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Kernel+LibC: Add a dbgputch() syscall and use it for userspace dbgprintf().

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The "stddbg" stream was a cute idea but we never ended up using it in
practice, so let's simplify this and implement userspace dbgprintf() on top
of a simple dbgputch() syscall instead.

This makes debugging LibC startup a little bit easier. :^)
This commit is contained in:
Andreas Kling 2019-07-21 19:45:31 +02:00
parent be7dcca1a6
commit 3fce2fb205
6 changed files with 18 additions and 15 deletions
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19
Libraries/LibC/stdio.cpp
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@ -18,7 +18,6 @@ static FILE __default_streams[4];
FILE* stdin;
FILE* stdout;
FILE* stderr;
FILE* stddbg;
void init_FILE(FILE& fp, int fd, int mode)
{
@ -41,16 +40,9 @@ void __stdio_init()
stdin = &__default_streams[0];
stdout = &__default_streams[1];
stderr = &__default_streams[2];
stddbg = &__default_streams[3];
init_FILE(*stdin, 0, isatty(0) ? _IOLBF : _IOFBF);
init_FILE(*stdout, 1, isatty(1) ? _IOLBF : _IOFBF);
init_FILE(*stderr, 2, _IONBF);
int fd = open("/dev/debuglog", O_WRONLY | O_CLOEXEC);
if (fd < 0) {
perror("open /dev/debuglog");
ASSERT_NOT_REACHED();
}
init_FILE(*stddbg, fd, _IOLBF);
}
int setvbuf(FILE* stream, char* buf, int mode, size_t size)
@ -337,14 +329,10 @@ void rewind(FILE* stream)
int dbgprintf(const char* fmt, ...)
{
// if this fails, you're printing too early.
ASSERT(stddbg);
int errno_backup = errno;
va_list ap;
va_start(ap, fmt);
int ret = vfprintf(stddbg, fmt, ap);
int ret = printf_internal([](char*&, char ch) { dbgputch(ch); }, nullptr, fmt, ap);
va_end(ap);
errno = errno_backup;
return ret;
}
@ -495,6 +483,11 @@ int rename(const char* oldpath, const char* newpath)
__RETURN_WITH_ERRNO(rc, rc, -1);
}
void dbgputch(char ch)
{
syscall(SC_dbgputch, ch);
}
char* tmpnam(char*)
{
ASSERT_NOT_REACHED();