1 | #ifdef HAVE_CONFIG_H |
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2 | #include "singularconfig.h" |
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3 | #endif /* HAVE_CONFIG_H */ |
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4 | |
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5 | #include <kernel/mod2.h> |
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6 | |
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7 | #ifdef HAVE_SIMPLEIPC |
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8 | |
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9 | # include "simpleipc.h" |
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10 | |
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11 | #include <Singular/cntrlc.h> |
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12 | #include <Singular/si_signals.h> |
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13 | |
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14 | #include <semaphore.h> |
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15 | #include <fcntl.h> |
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16 | #include <sys/types.h> |
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17 | #include <sys/stat.h> |
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18 | #include <stdio.h> |
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19 | #include <stdlib.h> |
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20 | |
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21 | |
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22 | // Not yet implemented: SYSV IPC Semaphores |
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23 | // They are more difficult to clean up after a process crash |
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24 | // but are supported more widely. |
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25 | |
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26 | sem_t *semaphore[SIPC_MAX_SEMAPHORES]; |
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27 | int sem_acquired[SIPC_MAX_SEMAPHORES]; |
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28 | |
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29 | /* return 1 on success, |
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30 | * 0 if already initialized, |
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31 | * -1 for errors |
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32 | */ |
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33 | int sipc_semaphore_init(int id, int count) |
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34 | { |
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35 | char buf[100]; |
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36 | sem_t *sem; |
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37 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES)) |
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38 | return -1; |
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39 | // Already initialized? |
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40 | if (semaphore[id]) |
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41 | return 0; |
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42 | // to make it completely safe, we should generate a name |
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43 | // from /dev/urandom. |
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44 | #if USE_SEM_INIT |
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45 | // TODO: This should really use mapped memory so that processes |
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46 | // can keep using the semaphore after fork + exec. |
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47 | sem = malloc(sizeof(sem_t)); |
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48 | if (!sem) |
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49 | return -1; |
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50 | if (sem_init(sem, 1, count) < 0) |
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51 | { |
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52 | free(sem); |
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53 | return -1; |
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54 | } |
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55 | #else |
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56 | sprintf(buf, "/%d:sem%d", getpid(), id); |
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57 | sem_unlink(buf); |
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58 | sem = sem_open(buf, O_CREAT, 0600, count); |
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59 | #endif |
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60 | if (sem == SEM_FAILED || !sem) |
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61 | return -1; |
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62 | semaphore[id] = sem; |
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63 | #if !USE_SEM_INIT |
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64 | sem_unlink(buf); |
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65 | #endif |
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66 | return 1; |
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67 | } |
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68 | |
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69 | int sipc_semaphore_exists(int id) |
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70 | { |
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71 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES)) return -1; |
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72 | return semaphore[id] != NULL; |
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73 | } |
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74 | |
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75 | int sipc_semaphore_acquire(int id) |
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76 | { |
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77 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES) || (semaphore[id]==NULL)) return -1; |
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78 | defer_shutdown++; |
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79 | si_sem_wait(semaphore[id]); |
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80 | sem_acquired[id]++; |
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81 | defer_shutdown--; |
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82 | if (!defer_shutdown && do_shutdown) m2_end(1); |
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83 | return 1; |
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84 | } |
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85 | |
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86 | int sipc_semaphore_try_acquire(int id) |
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87 | { |
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88 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES) || (semaphore[id]==NULL)) return -1; |
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89 | defer_shutdown++; |
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90 | int trywait = si_sem_trywait(semaphore[id]); |
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91 | if (!trywait) |
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92 | { |
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93 | sem_acquired[id]++; |
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94 | } |
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95 | defer_shutdown--; |
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96 | if (!defer_shutdown && do_shutdown) m2_end(1); |
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97 | return !trywait; |
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98 | } |
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99 | |
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100 | int sipc_semaphore_release(int id) |
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101 | { |
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102 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES) || (semaphore[id]==NULL)) return -1; |
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103 | defer_shutdown++; |
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104 | sem_post(semaphore[id]); |
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105 | sem_acquired[id]--; |
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106 | defer_shutdown--; |
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107 | if (!defer_shutdown && do_shutdown) m2_end(1); |
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108 | return 1; |
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109 | } |
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110 | |
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111 | int sipc_semaphore_get_value(int id) |
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112 | { |
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113 | int val; |
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114 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES) || (semaphore[id]==NULL)) return -1; |
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115 | sem_getvalue(semaphore[id], &val); |
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116 | return val; |
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117 | } |
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118 | |
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119 | int simpleipc_cmd(char *cmd, int id, int v) |
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120 | { |
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121 | if (strcmp(cmd,"init")==0) |
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122 | return sipc_semaphore_init(id,v); |
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123 | else if (strcmp(cmd,"exists")==0) |
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124 | return sipc_semaphore_exists(id); |
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125 | else if (strcmp(cmd,"acquire")==0) |
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126 | return sipc_semaphore_acquire(id); |
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127 | else if (strcmp(cmd,"try_acquire")==0) |
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128 | return sipc_semaphore_try_acquire(id); |
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129 | else if (strcmp(cmd,"release")==0) |
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130 | return sipc_semaphore_release(id); |
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131 | else if (strcmp(cmd,"get_value")==0) |
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132 | return sipc_semaphore_get_value(id); |
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133 | else printf("unknown\n"); |
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134 | return -2; |
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135 | } |
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136 | #endif |
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