c24694a8e9
syslog_write_foreach() compares an unsigned count against a signed
accumulator:
size_t nwritten = 0;
ssize_t nwritten_max = -EIO;
...
if (nwritten > nwritten_max)
{
nwritten_max = nwritten;
}
return nwritten_max;
The usual arithmetic conversions promote nwritten_max to size_t, so -EIO
becomes 4294967291 on a 32-bit target, and the comparison is never true.
nwritten_max keeps its initial value and the function returns -EIO no
matter how many bytes actually went out. Observed under gdb on a running
target: nwritten == 64, nwritten_max == -5, (nwritten > nwritten_max) == 0.
Most callers discard the result -- syslog() itself returns void -- so this
is normally invisible. It becomes fatal when /dev/console is backed by
syslog_console_write(), because then stdio acts on it.
lib_fflush_unlocked() sees a negative return, sets __FS_FLAG_ERROR and
returns early, before resetting fs_bufpos. The bytes have already been
emitted, but the buffer is never cleared, so every subsequent stdio call
re-flushes the same CONFIG_STDIO_BUFFER_SIZE bytes. The console fills
with one repeated fragment and the system makes no further progress.
Reaching that state needs CONFIG_CONSOLE_SYSLOG=y together with no driver
claiming /dev/console ahead of syslog_console_init(). Three in-tree
defconfigs qualify: x86/qemu-i486:ostest, renesas/skp16c26:ostest and
x86_64/qemu-intel64:earlyfb. The other 56 CONSOLE_SYSLOG configurations
have a serial console that registers /dev/console first, which is why this
has gone unnoticed.
Introduced by
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|---|---|---|
| .github | ||
| arch | ||
| audio | ||
| binfmt | ||
| boards | ||
| cmake | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| dummy | ||
| fs | ||
| graphics | ||
| include | ||
| libs | ||
| mm | ||
| net | ||
| openamp | ||
| pass1 | ||
| sched | ||
| syscall | ||
| tools | ||
| video | ||
| wireless | ||
| .asf.yaml | ||
| .codespell-ignore-lines | ||
| .codespellrc | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmessage | ||
| .pre-commit-config.yaml | ||
| .yamllint | ||
| AUTHORS | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
| Kconfig | ||
| LICENSE | ||
| Makefile | ||
| NOTICE | ||
| README.md | ||
| ReleaseNotes | ||
Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).
For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.
Getting Started
First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.
Documentation
You can find the current NuttX documentation on the Documentation Page.
Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.
The old NuttX documentation is still available in the Apache wiki.
Supported Boards
NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.
Contributing
If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.
License
The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.