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authorSanto Cariotti <santo@dcariotti.me>2021-09-27 18:00:55 +0200
committerSanto Cariotti <santo@dcariotti.me>2021-09-27 18:00:55 +0200
commite9d64ba213280139af9b4be2874bb867a856f5de (patch)
tree35ae83825dc0ae6b01386866e58afe60be19a0a5 /Year_2
parentdb58f5aa1e173fd185ff87ee95a06644f86c41b1 (diff)
os: add exercise 2021-01-22
Diffstat (limited to 'Year_2')
-rw-r--r--Year_2/OS/filter.c196
1 files changed, 196 insertions, 0 deletions
diff --git a/Year_2/OS/filter.c b/Year_2/OS/filter.c
new file mode 100644
index 0000000..2312667
--- /dev/null
+++ b/Year_2/OS/filter.c
@@ -0,0 +1,196 @@
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ipc.h>
+#include <sys/sem.h>
+#include <sys/shm.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#define MAX_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
+filter(int id_shm, int id_sem, int index, int n, char* expr)
+{
+ char* msg;
+ int quit;
+ char* token;
+ int action;
+ char* word;
+ char* j;
+ char k[MAX_LEN];
+ unsigned w;
+ char c[1];
+ char next_msg[MAX_LEN];
+ char *pre_word, *next_word;
+
+ char *token_str, *token_word;
+
+ if ((msg = (char*)shmat(id_shm, NULL, 0)) == (char*)-1) {
+ perror("shmat");
+ exit(1);
+ }
+
+ quit = 0;
+ while (!quit) {
+ WAIT(id_sem, index);
+ if (strcmp(msg, "{{EOF}}") == 0) {
+ quit = 1;
+ } else {
+ switch (expr[0]) {
+ case '^':
+ action = 0;
+ break;
+ case '_':
+ action = 1;
+ break;
+ case '%':
+ action = 2;
+ break;
+ }
+ word = expr + 1;
+
+ token = strtok_r(msg, " ", &token_str);
+ next_msg[0] = '\0';
+ while (token) {
+ if (action == 0 || action == 1) {
+ j = strstr(token, word);
+ if (j) {
+ k[0] = '\0';
+ for (w = 0; w < strlen(word); ++w) {
+ if (action == 0)
+ c[0] = toupper(word[w]);
+ else
+ c[0] = tolower(word[w]);
+
+ strcat(k, c);
+ }
+ strncpy(j, k, strlen(word));
+ }
+ } else {
+ strcpy(pre_word, word);
+ pre_word = strtok_r(pre_word, ",", &token_word);
+ next_word = strtok_r(NULL, ",", &token_word);
+
+ j = strstr(token, pre_word);
+ if (j) {
+ strcpy(j, next_word);
+ }
+ }
+ strcat(next_msg, token);
+ strcat(next_msg, " ");
+
+ token = strtok_r(NULL, " ", &token_str);
+ }
+ strcpy(msg, next_msg);
+ }
+
+ SIGNAL(id_sem, 0);
+ if (index == n)
+ SIGNAL(id_sem, 0);
+ }
+}
+
+int
+main(int argc, char* argv[])
+{
+ int id_shm;
+ int id_sem;
+ int i;
+ pid_t pid;
+ char buffer[MAX_LEN];
+ char ch;
+ FILE* f;
+ char* msg;
+
+ if (argc < 3) {
+ fprintf(stderr, "Usage: %s <file.txt> <filter-1> [filter-2] [...]", argv[0]);
+ exit(1);
+ }
+
+ if ((f = fopen(argv[1], "r")) == NULL) {
+ perror("fopen");
+ exit(1);
+ }
+
+ if ((id_shm = shmget(IPC_PRIVATE, 1024, IPC_CREAT | IPC_EXCL | 0644)) == -1) {
+ perror("shmget");
+ exit(1);
+ }
+
+ if ((id_sem = semget(IPC_PRIVATE, argc - 1, IPC_CREAT | IPC_EXCL | 0644)) == -1) {
+ perror("semget");
+ exit(1);
+ }
+
+ semctl(id_sem, 0, SETVAL, 1);
+
+ /* Create n process for n filters */
+ for (i = 0; i < argc - 2; ++i) {
+ semctl(id_sem, i + 1, SETVAL, 0);
+ pid = fork();
+ if (pid == -1) {
+ perror("fork");
+ exit(1);
+ }
+
+ if (pid == 0) {
+ filter(id_shm, id_sem, i + 1, argc - 2, argv[i + 2]);
+ exit(0);
+ }
+ }
+
+ i = 0;
+ if ((msg = (char*)shmat(id_shm, NULL, 0)) == (char*)-1) {
+ perror("shmat");
+ exit(1);
+ }
+
+ while ((ch = fgetc(f)) != EOF) {
+ buffer[i++] = ch;
+ if (ch == '\n') {
+ buffer[i - 1] = '\0';
+ WAIT(id_sem, 0);
+ strncpy(msg, buffer, strlen(buffer) + 1);
+ for (i = 0; i < argc - 2; ++i) {
+ SIGNAL(id_sem, i + 1);
+ WAIT(id_sem, 0);
+ }
+ printf("%s\n", msg);
+ i = 0;
+ }
+ }
+
+ WAIT(id_sem, 0);
+ strcpy(msg, "{{EOF}}");
+ for (i = 0; i < argc - 2; ++i) {
+ SIGNAL(id_sem, i + 1);
+ WAIT(id_sem, 0);
+ }
+
+ for (i = 0; i < argc - 2; ++i)
+ wait(NULL);
+
+ shmctl(id_shm, IPC_RMID, NULL);
+ semctl(id_sem, argc - 1, IPC_RMID);
+
+ return 0;
+}