monocoque initial commit

tests/sharedmemoryproducer.c

@@ -0,0 +1,87 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/shm.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <errno.h>
+
+void display(char* prog, char* bytes, int n);
+
+int main(void)
+{
+    const char* name = "/shm-example";    // file name
+    const int SIZE = 4096;        // file size
+
+    const char* message0 = "Studying ";
+    const char* message1 = "Operating Systems ";
+    const char* message2 = "Is Fun!";
+    const char* msg_end  = "\n";
+
+    int shm_fd;       // file descriptor, from shm_open()
+    char* shm_base;   // base address, from mmap()
+    char* ptr;        // shm_base is fixed, ptr is movable
+
+    /* create the shared memory segment as if it was a file */
+    shm_fd = shm_open(name, O_CREAT | O_RDWR, 0666);
+    if (shm_fd == -1)
+    {
+        printf("prod: Shared memory failed: %s\n", strerror(errno));
+        exit(1);
+    }
+
+    /* configure the size of the shared memory segment */
+    ftruncate(shm_fd, SIZE);
+
+    /* map the shared memory segment to the address space of the process */
+    shm_base = mmap(0, SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
+    if (shm_base == MAP_FAILED)
+    {
+        printf("prod: Map failed: %s\n", strerror(errno));
+        // close and shm_unlink?
+        exit(1);
+    }
+
+    /**
+     * Write to the mapped shared memory region.
+     *
+     * We increment the value of ptr after each write, but we
+     * are ignoring the possibility that sprintf() fails.
+     */
+    display("prod", shm_base, 64);
+    ptr = shm_base;
+    ptr += sprintf(ptr, "%s", message0);
+    ptr += sprintf(ptr, "%s", message1);
+    ptr += sprintf(ptr, "%s", message2);
+    ptr += sprintf(ptr, "%s", msg_end);
+    display("prod", shm_base, 64);
+
+    /* remove the mapped memory segment from the address space of the process */
+    if (munmap(shm_base, SIZE) == -1)
+    {
+        printf("prod: Unmap failed: %s\n", strerror(errno));
+        exit(1);
+    }
+
+    /* close the shared memory segment as if it was a file */
+    if (close(shm_fd) == -1)
+    {
+        printf("prod: Close failed: %s\n", strerror(errno));
+        exit(1);
+    }
+
+    return 0;
+}
+
+void display(char* prog, char* bytes, int n)
+{
+    printf("display: %s\n", prog);
+    for (int i = 0; i < n; i++)
+    {
+        printf("%02x%c", bytes[i], ((i+1)%16) ? ' ' : '\n');
+    }
+    printf("\n");
+}