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Paul Eggert
08c8a9228f
I ran into this problem when doing stress testing with GNU m4.
The problem is that ("%*d", INT_MAX, n) fails because the code
refuses to create a buffer of size INT_MAX + 1u,
due to problems when dealing with older nonconforming snprintf.
The simplest fix was to use snprintf only if it handles
sizes like INT_MAX + 1u, and to fall back on sprintf otherwise.
Nowadays I think snprintf should work on most practical targets.
Assuming this patch works out, perhaps we could simplify
lib/vasnprintf.c to ease further maintenance,
as nowadays I hope we can assume both HAVE_SNPRINTF_RETVAL_C99 and
HAVE_SNPRINTF_TRUNCATION_C99 on platforms where USE_SNPRINTF.
* lib/vasnprintf.c: Include minmax.h.
(USE_SNPRINTF): Define to 1 only if glibc 2+, Android, musl,
the BSDs, macOS, or Microsoft UCRT.
(VASNPRINTF) [USE_SNPRINTF]:
Allow maxlen to be 1 greater than INT_MAX on 64-bit platforms.
Document the limit’s derivation by using named locals.
Do not attempt to work around bugs in pre-C99 implementations,
as USE_SNPRINTF is pickier now.
* m4/vasnprintf.m4 (gl_PREREQ_VASNWPRINTF):
Move gl_MUSL_LIBC call from here ...
(gl_PREREQ_VASNXPRINTF): ... to here.
* modules/c-vasnprintf, modules/unistdio/u16-u16-vasnprintf:
* modules/unistdio/u16-vasnprintf:
* modules/unistdio/u32-u32-vasnprintf:
* modules/unistdio/u32-vasnprintf:
* modules/unistdio/u8-u8-vasnprintf:
* modules/unistdio/u8-vasnprintf, modules/unistdio/ulc-vasnprintf:
* modules/vasnprintf, modules/vasnwprintf:
(Files): Add m4/musl.m4 if it isn’t there already.
(Depends-on): Add minmax.
* tests/test-vasnprintf-posix.c:
* tests/test-vasprintf-posix.c:
* tests/test-vaszprintf-posix.c:
Include <limits.h> and <errno.h> if needed.
(test_function): Test for the bug, if RUN_EXPENSIVE_TESTS=yes
in the environment; this the coreutils tradition and I
didn’t see any Gnulib tradition so I just used it.
66 lines
817 B
Plaintext
66 lines
817 B
Plaintext
Description:
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vswprintf with automatic memory allocation and bounded output size.
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Files:
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lib/float+.h
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lib/printf-args.h
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lib/printf-args.c
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lib/wprintf-parse.h
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lib/wprintf-parse.c
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lib/printf-parse.c
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lib/vasnwprintf.h
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lib/vasnwprintf.c
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lib/vasnprintf.c
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lib/asnwprintf.c
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m4/wint_t.m4
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m4/intmax_t.m4
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m4/stdint_h.m4
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m4/inttypes_h.m4
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m4/vasnprintf.m4
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m4/printf.m4
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m4/mbrtowc.m4
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m4/math_h.m4
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m4/exponentd.m4
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m4/musl.m4
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Depends-on:
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stdio-h
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alloca-opt
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attribute
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float-h
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free-posix
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limits-h
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stdint-h
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xsize
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errno-h
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memchr
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assert-h
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wchar-h
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localeconv
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mbszero
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mbrtowc
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wmemcpy
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wmemset
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minmax
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streq
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configure.ac:
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AC_REQUIRE([AC_C_RESTRICT])
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gl_FUNC_VASNWPRINTF
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Makefile.am:
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lib_SOURCES += wprintf-parse.c vasnwprintf.c
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lib_SOURCES += asnwprintf.c
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Include:
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"vasnwprintf.h"
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Link:
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$(MBRTOWC_LIB)
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License:
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LGPLv2+
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Maintainer:
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all
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