i386/MIT/course/src/git.lab/lib/console.c

   1
   2 #include <inc/string.h>
   3 #include <inc/lib.h>
   4
   5 void
   6 cputchar(int ch)
   7 {
   8         char c = ch;
   9
  10         // Unlike standard Unix's putchar,
  11         // the cputchar function _always_ outputs to the system console.
  12         sys_cputs(&c, 1);
  13 }
  14
  15 int
  16 getchar(void)
  17 {
  18         unsigned char c;
  19         int r;
  20
  21         // JOS does, however, support standard _input_ redirection,
  22         // allowing the user to redirect script files to the shell and such.
  23         // getchar() reads a character from file descriptor 0.
  24         r = read(0, &c, 1);
  25         if (r < 0)
  26                 return r;
  27         if (r < 1)
  28                 return -E_EOF;
  29         return c;
  30 }
  31
  32
  33 // "Real" console file descriptor implementation.
  34 // The putchar/getchar functions above will still come here by default,
  35 // but now can be redirected to files, pipes, etc., via the fd layer.
  36
  37 static ssize_t devcons_read(struct Fd*, void*, size_t);
  38 static ssize_t devcons_write(struct Fd*, const void*, size_t);
  39 static int devcons_close(struct Fd*);
  40 static int devcons_stat(struct Fd*, struct Stat*);
  41
  42 struct Dev devcons =
  43 {
  44         .dev_id =       'c',
  45         .dev_name =     "cons",
  46         .dev_read =     devcons_read,
  47         .dev_write =    devcons_write,
  48         .dev_close =    devcons_close,
  49         .dev_stat =     devcons_stat
  50 };
  51
  52 int
  53 iscons(int fdnum)
  54 {
  55         int r;
  56         struct Fd *fd;
  57
  58         if ((r = fd_lookup(fdnum, &fd)) < 0)
  59                 return r;
  60         return fd->fd_dev_id == devcons.dev_id;
  61 }
  62
  63 int
  64 opencons(void)
  65 {
  66         int r;
  67         struct Fd* fd;
  68
  69         if ((r = fd_alloc(&fd)) < 0)
  70                 return r;
  71         if ((r = sys_page_alloc(0, fd, PTE_P|PTE_U|PTE_W|PTE_SHARE)) < 0)
  72                 return r;
  73         fd->fd_dev_id = devcons.dev_id;
  74         fd->fd_omode = O_RDWR;
  75         return fd2num(fd);
  76 }
  77
  78 static ssize_t
  79 devcons_read(struct Fd *fd, void *vbuf, size_t n)
  80 {
  81         int c;
  82
  83         if (n == 0)
  84                 return 0;
  85
  86         while ((c = sys_cgetc()) == 0)
  87                 sys_yield();
  88         if (c < 0)
  89                 return c;
  90         if (c == 0x04)  // ctl-d is eof
  91                 return 0;
  92         *(char*)vbuf = c;
  93         return 1;
  94 }
  95
  96 static ssize_t
  97 devcons_write(struct Fd *fd, const void *vbuf, size_t n)
  98 {
  99         int tot, m;
 100         char buf[128];
 101
 102         // mistake: have to nul-terminate arg to sys_cputs,
 103         // so we have to copy vbuf into buf in chunks and nul-terminate.
 104         for (tot = 0; tot < n; tot += m) {
 105                 m = n - tot;
 106                 if (m > sizeof(buf) - 1)
 107                         m = sizeof(buf) - 1;
 108                 memmove(buf, (char*)vbuf + tot, m);
 109                 sys_cputs(buf, m);
 110         }
 111         return tot;
 112 }
 113
 114 static int
 115 devcons_close(struct Fd *fd)
 116 {
 117         USED(fd);
 118
 119         return 0;
 120 }
 121
 122 static int
 123 devcons_stat(struct Fd *fd, struct Stat *stat)
 124 {
 125         strcpy(stat->st_name, "<cons>");
 126         return 0;
 127 }
 128