parsers: make pack_dirstate take now in integer for consistency
On recent OS, 'stat.st_mtime' has a double precision floating point
value to represent nano seconds, but it is not wide enough for actual
file timestamp: nowadays, only 52 - 32 = 20 bit width is available for
decimal places in sec.
Therefore, casting it to 'int' may cause unexpected result. See also
changeset 13272104bb07 fixing issue4836 for detail.
For example, changed file A may be treated as "clean" unexpectedly in
steps below. "rounded now" is the value gotten by rounding via
'int(st.st_mtime)' or so.
---------------------+--------------------+------------------------
"now" | | timestamp of A (time_t)
float rounded time_t| action | FS dirstate
------ ------- ------+--------------------+-------- ---------------
N+.nnn N N | | --- ---
| update file A | N
| dirstate.normal(A) | N
N+.999 N+1 N | |
| dirstate.write() | N (*1)
| : |
| change file A | N
| : |
N+1.00 N+1 N+1 | |
| "hg status" (*2) | N N
------ ------- ------+--------------------+-------- ---------------
Timestamp N of A in dirstate isn't dropped at (*1), because "rounded
now" is N+1 at that time, even if 'st_mtime' in 'time_t' is still N.
Then, file A is unexpectedly treated as "clean" at (*2) in this case.
For consistent handling of 'stat.st_mtime', this patch makes
'pack_dirstate()' take 'now' argument not in floating point but in
integer.
This patch makes 'PyArg_ParseTuple()' in 'pack_dirstate()' use format
'i' (= checking type mismatch or overflow), even though it is ensured
that 'now' is in the range of 32bit signed integer by masking with
'_rangemask' (= 0x7fffffff) on caller side.
It should be cheaper enough than packing itself, and useful to
detect that legacy code invokes 'pack_dirstate()' with 'now' in
floating point value.
#!/usr/bin/env python
__doc__ = """Same as `echo a >> b`, but ensures a changed mtime of b.
Without this svn will not detect workspace changes."""
import sys, os
text = sys.argv[1]
fname = sys.argv[2]
f = open(fname, "ab")
try:
before = os.fstat(f.fileno()).st_mtime
f.write(text)
f.write("\n")
finally:
f.close()
inc = 1
now = os.stat(fname).st_mtime
while now == before:
t = now + inc
inc += 1
os.utime(fname, (t, t))
now = os.stat(fname).st_mtime