/**
* Close and unlock a file which was previously opened and locked using sfs_fopen.
*
* Parameters: fp - file pointer to the file which you wish to close
* Returns: 1 on success, 0 otherwise
*/
int sfs_fclose(FILE *fp) {
if(fp == NULL) return 0;
mutex_lock(memory);
// Find this process and file resource
node *resource = find_file_node_fp(memory, fp);
node *process = find_process_node(memory, getpid());
if(resource == NULL || process == NULL) {
mutex_unlock(memory);
return 0;
}
resource->fp = NULL;
// Convert back to claim edge
delete_out_edge(memory, resource, process);
add_out_edge(memory, process, resource);
// Close file
int result = fclose(fp);
// Broadcast conditional variable
pthread_cond_broadcast(get_cycle_cond(memory));
mutex_unlock(memory);
return (result != EOF);
}
/**
* Open and lock the given file, ensuring that no deadlock will occur now or in the future over contention for this file.
* If opening this file immediately would cause a deadlock, this method will block until the file can be safely opened and locked.
* If the file cannot be opened, NULL is returned.
*
* Parameters: path - path to the file you wish to open and lock
* mode - mode in which to open the file (same as the argument to fopen())
* Returns: A file pointer to the opened file or NULL on error
*/
FILE *sfs_fopen(char *path, char *mode) {
mutex_lock(memory);
// Turn claim edge to assignment edge
node *resource = find_file_node(memory, path);
node *process = find_process_node(memory, getpid());
if(resource == NULL || process == NULL) {\
mutex_unlock(memory);
return NULL;
}
delete_out_edge(memory, process, resource);
add_out_edge(memory, resource, process);
// While a cycle exists
while(cycle_exists(memory)) {
// Convert back to claim edge
delete_out_edge(memory, resource, process);
add_out_edge(memory, process, resource);
// Wait
pthread_cond_wait(get_cycle_cond(memory), get_lock(memory));
// Add edge back
delete_out_edge(memory, process, resource);
add_out_edge(memory, resource, process);
}
// Upon getting the lock and assuring no cycle, open the file
FILE *res = fopen(path, mode);
resource->fp = res;
mutex_unlock(memory);
return res;
}
static ATCODEC_RET process_received_data(ATcodec_Tree_t *tree, int nb, char *global_buffer, int *global_len)
{
ATCODEC_RET res = ATCODEC_TRUE;
int len_dec;
char memory[INTERNAL_BUFFER_SIZE];
ATcodec_Memory_t mem;
while (nb--) /* nb is the number of \r in the buffer, ie. the number of potential AT commands */
{
ATcodec_Memory_Init(&mem, &memory[0], sizeof(memory), 1, NULL, NULL);
if (find_process_node(tree, global_buffer, &mem, &len_dec) != ATCODEC_TRUE)
{
/* Go to the next potential command */
for(len_dec = 0 ; len_dec < *global_len && global_buffer[len_dec] != '\r' ; len_dec++)
{
// nothing
}
ATCODEC_PRINT("PURGE\n");
if(global_buffer[len_dec++] == '\r')
{
if(global_buffer[len_dec++] == '\0')
len_dec++;
}
}
if (--len_dec >= *global_len)
len_dec = *global_len;
if (*global_len == len_dec)
{
ATCODEC_ZERO_MEMSET(global_buffer, 0, *global_len*sizeof(char));
*global_len = 0;
}
else
{
memmove(/*dest*/global_buffer, /*src*/global_buffer+len_dec, /*nb bytes*/*global_len-len_dec);
ATCODEC_ZERO_MEMSET(global_buffer+*global_len-len_dec, 0, (len_dec)*sizeof(char));
*global_len -= len_dec;
}
}
return res;
}
