os: add exercise 2021-09-15

1 files changed, 346 insertions, 0 deletions

diff --git a/Year_2/OS/lookup-database.c b/Year_2/OS/lookup-database.c
new file mode 100644
index 0000000..d600898
--- /dev/null
+++ b/Year_2/OS/lookup-database.c
@@ -0,0 +1,346 @@
+#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 DIM_MSG 1024
+
+typedef struct {
+    char name[256];
+    int value;
+} pairs;
+
+typedef struct {
+    int n;
+    long value;
+} out_row;
+
+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);
+}
+
+pairs*
+find_row(char* name, pairs* rows, int n)
+{
+    for (int i = 0; i < n; ++i) {
+        if (strcmp(rows[i].name, name) == 0)
+            return &rows[i];
+    }
+
+    return NULL;
+}
+
+void
+parse_rows(FILE* f, pairs* rows)
+{
+    int i, ci; /* ci stands for character index */
+    char* token;
+    char buf[1024];
+    int pi; /* pi stands for pair index */
+    i = ci = 0;
+    char ch;
+
+    while ((ch = (char)fgetc(f)) != EOF) {
+        if (ch != '\n') {
+            buf[ci++] = ch;
+        } else {
+            buf[ci] = '\0';
+            token = strtok(buf, ";");
+            if (token == NULL) {
+                goto free_and_return;
+            }
+
+            pi = 0;
+            while (token != NULL) {
+                if (pi == 0) {
+                    strcpy(rows[i].name, token);
+                } else if (pi == 1) {
+                    rows[i].value = atoi(token);
+                } else {
+                    goto free_and_return;
+                }
+                pi++;
+                token = strtok(NULL, ";");
+            }
+
+            ci = 0;
+            i++;
+        }
+    }
+
+    return;
+
+free_and_return:
+    perror("<db-file> has a bad format");
+    free(rows);
+    exit(1);
+}
+
+void
+db(pairs* rows, char* db_path, int id_shm_db_in, int id_shm_db_out, int id_sem, int fin_n)
+{
+    FILE* f;
+    int n; /* It represents the number of lines of the file <db-file> */
+    char ch;
+    char* msg;
+    char* msgout;
+    int count_newline;
+    char* token;
+    int in_n;
+    pairs* row;
+
+    if ((f = fopen(db_path, "r")) == NULL) {
+        perror("fopen");
+        exit(1);
+    }
+
+    n = 0;
+    while ((ch = (char)fgetc(f)) != EOF) {
+        if (ch == '\n')
+            n++;
+    }
+
+    fseek(f, 0, SEEK_SET);
+    rows = malloc(sizeof(pairs) * n);
+    parse_rows(f, rows);
+    fclose(f);
+
+    printf("DB: letti n. %d record da file\n", n);
+
+    if ((msg = (char*)shmat(id_shm_db_in, NULL, 0)) == (char*)-1) {
+        perror("shmat");
+        exit(1);
+    }
+
+    if ((msgout = (char*)shmat(id_shm_db_out, NULL, 0)) == (char*)-1) {
+        perror("shmat");
+        exit(1);
+    }
+
+    count_newline = 0;
+    while (count_newline < fin_n) {
+        WAIT(id_sem, 0);
+        if (strcmp(msg, "") == 0) {
+            count_newline++;
+        } else {
+            token = strtok(msg, ";");
+            in_n = atoi(token);
+            token = strtok(NULL, ";");
+            row = find_row(token, rows, n);
+            if (row == NULL) {
+                printf("DB: query '%s' da IN%d non trovata\n", token, in_n);
+            } else {
+                WAIT(id_sem, 3);
+                sprintf(msgout, "%d;%s;%d", in_n, row->name, row->value);
+                SIGNAL(id_sem, 2);
+                printf("DB: query '%s' da IN%d trovata con valore %d\n", token, in_n, row->value);
+            }
+        }
+        SIGNAL(id_sem, 1);
+    }
+
+    WAIT(id_sem, 3);
+    strcpy(msgout, "");
+    SIGNAL(id_sem, 2);
+}
+
+void
+out(int id_shm_db_out, int id_sem, int fin_n)
+{
+    char* msg;
+    out_row* processes; /* at i-index there is the data of process-i */
+    char* token;
+    int* n = &fin_n;
+    int index;
+    int i;
+
+    processes = malloc(sizeof(out_row) * (*n));
+    for (i = 0; i < *n; ++i) {
+        processes[i].n = 0;
+        processes[i].value = 0;
+    }
+
+    if ((msg = (char*)shmat(id_shm_db_out, NULL, 0)) == (char*)-1) {
+        perror("shmat");
+        exit(1);
+    }
+
+    while (1) {
+        WAIT(id_sem, 2);
+
+        if (strcmp(msg, "") == 0)
+            break;
+
+        token = strtok(msg, ";");
+        index = atoi(token);
+        strtok(NULL, ";"); /* Ignore the `name` param */
+        token = strtok(NULL, ";");
+        processes[index - 1].n++;
+        processes[index - 1].value += atol(token);
+
+        SIGNAL(id_sem, 3);
+    }
+
+    for (i = 0; i < *n; ++i) {
+        printf("OUT: ricevuti n.%d valori validi per IN%d con totale %lu\n", processes[i].n, i + 1, processes[i].value);
+    }
+
+    free(processes);
+}
+
+void
+fn_in(int id_in, char* input_file, int id_shm_db_in, int id_sem)
+{
+    FILE* f;
+    char buf[DIM_MSG];
+    char ch;
+    int ci;
+    char* msg;
+    int i;
+    char id_in_str[5]; /* Max process is 99999 */
+
+    sprintf(id_in_str, "%d", id_in);
+
+    if ((f = fopen(input_file, "r")) == NULL) {
+        perror("fopen");
+        exit(1);
+    }
+
+    if ((msg = (char*)shmat(id_shm_db_in, NULL, 0)) == (char*)-1) {
+        perror("shmat");
+        exit(1);
+    }
+
+    ci = strlen(id_in_str) + 1;
+    for (i = 0; i < strlen(id_in_str); ++i) {
+        buf[i] = id_in_str[i];
+    }
+    buf[i] = ';';
+
+    i = 1;
+
+    while ((ch = fgetc(f)) != EOF) {
+        buf[ci++] = ch;
+        if (ch == '\n') {
+            buf[ci - 1] = '\0';
+
+            WAIT(id_sem, 1);
+            /* Write the `buf` into the shared memory buffer with db */
+            strncpy(msg, buf, ci);
+
+            printf("IN%d: inviata query n.%d '%s'\n", id_in, i, msg + strlen(id_in_str) + 1);
+
+            ci = strlen(id_in_str) + 1;
+            SIGNAL(id_sem, 0);
+            i++;
+        }
+    }
+    WAIT(id_sem, 1);
+    strncpy(msg, "", 1);
+    SIGNAL(id_sem, 0);
+
+    fclose(f);
+}
+
+int
+main(int argc, char** argv)
+{
+    int i;
+    int id_shm_db_in;
+    int id_shm_db_out;
+    int id_sem;
+
+    pid_t pid_db;
+    pid_t pid_out;
+    pid_t pid_in[argc - 2];
+
+    pairs* rows;
+    rows = NULL;
+
+    if (argc < 3) {
+        fprintf(stderr, "Usage: %s <db-file> <query-file-1> [<query-file-2>] .. [<query-file-n>]", argv[0]);
+        exit(1);
+    }
+
+    /* Create the shared memory blocks */
+    if ((id_shm_db_in = shmget(IPC_PRIVATE, DIM_MSG, IPC_CREAT | 0644)) == -1) {
+        perror("shmget");
+        exit(1);
+    }
+
+    if ((id_shm_db_out = shmget(IPC_PRIVATE, DIM_MSG, IPC_CREAT | 0644)) == -1) {
+        perror("shmget");
+        exit(1);
+    }
+
+    /* These are two semaphore used as mutexs */
+    if ((id_sem = semget(IPC_PRIVATE, 4, IPC_CREAT | IPC_EXCL | 0644)) == -1) {
+        perror("semget");
+        exit(1);
+    }
+    /* Set values to 0 */
+    semctl(id_sem, 0, SETVAL, 0);
+    semctl(id_sem, 1, SETVAL, 1);
+    semctl(id_sem, 2, SETVAL, 0);
+    semctl(id_sem, 3, SETVAL, 1);
+
+    pid_db = fork();
+    if (pid_db == -1) {
+        perror("fork");
+        exit(1);
+    }
+
+    if (pid_db == 0) {
+        db(rows, argv[1], id_shm_db_in, id_shm_db_out, id_sem, argc - 2);
+        exit(0);
+    }
+
+    pid_out = fork();
+    if (pid_out == -1) {
+        perror("fork");
+        exit(1);
+    }
+
+    if (pid_out == 0) {
+        out(id_shm_db_out, id_sem, argc - 2);
+        exit(0);
+    }
+
+    for (i = 0; i < argc - 2; ++i) {
+        pid_in[i] = fork();
+        if (pid_in[i] == -1) {
+            perror("fork");
+            exit(1);
+        }
+
+        if (pid_in[i] == 0) {
+            fn_in(i + 1, argv[i + 2], id_shm_db_in, id_sem);
+            exit(0);
+        }
+    }
+
+    for (i = 0; i < argc; ++i)
+        wait(NULL);
+
+    shmctl(id_shm_db_in, IPC_RMID, 0);
+    shmctl(id_shm_db_out, IPC_RMID, 0);
+    semctl(id_sem, 4, IPC_RMID);
+    free(rows);
+
+    return 0;
+}