diff options
| -rw-r--r-- | Year_2/OS/my-dus-c.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/Year_2/OS/my-dus-c.c b/Year_2/OS/my-dus-c.c new file mode 100644 index 0000000..5961c77 --- /dev/null +++ b/Year_2/OS/my-dus-c.c @@ -0,0 +1,204 @@ +/* + * Test the equivalent execution of this propgram with `du`: + * + * du --block-size=512 -s <path> + * + */ +#include <dirent.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/ipc.h> +#include <sys/sem.h> +#include <sys/shm.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <sys/wait.h> +#include <unistd.h> + +#define MAX_PATH_LEN 1024 + +int +WAIT(int id_sem, int n) +{ + struct sembuf sops[1] = { { n, -1, 0 } }; + + return semop(id_sem, sops, 1); +} + +int +SIGNAL(int id_sem, int n) +{ + struct sembuf sops[1] = { { n, 1, 0 } }; + + return semop(id_sem, sops, 1); +} + +void +handle_scanner_end(int id_shm, int id_sem, int id_scanner, char* pathname) +{ + char* msg; + + if ((msg = (char*)shmat(id_shm, NULL, 0)) == (char*)-1) { + perror("shmat"); + exit(1); + } + + WAIT(id_sem, 0); + sprintf(msg, "%d;END;%s", id_scanner, pathname); + SIGNAL(id_sem, 1); +} + +void +stater(int id_shm, int id_sem, int* scanners, int scanners_n) +{ + char* msg; + int n; + struct stat sb; + char* token; + char* pathname; + int sid; + + if ((msg = (char*)shmat(id_shm, NULL, 0)) == (char*)-1) { + perror("shmat"); + exit(1); + } + + n = 0; + while (n < scanners_n) { + WAIT(id_sem, 1); + /* I previously opened the file with `open` so I know I can read + * that. So now I open that file with stat, because `msg` contains + * the patname as string. + * But first I have to parse the `msg` receiving the scanner id. + */ + token = strtok(msg, ";"); + sid = atoi(token); + pathname = strtok(NULL, ";"); + + if (strcmp(pathname, "END") == 0) { + pathname = strtok(NULL, ";"); + printf("%d\t%s\n", scanners[sid], pathname); + n++; + } else { + stat(pathname, &sb); + scanners[sid] += sb.st_blocks; + } + SIGNAL(id_sem, 0); + } +} + +void +scanner(int id_shm, int id_sem, int scanner_id, char* pathname) +{ + char* msg; + struct stat sb; + struct dirent* db; + int fd; + DIR* dp; + char buffer[MAX_PATH_LEN]; + + if ((msg = (char*)shmat(id_shm, NULL, 0)) == (char*)-1) { + perror("shmat"); + exit(1); + } + + if ((fd = open(pathname, O_RDONLY)) == -1) { + perror("open"); + exit(1); + } + + fstat(fd, &sb); + + if ((sb.st_mode & S_IFMT) == S_IFDIR) { + if ((dp = opendir(pathname)) == NULL) { + perror("opendir"); + exit(1); + } + + while ((db = readdir(dp)) != NULL) { + if ((strcmp(db->d_name, ".") == 0) || strcmp(db->d_name, "..") == 0) + continue; + sprintf(buffer, "%s/%s", pathname, db->d_name); + scanner(id_shm, id_sem, scanner_id, buffer); + } + + closedir(dp); + } + + WAIT(id_sem, 0); + sprintf(msg, "%d;%s", scanner_id, pathname); + SIGNAL(id_sem, 1); +} + +int +main(int argc, char* argv[]) +{ + int id_shm; + int i; + pid_t pid; + pid_t pid_scanners[argc - 1]; + int scanners[argc - 1]; + int id_sem; + + for (i = 0; i < argc - 1; ++i) + scanners[i] = 0; + + if ((id_shm = shmget(IPC_PRIVATE, 1024, IPC_CREAT | IPC_EXCL | 0644)) == -1) { + perror("shmget"); + exit(1); + } + + if ((id_sem = semget(IPC_PRIVATE, 2, IPC_CREAT | IPC_EXCL | 0644)) == -1) { + perror("semget"); + exit(1); + } + + semctl(id_sem, 0, SETVAL, 1); + semctl(id_sem, 1, SETVAL, 0); + + if (argc < 2) { + exit(0); + } + + pid = fork(); + if (pid == -1) { + perror("fork"); + exit(1); + } + + if (pid == 0) { + stater(id_shm, id_sem, scanners, argc - 1); + exit(0); + } + + for (i = 1; i < argc; ++i) { + pid_scanners[i - 1] = fork(); + if (pid_scanners[i - 1] == -1) { + perror("fork"); + exit(1); + } + + if (pid_scanners[i - 1] == 0) { + scanner(id_shm, id_sem, i - 1, argv[i]); + handle_scanner_end(id_shm, id_sem, i - 1, argv[i]); + exit(0); + } + } + + for (i = 0; i < argc; ++i) + wait(NULL); + + if (shmctl(id_shm, IPC_RMID, NULL) == -1) { + perror("shmctl"); + exit(1); + } + + if (semctl(id_sem, 2, IPC_RMID) == -1) { + perror("semctl"); + exit(1); + } + + return 0; +} |