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  1.  
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  4. SEMCTL                C Library Procedures                 SEMCTL
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  8. NNAAMMEE
  9.      semctl - semaphore control operations
  10.  
  11. SSYYNNOOPPSSIISS
  12.      ##iinncclluuddee <<ssyyss//ttyyppeess..hh>>
  13.      ##iinncclluuddee <<ssyyss//iippcc..hh>>
  14.      ##iinncclluuddee <<ssyyss//sseemm..hh>>
  15.  
  16.      iinntt sseemmccttll ((sseemmiidd,, sseemmnnuumm,, ccmmdd,, aarrgg))
  17.      iinntt sseemmiidd,, ccmmdd;;
  18.      iinntt sseemmnnuumm;;
  19.      uunniioonn sseemmuunn {{
  20.           vvaall;;
  21.           ssttrruucctt sseemmiidd__ddss **bbuuff;;
  22.           uusshhoorrtt **aarrrraayy;;
  23.      }} aarrgg;;
  24.  
  25. DDEESSCCRRIIPPTTIIOONN
  26.      sseemmccttll(()) provides a variety of semaphore control operations
  27.      as specified by _c_m_d.
  28.  
  29.      The following _c_m_ds are executed with respect to the sema-
  30.      phore specified by _s_e_m_i_d and _s_e_m_n_u_m:
  31.  
  32.           GGEETTVVAALL              Return the value of _s_e_m_v_a_l (see
  33.                               iinnttrroo(2)).  {{RREEAADD}}
  34.  
  35.           SSEETTVVAALL              Set the value of _s_e_m_v_a_l to _a_r_g._v_a_l.
  36.                               {{AALLTTEERR}}
  37.  
  38.           GGEETTPPIIDD              Return the value of _s_e_m_p_i_d.  {{RREEAADD}}
  39.  
  40.           GGEETTNNCCNNTT             Return the value of _s_e_m_n_c_n_t.
  41.                               {{RREEAADD}}
  42.  
  43.           GGEETTZZCCNNTT             Return the value of _s_e_m_z_c_n_t.
  44.                               {{RREEAADD}}
  45.  
  46.      The following _c_m_ds return and set, respectively, every _s_e_m_-
  47.      _v_a_l in the set of semaphores.
  48.  
  49.           GGEETTKKEEYYSS
  50.                Place the partial contents of all semaphore
  51.                entries into the array pointed to by _a_r_g._b_u_f .
  52.  
  53.           GGEETTAALLLL
  54.                Place _s_e_m_v_a_l_s into the array pointed to by
  55.                _a_r_g._a_r_r_a_y.  {{RREEAADD}}
  56.  
  57.           SSEETTAALLLL
  58.                Set _s_e_m_v_a_l_s according to the array pointed to by
  59.                _a_r_g._a_r_r_a_y.  {{AALLTTEERR}}
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  70. SEMCTL                C Library Procedures                 SEMCTL
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  73.  
  74.      The following _c_m_ds are also available:
  75.  
  76.           IIPPCC__SSTTAATT            Place the current value of each
  77.                               member of the data structure asso-
  78.                               ciated with _s_e_m_i_d into the struc-
  79.                               ture pointed to by _a_r_g._b_u_f.  The
  80.                               contents of this structure are
  81.                               defined in iinnttrroo(2).  {{RREEAADD}}
  82.  
  83.           IIPPCC__SSEETT             Set the value of the following
  84.                               members of the data structure asso-
  85.                               ciated with _s_e_m_i_d to the
  86.                               corresponding value found in the
  87.                               structure pointed to by _a_r_g._b_u_f:
  88.  
  89.  
  90.                               sseemm__ppeerrmm..uuiidd
  91.                               sseemm__ppeerrmm..ggiidd
  92.                               sseemm__ppeerrmm..mmooddee //** oonnllyy llooww 99 bbiittss **//
  93.  
  94.                               This _c_m_d can only be executed by a
  95.                               process that has an effective user
  96.                               ID equal to either that of super-
  97.                               user, or to the value of
  98.                               sseemm__ppeerrmm..ccuuiidd or sseemm__ppeerrmm..uuiidd in
  99.                               the data structure associated with
  100.                               _s_e_m_i_d.
  101.  
  102.           IIPPCC__RRMMIIDD            Remove the semaphore identifier
  103.                               specified by _s_e_m_i_d from the system
  104.                               and destroy the set of semaphores
  105.                               and data structure associated with
  106.                               it.  This cmd can only be executed
  107.                               by a process that has an effective
  108.                               user ID equal to either that of
  109.                               super-user, or to the value of
  110.                               sseemm__ppeerrmm..ccuuiidd or sseemm__ppeerrmm..uuiidd in
  111.                               the data structure associated with
  112.                               _s_e_m_i_d.
  113.  
  114. RREETTUURRNN VVAALLUUEE
  115.      Upon successful completion, the value returned depends on
  116.      _c_m_d as follows:
  117.           GGEETTVVAALL              The value of _s_e_m_v_a_l.
  118.           GGEETTPPIIDD              The value of _s_e_m_p_i_d.
  119.           GGEETTNNCCNNTT             The value of _s_e_m_n_c_n_t.
  120.           GGEETTZZCCNNTT             The value of _s_e_m_z_c_n_t.
  121.           All others          A value of 0.
  122.      Otherwise, a value of -1 is returned and eerrrrnnoo is set to
  123.      indicate the error.
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  136. SEMCTL                C Library Procedures                 SEMCTL
  137.  
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  139.  
  140. EERRRROORRSS
  141.      sseemmccttll(()) will fail if one or more of the following are true:
  142.  
  143.      EINVAL              _s_e_m_i_d is not a valid semaphore identif-
  144.                          ier.
  145.  
  146.      EINVAL              _s_e_m_n_u_m is less than zero or greater than
  147.                          sseemm__nnsseemmss.
  148.  
  149.      EINVAL              _c_m_d is not a valid command.
  150.  
  151.      EACCES              Operation permission is denied to the
  152.                          calling process (see iinnttrroo(2)).
  153.  
  154.      ERANGE              _c_m_d is SSEETTVVAALL or SSEETTAALLLL and the value to
  155.                          which _s_e_m_v_a_l is to be set is greater
  156.                          than the system imposed maximum.
  157.  
  158.      EPERM               _c_m_d is equal to IIPPCC__RRMMIIDD or IIPPCC__SSEETT and
  159.                          the effective user ID of the calling
  160.                          process is not equal to that of super-
  161.                          user, or to the value of sseemm__ppeerrmm..ccuuiidd
  162.                          or sseemm__ppeerrmm..uuiidd in the data structure
  163.                          associated with _s_e_m_i_d.
  164.  
  165.      EFAULT              _a_r_g._b_u_f points to an illegal address.
  166.  
  167. SSEEEE AALLSSOO
  168.      iinnttrroo(2), sseemmggeett(2), sseemmoopp(2).
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