53 lines
1.0 KiB
C
53 lines
1.0 KiB
C
/*
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* shm-client - client program to demonstrate shared memory.
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*/
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#include <sys/types.h>
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#include <syscall.h>
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#include <stdio.h>
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#include <stdlib.h>
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DEFN_SYSCALL2(shm_obtain, 35, char *, int)
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DEFN_SYSCALL1(shm_release, 36, char *)
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#define SHMSZ 27
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int main(int argc, char ** argv) {
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int shmid;
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volatile char *shm;
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volatile char *s;
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if (argc < 2) {
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fprintf(stderr, "%s: expected argument\n", argv[0]);
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return 1;
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}
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char * key = argv[1];
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/*
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* Attach the segment to our data space.
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*/
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malloc(9 * 0x1000); // Make our heap a bit different from the server
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if ((shm = (char *)syscall_shm_obtain(key, SHMSZ)) == (char *) NULL) {
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printf("Client: syscall_shm_mount returned NULL!\n");
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return 1;
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}
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printf("Client: mounted to 0x%x\n", shm);
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/*
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* Now read what the server put in the memory.
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*/
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while (*shm != 'a');
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for (s = shm; *s != '\0'; s++)
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printf("%c", *s);
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printf("\n");
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/*
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* Finally, change the first character of the
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* segment to '*', indicating we have read
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* the segment.
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*/
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*shm = '*';
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return 0;
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}
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