Creating dynamically a file name in C - c

Question

I'm working on a client, server project. I receive a response from the server where I have to create two files. The first file is a .html file and the second file is .png file. I parse the response and I try to dynamically create the files in a while loop.
...
FILE *fwrp;
char *response = malloc(MAXDATASIZE * sizeof(char));
memset(response, '\0', sizeof(char) * MAXDATASIZE);
char *r = &response[0];
while (fread(field, sizeof(field), 1, fpr)) {
for (int i = 0; i < MAXDATASIZE; i++) {
*r = field[i];
r++;
//Some unecessary code...
if (strstr(response,"file=")){
char* newFileName = strchr(response, '=');
newFileName++;
fwrp = fopen(newFileName, "w");
data = false;
//...
I hope I didn't cut too much necessary information. The problem is the following: The files are created. Also with the right content.
The problem just the dynamic name of the file. One time the name should be ok.png, but instead it is 'ok.png'$'\n'
The same problem for the html file. The name should be example.html but is 'example.html'$'\n'
Already tried to print the names before they are created. They have the right format when they are printed. And I tried to allocate the memory with strdup, but it did not work for some reason. Anybody have an idea why this problem appears?
SOLUTION:
For those who are interested. Here is my solution
int receiveResponse(int sockfd) {
int sdw = dup(sockfd);
FILE *fpr = fdopen(sdw, "r");
FILE *fwrp;
int lenOfRecord = 0;
bool data = false;
bool status_checked = false;
bool first = true;
unsigned char field[MAXDATASIZE] = {0};
char *response = malloc(MAXDATASIZE * sizeof(char));
memset(response, '\0', sizeof(char) * MAXDATASIZE);
char *r = &response[0];
while (fread(field, sizeof(field), 1, fpr)) {
for (int i = 0; i < MAXDATASIZE; i++) {
*r = field[i];
r++;
if ((field[i] == '\n') && (data == false)){
if (strstr(response, "status=") && (status_checked == false)){
status_checked = true;
char* status = strchr(response,'=');
status++;
}
if (strstr(response, "len=")){
char *len = strchr(response, '=');
len++;
char *ptr;
lenOfRecord = strtol(len,&ptr,10);
data = true;
first = true;
}
if (strstr(response,"file=")){
char* tmp = strchr(response, '=');
tmp++;
char* newFileName = malloc(strlen(tmp) * sizeof(char));
memcpy(newFileName, tmp, strlen(tmp) * sizeof(char));
newFileName[strlen(newFileName) - 1] = 0;
fwrp = fopen(newFileName, "w");
free(newFileName);
data = false;
}
free(response);
char* response = malloc(MAXDATASIZE * sizeof(char));
memset(response, '\0', sizeof(char) * MAXDATASIZE);
r = &response[0];
}
if (--lenOfRecord == 0){
data = false;
fflush(fwrp);
fclose(fwrp);
}
if ((data == true) && (first == false)) {
fputc(field[i], fwrp);
}
if ((data == true) && (first == true)){
first = false;
}
}
}
}
So the problem was solved with this modification
newFileName[strlen(newFileName) - 1] = 0;

Answer 1

I've no idea, why are you copying readed field content into response instead of reading strictly into response. Additionaly, you didn't show the declaration of field.
Probably you should take the better care on count of readed chars (returned by fread()): it can be negative (means: error), not only positive or 0.
What about zero-termination?
So, my proposition is:
//...
// for better readability
#define MAX_RESPONSE_SIZE (MAXDATASIZE * sizeof(char))
// below: added 1 byte for preserving the proper string termination ('\0' byte)
#define RESPONSE_BUFFER_SIZE (MAXDATASIZE + 1)
FILE *fwrp;
char *response = malloc(RESPONSE_BUFFER_SIZE);
memset(response, '\0', RESPONSE_BUFFER_SIZE);
int readOffset = 0; // offset for reading the next chunk
int readCount; // count of readed characters/bytes
// below: return of fread() can be positive, 0 if no more data, or negative if error
while ((readCount = fread(response + readOffset, MAX_RESPONSE_SIZE - readOffset, 1, fpr)) > 0) {
readOffset += readCount;
}
//Some unecessary code...
if (strstr(response, "file=")) {
char* newFileName = strchr(response, '=');
newFileName++;
fwrp = fopen(newFileName, "w");
data = false;
//...