1 | /////////////////////////////////////////////////////////////////////////////////////// |
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2 | // File : init.c |
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3 | // Date : January 2018 |
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4 | // Author : Alain Greiner |
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5 | /////////////////////////////////////////////////////////////////////////////////////// |
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6 | // This single thread application implement the "init" process for ALMOS-MKH. |
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7 | // It uses the fork/exec syscalls to create N KSH child processes |
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8 | // (one child process per user terminal). |
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9 | // It includes the hard_config.h file to get th NB_TXT_CHANNELS parameter. |
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10 | // |
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11 | // TODO : Register the PIDs for all KSH[i] in a ksh_pid[] array. |
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12 | // Then calls the wait() function to block, and reactivate any child KSH process |
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13 | // that has been deleted, using a new fork/exec. |
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14 | /////////////////////////////////////////////////////////////////////////////////////// |
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15 | |
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16 | #include <hard_config.h> |
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17 | |
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18 | #include <stdlib.h> |
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19 | #include <stdio.h> |
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20 | #include <pthread.h> |
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21 | |
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22 | #define DELAY_BETWEEN_FORK 100000 |
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23 | |
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24 | ////////// |
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25 | int main() |
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26 | { |
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27 | int i; |
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28 | int ret_fork; // fork return value |
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29 | int ret_exec; // fork return value |
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30 | int received_pid; // pid received from the wait syscall |
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31 | int status; // used by the wait syscall |
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32 | char string[64]; |
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33 | |
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34 | // check number of TXT channels |
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35 | assert( NB_TXT_CHANNELS > 1 ); |
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36 | |
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37 | // create the KSH processes (one per user terminal) |
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38 | for( i = 1 ; i < NB_TXT_CHANNELS ; i++ ) |
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39 | { |
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40 | |
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41 | snprintf( string , 64 , "@@@ before fork / iter = %d\n" , i ); |
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42 | display_string( string ); |
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43 | |
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44 | // INIT process fork process CHILD[i] |
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45 | ret_fork = fork(); |
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46 | |
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47 | snprintf( string , 64 , "@@@ after fork / iter = %d / ret_fork = %d\n" , i , ret_fork ); |
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48 | display_string( string ); |
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49 | |
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50 | if( ret_fork< 0 ) // error in fork |
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51 | { |
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52 | // INIT display error message on TXT0 terminal |
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53 | snprintf( string , 64 , "init cannot fork child[%d]\n" , i ); |
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54 | display_string( string ); |
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55 | |
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56 | // INIT exit |
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57 | exit( 0 ); |
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58 | } |
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59 | else if( ret_fork == 0 ) // we are in CHILD[i] process |
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60 | { |
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61 | // CHILD[i] process exec process KSH[i] |
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62 | ret_exec = exec( "/bin/user/ksh.elf" , NULL , NULL ); |
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63 | |
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64 | if ( ret_exec ) // error in exec |
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65 | { |
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66 | // display error message on TXT0 terminal |
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67 | snprintf( string , 64 , "child[%d] cannot exec ksh[%d]\n" , i , i ); |
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68 | display_string( string ); |
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69 | |
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70 | // CHILD[i] exit |
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71 | // exit( 0 ); |
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72 | } |
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73 | } |
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74 | else // we are in INIT process |
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75 | { |
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76 | // INIT display CHILD[i] process PID |
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77 | snprintf( string , 64 , "INIT forked CHILD[%d] / pid = %x\n", i , ret_fork ); |
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78 | display_string( string ); |
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79 | |
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80 | // INIT delay |
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81 | int x; |
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82 | for( x=0 ; x<DELAY_BETWEEN_FORK ; x++) asm volatile ("nop"); |
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83 | |
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84 | /* |
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85 | // INIT wait exec completion by CHILD[i] |
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86 | while( 1 ) |
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87 | { |
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88 | // get terminating process PID |
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89 | received_pid = wait( &status ); |
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90 | |
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91 | if( received_pid == ret_fork ) break; |
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92 | else |
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93 | { |
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94 | snprintf( string , 64 , |
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95 | "expected_pid %d / received_pid %d" , ret_fork , received_pid ); |
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96 | display_string( string ); |
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97 | } |
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98 | } |
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99 | |
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100 | */ |
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101 | // INIT display string on kernel TXT0 |
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102 | snprintf( string , 64 , "INIT created KSH[%d]\n", i ); |
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103 | display_string( string ); |
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104 | // @@@ |
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105 | display_process( 0 ); |
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106 | display_sched( 0 , 0 ); |
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107 | // @@@ |
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108 | } |
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109 | |
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110 | } |
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111 | |
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112 | // This blocking loop is only for debug, because KSH[i] processes |
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113 | // should never be killed, and INIT should never return from the wait() function. |
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114 | while( 1 ) |
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115 | { |
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116 | // block on child process termination |
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117 | received_pid = wait( &status ); |
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118 | |
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119 | // display string to report unexpected KSH process termination |
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120 | snprintf( string , 64 , "KSH process %x unexpectedly terminated" , received_pid ); |
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121 | display_string( string ); |
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122 | } |
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123 | |
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124 | } // end main() |
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125 | |
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