*-based printf path is
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* dead code.
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*
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* These stubs redirect through vsnprintf() (which is already in the binary)
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* and fwrite(), allowing the linker to dead-code eliminate _vfprintf_r.
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*
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* Saves ~8.9 KB of flash.
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*/
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#if defined(USE_RP2040) && !defined(USE_FULL_PRINTF)
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#include <cstdarg>
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#include <cstdio>
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#include <cstdlib>
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namespace esphome::rp2040 {}
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static constexpr size_t PRINTF_BUFFER_SIZE = 512;
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// These stubs are essentially dead code at runtime — ESPHome uses its own
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// logging through snprintf/vsnprintf, not libc printf.
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// The buffer overflow check is purely defensive and should never trigger.
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static int write_printf_buffer(FILE *stream, char *buf, int len) {
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if (len < 0) {
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return len;
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}
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size_t write_len = len;
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if (write_len >= PRINTF_BUFFER_SIZE) {
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fwrite(buf, 1, PRINTF_BUFFER_SIZE - 1, stream);
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abort();
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}
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if (fwrite(buf, 1, write_len, stream) < write_len || ferror(stream)) {
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return -1;
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}
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return len;
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}
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// NOLINTBEGIN(bugprone-reserved-identifier,cert-dcl37-c,cert-dcl51-cpp,readability-identifier-naming)
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extern "C" {
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int __wrap_vprintf(const char *fmt, va_list ap) {
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char buf[PRINTF_BUFFER_SIZE];
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return write_printf_buffer(stdout, buf, vsnprintf(buf, sizeof(buf), fmt, ap));
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}
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int __wrap_printf(const char *fmt, ...) {
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va_list ap;
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va_start(ap, fmt);
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int len = __wrap_vprintf(fmt, ap);
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va_end(ap);
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return len;
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}
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int __wrap_fprintf(FILE *stream, const char *fmt, ...) {
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va_list ap;
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va_start(ap, fmt);
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char buf[PRINTF_BUFFER_SIZE];
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int len = write_printf_buffer(stream, buf, vsnprintf(buf, sizeof(buf), fmt, ap));
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va_end(ap);
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return len;
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}
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} // extern "C"
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// NOLINTEND(bugprone-reserved-identifier,cert-dcl37-c,cert-dcl51-cpp,readability-identifier-naming)
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#endif // USE_RP2040 && !USE_FULL_PRINTF
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