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Work around ftruncate implementations that don't support extending 

files.
This commit is contained in:
Alexandre Julliard 2002-01-29 02:51:12 +00:00
parent 5d93b6ede9
commit 86e5efb6b3
1 changed files with 41 additions and 17 deletions
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58
server/file.c
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@ -456,29 +456,46 @@ static int set_file_pointer( handle_t handle, unsigned int *low, int *high, int
return 1;
}
static int truncate_file( handle_t handle )
/* extend a file beyond the current end of file */
static int extend_file( struct file *file, off_t size )
{
struct file *file;
off_t result;
static const char zero;
if (!(file = get_file_obj( current->process, handle, GENERIC_WRITE )))
return 0;
if (((result = lseek( file->obj.fd, 0, SEEK_CUR )) == -1) ||
(ftruncate( file->obj.fd, result ) == -1))
/* extend the file one byte beyond the requested size and then truncate it */
/* this should work around ftruncate implementations that can't extend files */
if ((lseek( file->obj.fd, size, SEEK_SET ) != -1) &&
(write( file->obj.fd, &zero, 1 ) != -1))
{
file_set_error();
release_object( file );
return 0;
ftruncate( file->obj.fd, size );
return 1;
}
release_object( file );
return 1;
file_set_error();
return 0;
}
/* truncate file at current position */
static int truncate_file( struct file *file )
{
int ret = 0;
off_t pos = lseek( file->obj.fd, 0, SEEK_CUR );
off_t eof = lseek( file->obj.fd, 0, SEEK_END );
if (eof < pos) ret = extend_file( file, pos );
else
{
if (ftruncate( file->obj.fd, pos ) != -1) ret = 1;
else file_set_error();
}
lseek( file->obj.fd, pos, SEEK_SET ); /* restore file pos */
return ret;
}
/* try to grow the file to the specified size */
int grow_file( struct file *file, int size_high, int size_low )
{
int ret = 0;
struct stat st;
off_t size = size_low + (((off_t)size_high)<<32);
off_t old_pos, size = size_low + (((off_t)size_high)<<32);
if (fstat( file->obj.fd, &st ) == -1)
{
@ -486,9 +503,10 @@ int grow_file( struct file *file, int size_high, int size_low )
return 0;
}
if (st.st_size >= size) return 1; /* already large enough */
if (ftruncate( file->obj.fd, size ) != -1) return 1;
file_set_error();
return 0;
old_pos = lseek( file->obj.fd, 0, SEEK_CUR ); /* save old pos */
ret = extend_file( file, size );
lseek( file->obj.fd, old_pos, SEEK_SET ); /* restore file pos */
return ret;
}
static int set_file_time( handle_t handle, time_t access_time, time_t write_time )
@ -604,7 +622,13 @@ DECL_HANDLER(set_file_pointer)
/* truncate (or extend) a file */
DECL_HANDLER(truncate_file)
{
truncate_file( req->handle );
struct file *file;
if ((file = get_file_obj( current->process, req->handle, GENERIC_WRITE )))
{
truncate_file( file );
release_object( file );
}
}
/* flush a file buffers */