bee04eadf8
The test was failing (after hanging for several hours) because of a hard-coded assumption about which file descriptor would be returned by memfd_create(). The actual file descriptor gets printed by the test program though, so read this and use it instead. (Adjust the test program so that this is not printed until the file is ready.) Resolve compiler warnings about implicit function declarations, by using the #include statements listed in the kernel.org man-pages.
107 lines
2.6 KiB
C
107 lines
2.6 KiB
C
/*
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* Copyright (c) 2016 Red Hat, Inc.
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*
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* This program is free software: you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be
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* useful, but WITHOUT ANY WARRANTY; without even the implied
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* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see http://www.gnu.org/licenses/.
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*
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*/
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#define _GNU_SOURCE
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <sys/syscall.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \
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} while (0)
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int main(int argc, char *argv[])
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{
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int fd;
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unsigned int seals;
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char *addr;
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char *name, *seals_arg;
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ssize_t len;
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char* message = "this is a test message for memfd\n";
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if (argc < 3) {
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fprintf(stderr, "%s name size [seals]\n", argv[0]);
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fprintf(stderr, "\t'seals' can contain any of the "
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"following characters:\n");
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fprintf(stderr, "\t\tg - F_SEAL_GROW\n");
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fprintf(stderr, "\t\ts - F_SEAL_SHRINK\n");
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fprintf(stderr, "\t\tw - F_SEAL_WRITE\n");
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fprintf(stderr, "\t\tS - F_SEAL_SEAL\n");
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exit(EXIT_FAILURE);
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}
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name = argv[1];
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len = atoi(argv[2]);
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seals_arg = argv[3];
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/* Create an anonymous file in tmpfs; allow seals to be
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placed on the file */
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fd = syscall(SYS_memfd_create, name, MFD_ALLOW_SEALING);
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if (fd == -1)
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errExit("memfd_create");
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/* Size the file as specified on the command line */
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if (ftruncate(fd, len) == -1)
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errExit("truncate");
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if (write(fd, message, strlen(message)) <= 0)
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errExit("write");
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/* Code to map the file and populate the mapping with data
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omitted */
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/* If a 'seals' command-line argument was supplied, set some
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seals on the file */
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if (seals_arg != NULL) {
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seals = 0;
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if (strchr(seals_arg, 'g') != NULL)
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seals |= F_SEAL_GROW;
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if (strchr(seals_arg, 's') != NULL)
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seals |= F_SEAL_SHRINK;
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if (strchr(seals_arg, 'w') != NULL)
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seals |= F_SEAL_WRITE;
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if (strchr(seals_arg, 'S') != NULL)
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seals |= F_SEAL_SEAL;
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if (fcntl(fd, F_ADD_SEALS, seals) == -1)
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errExit("fcntl");
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}
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/* Output the pathname of (a symbolic link to) the file
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created by memfd_create() */
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printf("/proc/%ld/fd/%d\n", (long) getpid(), fd);
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fflush(stdout);
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/* Keep running, so that the file created by memfd_create()
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continues to exist */
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pause();
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exit(EXIT_SUCCESS);
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}
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