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musl/src/stdio/__stdio_exit.c

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stdio: handle file position correctly at program exit for seekable files, posix imposed requirements on the offset of the underlying open file description after a stream is closed. this was correctly handled (as a side effect of the unconditional fflush call) when streams were explicitly closed by fclose, but was not handled correctly at program exit time, where fflush(0) was being used. the weak symbol hackery is to pull in __stdio_exit if either of __toread or __towrite is used, but avoid calling it twice so we don't have to keep extra state. the new __stdio_exit is a streamlined fflush variant that avoids performing any unnecessary operations and which never unlocks the files or open file list, so we can be sure no other threads write new data to a stream's buffer after it's already flushed.
2012-06-19 01:27:26 -04:00
#include "stdio_impl.h"
static FILE *const dummy_file = 0;
weak_alias(dummy_file, __stdin_used);
weak_alias(dummy_file, __stdout_used);
weak_alias(dummy_file, __stderr_used);
static void close_file(FILE *f)
{
if (!f) return;
fix more unused variable warnings some of these were coming from stdio functions locking files without unlocking them. I believe it's useful for this to throw a warning, so I added a new macro that's self-documenting that the file will never be unlocked to avoid the warning in the few places where it's wrong.
2012-11-01 23:46:39 -04:00
FFINALLOCK(f);
stdio: handle file position correctly at program exit for seekable files, posix imposed requirements on the offset of the underlying open file description after a stream is closed. this was correctly handled (as a side effect of the unconditional fflush call) when streams were explicitly closed by fclose, but was not handled correctly at program exit time, where fflush(0) was being used. the weak symbol hackery is to pull in __stdio_exit if either of __toread or __towrite is used, but avoid calling it twice so we don't have to keep extra state. the new __stdio_exit is a streamlined fflush variant that avoids performing any unnecessary operations and which never unlocks the files or open file list, so we can be sure no other threads write new data to a stream's buffer after it's already flushed.
2012-06-19 01:27:26 -04:00
if (f->wpos > f->wbase) f->write(f, 0, 0);
if (f->rpos < f->rend) f->seek(f, f->rpos-f->rend, SEEK_CUR);
}
void __stdio_exit(void)
{
FILE *f;
OFLLOCK();
for (f=libc.ofl_head; f; f=f->next) close_file(f);
close_file(__stdin_used);
close_file(__stdout_used);
}
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