Тексты программ
report1.c
1 #include <sys/types.h>
2 #include <unistd.h>
3 #include <stdlib.h>
4 #include <stdio.h>
5 #include <fcntl.h>
6 #include <errno.h>
7 #include "employee.h"
8 #define MAXTRIES 5
9 main(int argc, char *argv[])
10 {
11 struct flock lock;
12 struct employee record;
13 int fd, sum = 0, try = 0;
14 if ((fd = open(argv[1], O_RDONLY)) == -1) {
15 perror(argv[1]);
16 exit(1);
17 }
18 lock.l_type = F_RDLCK;
19 lock.l_whence = SEEK_SET;
20 lock.l_start = 0;
21 lock.l_len = 0; /* whole file address space */
22 while (fcntl(fd, F_SETLK, &lock) == -1) {
23 if ((errno == EACCES) || (errno == EAGAIN)) {
24 if (try++ < MAXTRIES) {
25 sleep(1);
26 continue;
27 }
28 printf("%s busy -- try later\n",
29 argv[1]);
30 exit(2);
31 }
32 perror(argv[1]); exit(3);
33 }
34 sum = 0;
35 while (read(fd, &record, sizeof(record)) > 0) {
36 printf("Employee: %s, Salary: %d\n",
37 record.name, record.salary);
38 sum += record.salary;
39 }
40 printf("\nTotal salary: %d\n", sum);
41
42 lock.l_type = F_UNLCK; /* unlock file */
43 fcntl(fd, F_SETLK, &lock);
44 close(fd);
45 }
update1.c
1 #include <sys/types.h>
2 #include <stdio.h>
3 #include <unistd.h>
4 #include <fcntl.h>
5 #include <stdlib.h>
6 #include <errno.h>
7 #include "employee.h"
8
9 main(int argc, char *argv[])
10 {
11 struct flock lock;
12 struct employee record;
13 int fd, recnum;
14 unsigned short uid;
15 off_t position;
16
17 if ((fd = open(argv[1], O_RDWR)) == -1) {
18 perror(argv[1]);
19 exit(1);
20 }
21
22 uid = getuid();
23 for(;;) {
24 printf("\nEnter record number: ");
25 scanf("%d", &recnum);
26 if (recnum <= 0)
27 break;
28 position = (recnum-1) * sizeof(record);
29 lock.l_type = F_WRLCK; /* lock record */
30 lock.l_whence = SEEK_SET;
31 lock.l_start = position;
32 lock.l_len = sizeof(record);
33 if (fcntl(fd, F_SETLKW, &lock) == -1) {
34 perror(argv[1]);
35 exit(2);
36 }
37
38 lseek(fd, position, SEEK_SET); /* read record */
39 if (read(fd, &record, sizeof(record)) == 0) {
40 printf("record %d not found\n", recnum);
41 lock.l_type = F_UNLCK;
42 fcntl(fd, F_SETLK, &lock);
43 continue;
44 }
45 printf("Employee: %s, salary: %d\n",
46 record.name, record.salary);
47
48 record.uid = uid; /* update record */
49 printf("Enter new salary: ");
50 scanf("%d", &record.salary);
51 lseek(fd, position, SEEK_SET);
52 write(fd, &record, sizeof(record));
53
54 lock.l_type = F_UNLCK; /* release record */
55 fcntl(fd, F_SETLK, &lock);
56 }
57 close(fd);
58 }
updatem.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 struct flock lock;
13 off_t size;
14 struct employee *p;
15 int position, fd, recnum;
16 unsigned short uid;
17
18 if ((fd = open(argv[1], O_RDWR)) == -1) {
19 perror(argv[1]);
20 exit(1);
21 }
22
23 size = lseek(fd, 0, SEEK_END);
24 p = (struct employee *)mmap(0, size,
25 PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
26
27 uid = getuid();
28 for(;;) {
29 printf("\nEnter record number: ");
30 scanf("%d", &recnum);
31 if (recnum <= 0)
32 break;
33
34 position = recnum * sizeof(struct employee);
35 if (position >= size) {
36 printf("record %d not found\n", recnum);
37 continue;
38 }
39
40 lock.l_type = F_WRLCK; /* lock record */
41 lock.l_whence = SEEK_SET;
42 lock.l_start = position;
43 lock.l_len = sizeof(struct employee);
44 if (fcntl(fd, F_SETLKW, &lock) == -1) {
45 perror(argv[1]);
46 exit(2);
47 }
48
49 printf("Employee: %s, salary: %d\n",
50 p[recnum].name, p[recnum].salary);
51
52 p[recnum].uid = uid; /* update */
53 printf("Enter new salary: ");
54 scanf("%d", &p[recnum].salary);
55 msync(p, size, MS_ASYNC);
56
57 lock.l_type = F_UNLCK; /* release record */
58 fcntl(fd, F_SETLK, &lock);
59 }
60 munmap(p, size);
61 close(fd);
62 }
update2.c
1 #include <sys/types.h>
2 #include <stdlib.h>
3 #include <stdio.h>
4 #include <fcntl.h>
5 #include <unistd.h>
6 #include <errno.h>
7 #include "employee.h"
8
9 main(int argc, char *argv[])
10 {
11 struct flock lock;
12 struct employee record;
13 int fd, recnum;
14 unsigned short uid;
15 char ans[5];
16 off_t position;
17
18 if ((fd = open(argv[1], O_RDWR)) == -1) {
19 perror(argv[1]);
20 exit(1);
21 }
22 uid = getuid();
23 for(;;) {
24 printf("\nEnter record number: ");
25 scanf("%d", &recnum);
26 if (recnum <= 0)
27 break;
28 position = (recnum-1) * sizeof(record);
29 lock.l_type = F_RDLCK; /* read lock */
30 lock.l_whence = SEEK_SET;
31 lock.l_start = position;
32 lock.l_len = sizeof(record);
33 if (fcntl(fd, F_SETLKW, &lock) == -1) {
34 perror(argv[1]);
35 exit(2);
36 }
37 lseek(fd, position, SEEK_SET); /* read record */
38 if (read(fd, &record, sizeof(record))
39 == 0) {
40 printf("record %d not found\n", recnum);
41 lock.l_type = F_UNLCK;
42 fcntl(fd, F_SETLK, &lock);
43 continue;
44 }
45 printf("Employee: %s, salary: %d\n",
46 record.name, record.salary);
47
48 printf("Do you want to update salary (y or n)? ");
49 scanf("%s", ans);
50 if (ans[0] != 'y') {
51 lock.l_type = F_UNLCK;
52 fcntl(fd, F_SETLK, &lock);
53 continue;
54 }
55 lock.l_type = F_WRLCK; /* write lock */
56 if (fcntl(fd, F_SETLKW, &lock) == -1) {
57 perror(argv[1]);
58 exit(3);
59 }
60 record.uid = uid; /* update record */
61 printf("Enter new salary: ");
62 scanf("%d", &record.salary);
63 lseek(fd, position, SEEK_SET);
64 write(fd, &record, sizeof(record));
65
66 lock.l_type = F_UNLCK; /* release record */
67 fcntl(fd, F_SETLK, &lock);
68 }
69 close(fd);
70 }
getlocks.c
1 #include <sys/types.h>
2 #include <stdlib.h>
3 #include <stdio.h>
4 #include <fcntl.h>
5 #include <unistd.h>
6 #include <errno.h>
7 #include "employee.h"
8
9 main(int argc, char *argv[])
10 {
11 struct employee record;
12 struct flock lock;
13 off_t size;
14 int fd;
15
16 if ((fd = open(argv[1], O_WRONLY)) == -1) {
17 perror(argv[1]);
18 exit(1);
19 }
20 size = lseek(fd, 0, SEEK_END); /* size of file */
21
22 lock.l_whence = SEEK_SET;
23 lock.l_len = sizeof(record);
24 printf("File: %s\n", argv[1]);
25 for (lock.l_start = 0; lock.l_start < size;
26 lock.l_start += lock.l_len) {
27 lock.l_type = F_WRLCK;
28 fcntl(fd, F_GETLK, &lock);
29 if (lock.l_type == F_UNLCK) /* not locked */
30 continue;
31 printf("Pid: %ld", lock.l_pid);
32 printf("\t%s lock",
33 (lock.l_type == F_WRLCK)? "Write" : "Read");
34 printf("\tRecord number: %ld",
35 lock.l_start/sizeof(record));
36 if (lock.l_len == 0) { /* rest of file */
37 lock.l_len = size - lock.l_start;
38 lock.l_start = size; /* terminate for loop */
39 }
40 printf("\tNumber of records: %ld\n",
41 lock.l_len/sizeof(record));
42 }
43 }
report2.c
1 #include <sys/types.h>
2 #include <stdio.h>
3 #include <fcntl.h>
4 #include <unistd.h>
5 #include <stdlib.h>
6 #include <errno.h>
7 #include "employee.h"
8 #define MAXTRIES 5
9
10 main(int argc, char *argv[])
11 {
12 struct employee record;
13 int fd, sum = 0, try = 0;
14
15 if ((fd = open(argv[1], O_RDWR)) == -1) {
16 perror(argv[1]);
17 exit(1);
18 }
19 while (lockf(fd, F_TLOCK, 0) == -1) {
20 if ((errno == EACCES) || (errno == EAGAIN)) {
21 if (try++ < MAXTRIES) {
22 sleep(1);
23 continue;
24 }
25 printf("%s busy -- try later\n",
26 argv[1]);
27 exit(2);
28 }
29 perror(argv[1]);
30 exit(3);
31 }
32
33 sum = 0;
34 while (read(fd, &record, sizeof(record)) > 0) {
35 printf("Employee: %s, Salary: %d\n",
36 record.name, record.salary);
37 sum += record.salary;
38 }
39 printf("\nTotal salary: %d\n", sum);
40
41 lseek(fd, 0, SEEK_SET);
42 lockf(fd, F_ULOCK, 0);
43 close(fd);
44 }
update3.c
1 #include <sys/types.h>
2 #include <stdlib.h>
3 #include <stdio.h>
4 #include <unistd.h>
5 #include <fcntl.h>
6 #include "employee.h"
7
8 main(int argc, char *argv[])
9 {
10 struct employee record;
11 unsigned short uid;
12 int fd, recnum;
13 off_t position;
14
15 if ((fd = open(argv[1], O_RDWR)) == -1) {
16 perror(argv[1]);
17 exit(1);
18 }
19
20 uid = getuid();
21 for(;;) {
22 printf("\nEnter record number: ");
23 scanf("%d", &recnum);
24 if (recnum <= 0)
25 break;
26 position = (recnum-1) * sizeof(record);
27
28 lseek(fd, position, SEEK_SET);
29 if (lockf(fd, F_LOCK, sizeof(record)) == -1) {
30 perror(argv[1]);
31 exit(2);
32 }
33 if (read(fd, &record, sizeof(record)) == 0) {
34 printf("record %d not found\n", recnum);
35 lockf(fd, F_ULOCK, sizeof(record));
36 continue;
37 }
38 printf("Employee: %s, salary: %d\n",
39 record.name, record.salary);
40
41 record.uid = uid; /* update record */
42 printf("Enter new salary: ");
43 scanf("%d", &record.salary);
44 lseek(fd, position, SEEK_SET);
45 write(fd, &record, sizeof(record));
46
47 lseek(fd, position, SEEK_SET);
48 lockf(fd, F_ULOCK, sizeof(record));
49 } 50 close(fd);
51 }