multithreading - What is the correct approach to write multiple small pieces to a temp file in c, in multithreads? -

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i simulating multithreads file downloading. strategy in each thread receive small file pieces( each file piece has piece_length , piece_size , start_writing_pos )

and each thread writes same buffer. how realize ? have worry collisions ?

//=================== follow ============//

so write small demo follows: 

#include <stdio.h>  int main(){    char* tempfilepath = "./testing";  file *fp;  fp = fopen(tempfilepath,"w+");//w+: reading , writing   fseek( fp, 9, seek_set);//starting in 10-th bytes  fwrite("----------",sizeof(char), 10, fp);  fclose(fp); }

and before execution let content in "./testing" "xxxxxxxxxxxxxxxxxxx", after above "^@^@^@^@^@^@^@^@^@----------" wonder problem ....

do torrent clients do. create file final size having extension .part. allocate non-overlapping parts of file each thread, shall have own file-descriptors. collisions avoided. rename final name when finished.


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