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author | Lennart Poettering <lennart@poettering.net> | 2018-06-05 16:52:22 +0200 |
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committer | Lennart Poettering <lennart@poettering.net> | 2018-06-07 17:40:14 +0200 |
commit | ec6bdf72597937c0fb981f5b1e04bbbe15000cc5 (patch) | |
tree | 5d34b9b7bfabc4311e982267d1bc60484fdfb8ca /src/basic/copy.c | |
parent | 3f4030399350a853803aad244812b83c1dda3a35 (diff) | |
download | systemd-ec6bdf72597937c0fb981f5b1e04bbbe15000cc5.tar.gz systemd-ec6bdf72597937c0fb981f5b1e04bbbe15000cc5.tar.bz2 systemd-ec6bdf72597937c0fb981f5b1e04bbbe15000cc5.zip |
copy: rework copy_file_atomic() to copy the specified file via O_TMPFILE if possible
Diffstat (limited to 'src/basic/copy.c')
-rw-r--r-- | src/basic/copy.c | 48 |
1 files changed, 36 insertions, 12 deletions
diff --git a/src/basic/copy.c b/src/basic/copy.c index 650de612b8..80d3a9dcdf 100644 --- a/src/basic/copy.c +++ b/src/basic/copy.c @@ -681,31 +681,55 @@ int copy_file(const char *from, const char *to, int flags, mode_t mode, unsigned } int copy_file_atomic(const char *from, const char *to, mode_t mode, unsigned chattr_flags, CopyFlags copy_flags) { - _cleanup_free_ char *t = NULL; + _cleanup_(unlink_and_freep) char *t = NULL; + _cleanup_close_ int fdt = -1; int r; assert(from); assert(to); - r = tempfn_random(to, NULL, &t); - if (r < 0) - return r; + /* We try to use O_TMPFILE here to create the file if we can. Note that that only works if COPY_REPLACE is not + * set though as we need to use linkat() for linking the O_TMPFILE file into the file system but that system + * call can't replace existing files. Hence, if COPY_REPLACE is set we create a temporary name in the file + * system right-away and unconditionally which we then can renameat() to the right name after we completed + * writing it. */ + + if (copy_flags & COPY_REPLACE) { + r = tempfn_random(to, NULL, &t); + if (r < 0) + return r; + + fdt = open(t, O_CREAT|O_EXCL|O_NOFOLLOW|O_NOCTTY|O_WRONLY|O_CLOEXEC, 0600); + if (fdt < 0) { + t = mfree(t); + return -errno; + } + } else { + fdt = open_tmpfile_linkable(to, O_WRONLY|O_CLOEXEC, &t); + if (fdt < 0) + return fdt; + } - r = copy_file(from, t, O_NOFOLLOW|O_EXCL, mode, chattr_flags, copy_flags); + if (chattr_flags != 0) + (void) chattr_fd(fdt, chattr_flags, (unsigned) -1); + + r = copy_file_fd(from, fdt, copy_flags); if (r < 0) return r; + if (fchmod(fdt, mode) < 0) + return -errno; + if (copy_flags & COPY_REPLACE) { - r = renameat(AT_FDCWD, t, AT_FDCWD, to); + if (renameat(AT_FDCWD, t, AT_FDCWD, to) < 0) + return -errno; + } else { + r = link_tmpfile(fdt, t, to); if (r < 0) - r = -errno; - } else - r = rename_noreplace(AT_FDCWD, t, AT_FDCWD, to); - if (r < 0) { - (void) unlink(t); - return r; + return r; } + t = mfree(t); return 0; } |