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libext2fs: have UNIX IO manager use pread64/pwrite64 

Commit baa3544609 ("libext2fs: have UNIX IO manager use
pread/pwrite) causes a breakage on 32-bit systems where off_t is
32-bits for file systems larger than 4GB.  Fix this by using
pread64/pwrite64 if possible, and if pread64/pwrite64 is not present,
using pread/pwrite only if the size of off_t is at least as big as
ext2_loff_t.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
test-maint
Theodore Ts'o 2014-08-08 16:42:05 -04:00
parent b6edbf6b90
commit f00948ad1d
4 changed files with 31 additions and 3 deletions
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2
configure vendored
View File

@ -12994,7 +12994,7 @@ if test "$ac_res" != no; then :
fi
fi
for ac_func in __secure_getenv backtrace blkid_probe_get_topology blkid_probe_enable_partitions chflags fadvise64 fallocate fallocate64 fchown fdatasync fstat64 ftruncate64 futimes getcwd getdtablesize getmntinfo getpwuid_r getrlimit getrusage jrand48 llseek lseek64 mallinfo mbstowcs memalign mempcpy mmap msync nanosleep open64 pathconf posix_fadvise posix_fadvise64 posix_memalign prctl pread pwrite secure_getenv setmntent setresgid setresuid snprintf srandom stpcpy strcasecmp strdup strnlen strptime strtoull sync_file_range sysconf usleep utime valloc
for ac_func in __secure_getenv backtrace blkid_probe_get_topology blkid_probe_enable_partitions chflags fadvise64 fallocate fallocate64 fchown fdatasync fstat64 ftruncate64 futimes getcwd getdtablesize getmntinfo getpwuid_r getrlimit getrusage jrand48 llseek lseek64 mallinfo mbstowcs memalign mempcpy mmap msync nanosleep open64 pathconf posix_fadvise posix_fadvise64 posix_memalign prctl pread pwrite pread64 pwrite64 secure_getenv setmntent setresgid setresuid snprintf srandom stpcpy strcasecmp strdup strnlen strptime strtoull sync_file_range sysconf usleep utime valloc
do :
as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"

2
configure.in
View File

@ -1061,6 +1061,8 @@ AC_CHECK_FUNCS(m4_flatten([
prctl
pread
pwrite
pread64
pwrite64
secure_getenv
setmntent
setresgid

6
lib/config.h.in
View File

@ -328,6 +328,9 @@
/* Define to 1 if you have the `pread' function. */
#undef HAVE_PREAD
/* Define to 1 if you have the `pread64' function. */
#undef HAVE_PREAD64
/* Define if the <pthread.h> defines PTHREAD_MUTEX_RECURSIVE. */
#undef HAVE_PTHREAD_MUTEX_RECURSIVE
@ -340,6 +343,9 @@
/* Define to 1 if you have the `pwrite' function. */
#undef HAVE_PWRITE
/* Define to 1 if you have the `pwrite64' function. */
#undef HAVE_PWRITE64
/* Define to 1 if dirent has d_reclen */
#undef HAVE_RECLEN_DIRENT

24
lib/ext2fs/unix_io.c
View File

@ -131,11 +131,21 @@ static errcode_t raw_read_blk(io_channel channel,
data->io_stats.bytes_read += size;
location = ((ext2_loff_t) block * channel->block_size) + data->offset;
#ifdef HAVE_PREAD
#ifdef HAVE_PREAD64
/* Try an aligned pread */
if ((channel->align == 0) ||
(IS_ALIGNED(buf, channel->align) &&
IS_ALIGNED(size, channel->align))) {
actual = pread64(data->dev, buf, size, location);
if (actual == size)
return 0;
}
#elif HAVE_PREAD
/* Try an aligned pread */
if ((sizeof(off_t) >= sizeof(ext2_loff_t)) &&
((channel->align == 0) ||
(IS_ALIGNED(buf, channel->align) &&
IS_ALIGNED(size, channel->align)))) {
actual = pread(data->dev, buf, size, location);
if (actual == size)
return 0;
@ -213,11 +223,21 @@ static errcode_t raw_write_blk(io_channel channel,
location = ((ext2_loff_t) block * channel->block_size) + data->offset;
#ifdef HAVE_PWRITE
#ifdef HAVE_PWRITE64
/* Try an aligned pwrite */
if ((channel->align == 0) ||
(IS_ALIGNED(buf, channel->align) &&
IS_ALIGNED(size, channel->align))) {
actual = pwrite64(data->dev, buf, size, location);
if (actual == size)
return 0;
}
#elif HAVE_PWRITE
/* Try an aligned pwrite */
if ((sizeof(off_t) >= sizeof(ext2_loff_t)) &&
((channel->align == 0) ||
(IS_ALIGNED(buf, channel->align) &&
IS_ALIGNED(size, channel->align)))) {
actual = pwrite(data->dev, buf, size, location);
if (actual == size)
return 0;