minix/drivers/tty/pty/ptyfs.c

   1 /* ptyfs.c - communication to PTYFS */
   2
   3 #include <minix/driver.h>
   4 #include <minix/ds.h>
   5
   6 #include "ptyfs.h"
   7
   8 /*
   9  * Perform synchronous communication with PTYFS, if PTYFS is actually running.
  10  * This function is expected to return only once PTYFS has acknowledged
  11  * processing the request, in order to avoid race conditions between PTYFS and
  12  * userland.  The function must always fail when PTYFS is not available for any
  13  * reason.  Return OK on success, or an IPC-level error on failure.
  14  */
  15 static int
  16 ptyfs_sendrec(message * m_ptr)
  17 {
  18         endpoint_t endpt;
  19
  20         /*
  21          * New pseudoterminals are created sufficiently rarely that we need not
  22          * optimize this by for example caching the PTYFS endpoint,  especially
  23          * since caching brings along new issues, such as having to reissue the
  24          * request if the cached endpoint turns out to be outdated (e.g., when
  25          * ptyfs is unmounted and remounted for whatever reason).
  26          */
  27         if (ds_retrieve_label_endpt("ptyfs", &endpt) != OK)
  28                 return EDEADSRCDST; /* ptyfs is not available */
  29
  30         return ipc_sendrec(endpt, m_ptr);
  31 }
  32
  33 /*
  34  * Add or update a node on PTYFS, with the given node index and attributes.
  35  * Return OK on success, or an error code on failure.  Errors may include
  36  * communication failures and out-of-memory conditions.
  37  */
  38 int
  39 ptyfs_set(unsigned int index, mode_t mode, uid_t uid, gid_t gid, dev_t dev)
  40 {
  41         message m;
  42         int r;
  43
  44         memset(&m, 0, sizeof(m));
  45
  46         m.m_type = PTYFS_SET;
  47         m.m_pty_ptyfs_req.index = index;
  48         m.m_pty_ptyfs_req.mode = mode;
  49         m.m_pty_ptyfs_req.uid = uid;
  50         m.m_pty_ptyfs_req.gid = gid;
  51         m.m_pty_ptyfs_req.dev = dev;
  52
  53         if ((r = ptyfs_sendrec(&m)) != OK)
  54                 return r;
  55
  56         return m.m_type;
  57 }
  58
  59 /*
  60  * Remove a node from PTYFS.  Return OK on success, or an error code on
  61  * failure.  The function succeeds even if no node existed for the given index.
  62  */
  63 int
  64 ptyfs_clear(unsigned int index)
  65 {
  66         message m;
  67         int r;
  68
  69         memset(&m, 0, sizeof(m));
  70
  71         m.m_type = PTYFS_CLEAR;
  72         m.m_pty_ptyfs_req.index = index;
  73
  74         if ((r = ptyfs_sendrec(&m)) != OK)
  75                 return r;
  76
  77         return m.m_type;
  78 }
  79
  80 /*
  81  * Obtain the file name for the PTYFS node with the given index, and store it
  82  * in the given 'name' buffer which consists of 'size' bytes.  On success,
  83  * return OK, with the file name stored as a null-terminated string.  The
  84  * returned name does not include the PTYFS mount path.  On failure, return an
  85  * error code.  Among other reasons, the function fails if no node is allocated
  86  * for the given index, and if the name does not fit in the given buffer.
  87  */
  88 int
  89 ptyfs_name(unsigned int index, char * name, size_t size)
  90 {
  91         message m;
  92         int r;
  93
  94         memset(&m, 0, sizeof(m));
  95
  96         m.m_type = PTYFS_NAME;
  97         m.m_pty_ptyfs_req.index = index;
  98
  99         if ((r = ptyfs_sendrec(&m)) != OK)
 100                 return r;
 101
 102         if (m.m_type != OK)
 103                 return m.m_type;
 104
 105         /* Ensure null termination, and make sure the string fits. */
 106         m.m_ptyfs_pty_name.name[sizeof(m.m_ptyfs_pty_name.name) - 1] = 0;
 107         if (strlen(m.m_ptyfs_pty_name.name) >= size)
 108                 return ENAMETOOLONG;
 109
 110         strlcpy(name, m.m_ptyfs_pty_name.name, size);
 111         return OK;
 112 }