Prova pratica 2015.01.21
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Testo: [1]
Esercizio 1
//ESERCIZIO 1
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#define BUFFLEN 4096 //probably there is a system constant
int main(int argc,const char* argv[]){
//take the path name and open the file
FILE* fd = fopen(argv[1],"r");
//read the the file and put its content in a array of pointers
char commands[2][BUFFLEN]; //migliorabile
char buffer[BUFFLEN];
int i = 0;
while (fgets(buffer,sizeof(buffer),fd) != NULL){
strcpy(commands[i],buffer);
i ++;
}
//printf("%s\n%s\n",commands[0],commands[1] );
//create a pipe
int fpipe[2];
pipe(fpipe); //0 reading,1 writing
//fork
int pid;
pid = fork();
switch (pid){
case 0 : //children
close(fpipe[0]);
//children's stout = pipe output
dup2(fpipe[1],STDOUT_FILENO);
close(fpipe[1]);
//execution of the command
system(commands[0]);
break;
default : //parent
close(fpipe[1]);
//father's stdin = pipe input
dup2(fpipe[0],STDIN_FILENO);
close(fpipe[0]);
//receive the comnmand
system(commands[1]);
break;
}
}
--LeonardoF (talk) 15:39, 26 March 2017 (CEST)LeonardoF
//ESERCIZIO 2
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define AOS_LENSTEP 8
/*
* Define a struct for managing and array of pointer to strings.
*/
struct array_of_strings {
char **strings;
size_t currentlength; //the length of number of string in memory
size_t arraylength; //the length of memory allocated
};
typedef struct array_of_strings array_of_strings;
void array_of_strings_add(array_of_strings *arrayOfStrings, char *string) {
//if there is not enough space for the string increase it
if (arrayOfStrings->currentlength >= arrayOfStrings->arraylength) {
//increase the array length by the size of a string pointer
size_t newlength = arrayOfStrings->arraylength + AOS_LENSTEP;
//reallocate the arrayOfString with the new size
char **new_string = realloc(arrayOfStrings->strings, newlength * sizeof(arrayOfStrings->strings[0]));
//if the reallocation is successful
if (new_string != NULL) {
arrayOfStrings->arraylength = newlength;
arrayOfStrings->strings = new_string;
}
}
//if there is enough space for the string insert it
if (arrayOfStrings->currentlength < arrayOfStrings->arraylength)
//strdup return a pointer to a duplicate of the string
arrayOfStrings->strings[arrayOfStrings->currentlength++] = strdup(string);
}
void array_of_strings_print(array_of_strings *v) {
size_t i;
for (i = 0; i < v->currentlength; i++)
printf("[%3lu]: %s\n", i, v->strings[i]);
}
int main(int argc, char *argv[]) {
int commandNumber= 0;
char* line = NULL;
size_t lineLength = 0;
ssize_t numberOfCharactersRead;
static array_of_strings arrayOfStrings;
FILE* fd = fopen(argv[1],"r");
while ((numberOfCharactersRead = getline(&line, &lineLength, fd)) >= 0) {
if (line[numberOfCharactersRead - 1] == '\n')
line[numberOfCharactersRead - 1] = 0;
array_of_strings_add(&arrayOfStrings, line);
commandNumber ++;
}
free(line);
//array_of_strings_print(&arrayOfStrings);
//printf("%d\n",commandNumber );
//open the pipe
int fpipe[2];
pipe(fpipe); //0 reading,1 writing
int i = 0;
while(commandNumber > 0 ){
if(commandNumber > 1) {
int pid = fork();
switch(pid){
case 0: //children
close(fpipe[0]);
//children's stout = pipe output
dup2(fpipe[1],STDOUT_FILENO);
close(fpipe[1]);
//execution of the command
//usleep( commandNumber* 1000000);
system(arrayOfStrings.strings[i]);
commandNumber = 0;
break;
default: //parent
commandNumber --;
i ++;
break;
}
}
else{ //last command
close(fpipe[1]);
//father's stdin = pipe input
dup2(fpipe[0],STDIN_FILENO);
close(fpipe[0]);
//receive the comnmand
system(arrayOfStrings.strings[i]);
commandNumber --;
}
}
}
--LeonardoF (talk) 15:39, 26 March 2017 (CEST)LeonardoF
Esercizio 3 Script Bash
#!/bin/bash
#ESERCISIO 3
find $1 -exec md5sum {} \; |sort | uniq --all-repeated=separate --check-chars=32
shift
for i in $@ ; do
find $1 -exec md5sum {} \; |sort | uniq --all-repeated=separate --check-chars=32
shift
done
--LeonardoF (talk) 15:39, 26 March 2017 (CEST)LeonardoF
Esercizio 3 Script Python
#!/usr/bin/env python3
#ESERCIZIO 3
import sys
# os.syscall way to use linux syscalls
import os
import hashlib
dictionary = {}
def add(md5val,path):
"""function that insert the given file path in a dictionary
using as key the given md5sum"""
#in this way i avoid duplicates
dictionary.setdefault(md5val,set()).add(path)
def md5add(path):
"""function that takes a filepath and calculate is md5sum
then it calls a function to insert the file in a dictionary"""
md5val = hashlib.md5()
with open(path, "rb") as f:
#Note that sometimes you won't be able to fit the whole file in memory.
#In that case, you'll have to read chunks of 4096 bytes sequentially and feed them to the Md5 function:
for chunk in iter(lambda: f.read(4096), b""):
md5val.update(chunk)
add(md5val.hexdigest(),path)
def movmd5add(path):
"""recursive fuction that moves in the file system and call the mdadd function
it takes a path in input (main checks the path given by the user) """
for root, dirs, files in os.walk(path):
for f in files:
#if file call the function for the md5sum
md5add(os.path.join(root,f)) # os.path.join(root,f)
def printdict():
"""funtion that prints the dictionary"""
for x in dictionary:
#doesn't print single lines
if len(dictionary[x]) > 1 :
print('\r')
for y in dictionary[x]:
print(x," : ",y)
def main(args):
"""main checks the path and call the functions"""
if len(args) < 1:
args = "."
for path in args:
movmd5add(path)
printdict()
if __name__ == "__main__":
main(sys.argv[1:])
--LeonardoF (talk) 15:39, 26 March 2017 (CEST)LeonardoF
Esercizio 3
#!/usr/bin/python
"""
Esercizio 3: Script bash o Python: (10 punti):
Scrivere un programma python o uno script bash che scandisca il sottoalbero relativo alle directory passate come
parametri (o alla direcotry corrente se non ci sono parametri) e fornisca in output l'elenco dei file che hanno la
stessa somma MD5 (i.e. l'output del comando md5sum).
In output ogni riga deve mostrare un elenco di pathname realtivi a file che hanno la stessa somma MD5 (che quindi
sono molto molto probabilmente uguali).
"""
import sys
import os
import hashlib
def sha1sum(root, filename):
sha1 = hashlib.sha1()
with open(os.path.join(root, filename), "rb") as thefile:
buf = thefile.read()
sha1.update(buf)
return sha1.hexdigest()
def initSha1vect(path):
""" Inizializza il dizionario utilizzando come chiave il sha1
del file, e come valore il percorso del file. """
shafiles = {}
for root, dirs, files in os.walk(path):
for file in files:
shaKey = sha1sum(root, file)
shafiles.setdefault(shaKey, [])
shafiles[shaKey].append(file)
return shafiles
def main(args):
for path in args:
msg = True
print "\n", path
shafiles = initSha1vect(path)
for k in shafiles:
if len(shafiles[k]) > 1:
msg = False
print k, "\t", shafiles[k]
if msg:
print "Nessun file con lo stesso sha1"
if __name__ == "__main__":
main(sys.argv[1:])
S.G (talk) 14:39, 18 November 2016 (CET)
Ho scritto una possibile soluzione dell'esercizio 3
perché proporre una soluzione in un linguaggio che non ho ancora spiegato?Renzo (talk) 19:36, 21 November 2016 (CET)