Mirk M: Created page with "

http://www.cs.unibo.it/~renzo/so/pratiche/2009.09.23.pdf

== Esercizio 1 == #include #include #include #in..."

2014-04-30T13:59:34Z

Created page with "<h1>http://www.cs.unibo.it/~renzo/so/pratiche/2009.09.23.pdf</h1> == Esercizio 1 == <syntaxhighlight lang="C"> #include <stdlib.h> #include <stdio.h> #include <unistd.h> #in..."

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<h1>http://www.cs.unibo.it/~renzo/so/pratiche/2009.09.23.pdf</h1>

== Esercizio 1 ==

<syntaxhighlight lang="C">
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>

#define BUFSIZE 4096

void buf_invert(char *b_input, char *b_output)
{
int i;

for(i=0; i<BUFSIZE; i++)
{
if(b_input[i] == EOF)
break;
b_output[i] = b_input[BUFSIZE-i];
}
}

off_t file_dim(char *path)
{
struct stat buf;
int ris;

ris = stat (path, &buf);
if(ris == -1)
{
printf("Stat, error %d: %s\n", errno, strerror(errno));
return -1;
}

return buf.st_size;
}

int invert(int input, int output, off_t file_size)
{
char b_input[BUFSIZE], b_output[BUFSIZE];
int rris, wris;
off_t i=0;

while(i < file_size)
{
rris = pread(input, b_input, BUFSIZE, i);
if(rris == -1)
{
printf("Pread error %d: %s\n", errno, strerror(errno));
return -1;
}

i += rris;

wris = pwrite(output, b_output, BUFSIZE, file_size-i);
if(wris == -1)
{
printf("Pwrite error %d: %s\n", errno, strerror(errno));
return -1;
}

if(rris != wris)
{
printf("Invert error\n");
return -1;
}

}

return 0;
}

int main(int argc, char *argv[])
{
int input, output, ris;
off_t file_size;

if(argc > 3)
{
printf("Too many arguments\n");
return -1;
}

input = open(argv[1], O_RDONLY);
if(input == -1)
{
printf("Open error %d: %s\n", errno, strerror(errno));
return -1;
}

file_size = file_dim(argv[1]);
if(file_size == -1)
{
printf("File_dim error\n");
return -1;
}

printf("File size %d\n", file_size);

output = open(argv[2], O_CREAT | O_RDWR /*| O_APPEND*/);
if(output == -1)
{
printf("File creation (open) error %d: %s\n", errno, strerror(errno));
return -1;
}

ris = invert(input, output, file_size);
if(ris == -1)
{
printf("Invert error\n");
return -1;
}

return 0;
}
</syntaxhighlight>

Mirko_M

ProvaPratica 2009.09.23 - Revision history

Mirk M: Created page with "

http://www.cs.unibo.it/~renzo/so/pratiche/2009.09.23.pdf