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| author | Alejandro Colomar <alx@kernel.org> | 2024-04-26 15:06:49 +0200 |
|---|---|---|
| committer | Alejandro Colomar <alx@kernel.org> | 2024-05-02 01:24:19 +0200 |
| commit | dcde2f70372b49ec43efc5db864c9ff585d0a2dd (patch) | |
| tree | 78b9b7425130e4a5858e4c01a524d802423879ed /man/man3/getentropy.3 | |
| parent | 12aca537ce78a41bbcdaf485209691e10f8002d7 (diff) | |
| download | man-pages-dcde2f70372b49ec43efc5db864c9ff585d0a2dd.tar.gz | |
man/, share/mk/: Move man*/ to man/
This is a scripted change:
$ mkdir man/;
$ mv man* man/;
$ ln -st . man/man*;
$ find share/mk/ -type f \
| xargs grep -l '^MANDIR *:=' \
| xargs sed -i '/^MANDIR *:=/s,$,/man,';
$ find share/mk/dist/ -type f \
| xargs grep -l man \
| xargs sed -i 's,man%,man/%,g';
Link: <https://lore.kernel.org/linux-man/YxcV4h+Xn7cd6+q2@pevik/T/>
Cc: Petr Vorel <pvorel@suse.cz>
Cc: Jakub Wilk <jwilk@jwilk.net>
Cc: Stefan Puiu <stefan.puiu@gmail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Diffstat (limited to 'man/man3/getentropy.3')
| -rw-r--r-- | man/man3/getentropy.3 | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/man/man3/getentropy.3 b/man/man3/getentropy.3 new file mode 100644 index 0000000000..a26a4eff56 --- /dev/null +++ b/man/man3/getentropy.3 @@ -0,0 +1,103 @@ +.\" Copyright (C) 2017, Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH getentropy 3 (date) "Linux man-pages (unreleased)" +.SH NAME +getentropy \- fill a buffer with random bytes +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.B #include <unistd.h> +.P +.BI "int getentropy(void " buffer [. length "], size_t " length ); +.fi +.P +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.P +.BR getentropy (): +.nf + _DEFAULT_SOURCE +.fi +.SH DESCRIPTION +The +.BR getentropy () +function writes +.I length +bytes of high-quality random data to the buffer starting +at the location pointed to by +.IR buffer . +The maximum permitted value for the +.I length +argument is 256. +.P +A successful call to +.BR getentropy () +always provides the requested number of bytes of entropy. +.SH RETURN VALUE +On success, this function returns zero. +On error, \-1 is returned, and +.I errno +is set to indicate the error. +.SH ERRORS +.TP +.B EFAULT +Part or all of the buffer specified by +.I buffer +and +.I length +is not in valid addressable memory. +.TP +.B EIO +.I length +is greater than 256. +.TP +.B EIO +An unspecified error occurred while trying to overwrite +.I buffer +with random data. +.TP +.B ENOSYS +This kernel version does not implement the +.BR getrandom (2) +system call required to implement this function. +.SH STANDARDS +None. +.SH HISTORY +glibc 2.25. +OpenBSD. +.SH NOTES +The +.BR getentropy () +function is implemented using +.BR getrandom (2). +.P +Whereas the glibc wrapper makes +.BR getrandom (2) +a cancelation point, +.BR getentropy () +is not a cancelation point. +.P +.BR getentropy () +is also declared in +.BR <sys/random.h> . +(No feature test macro need be defined to obtain the declaration from +that header file.) +.P +A call to +.BR getentropy () +may block if the system has just booted and the kernel has +not yet collected enough randomness to initialize the entropy pool. +In this case, +.BR getentropy () +will keep blocking even if a signal is handled, +and will return only once the entropy pool has been initialized. +.SH SEE ALSO +.BR getrandom (2), +.BR urandom (4), +.BR random (7) |