56 lines
1.0 KiB
C
56 lines
1.0 KiB
C
/*
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* shm-server - 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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#include <unistd.h>
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DEFN_SYSCALL2(shm_obtain, 35, char *, size_t *)
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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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char c;
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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 to the shared memory chunk
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*/
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size_t size = SHMSZ;
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if ((shm = (char *)syscall_shm_obtain(key, &size)) == (char *) NULL) {
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return 1;
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}
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printf("Server: mounted to 0x%x\n", shm);
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/*
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* Now put some things into the memory for the
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* other process to read.
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*/
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s = shm;
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for (c = 'a'; c <= 'z'; c++)
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*s++ = c;
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*s = '\0';
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/*
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* Finally, we wait until the other process
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* changes the first character of our memory
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* to '*', indicating that it has read what
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* we put there.
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*/
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while (*shm != '*') {}
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return 0;
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}
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