Difference between revisions of "ProvaPratica 2011.05.30"

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(Created page with "[http://www.cs.unibo.it/~renzo/so/pratiche/2011.05.30.pdf Link to exam] Esercizio 1 sender.c <syntaxhighlight lang="C"> #include <stdlib.h> #include <stdio.h> #include <un...")
 
(Aggiunta soluzione es 1)
 
(2 intermediate revisions by 2 users not shown)
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[http://www.cs.unibo.it/~renzo/so/pratiche/2011.05.30.pdf Link to exam]
 
[http://www.cs.unibo.it/~renzo/so/pratiche/2011.05.30.pdf Link to exam]
  
−
Esercizio 1
+
==Esercizio 1==
−
 
+
<source lang="text">
−
 
+
Scrivere due programmi in modo che i parametri passati al
 +
primo vengano stampati dal secondo. La comunicazione deve avvenire tramite una shared memory realizzata
 +
con la chiamata POSIX shm_open, la sincronizzazione tramite segnali. Viene attivato per primo il programma
 +
ricevente. (anche i pid dei processi possono venir scambiati attraverso la shared memory!).
 +
Es: scrivere in un terminale:
 +
$./receiver
 +
l'esecuzione di “receiver rimane in attesa”. in un secondo terminale scrivere:
 +
$./sender a bb ccc
 +
nel primo deve comparire
 +
./sender
 +
a
 +
bb
 +
ccc
 +
</source>
 +
===Soluzione di Gab===
 
sender.c
 
sender.c
  
Line 101: Line 115:
 
}
 
}
 
</syntaxhighlight>
 
</syntaxhighlight>
 +
 +
Gab
 +
===Soluzione di Dado e Pierg===
 +
 +
sender.c
 +
<source lang="c">
 +
#include <stdio.h>
 +
#include <stdlib.h>
 +
#include <sys/mman.h>
 +
#include <sys/stat.h>
 +
#include <fcntl.h>
 +
 +
int main(int argc, char * argv[]){
 +
int fd,i;
 +
fd=shm_open("/shared",O_RDWR,'w');
 +
if(fd==-1){
 +
fprintf(stderr,"Error while opening the shared memory\n");
 +
}
 +
for(i=0;i<argc;i++){
 +
write(fd,argv[i],sizeof(argv[i]));
 +
write(fd,"\n",1);
 +
}
 +
return 0;
 +
}
 +
</source>
 +
 +
receiver.c
 +
<source lang="c">
 +
#include <stdio.h>
 +
#include <stdlib.h>
 +
#include <sys/mman.h>
 +
#include <sys/stat.h>
 +
#include <fcntl.h>
 +
#define MAXLENGTH 1024
 +
 +
int main(int argc, char * argv[]){
 +
int fd;
 +
ssize_t dim;
 +
char buff[MAXLENGTH];
 +
fd=shm_open("/shared",O_RDWR,'r');
 +
while((dim=read(fd,&buff,MAXLENGTH))){
 +
write(stdout,buff,MAXLENGTH);
 +
}
 +
return 0;
 +
}
 +
</source>
 +
Manca la sincronizzazione tramite segnali --[[User:FedericoB|FedericoB]] ([[User talk:FedericoB|talk]]) 16:33, 27 May 2017 (CEST)
 +
 +
===Soluzione di FedericoB===
 +
receiver
 +
<source lang="C">
 +
#define _GNU_SOURCE
 +
 +
#include <stdlib.h>
 +
#include <stdio.h>
 +
#include <unistd.h>
 +
#include <sys/mman.h>
 +
#include <sys/stat.h>
 +
#include <signal.h>
 +
#include <fcntl.h>
 +
#include <string.h>
 +
 +
#define MAXSIZE 4096
 +
 +
int main(int argc, char* argv[]) {
 +
    int sharedFD;
 +
    printf("pid = %d\n", getpid());
 +
    //create shared memory object
 +
    if ((sharedFD = shm_open("/sharedPID", O_CREAT | O_RDWR, S_IRUSR | S_IWUSR)) != -1) {
 +
        //set size of shared memory object
 +
        if (ftruncate(sharedFD, MAXSIZE) == 0) {
 +
            //create a memory mapping with sharedVariable and the shared memory object
 +
            #define OFFSET 0
 +
            #define ADDRESS NULL
 +
            char* sharedVariable = mmap(ADDRESS, MAXSIZE, PROT_READ | PROT_WRITE, MAP_SHARED, sharedFD, OFFSET);
 +
            if (sharedVariable != MAP_FAILED) {
 +
                sprintf(sharedVariable, "%d\n", getpid());
 +
                sigset_t mask;
 +
                //initialize signal mask
 +
                sigemptyset(&mask);
 +
                sigaddset(&mask, SIGUSR1);
 +
                //block default handler for SIGUSR1
 +
                sigprocmask(SIG_BLOCK, &mask, NULL);
 +
                int sig;
 +
                //wait for a SIGURS1
 +
                sigwait(&mask, &sig);
 +
                printf("%s\n", sharedVariable);
 +
                shm_unlink("/sharedPID");
 +
                return 0;
 +
            } else {
 +
                perror(NULL);
 +
            }
 +
        } else {
 +
            perror(NULL);
 +
        }
 +
    } else {
 +
        perror(NULL);
 +
    }
 +
 +
}
 +
</source>
 +
sender
 +
<source lang="c">
 +
#include <stdlib.h>
 +
#include <stdio.h>
 +
#include <unistd.h>
 +
#include <sys/mman.h>
 +
#include <sys/stat.h>
 +
#include <fcntl.h>
 +
#include <string.h>
 +
#include <signal.h>
 +
 +
#define MAXSIZE 4096
 +
 +
int main(int argc,char *argv[]) {
 +
    int sharedFD;
 +
    //create shared memory object
 +
    if ((sharedFD = shm_open("/sharedPID", O_CREAT | O_RDWR, S_IRUSR | S_IWUSR)) != -1) {
 +
        ftruncate(sharedFD, MAXSIZE);
 +
        #define OFFSET 0
 +
        #define ADDRESS NULL
 +
        char* sharedVariable = mmap(ADDRESS, MAXSIZE, PROT_READ | PROT_WRITE, MAP_SHARED, sharedFD, OFFSET);
 +
        int effectivePID = atoi(sharedVariable);
 +
        printf("pid = %d\n",effectivePID);
 +
        shm_unlink("/sharedPID");
 +
        int i;
 +
        for (i=0;i<MAXSIZE;i++) sharedVariable[i]='\0';
 +
        for (i = 1; i < argc; i++) {
 +
            strcat(sharedVariable, argv[i]);
 +
            strcat(sharedVariable, " ");
 +
        }
 +
        kill(effectivePID, SIGUSR1);
 +
        return 0;
 +
    } else {
 +
        perror(NULL);
 +
    }
 +
}
 +
</source>

Latest revision as of 15:33, 27 May 2017

Link to exam

Esercizio 1

Scrivere due programmi in modo che i parametri passati al
primo vengano stampati dal secondo. La comunicazione deve avvenire tramite una shared memory realizzata
con la chiamata POSIX shm_open, la sincronizzazione tramite segnali. Viene attivato per primo il programma
ricevente. (anche i pid dei processi possono venir scambiati attraverso la shared memory!).
Es: scrivere in un terminale:
$./receiver
l'esecuzione di “receiver rimane in attesa”. in un secondo terminale scrivere:
$./sender a bb ccc
nel primo deve comparire
./sender
a
bb
ccc

Soluzione di Gab

sender.c 

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <signal.h>

#define COMMUNICATION_SIGNAL 25
#define MAXIMUM_LENGTH 4096

#define PID_LENGTH 10


int main(int argc,char *argv[])
{
	int sharedFD = shm_open("/sharedPID", O_CREAT | O_RDWR, S_IRUSR | S_IWUSR);
	if(!sharedFD)
		return;
	ftruncate(sharedFD,sizeof(char)*PID_LENGTH);
	char *sharedVariable = mmap(NULL,sizeof(char)*PID_LENGTH,PROT_READ | PROT_WRITE,MAP_SHARED,sharedFD,0);
	int effectivePID = atoi(sharedVariable);
	int sharedParametersFD = shm_open("/sharedParameters", O_CREAT | O_RDWR, S_IRUSR | S_IWUSR);
	if(!sharedParametersFD)
		return;
	ftruncate(sharedParametersFD,sizeof(char)*MAXIMUM_LENGTH);
	char *parameters = mmap(NULL,sizeof(char)*MAXIMUM_LENGTH,PROT_READ | PROT_WRITE,MAP_SHARED,sharedParametersFD,0);
	char parametersToPass[MAXIMUM_LENGTH];
	int i;
	for(i=0;i<MAXIMUM_LENGTH;i++)
		parametersToPass[i]='\0';
	for(i=0;i<argc;i++)
	{
		strcat(parametersToPass,argv[i]);
		strcat(parametersToPass,"\n");
	}	
	strcpy(parameters,parametersToPass);
	kill(effectivePID,COMMUNICATION_SIGNAL);
	return 0;
}


receiver.c 

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <signal.h>
#include <fcntl.h>
#include <string.h>

#define COMMUNICATION_SIGNAL 25

#define MAXIMUM_LENGTH 4096

#define PID_LENGTH 10



static void signalHandler (int sig, siginfo_t *siginfo, void *context)
{
	int sharedFD = shm_open("/sharedParameters", O_CREAT | O_RDWR, S_IRUSR | S_IWUSR);
	if(!sharedFD)
		return;
	ftruncate(sharedFD,sizeof(char)*MAXIMUM_LENGTH);
	char *parameters = mmap(NULL,sizeof(char)*MAXIMUM_LENGTH,PROT_READ | PROT_WRITE,MAP_SHARED,sharedFD,0);
	printf("Parameters: %s",parameters);
	exit(0);
}


int main(int argc,char *argv[])
{
	int sharedFD = shm_open("/sharedPID", O_CREAT | O_RDWR, S_IRUSR | S_IWUSR);
	if(!sharedFD)
		return;
	char *currentPIDToPass; 	
	asprintf(&currentPIDToPass,"%d",getpid());
	ftruncate(sharedFD,sizeof(char)*PID_LENGTH);
	char *sharedVariable = mmap(NULL,sizeof(char)*PID_LENGTH,PROT_READ | PROT_WRITE,MAP_SHARED,sharedFD,0);
	strcpy(sharedVariable,currentPIDToPass);
	struct sigaction signalStruct;
	signalStruct.sa_sigaction = &signalHandler;
	sigaction(COMMUNICATION_SIGNAL,&signalStruct,NULL);
	while(1){}
	return 0;
}

Gab

Soluzione di Dado e Pierg

sender.c 

#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h> 

int main(int argc, char * argv[]){
	int fd,i;
	fd=shm_open("/shared",O_RDWR,'w');
	if(fd==-1){
		fprintf(stderr,"Error while opening the shared memory\n");
	}
	for(i=0;i<argc;i++){
		write(fd,argv[i],sizeof(argv[i]));
		write(fd,"\n",1);
	}
	return 0;
}

receiver.c 

#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h> 
#define MAXLENGTH 1024

int main(int argc, char * argv[]){
	int fd;
	ssize_t dim;
	char buff[MAXLENGTH];
	fd=shm_open("/shared",O_RDWR,'r');
	while((dim=read(fd,&buff,MAXLENGTH))){
		write(stdout,buff,MAXLENGTH);
	}
	return 0;
}

Manca la sincronizzazione tramite segnali --FedericoB (talk) 16:33, 27 May 2017 (CEST)

Soluzione di FedericoB

receiver 

#define _GNU_SOURCE

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <signal.h>
#include <fcntl.h>
#include <string.h>

#define MAXSIZE 4096

int main(int argc, char* argv[]) {
    int sharedFD;
    printf("pid = %d\n", getpid());
    //create shared memory object
    if ((sharedFD = shm_open("/sharedPID", O_CREAT | O_RDWR, S_IRUSR | S_IWUSR)) != -1) {
        //set size of shared memory object
        if (ftruncate(sharedFD, MAXSIZE) == 0) {
            //create a memory mapping with sharedVariable and the shared memory object
            #define OFFSET 0
            #define ADDRESS NULL
            char* sharedVariable = mmap(ADDRESS, MAXSIZE, PROT_READ | PROT_WRITE, MAP_SHARED, sharedFD, OFFSET);
            if (sharedVariable != MAP_FAILED) {
                sprintf(sharedVariable, "%d\n", getpid());
                sigset_t mask;
                //initialize signal mask
                sigemptyset(&mask);
                sigaddset(&mask, SIGUSR1);
                //block default handler for SIGUSR1
                sigprocmask(SIG_BLOCK, &mask, NULL);
                int sig;
                //wait for a SIGURS1
                sigwait(&mask, &sig);
                printf("%s\n", sharedVariable);
                shm_unlink("/sharedPID");
                return 0;
            } else {
                perror(NULL);
            }
        } else {
            perror(NULL);
        }
    } else {
        perror(NULL);
    }

}

sender 

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <signal.h>

#define MAXSIZE 4096

int main(int argc,char *argv[]) {
    int sharedFD;
    //create shared memory object
    if ((sharedFD = shm_open("/sharedPID", O_CREAT | O_RDWR, S_IRUSR | S_IWUSR)) != -1) {
        ftruncate(sharedFD, MAXSIZE);
        #define OFFSET 0
        #define ADDRESS NULL
        char* sharedVariable = mmap(ADDRESS, MAXSIZE, PROT_READ | PROT_WRITE, MAP_SHARED, sharedFD, OFFSET);
        int effectivePID = atoi(sharedVariable);
        printf("pid = %d\n",effectivePID);
        shm_unlink("/sharedPID");
        int i;
        for (i=0;i<MAXSIZE;i++) sharedVariable[i]='\0';
        for (i = 1; i < argc; i++) {
            strcat(sharedVariable, argv[i]);
            strcat(sharedVariable, " ");
        }
        kill(effectivePID, SIGUSR1);
        return 0;
    } else {
        perror(NULL);
    }
}
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