What are the different use of gets()

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Hi,

I was trying to send a video file from Android to C using TCP/IP protocol. I was having data loss(some bytes were lost in the transmission).

After i used gets() i am able to receive all the data, irrespective of the file size.

[edit] Added code from comment below:[/edit]

C++

int receive_text(int new_socket)
{
	long int buffersize = 0, recv_size = 0, size = 0, read_size, write_size;
	int errno;
	FILE *text;
	char *pBuf,a[50],filename[50],*filename2;
	printf("Enter Filename:\n");
	gets(filename);
	printf("%s",filename);
	strcat(str,filename);
	filename2 = fopen(str,"w");
	printf("Filename2:\n");
	(filename2);	
	text = fopen(str,"w");
 	if (text == NULL)
	{
		puts("Error has occurred. Text file could not be opened \n");
		gets(a);
		return -1;
	}

 	//Loop while we have not received the entire file yet
	
	while (1)
	{ 
		
		ioctl(new_socket, FIONREAD, &buffersize);//We check to see if there is data to be read from the socket
		printf("Buffersize ioctl value is %ld \n",buffersize);
		gets(a); 		
		if (buffersize > 0)
		{
			printf("Buffersize value is: %ld \n", buffersize);
			gets(a);
			pBuf = malloc(buffersize);
			if (!pBuf)
			{
				fprintf(stderr, "Memory Error. Cannot allocate!\n");
				gets(a);
				exit(-1);
			}				
			read_size = recv(new_socket, pBuf, buffersize, 0); 
			printf("Read size value is: %li \n", read_size);
			gets(a);				
			if (read_size < 1)
			{
				printf("%s", strerror(errno));
				gets(a);
				goto free;
			}
 				
			//Write the currently read data into our text file
					
			write_size = fwrite(pBuf, 1, read_size, text);		
			free(pBuf);
			printf("Writesize value is: %li \n", write_size);
			gets(a);	

			//Increment the total number of bytes read
				
			recv_size += read_size;		
			printf("Receivedsize value is: %li \n", recv_size);
			gets(a);
		}
		if((buffersize == 0) && (recv_size != 0))
		{
			goto free;
		}
	}
	free:

	//close(new_socket);
	fclose(text);
	send_text(new_socket);
	printf("Text successfully received: \n");
	gets(a);
	return 0;

}

The code has been put for further reference

Posted 12-Jul-15 18:53pm

venkat28vk

Updated 13-Jul-15 1:25am

Stefan_Lang

v2

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Comments

[no name] 13-Jul-15 1:20am

Question not decipherable.

venkat28vk 13-Jul-15 1:45am

I am receiving video file from Android to C using TCP/IP protocol. In the initial phases there were data loss when video file was sent, i rectified the error by giving gets() and now there is no data loss. How did gets() solved the error.

[no name] 13-Jul-15 1:48am

Without your code how do we know what you are talking about.

venkat28vk 13-Jul-15 6:13am

Just check for the code

Stefan_Lang 13-Jul-15 3:01am

What you wrote here is like going to the garage and telling the mechanic: "My green car is broken. The red works, though", without bringing either car.

What is the mechanic supposed to do without seeing the broken car or any other information to work with? What are we to do without seeing the code and any information to work with?

venkat28vk 13-Jul-15 6:13am

int receive_text(int new_socket)
{
long int buffersize = 0, recv_size = 0, size = 0, read_size, write_size;
int errno;
FILE *text;
char *pBuf,a[50],filename[50],*filename2;
printf("Enter Filename:\n");
gets(filename);
printf("%s",filename);
strcat(str,filename);
filename2 = fopen(str,"w");
printf("Filename2:\n");
(filename2);
text = fopen(str,"w");
if (text == NULL)
{
puts("Error has occurred. Text file could not be opened \n");
gets(a);
return -1;
}

//Loop while we have not received the entire file yet

while (1)
{

ioctl(new_socket, FIONREAD, &buffersize);//We check to see if there is data to be read from the socket
printf("Buffersize ioctl value is %ld \n",buffersize);
gets(a);
if (buffersize > 0)
{
printf("Buffersize value is: %ld \n", buffersize);
gets(a);
pBuf = malloc(buffersize);
if (!pBuf)
{
fprintf(stderr, "Memory Error. Cannot allocate!\n");
gets(a);
exit(-1);
}
read_size = recv(new_socket, pBuf, buffersize, 0);
printf("Read size value is: %li \n", read_size);
gets(a);
if (read_size < 1)
{
printf("%s", strerror(errno));
gets(a);
goto free;
}

//Write the currently read data into our text file

write_size = fwrite(pBuf, 1, read_size, text);
free(pBuf);
printf("Writesize value is: %li \n", write_size);
gets(a);

//Increment the total number of bytes read

recv_size += read_size;
printf("Receivedsize value is: %li \n", recv_size);
gets(a);
}
if((buffersize == 0) && (recv_size != 0))
{
goto free;
}
}
free:

//close(new_socket);
fclose(text);
send_text(new_socket);
printf("Text successfully received: \n");
gets(a);
return 0;

}

The code has been put for further reference

Stefan_Lang 13-Jul-15 7:28am

Please don't put relevant information just into a comment, put it in your original question instead, so all can see it! I have done it for you, this time, but next time please do it yourself.

You can edit your question by clicking on the green "Improve question" tag at the bottom right of your question. (you may need to hover your mouse in that area to see it)

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Stefan_Lang · Accepted Answer · 2015-07-12T21:11:00

Never use gets() for reading binary data: it will swallow '\n' bytes, and you will have trouble interpreting the data if it contains 0-bytes. Even worse, you are risking a buffer overflow if you can't guarantee your buffer is big enough to hold all data up to and including the next occurence of '\n'!

gets() is meant for getting printable text, not binary data. See http://www.cplusplus.com/reference/cstdio/gets/[^]

[edit]
After you posted your code, the question becomes much clearer: You have inserted calls to gets() in addition to your original socket reads, not replaced those calls by gets() as I thought!

Obviously, calling a second - unrelated - reading function does not serve any real purpose. But since that change appeared to make your program work, maybe the calls to gets() have a hidden side effect, e. g. forcing a synchronization of your socket.

I have no experience with socket programming, but I believe it works different on different systems, so you should mention what OS you're working on!

In any case, you really should check for errors, especially after the call to recv. Check the appropriate documentation for socket programming on your OS.
[/edit]

P.S.:
Have a look at this: http://stackoverflow.com/questions/6979769/linux-ioctl-with-fionread-always-0[^] Your problem may be related to what is explained in the second response - that you should use select() rather than ioctl()

akriti singh · Accepted Answer · 2015-07-12T19:14:00

Solution 1

gets() is used to in a string for taking value and as work as scanf() works

Posted 12-Jul-15 19:14pm

akriti singh