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Use truncate(2) where appropriate.

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When truncating files by name, use truncate(2).  Windows hasn't got it,
so keep our previous coding based on ftruncate(2) as a fallback.

Discussion: https://postgr.es/m/16663-fe97ccf9932fc800%40postgresql.org
This commit is contained in:
Thomas Munro 2020-12-01 15:34:57 +13:00
parent 9f35f94373
commit 57faaf376e
3 changed files with 29 additions and 12 deletions
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27
src/backend/storage/file/fd.c
View File

@ -622,6 +622,33 @@ pg_flush_data(int fd, off_t offset, off_t nbytes)
#endif
}
/*
* Truncate a file to a given length by name.
*/
int
pg_truncate(const char *path, off_t length)
{
#ifdef WIN32
int save_errno;
int ret;
int fd;
fd = OpenTransientFile(path, O_RDWR | PG_BINARY);
if (fd >= 0)
{
ret = ftruncate(fd, 0);
save_errno = errno;
CloseTransientFile(fd);
errno = save_errno;
}
else
ret = -1;
return ret;
#else
return truncate(path, length);
#endif
}
/*
* fsync_fname -- fsync a file or directory, handling errors properly

13
src/backend/storage/smgr/md.c
View File

@ -294,19 +294,8 @@ do_truncate(const char *path)
{
int save_errno;
int ret;
int fd;
/* truncate(2) would be easier here, but Windows hasn't got it */
fd = OpenTransientFile(path, O_RDWR | PG_BINARY);
if (fd >= 0)
{
ret = ftruncate(fd, 0);
save_errno = errno;
CloseTransientFile(fd);
errno = save_errno;
}
else
ret = -1;
ret = pg_truncate(path, 0);
/* Log a warning here to avoid repetition in callers. */
if (ret < 0 && errno != ENOENT)

1
src/include/storage/fd.h
View File

@ -153,6 +153,7 @@ extern int pg_fsync_no_writethrough(int fd);
extern int pg_fsync_writethrough(int fd);
extern int pg_fdatasync(int fd);
extern void pg_flush_data(int fd, off_t offset, off_t amount);
extern int pg_truncate(const char *path, off_t length);
extern void fsync_fname(const char *fname, bool isdir);
extern int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel);
extern int durable_rename(const char *oldfile, const char *newfile, int loglevel);