Messages in this thread | | | From | Andy Lutomirski <> | Date | Thu, 1 Aug 2013 18:51:33 -0700 | Subject | O_TMPFILE and linkat(/proc/self/fd/...) on tmpfs creates a weird file |
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This test program:
#include <stdio.h> #include <err.h> #include <fcntl.h> #include <unistd.h>
#define __O_TMPFILE 020000000 #define O_TMPFILE (__O_TMPFILE | O_DIRECTORY) #define AT_EMPTY_PATH 0x1000
int main(int argc, char **argv) { char buf[128];
if (argc != 3) errx(1, "Usage: flinktest PATH linkat|proc");
int fd = open(".", O_TMPFILE | O_RDWR); if (fd == -1) err(1, "O_TMPFILE"); write(fd, "test", 4);
if (!strcmp(argv[2], "linkat")) { if (linkat(fd, "", AT_FDCWD, argv[1], AT_EMPTY_PATH) != 0) err(1, "linkat"); } else if (!strcmp(argv[2], "proc")) { sprintf(buf, "/proc/self/fd/%d", fd); if (linkat(AT_FDCWD, buf, AT_FDCWD, argv[1], AT_SYMLINK_FOLLOW) != 0) err(1, "linkat"); } else { errx(1, "invalid mode"); } return 0; }
run on tmpfs results in a "weird file". stat thinks it has "Access: (0000/?--------) and cat says "Invalid argument".
This is on -linus from a couple minutes ago.
--Andy
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