// Try to lock a file with name based on host ID,
// to prevent 2 schedulers from running at same time for same host.
// Return:
// 0 if successful
// In this case store file descriptor in reply struct so we can unlock later
// In other cases store -1 in reply struct
// PID (>0) if another process has lock
// -1 if error (e.g. can't create file)
//
int lock_sched() {
char filename[256];
char pid_string[16];
int fd, pid, count;
g_reply->lockfile_fd=-1;
sprintf(filename, "%s/CGI_%07d",
config.sched_lockfile_dir, g_reply->host.id
);
fd = open(filename, O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
if (fd < 0) return -1;
// if we can't get an advisory write lock on the file,
// return the PID of the process that DOES hold the lock.
// (or -1 if failure)
//
pid = mylockf(fd);
if (pid) {
close(fd);
return pid;
}
// write PID into the CGI_<HOSTID> file and flush to disk
//
count = sprintf(pid_string, "%d\n", getpid());
ssize_t n = write(fd, pid_string, count);
if (n < 0) {
close(fd);
return -1;
}
fsync(fd);
g_reply->lockfile_fd = fd;
return 0;
}
// always returns HTML reply
//
int handle_get_file_size(char* file_name) {
struct stat sbuf;
char path[MAXPATHLEN], buf[256];
int retval, pid, fd;
// TODO: check to ensure path doesn't point somewhere bad
// Use 64-bit variant
//
retval = dir_hier_path(
file_name, config.upload_dir, config.uldl_dir_fanout, path
);
if (retval) {
log_messages.printf(MSG_CRITICAL,
"Failed to find/create directory for file '%s' in '%s'.\n",
file_name, config.upload_dir
);
return return_error(ERR_TRANSIENT, "can't open file");
}
// if the volume is full, report a transient error
// to prevent the client from starting a transfer
//
if (volume_full(config.upload_dir)) {
return return_error(ERR_TRANSIENT, "Server is out of disk space");
}
fd = open(path, O_WRONLY|O_APPEND);
if (fd<0 && ENOENT==errno) {
// file does not exist: return zero length
//
log_messages.printf(MSG_NORMAL,
"handle_get_file_size(): [%s] returning zero\n", file_name
);
return return_success("<file_size>0</file_size>");
}
if (fd<0) {
// can't get file descriptor: try again later
//
log_messages.printf(MSG_CRITICAL,
"handle_get_file_size(): cannot open [%s] %s\n",
file_name, strerror(errno)
);
return return_error(ERR_TRANSIENT, "can't open file");
}
if ((pid=mylockf(fd))) {
// file locked by another file_upload_handler: try again later
//
close(fd);
log_messages.printf(MSG_CRITICAL,
"handle_get_file_size(): [%s] returning error\n", file_name
);
return return_error(ERR_TRANSIENT,
"[%s] locked by file_upload_handler PID=%d", file_name, pid
);
}
// file exists, writable, not locked by anyone else, so return length.
//
retval = stat(path, &sbuf);
close(fd);
if (retval) {
// file DOES perhaps exist, but can't stat it: try again later
//
log_messages.printf(MSG_CRITICAL,
"handle_get_file_size(): [%s] returning error %s\n",
file_name, strerror(errno)
);
return return_error(ERR_TRANSIENT, "cannot stat file" );
}
log_messages.printf(MSG_NORMAL,
"handle_get_file_size(): [%s] returning %d\n",
file_name, (int)sbuf.st_size
);
sprintf(buf, "<file_size>%d</file_size>", (int)sbuf.st_size);
return return_success(buf);
}
// read from socket, write to file
// ALWAYS returns an HTML reply
//
int copy_socket_to_file(FILE* in, char* path, double offset, double nbytes) {
unsigned char buf[BLOCK_SIZE];
struct stat sbuf;
int pid;
// open file. Use raw IO not buffered IO so that we can use reliable
// posix file locking.
// Advisory file locking is not guaranteed reliable when
// used with stream buffered IO.
//
int fd = open(path,
O_WRONLY|O_CREAT,
S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH
);
if (fd<0) {
return return_error(ERR_TRANSIENT,
"can't open file %s: %s\n", path, strerror(errno)
);
}
// Put an advisory lock on the file.
// This will prevent OTHER instances of file_upload_handler
// from being able to write to the file.
//
pid = mylockf(fd);
if (pid>0) {
close(fd);
return return_error(ERR_TRANSIENT,
"can't lock file %s: %s locked by PID=%d\n",
path, strerror(errno), pid
);
} else if (pid < 0) {
close(fd);
return return_error(ERR_TRANSIENT, "can't lock file %s\n", path);
}
// check that file length corresponds to offset
// TODO: use a 64-bit variant
//
if (stat(path, &sbuf)) {
close(fd);
return return_error(ERR_TRANSIENT,
"can't stat file %s: %s\n", path, strerror(errno)
);
}
if (sbuf.st_size < offset) {
close(fd);
return return_error(ERR_TRANSIENT,
"length of file %s %d bytes < offset %.0f bytes",
path, (int)sbuf.st_size, offset
);
}
if (offset) lseek(fd, offset, SEEK_SET);
if (sbuf.st_size > offset) {
log_messages.printf(MSG_CRITICAL,
"file %s length on disk %d bytes; host upload starting at %.0f bytes.\n",
this_filename, (int)sbuf.st_size, offset
);
}
// caller guarantees that nbytes > offset
//
bytes_left = nbytes - offset;
while (bytes_left > 0) {
int n, m, to_write;
m = bytes_left<(double)BLOCK_SIZE ? (int)bytes_left : BLOCK_SIZE;
// try to get m bytes from socket (n>=0 is number actually returned)
//
n = fread(buf, 1, m, in);
// try to write n bytes to file
//
to_write=n;
while (to_write > 0) {
ssize_t ret = write(fd, buf+n-to_write, to_write);
if (ret < 0) {
close(fd);
const char* errmsg;
if (errno == ENOSPC) {
errmsg = "No space left on server";
} else {
errmsg = strerror(errno);
}
return return_error(ERR_TRANSIENT,
"can't write file %s: %s\n", path, errmsg
);
}
to_write -= ret;
}
// check that we got all bytes from socket that were requested
// Note: fread() reads less than requested only if there's
// an error or EOF (see the man page)
//
if (n != m) {
close(fd);
if (feof(in)) {
return return_error(ERR_TRANSIENT,
"EOF on socket read : asked for %d, got %d\n",
m, n
);
} else if (ferror(in)) {
return return_error(ERR_TRANSIENT,
"error %d (%s) on socket read: asked for %d, got %d\n",
ferror(in), strerror(ferror(in)), m, n
);
} else {
return return_error(ERR_TRANSIENT,
"incomplete socket read: asked for %d, got %d\n",
m, n
);
}
}
bytes_left -= n;
}
close(fd);
return return_success(0);
}