Re: [MINIOS PATCH v3 09/12] use file_ops and get_file_from_fd() for console

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Juergen Gross, le dim. 16 janv. 2022 09:33:25 +0100, a ecrit:
> Add struct file_ops for the console related file types (FTYPE_CONSOLE
> and savefile). FTYPE_CONSOLE remains statically defined, as it is used
> to statically init stdin, stdout and stderr.
> 
> Instead of directly accessing the files[] array use get_file_from_fd().
> 
> With CONSOLE now handled via file_ops the bogus file descriptor case in
> select_poll() now needs to be handled more explicit instead of dropping
> into console handling, assuming that this case was basically meant to
> cover SAVEFILE.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>

> ---
> V3:
> - switch to struct file * parameter for callbacks
> - use __attribute__((constructor))
> - make console_print() take a const pointer (Andrew Cooper)
> ---
>  console/console.c      |   2 +-
>  console/xenbus.c       | 112 +++++++++++++++++++++++++++++++++++++++++
>  console/xencons_ring.c |   6 +--
>  include/console.h      |   7 ++-
>  include/lib.h          |   3 +-
>  lib/sys.c              |  87 ++++++++------------------------
>  6 files changed, 144 insertions(+), 73 deletions(-)
> 
> diff --git a/console/console.c b/console/console.c
> index af1a6dd3..68c8435e 100644
> --- a/console/console.c
> +++ b/console/console.c
> @@ -76,7 +76,7 @@ void xencons_tx(void)
>  #endif
>  
>  
> -void console_print(struct consfront_dev *dev, char *data, int length)
> +void console_print(struct consfront_dev *dev, const char *data, int length)
>  {
>      char *curr_char, saved_char;
>      char copied_str[length+1];
> diff --git a/console/xenbus.c b/console/xenbus.c
> index 05fc31c0..d8950454 100644
> --- a/console/xenbus.c
> +++ b/console/xenbus.c
> @@ -192,3 +192,115 @@ void fini_consfront(struct consfront_dev *dev)
>  {
>      if (dev) free_consfront(dev);
>  }
> +
> +#ifdef HAVE_LIBC
> +static int consfront_read(struct file *file, void *buf, size_t nbytes)
> +{
> +    int ret;
> +    DEFINE_WAIT(w);
> +
> +    while ( 1 )
> +    {
> +        add_waiter(w, console_queue);
> +        ret = xencons_ring_recv(file->dev, buf, nbytes);
> +        if ( ret )
> +            break;
> +        schedule();
> +    }
> +
> +    remove_waiter(w, console_queue);
> +
> +    return ret;
> +}
> +
> +static int savefile_write(struct file *file, const void *buf, size_t nbytes)
> +{
> +    int ret = 0, tot = nbytes;
> +
> +    while ( nbytes > 0 )
> +    {
> +        ret = xencons_ring_send(file->dev, buf, nbytes);
> +        nbytes -= ret;
> +        buf = (char *)buf + ret;
> +    }
> +
> +    return tot - nbytes;
> +}
> +
> +static int console_write(struct file *file, const void *buf, size_t nbytes)
> +{
> +    console_print(file->dev, buf, nbytes);
> +
> +    return nbytes;
> +}
> +
> +static int consfront_close_fd(struct file *file)
> +{
> +    fini_consfront(file->dev);
> +
> +    return 0;
> +}
> +
> +static int consfront_fstat(struct file *file, struct stat *buf)
> +{
> +    buf->st_mode = S_IRUSR | S_IWUSR;
> +    buf->st_mode |= (file->type == FTYPE_CONSOLE) ? S_IFCHR : S_IFREG;
> +    buf->st_atime = buf->st_mtime = buf->st_ctime = time(NULL);
> +
> +    return 0;
> +}
> +
> +static bool consfront_select_rd(struct file *file)
> +{
> +    return xencons_ring_avail(file->dev);
> +}
> +
> +static const struct file_ops savefile_ops = {
> +    .name = "savefile",
> +    .read = consfront_read,
> +    .write = savefile_write,
> +    .close = consfront_close_fd,
> +    .fstat = consfront_fstat,
> +    .select_rd = consfront_select_rd,
> +    .select_wr = select_yes,
> +};
> +
> +const struct file_ops console_ops = {
> +    .name = "console",
> +    .read = consfront_read,
> +    .write = console_write,
> +    .close = consfront_close_fd,
> +    .fstat = consfront_fstat,
> +    .select_rd = consfront_select_rd,
> +    .select_wr = select_yes,
> +};
> +
> +static unsigned int ftype_savefile;
> +
> +__attribute__((constructor))
> +static void consfront_initialize(void)
> +{
> +    ftype_savefile = alloc_file_type(&savefile_ops);
> +}
> +
> +int open_consfront(char *nodename)
> +{
> +    struct consfront_dev *dev;
> +    struct file *file;
> +
> +    dev = init_consfront(nodename);
> +    if ( !dev )
> +        return -1;
> +
> +    dev->fd = alloc_fd(nodename ? ftype_savefile : FTYPE_CONSOLE);
> +    file = get_file_from_fd(dev->fd);
> +    if ( !file )
> +    {
> +        fini_consfront(dev);
> +        return -1;
> +    }
> +    file->dev = dev;
> +
> +    return dev->fd;
> +}
> +#endif
> diff --git a/console/xencons_ring.c b/console/xencons_ring.c
> index c348f3ce..efedf46b 100644
> --- a/console/xencons_ring.c
> +++ b/console/xencons_ring.c
> @@ -99,10 +99,10 @@ void console_handle_input(evtchn_port_t port, struct 
> pt_regs *regs, void *data)
>  {
>       struct consfront_dev *dev = (struct consfront_dev *) data;
>  #ifdef HAVE_LIBC
> -        int fd = dev ? dev->fd : -1;
> +        struct file *file = dev ? get_file_from_fd(dev->fd) : NULL;
>  
> -        if (fd != -1)
> -            files[fd].read = true;
> +        if ( file )
> +            file->read = true;
>  
>          wake_up(&console_queue);
>  #else
> diff --git a/include/console.h b/include/console.h
> index 0d7bf077..e76e4234 100644
> --- a/include/console.h
> +++ b/include/console.h
> @@ -39,6 +39,7 @@
>  #include <mini-os/os.h>
>  #include <mini-os/traps.h>
>  #include <mini-os/types.h>
> +#include <mini-os/lib.h>
>  #include <xen/grant_table.h>
>  #include <xenbus.h>
>  #include <xen/io/console.h>
> @@ -77,7 +78,7 @@ void xencons_tx(void);
>  
>  void get_console(void *p);
>  void init_console(void);
> -void console_print(struct consfront_dev *dev, char *data, int length);
> +void console_print(struct consfront_dev *dev, const char *data, int length);
>  void fini_consfront(struct consfront_dev *dev);
>  void suspend_console(void);
>  void resume_console(void);
> @@ -93,5 +94,9 @@ int xencons_ring_send_no_notify(struct consfront_dev *dev, 
> const char *data, uns
>  int xencons_ring_avail(struct consfront_dev *dev);
>  int xencons_ring_recv(struct consfront_dev *dev, char *data, unsigned len);
>  void free_consfront(struct consfront_dev *dev);
> +#ifdef HAVE_LIBC
> +extern const struct file_ops console_ops;
> +int open_consfront(char *nodename);
> +#endif
>  
>  #endif /* _LIB_CONSOLE_H_ */
> diff --git a/include/lib.h b/include/lib.h
> index b1beeed3..e815e0a3 100644
> --- a/include/lib.h
> +++ b/include/lib.h
> @@ -162,8 +162,7 @@ extern struct wait_queue_head event_queue;
>  #define FTYPE_FILE       2
>  #define FTYPE_SOCKET     3
>  #define FTYPE_MEM        4
> -#define FTYPE_SAVEFILE   5
> -#define FTYPE_N          6
> +#define FTYPE_N          5
>  #define FTYPE_SPARE     16
>  
>  struct file {
> diff --git a/lib/sys.c b/lib/sys.c
> index db26fd2d..74c82b2a 100644
> --- a/lib/sys.c
> +++ b/lib/sys.c
> @@ -101,6 +101,9 @@ static const struct file_ops file_ops_none = {
>  
>  static const struct file_ops *file_ops[FTYPE_N + FTYPE_SPARE] = {
>      [FTYPE_NONE] = &file_ops_none,
> +#ifdef CONFIG_CONSFRONT
> +    [FTYPE_CONSOLE] = &console_ops,
> +#endif
>  };
>  
>  unsigned int alloc_file_type(const struct file_ops *ops)
> @@ -212,31 +215,26 @@ int mkdir(const char *pathname, mode_t mode)
>  #ifdef CONFIG_CONSFRONT
>  int posix_openpt(int flags)
>  {
> -    struct consfront_dev *dev;
> +    int fd;
>  
>      /* Ignore flags */
> +    fd = open_consfront(NULL);
> +    printk("fd(%d) = posix_openpt\n", fd);
>  
> -    dev = init_consfront(NULL);
> -    dev->fd = alloc_fd(FTYPE_CONSOLE);
> -    files[dev->fd].dev = dev;
> -
> -    printk("fd(%d) = posix_openpt\n", dev->fd);
> -    return(dev->fd);
> +    return fd;
>  }
>  
>  int open_savefile(const char *path, int save)
>  {
> -    struct consfront_dev *dev;
> +    int fd;
>      char nodename[64];
>  
>      snprintf(nodename, sizeof(nodename), "device/console/%d", save ? 
> SAVE_CONSOLE : RESTORE_CONSOLE);
>  
> -    dev = init_consfront(nodename);
> -    dev->fd = alloc_fd(FTYPE_SAVEFILE);
> -    files[dev->fd].dev = dev;
> +    fd = open_consfront(nodename);
> +    printk("fd(%d) = open_savefile\n", fd);
>  
> -    printk("fd(%d) = open_savefile\n", dev->fd);
> -    return(dev->fd);
> +    return fd;
>  }
>  #else
>  int posix_openpt(int flags)
> @@ -291,20 +289,6 @@ int read(int fd, void *buf, size_t nbytes)
>          return ops->read(file, buf, nbytes);
>  
>      switch (file->type) {
> -        case FTYPE_SAVEFILE:
> -     case FTYPE_CONSOLE: {
> -         int ret;
> -            DEFINE_WAIT(w);
> -            while(1) {
> -                add_waiter(w, console_queue);
> -                ret = xencons_ring_recv(files[fd].dev, buf, nbytes);
> -                if (ret)
> -                    break;
> -                schedule();
> -            }
> -            remove_waiter(w, console_queue);
> -            return ret;
> -        }
>  #ifdef HAVE_LWIP
>          case FTYPE_SOCKET:
>           return lwip_read(files[fd].fd, buf, nbytes);
> @@ -332,18 +316,6 @@ int write(int fd, const void *buf, size_t nbytes)
>          return ops->write(file, buf, nbytes);
>  
>      switch (file->type) {
> -        case FTYPE_SAVEFILE: {
> -                int ret = 0, tot = nbytes;
> -                while (nbytes > 0) {
> -                    ret = xencons_ring_send(files[fd].dev, (char *)buf, 
> nbytes);
> -                    nbytes -= ret;
> -                    buf = (char *)buf + ret;
> -                }
> -                return tot - nbytes;
> -            }
> -     case FTYPE_CONSOLE:
> -         console_print(files[fd].dev, (char *)buf, nbytes);
> -         return nbytes;
>  #ifdef HAVE_LWIP
>       case FTYPE_SOCKET:
>           return lwip_write(files[fd].fd, (void*) buf, nbytes);
> @@ -446,12 +418,6 @@ int close(int fd)
>       case FTYPE_SOCKET:
>              res = lwip_close(files[fd].fd);
>              break;
> -#endif
> -#ifdef CONFIG_CONSFRONT
> -        case FTYPE_SAVEFILE:
> -        case FTYPE_CONSOLE:
> -            fini_consfront(files[fd].dev);
> -            break;
>  #endif
>       case FTYPE_NONE:
>              goto error;
> @@ -501,15 +467,8 @@ int fstat(int fd, struct stat *buf)
>          return ops->fstat(file, buf);
>  
>      switch (file->type) {
> -     case FTYPE_SAVEFILE:
> -     case FTYPE_CONSOLE:
>       case FTYPE_SOCKET: {
> -            if (files[fd].type == FTYPE_CONSOLE)
> -                buf->st_mode = S_IFCHR|S_IRUSR|S_IWUSR;
> -            else if (files[fd].type == FTYPE_SOCKET)
> -                buf->st_mode = S_IFSOCK|S_IRUSR|S_IWUSR;
> -            else if (files[fd].type == FTYPE_SAVEFILE)
> -                buf->st_mode = S_IFREG|S_IRUSR|S_IWUSR;
> +            buf->st_mode = S_IFSOCK|S_IRUSR|S_IWUSR;
>           buf->st_uid = 0;
>           buf->st_gid = 0;
>           buf->st_size = 0;
> @@ -630,7 +589,6 @@ int closedir(DIR *dir)
>  #if defined(LIBC_DEBUG) || defined(LIBC_VERBOSE)
>  static const char *const file_types[] = {
>      [FTYPE_NONE]    = "none",
> -    [FTYPE_CONSOLE] = "console",
>      [FTYPE_SOCKET]  = "socket",
>  };
>  
> @@ -799,21 +757,18 @@ static int select_poll(int nfds, fd_set *readfds, 
> fd_set *writefds, fd_set *exce
>              }
>  
>           if (FD_ISSET(i, readfds) || FD_ISSET(i, writefds) || FD_ISSET(i, 
> exceptfds))
> +            {
>               printk("bogus fd %d in select\n", i);
> -         /* Fallthrough.  */
> -        }
> -
> -     case FTYPE_CONSOLE:
> -         if (FD_ISSET(i, readfds)) {
> -                if (xencons_ring_avail(files[i].dev))
> -                 n++;
> -             else
> -                 FD_CLR(i, readfds);
> +                if ( FD_ISSET(i, readfds) )
> +                    FD_CLR(i, readfds);
> +                if ( FD_ISSET(i, writefds) )
> +                    FD_CLR(i, writefds);
> +                if ( FD_ISSET(i, exceptfds) )
> +                    FD_CLR(i, exceptfds);
>              }
> -         if (FD_ISSET(i, writefds))
> -                n++;
> -         FD_CLR(i, exceptfds);
>           break;
> +        }
> +
>  #ifdef HAVE_LWIP
>       case FTYPE_SOCKET:
>           if (FD_ISSET(i, readfds)) {
> -- 
> 2.26.2
> 

-- 
Samuel
<N> (* If you have a precise idea of the intended use of the following code, 
please
<N>    write to Eduardo.Gimenez@xxxxxxxx and ask for the prize :-)
<N>    -- Eduardo (11/8/97) *)
 -+- N sur #ens-mim - et c'était un des développeurs -+-