sets up a fake buffered FILE and then effectively calls itself
recursively. Unfortunately, gcc doesn't know how to do tail call
elimination in this case, and actually makes things worse by
inlining __sbprintf(). This means that f[w]printf() to stderr was
allocating about 5k of stack on 64-bit platforms, much of which was
never used.
I've reorganized things to eliminate the waste. In addition to saving
some stack space, this improves performance in my tests by anywhere
from 5% to 17% (depending on the test) when -fstack-protector is
enabled. I found no statistically significant performance difference
when stack protection is turned off. (The tests redirected stderr to
/dev/null.)
slightly less evil inline functions, and move the buffering state into
a struct. This will make it possible for helper routines to produce
output for printf() directly, making it possible to untangle the code
somewhat.
In wprintf(), use the same buffering mechanism to reduce diffs to
printf(). This has the side-effect of causing wprintf() to catch write
errors that it previously ignored.
by moving the positional argument handling code to a new file,
printf-pos.c, and moving common definitions to printflocal.h.
No functional change intended.
In particular, encapsulate the state of the type table in a struct,
and add inline functions to initialize, free, and manipulate that
state. This replaces some ugly macros that made proper error handling
impossible.
While here, remove an unneeded test for NULL and a variable that is
initialized (many times!) but never used. The compiler didn't catch
these because of rampant use of the same variable to mean different
things in different places.
This commit should not cause any changes in functionality.
__sFILE. This was supposed to be done in 6.0. Some notes:
- Where possible I restored the various lines to their pre-__sFILEX state.
- Retire INITEXTRA() and just initialize the wchar bits (orientation and
mbstate) explicitly instead. The various places that used INITEXTRA
didn't need the locking fields or _up initialized. (Some places needed
_up to exist and not be off the end of a NULL or garbage pointer, but
they didn't require it to be initialized to a specific value.)
- For now, stdio.h "knows" that pthread_t is a 'struct pthread *' to
avoid namespace pollution of including all the pthread types in stdio.h.
Once we remove all the inlines and make __sFILE private it can go back
to using pthread_t, etc.
- This does not remove any of the inlines currently and does not change
any of the public ABI of 'FILE'.
MFC after: 1 month
Reviewed by: peter
after their change from an array of char to an array of enum.
This fixes problems that occurred when using positional arguments in
format strings, particularly with more than STATIC_ARG_TBL_SIZE (8)
of them.
PR: 65841
Submitted by: Steven Smith (mostly)
string files (__SSTR flag set). This is necessary because __sputc()
does not respect the __SALC flag, and crashes trying to flush the buffer
instead of resizing it.
PR: 59167
- __vfprintf()'s 'buf' has never been used for floating point, so
don't define it in terms of (incorrect) constants describing
floating point numbers. The actual size needed depends on
sizeof(uintmax_t) and locale details, so I slightly overestimated.
- We don't need a 308-character buffer to store the string "308".
With long doubles and %a we need more than three characters, though.
