C file filled with garbage - c

Question

I need to fill my file with same numbers for example 00000.... I want to use asynchronous aio_write function. But here what I get
^# w▒(▒▒▒▒▒l▒#^#Y▒^#^#^#^#▒▒▒▒u▒l▒#*`▒^# w▒h▒▒▒ ......
Here's my code
int main(int argc, char *argv[] ){
int sk;
int d;
struct aiocb aior;
if(argc == 3){
sk = atoi(argv[2]);
char buffer[MB * MB * sk];
memset(&aior, 0, sizeof( struct aiocb ));
d = da_open(argv[1]);
da_aio_write( d, &aior, buffer, sizeof(buffer) );
da_test_wait( &aior );
da_close( d );
}
return 0;
}
and here's my asynchronous writing function (I think this function is bad)
int da_aio_write(const int d, struct aiocb *aiorp, void *buf, const int count){
int rv = 0;
memset( (void *)aiorp, 0, sizeof( struct aiocb ) );
aiorp->aio_fildes = d;
aiorp->aio_buf = buf;
aiorp->aio_nbytes = count;
aiorp->aio_offset = 0;
rv = aio_write( aiorp );
if( rv == -1) {
perror("Error da_aio_write\n");
exit(1);
return rv;
}
return rv;
}
Also here's I wait for asyncronius function to end
int da_test_wait( struct aiocb *aiorp ){
const struct aiocb *aioptr[1];
int rv;
aioptr[0] = aiorp;
rv = aio_suspend( aioptr, 1, NULL );
if( rv != 0 ){
perror( "aio_suspend failed" );
abort();
}
rv = aio_return( aiorp );
printf( "AIO complete, %d bytes write.\n", rv );
return 1;
}
Also here's my full program
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/time.h>
#include <string.h>
#include <aio.h>
#include <errno.h>
#define MB 1024
int da_open(const char *name);
int da_aio_write(const int d, struct aiocb *aiorp, void *buf, const int count);
int da_test_wait( struct aiocb *aiorp );
int da_close(int fd);
int da_open(const char *name){
int dskr;
int dskr2;
dskr = open( name, O_RDWR );
if( dskr == -1 ){
printf("File created\n");
dskr2 = open( name, O_WRONLY | O_CREAT, 0644);
}else{
printf("End job!\n");
exit(1);
}
printf( "dskr1 = %d\n", dskr2 );
return dskr2;
}
int da_aio_write(const int d, struct aiocb *aiorp, void *buf, const int count){
int rv = 0;
memset( (void *)aiorp, 0, sizeof( struct aiocb ) );
aiorp->aio_fildes = d;
aiorp->aio_buf = buf;
aiorp->aio_nbytes = count;
aiorp->aio_offset = 0;
rv = aio_write( aiorp );
if( rv == -1) {
perror("Error da_aio_write\n");
exit(1);
return rv;
}
return rv;
}
int da_test_wait( struct aiocb *aiorp ){
const struct aiocb *aioptr[1];
int rv;
aioptr[0] = aiorp;
rv = aio_suspend( aioptr, 1, NULL );
if( rv != 0 ){
perror( "aio_suspend failed" );
abort();
}
rv = aio_return( aiorp );
printf( "AIO complete, %d bytes write.\n", rv );
return 1;
}
int da_close(int fd){
int rv;
rv = close( fd );
if( rv != 0 ) perror ( "close() failed" );
else puts( "closed" );
return rv;
}
int main(int argc, char *argv[] ){
int sk;
int d;
struct aiocb aior;
if(argc == 3){
sk = atoi(argv[2]);
char buffer[MB * MB * sk];
memset(&aior, 0, sizeof( struct aiocb ));
d = da_open(argv[1]);
da_aio_write( d, &aior, buffer, sizeof(buffer) );
da_test_wait( &aior );
da_close( d );
}
return 0;
}

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/time.h>
#include <string.h>
#include <aio.h>
int da_open(const char *name);
int da_aio_read(const int d, struct aiocb *aiorp, void *buf, const int count);
int da_open(const char *name){
int dskr;
int dskr2;
dskr = open( name, O_RDWR );
if( dskr == -1 ){
dskr2 = open( name, O_WRONLY | O_CREAT, 0644);
}else{
exit(1);
}
return dskr2;
}
What is going on here? Is this an obfuscated way to make sure you don't write to a file if it already exists? It is obviously incorrect as the file could have appeared before the second open. You can use O_EXCL instead.
The code is additionaly obfuscted by not handling exit earlier.
int da_aio_read(const int d, struct aiocb *aiorp, void *buf, const int count){
int rv = 0;
memset( (void *)aiorp, 0, sizeof( struct aiocb ) );
//memset(buf, 0, sizeof( buf) );
aiorp->aio_fildes = d;
aiorp->aio_buf = buf;
aiorp->aio_nbytes = count;
aiorp->aio_offset = 0;
rv = aio_write( aiorp );
return rv;
}
First off, what the fsck. Why are you calling a writing function something_read?
What's the use of rv?
If you read any docs on aio you will see you have to explicitly wait for event completion.
int main(int argc, char *argv[] ){
int sk;
int d;
struct aiocb aior;
char buffer[100];
memset(buffer, 0, sizeof buffer);
if(argc == 3){
sk = atoi(argv[2]);
d = da_open(argv[1]);
da_aio_read( d, &aior, buffer, sizeof(buffer) );
}
return 0;
}