Re: [PATCH 20/22] bsd-user/bsd-file.h: Add implementations for read, pread, readv and preadv

[Warner Losh <imp@bsdimp.com>]

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On Tue, Feb 1, 2022 at 2:37 PM Richard Henderson <
richard.henderson@linaro.org> wrote:

> On 2/1/22 22:14, Warner Losh wrote:
> > Implement do_bsd_{read,pread,readv,preadv}. Connect them to the system
> > call table.
> >
> > Signed-off-by: Stacey Son <sson@FreeBSD.org>
> > Signed-off-by: Kyle Evans <kevans@FreeBSD.org>
> > Signed-off-by: Warner Losh <imp@bsdimp.com>
> > ---
> >   bsd-user/bsd-file.h           | 79 +++++++++++++++++++++++++++++++++++
> >   bsd-user/freebsd/os-syscall.c | 24 +++++++++++
> >   2 files changed, 103 insertions(+)
> >
> > diff --git a/bsd-user/bsd-file.h b/bsd-user/bsd-file.h
> > index 2f743db38e1..5934cbd5612 100644
> > --- a/bsd-user/bsd-file.h
> > +++ b/bsd-user/bsd-file.h
> > @@ -36,4 +36,83 @@ extern struct iovec *lock_iovec(int type, abi_ulong
> target_addr, int count,
> >   extern void unlock_iovec(struct iovec *vec, abi_ulong target_addr, int
> count,
> >           int copy);
> >
> > +ssize_t safe_read(int fd, void *buf, size_t nbytes);
> > +ssize_t safe_pread(int fd, void *buf, size_t nbytes, off_t offset);
> > +ssize_t safe_readv(int fd, const struct iovec *iov, int iovcnt);
> > +ssize_t safe_preadv(int fd, const struct iovec *iov, int iovcnt, off_t
> offset);
> > +
> > +/* read(2) */
> > +static inline abi_long do_bsd_read(abi_long arg1, abi_long arg2,
> abi_long arg3)
> > +{
> > +    abi_long ret;
> > +    void *p;
> > +
> > +    p = lock_user(VERIFY_WRITE, arg2, arg3, 0);
> > +    if (p == NULL) {
> > +        return -TARGET_EFAULT;
> > +    }
> > +    ret = get_errno(safe_read(arg1, p, arg3));
> > +    unlock_user(p, arg2, ret);
> > +
> > +    return ret;
> > +}
> > +
> > +/* pread(2) */
> > +static inline abi_long do_bsd_pread(void *cpu_env, abi_long arg1,
> > +    abi_long arg2, abi_long arg3, abi_long arg4, abi_long arg5,
> abi_long arg6)
> > +{
> > +    abi_long ret;
> > +    void *p;
> > +
> > +    p = lock_user(VERIFY_WRITE, arg2, arg3, 0);
> > +    if (p == NULL) {
> > +        return -TARGET_EFAULT;
> > +    }
> > +    if (regpairs_aligned(cpu_env) != 0) {
> > +        arg4 = arg5;
> > +        arg5 = arg6;
> > +    }
>
> This would be clearer if you had started labeling from arg0.
>

There's a number of other changes this would force, so I'll defer
it...

Warner


> But either way,
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
>
>
> r~
>
> > +    ret = get_errno(safe_pread(arg1, p, arg3, target_arg64(arg4,
> arg5)));
> > +    unlock_user(p, arg2, ret);
> > +
> > +    return ret;
> > +}
> > +
> > +/* readv(2) */
> > +static inline abi_long do_bsd_readv(abi_long arg1, abi_long arg2,
> abi_long arg3)
> > +{
> > +    abi_long ret;
> > +    struct iovec *vec = lock_iovec(VERIFY_WRITE, arg2, arg3, 0);
> > +
> > +    if (vec != NULL) {
> > +        ret = get_errno(safe_readv(arg1, vec, arg3));
> > +        unlock_iovec(vec, arg2, arg3, 1);
> > +    } else {
> > +        ret = -host_to_target_errno(errno);
> > +    }
> > +
> > +    return ret;
> > +}
> > +
> > +/* preadv(2) */
> > +static inline abi_long do_bsd_preadv(void *cpu_env, abi_long arg1,
> > +    abi_long arg2, abi_long arg3, abi_long arg4, abi_long arg5,
> abi_long arg6)
> > +{
> > +    abi_long ret;
> > +    struct iovec *vec = lock_iovec(VERIFY_WRITE, arg2, arg3, 1);
> > +
> > +    if (vec != NULL) {
> > +        if (regpairs_aligned(cpu_env) != 0) {
> > +            arg4 = arg5;
> > +            arg5 = arg6;
> > +        }
> > +        ret = get_errno(safe_preadv(arg1, vec, arg3, target_arg64(arg4,
> arg5)));
> > +        unlock_iovec(vec, arg2, arg3, 0);
> > +    } else {
> > +        ret = -host_to_target_errno(errno);
> > +    }
> > +
> > +    return ret;
> > +}
> > +
> >   #endif /* !BSD_FILE_H_ */
> > diff --git a/bsd-user/freebsd/os-syscall.c
> b/bsd-user/freebsd/os-syscall.c
> > index fcfa6221182..dda79af53de 100644
> > --- a/bsd-user/freebsd/os-syscall.c
> > +++ b/bsd-user/freebsd/os-syscall.c
> > @@ -42,6 +42,14 @@
> >
> >   #include "bsd-file.h"
> >
> > +/* I/O */
> > +safe_syscall3(ssize_t, read, int, fd, void *, buf, size_t, nbytes);
> > +safe_syscall4(ssize_t, pread, int, fd, void *, buf, size_t, nbytes,
> off_t,
> > +    offset);
> > +safe_syscall3(ssize_t, readv, int, fd, const struct iovec *, iov, int,
> iovcnt);
> > +safe_syscall4(ssize_t, preadv, int, fd, const struct iovec *, iov, int,
> iovcnt,
> > +    off_t, offset);
> > +
> >   void target_set_brk(abi_ulong new_brk)
> >   {
> >   }
> > @@ -212,6 +220,22 @@ abi_long do_freebsd_syscall(void *cpu_env, int num,
> abi_long arg1,
> >       }
> >
> >       switch (num) {
> > +
> > +        /*
> > +         * File system calls.
> > +         */
> > +    case TARGET_FREEBSD_NR_read: /* read(2) */
> > +        ret = do_bsd_read(arg1, arg2, arg3);
> > +        break;
> > +
> > +    case TARGET_FREEBSD_NR_pread: /* pread(2) */
> > +        ret = do_bsd_pread(cpu_env, arg1, arg2, arg3, arg4, arg5, arg6);
> > +        break;
> > +
> > +    case TARGET_FREEBSD_NR_readv: /* readv(2) */
> > +        ret = do_bsd_readv(arg1, arg2, arg3);
> > +        break;
> > +
> >       default:
> >           gemu_log("qemu: unsupported syscall: %d\n", num);
> >           ret = -TARGET_ENOSYS;
>
>

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