Marius Storm-Olsen <mstormo@xxxxxxxxx> writes:
> The MSVC Posix implementation doesn't contain ftruncate, so add our own
> which can handle large files (64bit offsets).
>
> Signed-off-by: Marius Storm-Olsen <mstormo@xxxxxxxxx>
> ---
> compat/msvc.c | 8 ++++++++
> compat/msvc.h | 2 ++
> 2 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/compat/msvc.c b/compat/msvc.c
> index ac04a4c..b96b045 100644
> --- a/compat/msvc.c
> +++ b/compat/msvc.c
> @@ -32,4 +32,12 @@ int closedir(DIR *dir)
> return 0;
> }
>
> +int ftruncate(int fd, __int64 length)
> +{
> + HANDLE fh = (HANDLE)_get_osfhandle(fd);
> + if (!fh || _lseeki64(fd, length, SEEK_SET))
> + return -1;
> + return SetEndOfFile(fh) ? 0 : -1;
> +}
> +
Wouldn't it break this toy program? ftruncate() should preserve the file
offset and use of the seek in the above feels iffy.
#include <stdlib.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
int main(int ac, char **av)
{
int fd = open("testfile", O_CREAT|O_WRONLY, 0666);
if (fd < 0)
exit(1);
write(fd, "abcdefghijklmnopqrstuvwxyz\n", 27);
lseek(fd, 7, SEEK_SET);
write(fd, "H", 1);
ftruncate(fd, 24);
write(fd, "IJ", 2);
close(fd);
exit(0);
}
The only two in-tree users of ftruncate() do not care about this, though.
They both seek to the beginning and then truncate to zero length.
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