106 lines
2.9 KiB
C
106 lines
2.9 KiB
C
/*
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Copyright (c) 2020 SUSE LLC
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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#define _GNU_SOURCE
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/syscall.h>
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#include <unistd.h>
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#include <errno.h>
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#include <getopt.h>
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#include <fcntl.h>
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#include <limits.h>
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#ifndef RENAME_EXCHANGE
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# define RENAME_EXCHANGE (1 << 1)
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#endif
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static int verbose;
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void help(const char* prog, int ret)
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{
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printf("Usage: %s SOURCE TARGET\n", prog);
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puts("Exchange names of SOURCE and TARGET");
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exit(ret);
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}
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int main(int argc, char** argv)
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{
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int c;
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int r;
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static struct option long_options[] = {
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{"verbose", no_argument, 0, 'v' },
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{"help", no_argument, 0, 255 },
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{0, 0, 0, 0 }
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};
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while ((c = getopt_long(argc, argv, "v", long_options, NULL)) != -1) {
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switch(c) {
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case 'v': ++verbose; break;
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case 255: help(argv[0], 0); break;
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}
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}
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if (argc-optind < 2)
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help(argv[0], 1);
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const char *source = argv[optind], *target = argv[optind+1];
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r = syscall (SYS_renameat2, AT_FDCWD, source, AT_FDCWD, target, RENAME_EXCHANGE);
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if (r < 0) {
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// FS not supporting RENAME_EXCHANGE -> EINVAL
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// No renameat2 syscall -> ENOSYS (eg WSL)
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if (errno != EINVAL && errno != ENOSYS) {
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perror("renameat2");
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return 1;
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}
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// Fallback for systems without renameat2 support
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puts("!!! WARNING: rename2 RENAME_EXCHANGE not supported !!!");
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puts("!!! fallback to unsafe rename !!!");
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char tmp[PATH_MAX];
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r = snprintf(tmp, sizeof(tmp), "%s.XXXXXX", target);
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if (r < 0) {
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perror("asprintf");
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return 1;
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}
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// not intended to be use in /tmp so good enough
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mktemp(tmp);
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r = renameat(AT_FDCWD, target, AT_FDCWD, tmp);
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if (!r)
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r = renameat(AT_FDCWD, source, AT_FDCWD, target);
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if (!r)
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r = renameat(AT_FDCWD, tmp, AT_FDCWD, source);
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if (r < 0) {
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perror("renameat");
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return 1;
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}
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}
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return 0;
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}
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