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mv, cp: Preserve nanosecond timestamps

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Otherwise, we run into problems in a typical autoconf-based build
system:

  - config.status is created at some point between two seconds.
  - config.status is run, generating Makefile by first writing to a file
    in /tmp, and then mv-ing it to Makefile.
  - If this mv happens before the beginning of the next second, Makefile
    will be created with the same tv_sec as config.status, but with
    tv_nsec = 0.
  - When make runs, it sees that Makefile is older than config.status,
    and re-runs config.status to generate Makefile.
This commit is contained in:
Michael Forney 2015-05-16 04:57:25 +00:00 committed by sin
parent 0ba81a0f84
commit 1d28fbd6cf
1 changed files with 4 additions and 4 deletions
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8
libutil/cp.c
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@ -30,7 +30,7 @@ cp(const char *s1, const char *s2, int depth)
FILE *f1, *f2;
struct dirent *d;
struct stat st;
struct utimbuf ut;
struct timespec times[2];
ssize_t r;
int (*statf)(const char *, struct stat *);
char target[PATH_MAX], ns1[PATH_MAX], ns2[PATH_MAX], *statf_name;
@ -154,9 +154,9 @@ cp(const char *s1, const char *s2, int depth)
if (cp_aflag || cp_pflag) {
/* timestamp and owner*/
if (!S_ISLNK(st.st_mode)) {
ut.actime = st.st_atime;
ut.modtime = st.st_mtime;
utime(s2, &ut);
times[0] = st.st_atim;
times[1] = st.st_mtim;
utimensat(AT_FDCWD, s2, times, 0);
if (chown(s2, st.st_uid, st.st_gid) < 0) {
weprintf("chown %s:", s2);