c - Seg fault with open command when trying to open very large file -

i'm taking networking class @ school , using c/gdb first time. our assignment make webserver communicates client browser. underway , can open files , send them client. goes great till open large file , seg fault. i'm not pro @ c/gdb i'm sorry if causing me ask silly questions , not able see solution myself when looked @ dumped core see seg fault comes here:

if (-1 == (openfd = open(path, o_rdonly))) 

specifically tasked opening file , sending client browser. algorithm goes:

1. open/error catch
2. read file buffer/error catch
3. send file

we tasked making sure server doesn't crash when sending large files. problem seems opening them. can send smaller files fine. file in question 29.5mb.

the whole algorithm is:

ssize_t send_file(int conn, char *path, int len, int blksize, char *mime) {   int openfd; // file descriptor file open @ path   int temp; // counter size of file send   char buffer[len]; // buffer read file opening len big    // open file   if (-1 == (openfd = open(path, o_rdonly))) {     send_head(conn, "", 400, strlen(error_400));     (void) send(conn, error_400, strlen(error_400), 0);     logwrite(stdout, cant_open);     return -1;   }    // read file   if (-1 == read(openfd, buffer, len)) {     send_head(conn, "", 400, strlen(error_400));     (void) send(conn, error_400, strlen(error_400), 0);     logwrite(stdout, cant_open);     return -1;   }   (void) close(openfd);    // send buffer   logwrite(stdout, suc_req);   send_head(conn, mime, 200, len);         send(conn, &buffer[0], len, 0);   return len; } 

i dunno if fact unix/c novice. sorry if is. =( you're appreciated.

rather using variable length array, perhaps try allocated memory using malloc.

char *buffer = malloc (len);  ...  free (buffer); 

i did simple tests on system, , when use variable length arrays of big size (like size you're having trouble with), segfault.