Question

Using the C language, I am trying to manipulate some files generated by openssl and containing a lot of (very) special characters. But the end of file seems to be prematurely detected.
For example see an extract of my program, that is supposed to copy a file to another :

(for simplicity reasons I do not show the test of the opening of the file but I do that in my program)

char msgcrypt[FFILE];
FILE* fMsg = fopen(f4Path,"r");
while(fgets(tmp,FFILE,fMsg) != NULL) strcat(msgcrypt,tmp);
fclose(fMsg);
FILE* fMsg2 = fopen(f5Path,"w");
fprintf(fMsg2,"%s",msgcrypt);
fclose(fMsg2);

here is the content of the file located at f4Path :

Salted__X¢~xÁïÈú™xe^„fl¯�˜<åD

now the content of the file located at f5Path :

Salted__X¢~xÁïÈú™xe^„fl¯

Notice that 4 characters are missing.

Do someone have an idea?

Answer 1

But the end of file seems to be prematurely detected

Sounds familiar.

• Use fopen(f4Path, "rb") when opening the file. This has real significance on Windows.
• Don’t use string functions (fprintf, strcat, fgets etc) they will choke on NUL characters. Use fread and fwrite instead.