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Joachim Wiberg
6537b11e34
Framework from libuEv. Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
71 lines
1.9 KiB
C
71 lines
1.9 KiB
C
/* Formatted truncate()
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*
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* Copyright (c) 2021 Joachim Wiberg <troglobit@gmail.com>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/**
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* @file truncatef.c
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* @author Joachim Wiberg
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* @date 2021
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* @copyright ISC License
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*/
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#include <errno.h>
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#include <stdio.h>
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#include <stdarg.h>
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#include <stdlib.h>
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#include <unistd.h>
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/**
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* Truncate a file based on the formatted string
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* @param length Size in bytes to truncate file to, zero to empty it
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* @param fmt Formatted string to be composed into a pathname
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*
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* This is an extension to the truncate() family, lessening the burden
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* of having to compose the filename from parts in a seprate buffer.
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*
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* @returns Upon successful completion truncate() returns POSIX OK(0),
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* otherwise, -1 is returned and @a errno is set to indicate error.
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*/
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int truncatef(off_t length, const char *fmt, ...)
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{
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va_list ap;
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char *file;
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int len;
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va_start(ap, fmt);
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len = vsnprintf(NULL, 0, fmt, ap);
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va_end(ap);
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file = alloca(len + 1);
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if (!file) {
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errno = ENOMEM;
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return -1;
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}
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va_start(ap, fmt);
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vsnprintf(file, len + 1, fmt, ap);
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va_end(ap);
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return truncate(file, length);
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}
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/**
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* Local Variables:
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* indent-tabs-mode: t
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* c-file-style: "linux"
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* End:
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*/
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