Coding Contest 25 novembre 2016 - Revision history

Alexp: /* Esercizio 3 */

2016-12-08T12:50:34Z

Esercizio 3

Renzo: /* Esercizio 4 */

2016-12-06T08:06:25Z

Esercizio 4

Renzo: Created page with "== Esercizio 1 == scrivere un programma che passato come parametro il path di una directory (cwd se manca il paramtro) stampi il path relativo di tutti i file con nome palind..."

2016-12-06T08:02:50Z

Created page with "== Esercizio 1 == scrivere un programma che passato come parametro il path di una directory (cwd se manca il paramtro) stampi il path relativo di tutti i file con nome palind..."

New page

== Esercizio 1 ==

scrivere un programma che passato come parametro il path di una directory (cwd se manca il paramtro) stampi il path relativo di tutti i file con nome palindromo presenti nel sottoalbero.

2720c84e673c75c20a27a07ffcd6826b31c8babc esercizio1.c [[User:Leonardo|Leonardo]] ([[User talk:Leonardo|talk]]) 17:23, 25 November 2016 (CET)

86aca4384a296bf12c69541fc5418fe4b6656e0d es1.c [[User:Fabio.capucci|Fabio.capucci]] ([[User talk:Fabio.capucci|talk]]) 17:30, 25 November 2016 (CET)

071fccfe63b8121f951444cb57001ccdd4ec02d0 Es1.c [[User:FilippoB|FilippoB]] ([[User talk:FilippoB|talk]]) 17:31, 25 November 2016 (CET)

235f2414cfe5b81973b1d388ce9431aa02b5f305 [[User:MatteoC|MatteoC]] ([[User talk:MatteoC|talk]]) 17:43, 25 November 2016 (CET)

168d3422b92fc78519e19d6a8e156b260a7798a6 testdir.c [[User:Tamino|Tamino]] ([[User talk:Tamino|talk]]) 18:06, 25 November 2016 (CET)

== Esercizio 2 ==

lancia tutti gli eseguibili della directory passata come primo paramtro e concatena gli output.
(i parametri rimanenti devono essere passati a tutti gli eseguibili)

<pre>
lanciatutti dir 1 2 3
</pre>

se nella directory ''dir'' sono presenti ''a'', ''b'' e ''c'' (eseguibili) lancia '''a 1 2 3''', '''b 1 2 3''', ''c 1 2 3'''

== Esercizio 3 ==

Scrivere un programma che deve ottenere il pid passato come parametro.
indicare se e' impossibile

fdf7b609e470c43a32a50801e76e78c32aebfbb1 main.tar.gz [[User:Alexp|Alexp]] ([[User talk:Alexp|talk]]) 17:22, 25 November 2016 (CET)

== Esercizio 4 ==

Trovare i file di contenuto uguale nella directory corrente e convertirli in link dello stesso file.

← Older revision		Revision as of 12:50, 8 December 2016
Line 31:		Line 31:

	fdf7b609e470c43a32a50801e76e78c32aebfbb1 main.tar.gz [[User:Alexp\|Alexp]] ([[User talk:Alexp\|talk]]) 17:22, 25 November 2016 (CET)		fdf7b609e470c43a32a50801e76e78c32aebfbb1 main.tar.gz [[User:Alexp\|Alexp]] ([[User talk:Alexp\|talk]]) 17:22, 25 November 2016 (CET)
		+
		+	In seguito il codice dell'esercizio --[[User:Alexp\|Alexp]] ([[User talk:Alexp\|talk]]) 13:50, 8 December 2016 (CET) :
		+	<syntaxhighlight lang=C>
		+	#include <unistd.h>
		+	#include <stdio.h>
		+	#include <signal.h>
		+	#include <errno.h>
		+	#include <sys/wait.h>
		+
		+	#define PID 6300
		+
		+	void do_something(){
		+	//print something
		+	printf("---doing something---\n");
		+	}
		+
		+	int main(int argc, char* argv[]) {
		+	int sPID = PID;
		+	if (argc > 1) {
		+	sPID = atoi(argv[1]);
		+	}
		+	pid_t pid;
		+	if (getpid() == sPID) {
		+	//if sPID matched
		+	printf("GOT PID (%d)!\n", sPID);
		+	//do something
		+	do_something();
		+	} else {
		+	if (kill(sPID, 0) != 0 && errno == ESRCH) {
		+	//while generated child has wrong sPID
		+	while ((pid = fork()) != sPID) {
		+	//if child
		+	if (pid == 0) {
		+	if (getpid() == sPID) {
		+	printf("GOT PID (%d)!\n", sPID);
		+	//do something
		+	do_something();
		+	}
		+	break;
		+	}
		+	//if parent and error occoured
		+	else if (pid == -1) {
		+	printf("Error: process table is full.\n");
		+	break;
		+	}
		+	//if parent and no error occoured
		+	else {
		+	//wait for child process to finish
		+	wait(NULL);
		+	}
		+	}
		+	//we must wait for the last child
		+	if (pid == sPID) {
		+	printf("Waiting for the last child.");
		+	wait(NULL);
		+	}
		+	} else {
		+	printf("Impossible to get pid %d(another process has it).\n", sPID);
		+	}
		+	}
		+	return 0;
		+	}
		+	</syntaxhighlight>

	== Esercizio 4 ==		== Esercizio 4 ==

← Older revision		Revision as of 08:06, 6 December 2016
Line 35:		Line 35:

	Trovare i file di contenuto uguale nella directory corrente e convertirli in link dello stesso file.		Trovare i file di contenuto uguale nella directory corrente e convertirli in link dello stesso file.
		+
		+	Esempio di soluzione dell'esercizio [[User:Renzo\|Renzo]] ([[User talk:Renzo\|talk]]) 09:06, 6 December 2016 (CET).
		+	(in aula sembrava avere un bug ma non era vero. Alcuni file in /tmp non sono stati convertiti in link perché appartenevano ad altro utente).
		+
		+	<syntaxhighlight lang=C>
		+	#include <stdio.h>
		+	#include <fcntl.h>
		+	#include <stdlib.h>
		+	#include <unistd.h>
		+	#include <stdarg.h>
		+	#include <string.h>
		+	#include <libgen.h>
		+	#include <errno.h>
		+	#include <dirent.h>
		+	#include <mhash.h>
		+	#include <sys/types.h>
		+	#include <sys/stat.h>
		+
		+	struct file {
		+	struct file *next;
		+	unsigned char hash[20];
		+	char *name;
		+	};
		+
		+	struct file *head;
		+
		+	static int ckcontents(int fd1, int fd2) {
		+	char buf1[BUFSIZ],buf2[BUFSIZ];
		+	ssize_t n1, n2;
		+	do {
		+	n1 = read(fd1, buf1, BUFSIZ);
		+	n2 = read(fd2, buf2, BUFSIZ);
		+	} while (n1 == n2 && n1 > 0 && memcmp(buf1, buf2, n2 == 0));
		+	return n1 == n2;
		+	}
		+
		+	static int cksize(int fd1, int fd2) {
		+	struct stat st1, st2;
		+	return
		+	fstat(fd1, &st1) == 0 &&
		+	fstat(fd2, &st2) == 0 &&
		+	st1.st_size == st2.st_size;
		+	}
		+
		+	int filecmp(char path1, char path2) {
		+	int fd1 = open(path1, O_RDONLY);
		+	int fd2 = open(path2, O_RDONLY);
		+	int rval =
		+	fd1 >= 0 && fd2 >=0 && cksize(fd1, fd2) && ckcontents(fd1, fd2);
		+	close(fd1);
		+	close(fd2);
		+	return rval;
		+	}
		+
		+	#if 0
		+	void printhash(unsigned char * hash) {
		+	int i;
		+	for (i = 0; i < mhash_get_block_size(MHASH_SHA1); i++)
		+	printf("%.2x", hash[i]);
		+	}
		+	#endif
		+
		+	void compute_sha1sum(char path, char hash) {
		+	int fd;
		+	MHASH td;
		+	if ((fd = open(path, O_RDONLY)) >= 0) {
		+	if ((td = mhash_init(MHASH_SHA1)) != MHASH_FAILED) {
		+	ssize_t n;
		+	char buf[BUFSIZ];
		+	while ((n = read(fd, buf, BUFSIZ)) > 0)
		+	mhash(td, buf, n);
		+	mhash_deinit(td, hash);
		+	}
		+	close(fd);
		+	}
		+	}
		+
		+	static void check_n_link(char *name) {
		+	struct file **scan;
		+	unsigned char hash[20];
		+	compute_sha1sum(name, hash);
		+	for (scan = &head; scan != NULL; scan = &((scan) -> next)) {
		+	//printhash((*scan)->hash); printf(" - "); printhash(hash); printf("\n");
		+	if (memcmp((*scan)->hash, hash, 20) == 0 &&
		+	filecmp((*scan)->name, name)) {
		+	unlink(name);
		+	link((*scan)->name, name);
		+	printf("%s and %s have the same contents\n", (*scan)->name, name);
		+	return;
		+	}
		+	}
		+	*scan = malloc(sizeof(struct file));
		+	if (*scan) {
		+	(*scan)->next = NULL;
		+	memcpy((*scan)->hash, hash, 20);
		+	(*scan)->name = name;
		+	//printf("%s\n",name);
		+	}
		+	}
		+
		+	static void freefilelist() {
		+	while (head) {
		+	struct file *delenda;
		+	delenda = head;
		+	head = head->next;
		+	free(delenda);
		+	}
		+	}
		+
		+	void err_exit(char *fmt, ...) {
		+	va_list ap;
		+
		+	va_start(ap, fmt);
		+	vfprintf(stderr, fmt, ap);
		+	va_end(ap);
		+	exit(2);
		+	}
		+
		+	static int regular_only(const struct dirent *d) {
		+	const char *name = d->d_name;
		+	struct stat st;
		+	return stat(name, &st) == 0 && S_ISREG(st.st_mode);
		+	}
		+
		+	int main(int argc, char *argv[]) {
		+	struct dirent **list;
		+	int n;
		+	int i;
		+	n = scandir(".", &list, regular_only, alphasort);
		+	if (n > 0) {
		+	for (i=0; i<n; i++) {
		+	char *name = list[i]->d_name;
		+	check_n_link(name);
		+	}
		+	freefilelist();
		+	for (i=0; i<n; i++)
		+	free(list[i]);
		+	free(list);
		+	}
		+	}
		+
		+	</syntaxhighlight>