Тексты программ
create.c

  1 #include <sys/types.h>
  2 #include <time.h>
  3 #include <string.h>
  4 #include <unistd.h>
  5 #include <stdlib.h>
  6 #include <fcntl.h>
  7 #include <stdio.h>
  8 #include <sys/uio.h>
  9 #include "employee.h"
 10 #include "empheader.h"
 11
 12 main(int argc, char *argv[])
 13 {
 14     int fd;
 15     struct employee record;
 16     struct recheader header;
 17     struct iovec iov[2];
 18
 19     if (argc < 2) {
 20         fprintf(stderr, "Usage: %s file\n", argv[0]);
 21         exit(1);
 22     }
 23     if ((fd = open(argv[1], O_WRONLY | O_CREAT |
 24         O_SYNC | O_EXCL, 0640)) == -1) {
 25         perror(argv[1]);
 26         exit(2);
 27     }
 28
 29     iov[0].iov_base = (caddr_t)&header;
 30     iov[1].iov_base = (caddr_t)&record;
 31     iov[0].iov_len = sizeof(header);
 32     iov[1].iov_len = sizeof(record);
 33
 34     init_header(&header);
 35
 36     for (;;) {
 37         printf("Enter employee name <SPACE> salary: ");
 38         scanf("%s", record.name);
 39         if (record.name[0] == '.')
 40             break;
 41         scanf("%d", &record.salary);
 42         writev(fd, iov, 2);
 43     }
 44     close(fd);
 45     exit(0);
 46 }
 47

 48 static void init_header(struct recheader *head)
 49 {
 50     long tloc;
 51
 52     tloc = time(0);
 53     strncpy(head->date,ctime(&tloc),24);
 54     head->uid = getuid();
 55 }
inquire.c
  1 #include <sys/types.h>
  2 #include <time.h>
  3 #include <string.h>
  4 #include <stdlib.h>
  5 #include <fcntl.h>
  6 #include <stdio.h>
  7 #include <unistd.h>
  8 #include <sys/uio.h>
  9 #include "employee.h"
 10 #include "empheader.h"
 11
 12 main(int argc, char *argv[])
 13 {
 14     int fd, recnum;
 15     struct employee record;
 16     struct recheader header;
 17     struct iovec iov[2];
 18
 19     if ((fd = open(argv[1], O_RDONLY)) == -1) {
 20         perror(argv[1]);
 21         exit(2);
 22     }
 23
 24     iov[0].iov_base = (caddr_t)&header;
 25     iov[1].iov_base = (caddr_t)&record;
 26     iov[0].iov_len = sizeof(header);
 27     iov[1].iov_len = sizeof(record);
 28
 29     for (;;) {
 30         printf("\nEnter record number: ");
 31         scanf("%d", &recnum);
 32         if (recnum == 0)
 33             break;
 34         lseek(fd, (recnum-1)*(sizeof(record)+sizeof(header)),
 35             SEEK_SET);
 36         if (readv(fd, iov, 2) > 0)
 37             printf("Employee: %s\tSalary: %d\n",
 38                 record.name, record.salary);
 39         else
 40             printf("Record %d not found\n", recnum);
 41     }
 42     close(fd);
 43     exit(0);
 44 }
update1.c
  1 #include <sys/mman.h>
  2 #include <stdlib.h>
  3 #include <stdio.h>
  4 #include <fcntl.h>
  5 #include <sys/types.h>
  6 #include <unistd.h>
  7 #include <errno.h>
  8 #include "employee.h"
  9
 10 main(int argc, char *argv[])
 11 {
 12    off_t size;
 13    struct employee *p;
 14    int fd, recnum;
 15
 16    if ((fd = open(argv[1], O_RDWR)) == -1) {
 17     perror(argv[1]);
 18     exit(1);
 19    }
 20
 21    size = lseek(fd, 0, SEEK_END);
 22    p = (struct employee *)mmap(0, size,
 23       PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
 24
 25    for(;;) {
 26        printf("\nEnter record number: ");
 27        scanf("%d", &recnum);
 28        recnum--;
 29        if (recnum < 0)
 30        break;
 31        if (recnum * sizeof(struct employee) >= size) {
 32        printf("record %d not found\n", recnum+1);
 33        continue;
 34        }
 35        printf("Employee: %s, salary: %d\n",
 36         p[recnum].name, p[recnum].salary);
 37
 38        printf("Enter new salary: ");
 39        scanf("%d", &p[recnum].salary);
 40        msync(p, size, MS_SYNC);
 41   }
 42   munmap(p, size);
 43   close(fd);
 44 }