/* utimecmp.c -- compare file time stamps
- Copyright (C) 2004, 2005, 2006, 2007, 2009 Free Software
- Foundation, Inc.
+ Copyright (C) 2004-2007, 2009-2013 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include "stat-time.h"
#include "utimens.h"
#include "verify.h"
-#include "xalloc.h"
#ifndef MAX
# define MAX(a, b) ((a) > (b) ? (a) : (b))
#endif
-enum { BILLION = 1000 * 1000 * 1000 };
+#define BILLION (1000 * 1000 * 1000)
/* Best possible resolution that utimens can set and stat can return,
due to system-call limitations. It must be a power of 10 that is
#if HAVE_UTIMENSAT
enum { SYSCALL_RESOLUTION = 1 };
#elif ((HAVE_FUTIMESAT || HAVE_WORKING_UTIMES) \
- && (defined HAVE_STRUCT_STAT_ST_ATIM_TV_NSEC \
- || defined HAVE_STRUCT_STAT_ST_ATIMESPEC_TV_NSEC \
- || defined HAVE_STRUCT_STAT_ST_ATIMENSEC \
- || defined HAVE_STRUCT_STAT_ST_ATIM_ST__TIM_TV_NSEC \
- || defined HAVE_STRUCT_STAT_ST_SPARE1))
+ && (defined HAVE_STRUCT_STAT_ST_ATIM_TV_NSEC \
+ || defined HAVE_STRUCT_STAT_ST_ATIMESPEC_TV_NSEC \
+ || defined HAVE_STRUCT_STAT_ST_ATIMENSEC \
+ || defined HAVE_STRUCT_STAT_ST_ATIM_ST__TIM_TV_NSEC \
+ || defined HAVE_STRUCT_STAT_ST_SPARE1))
enum { SYSCALL_RESOLUTION = 1000 };
#else
enum { SYSCALL_RESOLUTION = BILLION };
int
utimecmp (char const *dst_name,
- struct stat const *dst_stat,
- struct stat const *src_stat,
- int options)
+ struct stat const *dst_stat,
+ struct stat const *src_stat,
+ int options)
{
/* Things to watch out for:
The code uses a static hash table internally and is not safe in the
- presence of signals, multiple threads, etc.
+ presence of signals, multiple threads, etc. However, memory pressure
+ that prevents use of the hash table is not fatal - we just fall back
+ to redoing the computations on every call in that case.
int and long int might be 32 bits. Many of the calculations store
numbers up to 2 billion, and multiply by 10; they have to avoid
{
/* Look up the time stamp resolution for the destination device. */
- /* Hash table for devices. */
+ /* Hash table for caching information learned about devices. */
static Hash_table *ht;
/* Information about the destination file system. */
static struct fs_res *new_dst_res;
- struct fs_res *dst_res;
+ struct fs_res *dst_res = NULL;
+ struct fs_res tmp_dst_res;
/* Time stamp resolution in nanoseconds. */
int res;
/* Quick exit, if possible. Since the worst resolution is 2
- seconds, anything that differs by more than that does not
- needs source truncation. */
+ seconds, anything that differs by more than that does not
+ needs source truncation. */
if (dst_s == src_s && dst_ns == src_ns)
- return 0;
+ return 0;
if (dst_s <= src_s - 2)
- return -1;
+ return -1;
if (src_s <= dst_s - 2)
- return 1;
+ return 1;
+ /* Try to do a hash lookup, but fall back to stack variables and
+ recomputation on low memory situations. */
if (! ht)
- ht = hash_initialize (16, NULL, dev_info_hash, dev_info_compare, free);
- if (! new_dst_res)
- {
- new_dst_res = xmalloc (sizeof *new_dst_res);
- new_dst_res->resolution = 2 * BILLION;
- new_dst_res->exact = false;
- }
- new_dst_res->dev = dst_stat->st_dev;
- dst_res = hash_insert (ht, new_dst_res);
- if (! dst_res)
- xalloc_die ();
-
- if (dst_res == new_dst_res)
- {
- /* NEW_DST_RES is now in use in the hash table, so allocate a
- new entry next time. */
- new_dst_res = NULL;
- }
+ ht = hash_initialize (16, NULL, dev_info_hash, dev_info_compare, free);
+ if (ht)
+ {
+ if (! new_dst_res)
+ {
+ new_dst_res = malloc (sizeof *new_dst_res);
+ if (!new_dst_res)
+ goto low_memory;
+ new_dst_res->resolution = 2 * BILLION;
+ new_dst_res->exact = false;
+ }
+ new_dst_res->dev = dst_stat->st_dev;
+ dst_res = hash_insert (ht, new_dst_res);
+ if (! dst_res)
+ goto low_memory;
+
+ if (dst_res == new_dst_res)
+ {
+ /* NEW_DST_RES is now in use in the hash table, so allocate a
+ new entry next time. */
+ new_dst_res = NULL;
+ }
+ }
+ else
+ {
+ low_memory:
+ if (ht)
+ {
+ tmp_dst_res.dev = dst_stat->st_dev;
+ dst_res = hash_lookup (ht, &tmp_dst_res);
+ }
+ if (!dst_res)
+ {
+ dst_res = &tmp_dst_res;
+ dst_res->resolution = 2 * BILLION;
+ dst_res->exact = false;
+ }
+ }
res = dst_res->resolution;
#ifdef _PC_TIMESTAMP_RESOLUTION
- /* If the system will tell us the resolution, we're set! */
+ /* If the system will tell us the resolution, we're set! */
if (! dst_res->exact)
- {
- res = pathconf (dst_name, _PC_TIMESTAMP_RESOLUTION);
- if (0 < res)
- {
- dst_res->resolution = res;
- dst_res->exact = true;
- }
- }
+ {
+ res = pathconf (dst_name, _PC_TIMESTAMP_RESOLUTION);
+ if (0 < res)
+ {
+ dst_res->resolution = res;
+ dst_res->exact = true;
+ }
+ }
#endif
if (! dst_res->exact)
- {
- /* This file system's resolution is not known exactly.
- Deduce it, and store the result in the hash table. */
-
- time_t dst_a_s = dst_stat->st_atime;
- time_t dst_c_s = dst_stat->st_ctime;
- time_t dst_m_s = dst_s;
- int dst_a_ns = get_stat_atime_ns (dst_stat);
- int dst_c_ns = get_stat_ctime_ns (dst_stat);
- int dst_m_ns = dst_ns;
-
- /* Set RES to an upper bound on the file system resolution
- (after truncation due to SYSCALL_RESOLUTION) by inspecting
- the atime, ctime and mtime of the existing destination.
- We don't know of any file system that stores atime or
- ctime with a higher precision than mtime, so it's valid to
- look at them too. */
- {
- bool odd_second = (dst_a_s | dst_c_s | dst_m_s) & 1;
-
- if (SYSCALL_RESOLUTION == BILLION)
- {
- if (odd_second | dst_a_ns | dst_c_ns | dst_m_ns)
- res = BILLION;
- }
- else
- {
- int a = dst_a_ns;
- int c = dst_c_ns;
- int m = dst_m_ns;
-
- /* Write it this way to avoid mistaken GCC warning
- about integer overflow in constant expression. */
- int SR10 = SYSCALL_RESOLUTION; SR10 *= 10;
-
- if ((a % SR10 | c % SR10 | m % SR10) != 0)
- res = SYSCALL_RESOLUTION;
- else
- for (res = SR10, a /= SR10, c /= SR10, m /= SR10;
- (res < dst_res->resolution
- && (a % 10 | c % 10 | m % 10) == 0);
- res *= 10, a /= 10, c /= 10, m /= 10)
- if (res == BILLION)
- {
- if (! odd_second)
- res *= 2;
- break;
- }
- }
-
- dst_res->resolution = res;
- }
-
- if (SYSCALL_RESOLUTION < res)
- {
- struct timespec timespec[2];
- struct stat dst_status;
-
- /* Ignore source time stamp information that must necessarily
- be lost when filtered through utimens. */
- src_ns -= src_ns % SYSCALL_RESOLUTION;
-
- /* If the time stamps disagree widely enough, there's no need
- to interrogate the file system to deduce the exact time
- stamp resolution; return the answer directly. */
- {
- time_t s = src_s & ~ (res == 2 * BILLION);
- if (src_s < dst_s || (src_s == dst_s && src_ns <= dst_ns))
- return 1;
- if (dst_s < s
- || (dst_s == s && dst_ns < src_ns - src_ns % res))
- return -1;
- }
-
- /* Determine the actual time stamp resolution for the
- destination file system (after truncation due to
- SYSCALL_RESOLUTION) by setting the access time stamp of the
- destination to the existing access time, except with
- trailing nonzero digits. */
-
- timespec[0].tv_sec = dst_a_s;
- timespec[0].tv_nsec = dst_a_ns;
- timespec[1].tv_sec = dst_m_s | (res == 2 * BILLION);
- timespec[1].tv_nsec = dst_m_ns + res / 9;
-
- /* Set the modification time. But don't try to set the
- modification time of symbolic links; on many hosts this sets
- the time of the pointed-to file. */
- if ((S_ISLNK (dst_stat->st_mode)
- ? lutimens (dst_name, timespec)
- : utimens (dst_name, timespec)) != 0)
- return -2;
-
- /* Read the modification time that was set. */
- {
- int stat_result = (S_ISLNK (dst_stat->st_mode)
- ? lstat (dst_name, &dst_status)
- : stat (dst_name, &dst_status));
-
- if (stat_result
- | (dst_status.st_mtime ^ dst_m_s)
- | (get_stat_mtime_ns (&dst_status) ^ dst_m_ns))
- {
- /* The modification time changed, or we can't tell whether
- it changed. Change it back as best we can. */
- timespec[1].tv_sec = dst_m_s;
- timespec[1].tv_nsec = dst_m_ns;
- if (S_ISLNK (dst_stat->st_mode))
- lutimens (dst_name, timespec);
- else
- utimens (dst_name, timespec);
- }
-
- if (stat_result != 0)
- return -2;
- }
-
- /* Determine the exact resolution from the modification time
- that was read back. */
- {
- int old_res = res;
- int a = (BILLION * (dst_status.st_mtime & 1)
- + get_stat_mtime_ns (&dst_status));
-
- res = SYSCALL_RESOLUTION;
-
- for (a /= res; a % 10 != 0; a /= 10)
- {
- if (res == BILLION)
- {
- res *= 2;
- break;
- }
- res *= 10;
- if (res == old_res)
- break;
- }
- }
- }
-
- dst_res->resolution = res;
- dst_res->exact = true;
- }
+ {
+ /* This file system's resolution is not known exactly.
+ Deduce it, and store the result in the hash table. */
+
+ time_t dst_a_s = dst_stat->st_atime;
+ time_t dst_c_s = dst_stat->st_ctime;
+ time_t dst_m_s = dst_s;
+ int dst_a_ns = get_stat_atime_ns (dst_stat);
+ int dst_c_ns = get_stat_ctime_ns (dst_stat);
+ int dst_m_ns = dst_ns;
+
+ /* Set RES to an upper bound on the file system resolution
+ (after truncation due to SYSCALL_RESOLUTION) by inspecting
+ the atime, ctime and mtime of the existing destination.
+ We don't know of any file system that stores atime or
+ ctime with a higher precision than mtime, so it's valid to
+ look at them too. */
+ {
+ bool odd_second = (dst_a_s | dst_c_s | dst_m_s) & 1;
+
+ if (SYSCALL_RESOLUTION == BILLION)
+ {
+ if (odd_second | dst_a_ns | dst_c_ns | dst_m_ns)
+ res = BILLION;
+ }
+ else
+ {
+ int a = dst_a_ns;
+ int c = dst_c_ns;
+ int m = dst_m_ns;
+
+ /* Write it this way to avoid mistaken GCC warning
+ about integer overflow in constant expression. */
+ int SR10 = SYSCALL_RESOLUTION; SR10 *= 10;
+
+ if ((a % SR10 | c % SR10 | m % SR10) != 0)
+ res = SYSCALL_RESOLUTION;
+ else
+ for (res = SR10, a /= SR10, c /= SR10, m /= SR10;
+ (res < dst_res->resolution
+ && (a % 10 | c % 10 | m % 10) == 0);
+ res *= 10, a /= 10, c /= 10, m /= 10)
+ if (res == BILLION)
+ {
+ if (! odd_second)
+ res *= 2;
+ break;
+ }
+ }
+
+ dst_res->resolution = res;
+ }
+
+ if (SYSCALL_RESOLUTION < res)
+ {
+ struct timespec timespec[2];
+ struct stat dst_status;
+
+ /* Ignore source time stamp information that must necessarily
+ be lost when filtered through utimens. */
+ src_ns -= src_ns % SYSCALL_RESOLUTION;
+
+ /* If the time stamps disagree widely enough, there's no need
+ to interrogate the file system to deduce the exact time
+ stamp resolution; return the answer directly. */
+ {
+ time_t s = src_s & ~ (res == 2 * BILLION);
+ if (src_s < dst_s || (src_s == dst_s && src_ns <= dst_ns))
+ return 1;
+ if (dst_s < s
+ || (dst_s == s && dst_ns < src_ns - src_ns % res))
+ return -1;
+ }
+
+ /* Determine the actual time stamp resolution for the
+ destination file system (after truncation due to
+ SYSCALL_RESOLUTION) by setting the access time stamp of the
+ destination to the existing access time, except with
+ trailing nonzero digits. */
+
+ timespec[0].tv_sec = dst_a_s;
+ timespec[0].tv_nsec = dst_a_ns;
+ timespec[1].tv_sec = dst_m_s | (res == 2 * BILLION);
+ timespec[1].tv_nsec = dst_m_ns + res / 9;
+
+ /* Set the modification time. But don't try to set the
+ modification time of symbolic links; on many hosts this sets
+ the time of the pointed-to file. */
+ if ((S_ISLNK (dst_stat->st_mode)
+ ? lutimens (dst_name, timespec)
+ : utimens (dst_name, timespec)) != 0)
+ return -2;
+
+ /* Read the modification time that was set. */
+ {
+ int stat_result = (S_ISLNK (dst_stat->st_mode)
+ ? lstat (dst_name, &dst_status)
+ : stat (dst_name, &dst_status));
+
+ if (stat_result
+ | (dst_status.st_mtime ^ dst_m_s)
+ | (get_stat_mtime_ns (&dst_status) ^ dst_m_ns))
+ {
+ /* The modification time changed, or we can't tell whether
+ it changed. Change it back as best we can. */
+ timespec[1].tv_sec = dst_m_s;
+ timespec[1].tv_nsec = dst_m_ns;
+ if (S_ISLNK (dst_stat->st_mode))
+ lutimens (dst_name, timespec);
+ else
+ utimens (dst_name, timespec);
+ }
+
+ if (stat_result != 0)
+ return -2;
+ }
+
+ /* Determine the exact resolution from the modification time
+ that was read back. */
+ {
+ int old_res = res;
+ int a = (BILLION * (dst_status.st_mtime & 1)
+ + get_stat_mtime_ns (&dst_status));
+
+ res = SYSCALL_RESOLUTION;
+
+ for (a /= res; a % 10 == 0; a /= 10)
+ {
+ if (res == BILLION)
+ {
+ res *= 2;
+ break;
+ }
+ res *= 10;
+ if (res == old_res)
+ break;
+ }
+ }
+ }
+
+ dst_res->resolution = res;
+ dst_res->exact = true;
+ }
/* Truncate the source's time stamp according to the resolution. */
src_s &= ~ (res == 2 * BILLION);
/* Compare the time stamps and return -1, 0, 1 accordingly. */
return (dst_s < src_s ? -1
- : dst_s > src_s ? 1
- : dst_ns < src_ns ? -1
- : dst_ns > src_ns);
+ : dst_s > src_s ? 1
+ : dst_ns < src_ns ? -1
+ : dst_ns > src_ns);
}
projects / gnulib.git / blobdiff