xref: /PHP-8.0/docs/output-api.md (revision 1c94aac8) 
1# API adjustment to the old output control code
2
3Everything now resides beneath the php_output namespace, and there's an API call
4for every output handler op.
5
6    Checking output control layers status:
7        // Using OG()
8        php_output_get_status();
9
10    Starting the default output handler:
11        // php_start_ob_buffer(NULL, 0, 1);
12        php_output_start_default();
13
14    Starting an user handler by zval:
15        // php_start_ob_buffer(zhandler, chunk_size, erase);
16        php_output_start_user(zhandler, chunk_size, flags);
17
18    Starting an internal handler without context:
19        // php_ob_set_internal_handler(my_php_output_handler_func_t, buffer_size, "output handler name", erase);
20        php_output_start_internal(handler_name, handler_name_len, my_php_output_handler_func_t, chunk_size, flags);
21
22    Starting an internal handler with context:
23        // not possible with old API
24        php_output_handler *h;
25        h = php_output_handler_create_internal(handler_name, handler_name_len, my_php_output_handler_context_func_t, chunk_size, flags);
26        php_output_handler_set_context(h, my_context, my_context_dtor);
27        php_output_handler_start(h);
28
29    Testing whether a certain output handler has already been started:
30        // php_ob_handler_used("output handler name");
31        php_output_handler_started(handler_name, handler_name_len);
32
33    Flushing one output buffer:
34        // php_end_ob_buffer(1, 1);
35        php_output_flush();
36
37    Flushing all output buffers:
38        // not possible with old API
39        php_output_flush_all();
40
41    Cleaning one output buffer:
42        // php_ob_end_buffer(0, 1);
43        php_output_clean();
44
45    Cleaning all output buffers:
46        // not possible with old API
47        php_output_clean_all();
48
49    Discarding one output buffer:
50        // php_ob_end_buffer(0, 0);
51        php_output_discard();
52
53    Discarding all output buffers:
54        // php_ob_end_buffers(0);
55        php_output_discard_all();
56
57    Stopping (and dropping) one output buffer:
58        // php_ob_end_buffer(1, 0)
59        php_output_end();
60
61    Stopping (and dropping) all output buffers:
62        // php_ob_end_buffers(1, 0);
63        php_output_end_all();
64
65    Retrieving output buffers contents:
66        // php_ob_get_buffer(zstring);
67        php_output_get_contents(zstring);
68
69    Retrieving output buffers length:
70        // php_ob_get_length(zlength);
71        php_output_get_length(zlength);
72
73    Retrieving output buffering level:
74        // OG(nesting_level);
75        php_output_get_level();
76
77    Issue a warning because of an output handler conflict:
78        // php_ob_init_conflict("to be started handler name", "to be tested if already started handler name");
79        php_output_handler_conflict(new_handler_name, new_handler_name_len, set_handler_name, set_handler_name_len);
80
81    Registering a conflict checking function, which will be checked prior starting the handler:
82        // not possible with old API, unless hardcoding into output.c
83        php_output_handler_conflict_register(handler_name, handler_name_len, my_php_output_handler_conflict_check_t);
84
85    Registering a reverse conflict checking function, which will be checked prior starting the specified foreign handler:
86        // not possible with old API
87        php_output_handler_reverse_conflict_register(foreign_handler_name, foreign_handler_name_len, my_php_output_handler_conflict_check_t);
88
89    Facilitating a context from within an output handler callable with ob_start():
90        // not possible with old API
91        php_output_handler_hook(PHP_OUTPUT_HANDLER_HOOK_GET_OPAQ, (void *) &custom_ctx_ptr_ptr);
92
93    Disabling of the output handler by itself:
94        //not possible with old API
95        php_output_handler_hook(PHP_OUTPUT_HANDLER_HOOK_DISABLE, NULL);
96
97    Marking an output handler immutable by itself because of irreversibility of its operation:
98        // not possible with old API
99        php_output_handler_hook(PHP_OUTPUT_HANDLER_HOOK_IMMUTABLE, NULL);
100
101    Restarting the output handler because of a CLEAN operation:
102        // not possible with old API
103        if (flags & PHP_OUTPUT_HANDLER_CLEAN) { ... }
104
105    Recognizing by the output handler itself if it gets discarded:
106        // not possible with old API
107        if ((flags & PHP_OUTPUT_HANDLER_CLEAN) && (flags & PHP_OUTPUT_HANDLER_FINAL)) { ... }
108
109## Output handler hooks
110
111The output handler can change its abilities at runtime. Eg. the gz handler can
112remove the CLEANABLE and REMOVABLE bits when the first output has passed through it;
113or handlers implemented in C to be used with ob_start() can contain a non-global
114context:
115
116    PHP_OUTPUT_HANDLER_HOOK_GET_OPAQ
117        pass a void*** pointer as second arg to receive the address of a pointer
118        pointer to the opaque field of the output handler context
119    PHP_OUTPUT_HANDLER_HOOK_GET_FLAGS
120        pass a int* pointer as second arg to receive the flags set for the output handler
121    PHP_OUTPUT_HANDLER_HOOK_GET_LEVEL
122        pass a int* pointer as second arg to receive the level of this output handler
123        (starts with 0)
124    PHP_OUTPUT_HANDLER_HOOK_IMMUTABLE
125        the second arg is ignored; marks the output handler to be neither cleanable
126        nor removable
127    PHP_OUTPUT_HANDLER_HOOK_DISABLE
128        the second arg is ignored; marks the output handler as disabled
129
130## Open questions
131
132* Should the userland API be adjusted and unified?
133
134Many bits of the manual (and very first implementation) do not comply with the
135behaviour of the current (to be obsoleted) code, thus should the manual or the
136behaviour be adjusted?
137