diff options
Diffstat (limited to 'gold/ftruncate.c')
-rw-r--r-- | gold/ftruncate.c | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/gold/ftruncate.c b/gold/ftruncate.c new file mode 100644 index 0000000..ff7d11b --- /dev/null +++ b/gold/ftruncate.c @@ -0,0 +1,90 @@ +/* ftruncate emulations that work on some System V's. + This file is in the public domain. */ + +#include <config.h> + +/* Specification. */ +#include <unistd.h> + +#include <sys/types.h> +#include <fcntl.h> + +#ifdef F_CHSIZE + +int +ftruncate (int fd, off_t length) +{ + return fcntl (fd, F_CHSIZE, length); +} + +#else /* not F_CHSIZE */ +# ifdef F_FREESP + +/* By William Kucharski <kucharsk@netcom.com>. */ + +# include <sys/stat.h> +# include <errno.h> + +int +ftruncate (int fd, off_t length) +{ + struct flock fl; + struct stat filebuf; + + if (fstat (fd, &filebuf) < 0) + return -1; + + if (filebuf.st_size < length) + { + /* Extend file length. */ + if (lseek (fd, (length - 1), SEEK_SET) < 0) + return -1; + + /* Write a "0" byte. */ + if (write (fd, "", 1) != 1) + return -1; + } + else + { + + /* Truncate length. */ + + fl.l_whence = 0; + fl.l_len = 0; + fl.l_start = length; + fl.l_type = F_WRLCK; /* write lock on file space */ + + /* This relies on the *undocumented* F_FREESP argument to fcntl, + which truncates the file so that it ends at the position + indicated by fl.l_start. Will minor miracles never cease? */ + + if (fcntl (fd, F_FREESP, &fl) < 0) + return -1; + } + + return 0; +} + +# else /* not F_CHSIZE nor F_FREESP */ +# if HAVE_CHSIZE /* native Windows, e.g. mingw */ + +int +ftruncate (int fd, off_t length) +{ + return chsize (fd, length); +} + +# else /* not F_CHSIZE nor F_FREESP nor HAVE_CHSIZE */ + +# include <errno.h> + +int +ftruncate (int fd, off_t length) +{ + errno = EIO; + return -1; +} + +# endif /* not HAVE_CHSIZE */ +# endif /* not F_FREESP */ +#endif /* not F_CHSIZE */ |