[094ceb] | 1 | #include <semaphore.h> |
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| 2 | #include <fcntl.h> |
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| 3 | #include <sys/types.h> |
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| 4 | #include <sys/stat.h> |
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| 5 | #include <stdio.h> |
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| 6 | #include <stdlib.h> |
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[df326b] | 7 | |
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| 8 | #include <kernel/mod2.h> |
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[094ceb] | 9 | |
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| 10 | #ifdef HAVE_SIMPLEIPC |
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| 11 | #include "simpleipc.h" |
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| 12 | |
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| 13 | // Not yet implemented: SYSV IPC Semaphores |
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| 14 | // They are more difficult to clean up after a process crash |
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| 15 | // but are supported more widely. |
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| 16 | |
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| 17 | static sem_t *semaphore[SIPC_MAX_SEMAPHORES]; |
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| 18 | |
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| 19 | /* return 1 on success, |
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| 20 | * 0 if already initialized, |
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| 21 | * -1 for errors |
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| 22 | */ |
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| 23 | int sipc_semaphore_init(int id, int count) |
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| 24 | { |
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| 25 | char buf[100]; |
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| 26 | sem_t *sem; |
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| 27 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES)) |
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| 28 | return -1; |
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| 29 | // Already initialized? |
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| 30 | if (semaphore[id]) |
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| 31 | return 0; |
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| 32 | // to make it completely safe, we should generate a name |
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| 33 | // from /dev/urandom. |
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| 34 | #if USE_SEM_INIT |
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| 35 | // TODO: This should really use mapped memory so that processes |
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| 36 | // can keep using the semaphore after fork + exec. |
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| 37 | sem = malloc(sizeof(sem_t)); |
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| 38 | if (!sem) |
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| 39 | return -1; |
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| 40 | if (sem_init(sem, 1, count) < 0) |
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| 41 | { |
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| 42 | free(sem); |
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| 43 | return -1; |
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| 44 | } |
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| 45 | #else |
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| 46 | sprintf(buf, "/%d:sem%d", getpid(), id); |
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| 47 | sem_unlink(buf); |
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| 48 | sem = sem_open(buf, O_CREAT, 0600, count); |
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| 49 | #endif |
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| 50 | if (sem == SEM_FAILED || !sem) |
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| 51 | return -1; |
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| 52 | semaphore[id] = sem; |
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| 53 | #if !USE_SEM_INIT |
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| 54 | sem_unlink(buf); |
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| 55 | #endif |
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| 56 | return 1; |
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| 57 | } |
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| 58 | |
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| 59 | int sipc_semaphore_exists(int id) |
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| 60 | { |
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| 61 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES)) return -1; |
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| 62 | return semaphore[id] != NULL; |
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| 63 | } |
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| 64 | |
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| 65 | int sipc_semaphore_acquire(int id) |
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| 66 | { |
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| 67 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES) || (semaphore[id]==NULL)) return -1; |
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| 68 | sem_wait(semaphore[id]); |
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| 69 | return 1; |
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| 70 | } |
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| 71 | |
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| 72 | int sipc_semaphore_try_acquire(int id) |
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| 73 | { |
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| 74 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES) || (semaphore[id]==NULL)) return -1; |
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| 75 | return !sem_trywait(semaphore[id]); |
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| 76 | } |
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| 77 | |
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| 78 | int sipc_semaphore_release(int id) |
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| 79 | { |
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| 80 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES) || (semaphore[id]==NULL)) return -1; |
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| 81 | sem_post(semaphore[id]); |
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| 82 | return 1; |
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| 83 | } |
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| 84 | |
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| 85 | int sipc_semaphore_get_value(int id) |
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| 86 | { |
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| 87 | int val; |
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| 88 | if ((id<0) || (id >= SIPC_MAX_SEMAPHORES) || (semaphore[id]==NULL)) return -1; |
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| 89 | sem_getvalue(semaphore[id], &val); |
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| 90 | return val; |
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| 91 | } |
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| 92 | |
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| 93 | int simpleipc_cmd(char *cmd, int id, int v) |
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| 94 | { |
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| 95 | if (strcmp(cmd,"init")==0) |
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| 96 | return sipc_semaphore_init(id,v); |
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| 97 | else if (strcmp(cmd,"exists")==0) |
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| 98 | return sipc_semaphore_exists(id); |
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| 99 | else if (strcmp(cmd,"acquire")==0) |
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| 100 | return sipc_semaphore_acquire(id); |
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| 101 | else if (strcmp(cmd,"try_acquire")==0) |
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| 102 | return sipc_semaphore_try_acquire(id); |
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| 103 | else if (strcmp(cmd,"release")==0) |
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| 104 | return sipc_semaphore_release(id); |
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| 105 | else if (strcmp(cmd,"get_value")==0) |
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| 106 | return sipc_semaphore_get_value(id); |
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| 107 | else printf("unknown\n"); |
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| 108 | return -2; |
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| 109 | } |
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| 110 | #endif |
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