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weston/shared/file-util.c

118 lines
3.2 KiB

/*
* Copyright © 2015 Collabora, Ltd.
*
* Permission to use, copy, modify, distribute, and sell this software and
* its documentation for any purpose is hereby granted without fee, provided
* that the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of the copyright holders not be used in
* advertising or publicity pertaining to distribution of the software
* without specific, written prior permission. The copyright holders make
* no representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
* SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
* RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
* CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "config.h"
#include <stdio.h>
#include <errno.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "file-util.h"
static int
current_time_str(char *str, size_t len, const char *fmt)
{
time_t t;
struct tm *t_local;
int ret;
t = time(NULL);
t_local = localtime(&t);
if (!t_local) {
errno = ETIME;
return -1;
}
ret = strftime(str, len, fmt, t_local);
if (ret == 0) {
errno = ETIME;
return -1;
}
return ret;
}
static int
create_file_excl(const char *fname)
{
return open(fname, O_RDWR | O_CLOEXEC | O_CREAT | O_EXCL, 00666);
}
/** Create a unique file with date and time in the name
*
* \param path_prefix Path and file name prefix.
* \param suffix File name suffix.
* \param name_out[out] Buffer for the resulting file name.
* \param name_len Number of bytes usable in name_out.
* \return stdio FILE pointer, or NULL on failure.
*
* Create and open a new file with the name concatenated from
* path_prefix, date and time, and suffix. If a file with this name
* already exists, an counter number is added to the end of the
* date and time sub-string. The counter is increased until a free file
* name is found.
*
* Once creating the file succeeds, the name of the file is in name_out.
* On failure, the contents of name_out are undefined and errno is set.
*/
FILE *
file_create_dated(const char *path_prefix, const char *suffix,
char *name_out, size_t name_len)
{
char timestr[128];
int ret;
int fd;
int cnt = 0;
if (current_time_str(timestr, sizeof(timestr), "%F_%H-%M-%S") < 0)
return NULL;
ret = snprintf(name_out, name_len, "%s%s%s",
path_prefix, timestr, suffix);
if (ret < 0 || (size_t)ret >= name_len) {
errno = ENOBUFS;
return NULL;
}
fd = create_file_excl(name_out);
while (fd == -1 && errno == EEXIST) {
cnt++;
ret = snprintf(name_out, name_len, "%s%s-%d%s",
path_prefix, timestr, cnt, suffix);
if (ret < 0 || (size_t)ret >= name_len) {
errno = ENOBUFS;
return NULL;
}
fd = create_file_excl(name_out);
}
if (fd == -1)
return NULL;
return fdopen(fd, "w");
}