pipe_buffer

[struct pipe_buffer] [struct page] /*=========================================*/ ┌---> 0xffffea000010ee00|+0x00: 0x0100000000000000 0xffffea000010ee40 0x0000000800000000 | 0xffffea000010ee08|+0x08: 0x0000000000000000 | | | | 0xffffea000010ee10|+0x10: 0xdead000000000122 | | └-unsigned int offset | 0xffffea000010ee18|+0x18: 0x0000000000000000 | └-unsigned int len; | 0xffffea000010ee20|+0x20: 0x0000000000000000 └-struct page *page ---------------------------------┘ 0xffffea000010ee28|+0x28: 0x0000000000000000 0xffffffff8221e980 0x0000000000000010 0xffffea000010ee30|+0x30: 0x00000001ffffffff | | 0xffffea000010ee38|+0x38: 0x0000000000000000 | └-unsigned int flags ┌---> 0xffffea000010ee40|+0x40: 0x0100000000000000 └-const struct pipe_buf_operations *ops | 0xffffea000010ee48|+0x48: 0x0000000000000000 0x0000000000000000 0x0000000000000000 | 0xffffea000010ee50|+0x50: 0xdead000000000122 | | 0xffffea000010ee58|+0x58: 0x0000000000000000 └-unsigned long private | 0xffffea000010ee60|+0x60: 0x0000000000000000 | 0xffffea000010ee68|+0x68: 0x0000000000000000 /*=========================================*/ | 0xffffea000010ee70|+0x70: 0x00000001ffffffff 0xffffea000010ee80 0x0000000800000000 | 0xffffea000010ee78|+0x78: 0x0000000000000000 | | | | | | └-unsigned int offset | | └-unsigned int len; | [struct pipe_buf_operations] └-struct page *page ---------------------------------┘ 0xffffffff8221e980 0x0000000000000010 0xffffffff8221e980|+0x00: 0x0000000000000000 | | 0xffffffff8221e988|+0x08: 0xffffffff81292cd0 -> 0x48fa8948fa1e0ff3 | └-unsigned int flags 0xffffffff8221e990|+0x10: 0xffffffff81292d90 -> 0x48068b48fa1e0ff3 └-const struct pipe_buf_operations *ops 0xffffffff8221e998|+0x18: 0xffffffff81292b90 -> 0x48068b48fa1e0ff3 0x0000000000000000 0x0000000000000000 | └-unsigned long private

struct pipe_buf_operations { /* * ->confirm() verifies that the data in the pipe buffer is there * and that the contents are good. If the pages in the pipe belong * to a file system, we may need to wait for IO completion in this * hook. Returns 0 for good, or a negative error value in case of * error. If not present all pages are considered good. */ int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *); /* * When the contents of this pipe buffer has been completely * consumed by a reader, ->release() is called. */ void (*release)(struct pipe_inode_info *, struct pipe_buffer *); /* * Attempt to take ownership of the pipe buffer and its contents. * ->try_steal() returns %true for success, in which case the contents * of the pipe (the buf->page) is locked and now completely owned by the * caller. The page may then be transferred to a different mapping, the * most often used case is insertion into different file address space * cache. */ bool (*try_steal)(struct pipe_inode_info *, struct pipe_buffer *); /* * Get a reference to the pipe buffer. */ bool (*get)(struct pipe_inode_info *, struct pipe_buffer *); };

int **pipe_alloc(int n_pipes) { int **ret = (int **)calloc(n_pipes,sizeof(int *)); rep(i, n_pipes) { ret[i] = (int *)calloc(2,sizeof(int)); SYSCHK(pipe(ret[i])); } return ret; } int **pipe_alloc_2(int n_pipes, int start, int end) { int **ret = (int **)calloc(n_pipes,sizeof(int *)); for(int i=start;i<end;i++) { ret[i] = (int *)calloc(2,sizeof(int)); SYSCHK(pipe(ret[i])); } return ret; } void pipe_alloc_3(int **pp, int start, int end) { for(int i=start;i<end;i++) { pp[i] = (int *)calloc(2,sizeof(int)); SYSCHK(pipe(pp[i])); } } char *pipe_read(int *p, int len) { char *ret = (char *)malloc(sizeof(char)*len); SYSCHK(read(p[0],ret,len)); return ret; } void pipe_write(int *p, char *buf, int len) { SYSCHK(write(p[1],buf,len)); } void pipe_set_size(int *p, unsigned long sz) { SYSCHK(fcntl(p[0], F_SETPIPE_SZ, sz)); } void pipe_close(int *p) { SYSCHK(close(p[0])); SYSCHK(close(p[1])); }