mirror of
https://sourceware.org/git/glibc.git
synced 2024-09-20 08:30:00 +00:00
03bf8357e8
This patch removes the mergesort optimization on qsort implementation
and uses the introsort instead. The mergesort implementation has some
issues:
- It is as-safe only for certain types sizes (if total size is less
than 1 KB with large element sizes also forcing memory allocation)
which contradicts the function documentation. Although not required
by the C standard, it is preferable and doable to have an O(1) space
implementation.
- The malloc for certain element size and element number adds
arbitrary latency (might even be worse if malloc is interposed).
- To avoid trigger swap from memory allocation the implementation
relies on system information that might be virtualized (for instance
VMs with overcommit memory) which might lead to potentially use of
swap even if system advertise more memory than actually has. The
check also have the downside of issuing syscalls where none is
expected (although only once per execution).
- The mergesort is suboptimal on an already sorted array (BZ#21719).
The introsort implementation is already optimized to use constant extra
space (due to the limit of total number of elements from maximum VM
size) and thus can be used to avoid the malloc usage issues.
Resulting performance is slower due the usage of qsort, specially in the
worst-case scenario (partialy or sorted arrays) and due the fact
mergesort uses a slight improved swap operations.
This change also renders the BZ#21719 fix unrequired (since it is meant
to fix the sorted input performance degradation for mergesort). The
manual is also updated to indicate the function is now async-cancel
safe.
Checked on x86_64-linux-gnu.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
372 lines
13 KiB
C
372 lines
13 KiB
C
#ifndef _STDLIB_H
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#ifndef _ISOMAC
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# include <stdbool.h>
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# include <stddef.h>
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#endif
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/* Workaround PR90731 with GCC 9 when using ldbl redirects in C++. */
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#include <bits/floatn.h>
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#if defined __cplusplus && __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
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# if __GNUC_PREREQ (9, 0) && !__GNUC_PREREQ (9, 3)
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# pragma GCC system_header
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# endif
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#endif
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#include <stdlib/stdlib.h>
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/* Now define the internal interfaces. */
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#if !defined _ISOMAC
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# include <sys/stat.h>
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# include <rtld-malloc.h>
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extern __typeof (strtol_l) __strtol_l;
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extern __typeof (strtoul_l) __strtoul_l;
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extern __typeof (strtoll_l) __strtoll_l;
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extern __typeof (strtoull_l) __strtoull_l;
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extern __typeof (strtod_l) __strtod_l;
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extern __typeof (strtof_l) __strtof_l;
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extern __typeof (strtold_l) __strtold_l;
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libc_hidden_proto (__strtol_l)
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libc_hidden_proto (__strtoul_l)
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libc_hidden_proto (__strtoll_l)
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libc_hidden_proto (__strtoull_l)
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libc_hidden_proto (__strtod_l)
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libc_hidden_proto (__strtof_l)
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libc_hidden_proto (__strtold_l)
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extern __typeof (strtol) __isoc23_strtol __attribute_copy__ (strtol);
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extern __typeof (strtoul) __isoc23_strtoul __attribute_copy__ (strtoul);
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extern __typeof (strtoll) __isoc23_strtoll __attribute_copy__ (strtoll);
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extern __typeof (strtoull) __isoc23_strtoull __attribute_copy__ (strtoull);
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extern __typeof (strtol_l) __isoc23_strtol_l __attribute_copy__ (strtol_l);
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extern __typeof (strtoul_l) __isoc23_strtoul_l __attribute_copy__ (strtoul_l);
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extern __typeof (strtoll_l) __isoc23_strtoll_l __attribute_copy__ (strtoll_l);
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extern __typeof (strtoull_l) __isoc23_strtoull_l __attribute_copy__ (strtoull_l);
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libc_hidden_proto (__isoc23_strtol)
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libc_hidden_proto (__isoc23_strtoul)
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libc_hidden_proto (__isoc23_strtoll)
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libc_hidden_proto (__isoc23_strtoull)
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libc_hidden_proto (__isoc23_strtol_l)
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libc_hidden_proto (__isoc23_strtoul_l)
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libc_hidden_proto (__isoc23_strtoll_l)
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libc_hidden_proto (__isoc23_strtoull_l)
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#if __GLIBC_USE (C2X_STRTOL)
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/* Redirect internal uses of these functions to the C2X versions; the
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redirection in the installed header does not work with
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libc_hidden_proto. */
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# undef strtol
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# define strtol __isoc23_strtol
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# undef atoi
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# define atoi(nptr) __isoc23_strtol(nptr, NULL, 10)
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# undef strtoul
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# define strtoul __isoc23_strtoul
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# undef strtoll
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# define strtoll __isoc23_strtoll
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# undef strtoull
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# define strtoull __isoc23_strtoull
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# undef strtol_l
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# define strtol_l __isoc23_strtol_l
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# undef strtoul_l
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# define strtoul_l __isoc23_strtoul_l
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# undef strtoll_l
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# define strtoll_l __isoc23_strtoll_l
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# undef strtoull_l
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# define strtoull_l __isoc23_strtoull_l
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#endif
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libc_hidden_proto (exit)
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libc_hidden_proto (abort)
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libc_hidden_proto (getenv)
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extern __typeof (secure_getenv) __libc_secure_getenv;
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libc_hidden_proto (__libc_secure_getenv)
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libc_hidden_proto (bsearch)
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libc_hidden_proto (qsort)
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extern __typeof (qsort_r) __qsort_r;
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libc_hidden_proto (__qsort_r)
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libc_hidden_proto (lrand48_r)
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libc_hidden_proto (wctomb)
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extern long int __random (void) attribute_hidden;
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extern void __srandom (unsigned int __seed);
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extern char *__initstate (unsigned int __seed, char *__statebuf,
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size_t __statelen);
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extern char *__setstate (char *__statebuf);
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extern int __random_r (struct random_data *__buf, int32_t *__result)
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attribute_hidden;
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extern int __srandom_r (unsigned int __seed, struct random_data *__buf)
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attribute_hidden;
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extern int __initstate_r (unsigned int __seed, char *__statebuf,
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size_t __statelen, struct random_data *__buf)
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attribute_hidden;
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extern int __setstate_r (char *__statebuf, struct random_data *__buf)
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attribute_hidden;
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extern int __rand_r (unsigned int *__seed);
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extern int __erand48_r (unsigned short int __xsubi[3],
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struct drand48_data *__buffer, double *__result)
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attribute_hidden;
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extern int __nrand48_r (unsigned short int __xsubi[3],
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struct drand48_data *__buffer,
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long int *__result) attribute_hidden;
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extern int __jrand48_r (unsigned short int __xsubi[3],
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struct drand48_data *__buffer,
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long int *__result) attribute_hidden;
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extern int __srand48_r (long int __seedval,
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struct drand48_data *__buffer) attribute_hidden;
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extern int __seed48_r (unsigned short int __seed16v[3],
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struct drand48_data *__buffer) attribute_hidden;
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extern int __lcong48_r (unsigned short int __param[7],
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struct drand48_data *__buffer) attribute_hidden;
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/* Internal function to compute next state of the generator. */
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extern int __drand48_iterate (unsigned short int __xsubi[3],
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struct drand48_data *__buffer)
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attribute_hidden;
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/* Global state for non-reentrant functions. Defined in drand48-iter.c. */
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extern struct drand48_data __libc_drand48_data attribute_hidden;
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extern int __setenv (const char *__name, const char *__value, int __replace)
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attribute_hidden;
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extern int __unsetenv (const char *__name) attribute_hidden;
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extern int __clearenv (void) attribute_hidden;
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extern char *__mktemp (char *__template) __THROW __nonnull ((1));
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libc_hidden_proto (__mktemp)
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extern char *__canonicalize_file_name (const char *__name);
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extern char *__realpath (const char *__name, char *__resolved);
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libc_hidden_proto (__realpath)
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extern int __ptsname_r (int __fd, char *__buf, size_t __buflen)
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attribute_hidden;
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# ifndef _ISOMAC
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extern int __ptsname_internal (int fd, char *buf, size_t buflen,
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struct stat64 *stp) attribute_hidden;
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# endif
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extern int __getpt (void);
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extern int __posix_openpt (int __oflag) attribute_hidden;
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extern int __add_to_environ (const char *name, const char *value,
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const char *combines, int replace)
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attribute_hidden;
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extern int __on_exit (void (*__func) (int __status, void *__arg), void *__arg);
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extern int __cxa_atexit (void (*func) (void *), void *arg, void *d);
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libc_hidden_proto (__cxa_atexit);
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extern int __cxa_thread_atexit_impl (void (*func) (void *), void *arg,
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void *d);
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extern void __call_tls_dtors (void);
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libc_hidden_proto (__call_tls_dtors)
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extern void __cxa_finalize (void *d);
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extern int __posix_memalign (void **memptr, size_t alignment, size_t size);
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extern void *__libc_memalign (size_t alignment, size_t size)
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__attribute_malloc__;
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extern void *__libc_reallocarray (void *__ptr, size_t __nmemb, size_t __size)
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__THROW __attribute_warn_unused_result__;
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libc_hidden_proto (__libc_reallocarray)
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extern int __libc_system (const char *line);
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extern __typeof (getpt) __getpt;
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extern __typeof (ptsname_r) __ptsname_r;
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libc_hidden_proto (__getpt)
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libc_hidden_proto (__ptsname_r)
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libc_hidden_proto (grantpt)
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libc_hidden_proto (unlockpt)
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__typeof (arc4random) __arc4random;
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libc_hidden_proto (__arc4random);
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__typeof (arc4random_buf) __arc4random_buf;
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libc_hidden_proto (__arc4random_buf);
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__typeof (arc4random_uniform) __arc4random_uniform;
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libc_hidden_proto (__arc4random_uniform);
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extern void __arc4random_buf_internal (void *buffer, size_t len)
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attribute_hidden;
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extern double __strtod_internal (const char *__restrict __nptr,
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char **__restrict __endptr, int __group)
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__THROW __nonnull ((1)) __wur;
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extern float __strtof_internal (const char *__restrict __nptr,
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char **__restrict __endptr, int __group)
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__THROW __nonnull ((1)) __wur;
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extern long double __strtold_internal (const char *__restrict __nptr,
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char **__restrict __endptr,
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int __group)
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__THROW __nonnull ((1)) __wur;
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extern long int __strtol_internal (const char *__restrict __nptr,
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char **__restrict __endptr,
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int __base, int __group)
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__THROW __nonnull ((1)) __wur;
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extern unsigned long int __strtoul_internal (const char *__restrict __nptr,
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char **__restrict __endptr,
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int __base, int __group)
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__THROW __nonnull ((1)) __wur;
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__extension__
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extern long long int __strtoll_internal (const char *__restrict __nptr,
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char **__restrict __endptr,
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int __base, int __group)
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__THROW __nonnull ((1)) __wur;
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__extension__
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extern unsigned long long int __strtoull_internal (const char *
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__restrict __nptr,
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char **__restrict __endptr,
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int __base, int __group)
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__THROW __nonnull ((1)) __wur;
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libc_hidden_proto (__strtof_internal)
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libc_hidden_proto (__strtod_internal)
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libc_hidden_proto (__strtold_internal)
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libc_hidden_proto (__strtol_internal)
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libc_hidden_proto (__strtoll_internal)
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libc_hidden_proto (__strtoul_internal)
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libc_hidden_proto (__strtoull_internal)
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extern double ____strtod_l_internal (const char *__restrict __nptr,
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char **__restrict __endptr, int __group,
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locale_t __loc);
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extern float ____strtof_l_internal (const char *__restrict __nptr,
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char **__restrict __endptr, int __group,
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locale_t __loc);
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extern long double ____strtold_l_internal (const char *__restrict __nptr,
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char **__restrict __endptr,
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int __group, locale_t __loc);
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extern long int ____strtol_l_internal (const char *__restrict __nptr,
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char **__restrict __endptr,
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int __base, int __group,
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bool __bin_cst, locale_t __loc);
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extern unsigned long int ____strtoul_l_internal (const char *
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__restrict __nptr,
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char **__restrict __endptr,
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int __base, int __group,
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bool __bin_cst,
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locale_t __loc);
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__extension__
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extern long long int ____strtoll_l_internal (const char *__restrict __nptr,
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char **__restrict __endptr,
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int __base, int __group,
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bool __bin_cst, locale_t __loc);
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__extension__
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extern unsigned long long int ____strtoull_l_internal (const char *
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__restrict __nptr,
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char **
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__restrict __endptr,
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int __base, int __group,
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bool __bin_cst,
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locale_t __loc);
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libc_hidden_proto (____strtof_l_internal)
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libc_hidden_proto (____strtod_l_internal)
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libc_hidden_proto (____strtold_l_internal)
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libc_hidden_proto (____strtol_l_internal)
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libc_hidden_proto (____strtoll_l_internal)
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libc_hidden_proto (____strtoul_l_internal)
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libc_hidden_proto (____strtoull_l_internal)
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#include <bits/floatn.h>
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libc_hidden_proto (strtof)
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libc_hidden_proto (strtod)
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#if __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 0
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libc_hidden_proto (strtold)
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#endif
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libc_hidden_proto (strtol)
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libc_hidden_proto (strtoll)
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libc_hidden_proto (strtoul)
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libc_hidden_proto (strtoull)
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libc_hidden_proto (atoi)
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extern float __strtof_nan (const char *, char **, char);
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extern double __strtod_nan (const char *, char **, char);
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extern long double __strtold_nan (const char *, char **, char);
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extern float __wcstof_nan (const wchar_t *, wchar_t **, wchar_t);
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extern double __wcstod_nan (const wchar_t *, wchar_t **, wchar_t);
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extern long double __wcstold_nan (const wchar_t *, wchar_t **, wchar_t);
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libc_hidden_proto (__strtof_nan)
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libc_hidden_proto (__strtod_nan)
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libc_hidden_proto (__strtold_nan)
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libc_hidden_proto (__wcstof_nan)
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libc_hidden_proto (__wcstod_nan)
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libc_hidden_proto (__wcstold_nan)
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/* Enable _FloatN bits as needed. */
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#include <bits/floatn.h>
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#if __HAVE_DISTINCT_FLOAT128
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extern __typeof (strtof128_l) __strtof128_l;
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libc_hidden_proto (__strtof128_l)
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libc_hidden_proto (strtof128)
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extern _Float128 __strtof128_nan (const char *, char **, char);
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extern _Float128 __wcstof128_nan (const wchar_t *, wchar_t **, wchar_t);
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libc_hidden_proto (__strtof128_nan)
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libc_hidden_proto (__wcstof128_nan)
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extern _Float128 __strtof128_internal (const char *__restrict __nptr,
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char **__restrict __endptr,
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int __group);
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libc_hidden_proto (__strtof128_internal)
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extern _Float128 ____strtof128_l_internal (const char *__restrict __nptr,
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char **__restrict __endptr,
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int __group, locale_t __loc);
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libc_hidden_proto (____strtof128_l_internal)
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#endif
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extern char *__ecvt (double __value, int __ndigit, int *__restrict __decpt,
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int *__restrict __sign);
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extern char *__fcvt (double __value, int __ndigit, int *__restrict __decpt,
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int *__restrict __sign);
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extern char *__gcvt (double __value, int __ndigit, char *__buf);
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extern int __ecvt_r (double __value, int __ndigit, int *__restrict __decpt,
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int *__restrict __sign, char *__restrict __buf,
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size_t __len);
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libc_hidden_proto (__ecvt_r)
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extern int __fcvt_r (double __value, int __ndigit, int *__restrict __decpt,
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int *__restrict __sign, char *__restrict __buf,
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size_t __len);
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libc_hidden_proto (__fcvt_r)
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extern char *__qecvt (long double __value, int __ndigit,
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int *__restrict __decpt, int *__restrict __sign);
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extern char *__qfcvt (long double __value, int __ndigit,
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int *__restrict __decpt, int *__restrict __sign);
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extern char *__qgcvt (long double __value, int __ndigit, char *__buf);
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extern int __qecvt_r (long double __value, int __ndigit,
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int *__restrict __decpt, int *__restrict __sign,
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char *__restrict __buf, size_t __len);
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libc_hidden_proto (__qecvt_r)
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extern int __qfcvt_r (long double __value, int __ndigit,
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int *__restrict __decpt, int *__restrict __sign,
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char *__restrict __buf, size_t __len);
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libc_hidden_proto (__qfcvt_r)
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# if IS_IN (libc)
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# undef MB_CUR_MAX
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# define MB_CUR_MAX (_NL_CURRENT_WORD (LC_CTYPE, _NL_CTYPE_MB_CUR_MAX))
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# endif
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struct abort_msg_s
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{
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unsigned int size;
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char msg[0];
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};
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extern struct abort_msg_s *__abort_msg;
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libc_hidden_proto (__abort_msg)
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# if IS_IN (rtld)
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extern __typeof (unsetenv) unsetenv attribute_hidden;
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extern __typeof (__strtoul_internal) __strtoul_internal attribute_hidden;
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# endif
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#endif
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#endif /* include/stdlib.h */
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