buffer.h revision 107484 
1/* Declarations concerning the buffer data structure.  */
2
3#if defined (SERVER_SUPPORT) || defined (CLIENT_SUPPORT)
4
5/*
6 * We must read data from a child process and send it across the
7 * network.  We do not want to block on writing to the network, so we
8 * store the data from the child process in memory.  A BUFFER
9 * structure holds the status of one communication, and uses a linked
10 * list of buffer_data structures to hold data.
11 */
12
13struct buffer
14{
15    /* Data.  */
16    struct buffer_data *data;
17
18    /* Last buffer on data chain.  */
19    struct buffer_data *last;
20
21    /* Nonzero if the buffer is in nonblocking mode.  */
22    int nonblocking;
23
24    /* Functions must be provided to transfer data in and out of the
25       buffer.  Either the input or output field must be set, but not
26       both.  */
27
28    /* Read data into the buffer DATA.  There is room for up to SIZE
29       bytes.  In blocking mode, wait until some input, at least NEED
30       bytes, is available (NEED may be 0 but that is the same as NEED
31       == 1).  In non-blocking mode return immediately no matter how
32       much input is available; NEED is ignored. Return 0 on success,
33       or -1 on end of file, or an errno code.  Set the number of
34       bytes read in *GOT.
35
36       If there are a nonzero number of bytes available, less than NEED,
37       followed by end of file, just read those bytes and return 0.  */
38    int (*input) PROTO((void *closure, char *data, int need, int size,
39			int *got));
40
41    /* Write data.  This should write up to HAVE bytes from DATA.
42       This should return 0 on success, or an errno code.  It should
43       set the number of bytes written in *WROTE.  */
44    int (*output) PROTO((void *closure, const char *data, int have,
45			 int *wrote));
46
47    /* Flush any data which may be buffered up after previous calls to
48       OUTPUT.  This should return 0 on success, or an errno code.  */
49    int (*flush) PROTO((void *closure));
50
51    /* Change the blocking mode of the underlying communication
52       stream.  If BLOCK is non-zero, it should be placed into
53       blocking mode.  Otherwise, it should be placed into
54       non-blocking mode.  This should return 0 on success, or an
55       errno code.  */
56    int (*block) PROTO ((void *closure, int block));
57
58    /* Shut down the communication stream.  This does not mean that it
59       should be closed.  It merely means that no more data will be
60       read or written, and that any final processing that is
61       appropriate should be done at this point.  This may be NULL.
62       It should return 0 on success, or an errno code.  This entry
63       point exists for the compression code.  */
64    int (*shutdown) PROTO((struct buffer *));
65
66    /* This field is passed to the INPUT, OUTPUT, and BLOCK functions.  */
67    void *closure;
68
69    /* Function to call if we can't allocate memory.  */
70    void (*memory_error) PROTO((struct buffer *));
71};
72
73/* Data is stored in lists of these structures.  */
74
75struct buffer_data
76{
77    /* Next buffer in linked list.  */
78    struct buffer_data *next;
79
80    /*
81     * A pointer into the data area pointed to by the text field.  This
82     * is where to find data that has not yet been written out.
83     */
84    char *bufp;
85
86    /* The number of data bytes found at BUFP.  */
87    int size;
88
89    /*
90     * Actual buffer.  This never changes after the structure is
91     * allocated.  The buffer is BUFFER_DATA_SIZE bytes.
92     */
93    char *text;
94};
95
96/* The size we allocate for each buffer_data structure.  */
97#define BUFFER_DATA_SIZE (4096)
98
99/* The type of a function passed as a memory error handler.  */
100typedef void (*BUFMEMERRPROC) PROTO ((struct buffer *));
101
102extern struct buffer *buf_initialize PROTO((int (*) (void *, char *, int,
103						     int, int *),
104					    int (*) (void *, const char *,
105						     int, int *),
106					    int (*) (void *),
107					    int (*) (void *, int),
108					    int (*) (struct buffer *),
109					    void (*) (struct buffer *),
110					    void *));
111extern void buf_free PROTO((struct buffer *));
112extern struct buffer *buf_nonio_initialize PROTO((void (*) (struct buffer *)));
113extern struct buffer *stdio_buffer_initialize
114  PROTO((FILE *, int, int, void (*) (struct buffer *)));
115extern FILE *stdio_buffer_get_file PROTO((struct buffer *));
116extern struct buffer *compress_buffer_initialize
117  PROTO((struct buffer *, int, int, void (*) (struct buffer *)));
118extern struct buffer *packetizing_buffer_initialize
119  PROTO((struct buffer *, int (*) (void *, const char *, char *, int),
120	 int (*) (void *, const char *, char *, int, int *), void *,
121	 void (*) (struct buffer *)));
122extern int buf_empty_p PROTO((struct buffer *));
123extern void buf_output PROTO((struct buffer *, const char *, int));
124extern void buf_output0 PROTO((struct buffer *, const char *));
125extern void buf_append_char PROTO((struct buffer *, int));
126extern int buf_send_output PROTO((struct buffer *));
127extern int buf_flush PROTO((struct buffer *, int));
128extern int set_nonblock PROTO((struct buffer *));
129extern int set_block PROTO((struct buffer *));
130extern int buf_send_counted PROTO((struct buffer *));
131extern int buf_send_special_count PROTO((struct buffer *, int));
132extern void buf_append_data PROTO((struct buffer *,
133				   struct buffer_data *,
134				   struct buffer_data *));
135extern void buf_append_buffer PROTO((struct buffer *, struct buffer *));
136extern int buf_read_file PROTO((FILE *, long, struct buffer_data **,
137				struct buffer_data **));
138extern int buf_read_file_to_eof PROTO((FILE *, struct buffer_data **,
139				       struct buffer_data **));
140extern int buf_input_data PROTO((struct buffer *, int *));
141extern int buf_read_line PROTO((struct buffer *, char **, int *));
142extern int buf_read_data PROTO((struct buffer *, int, char **, int *));
143extern void buf_copy_lines PROTO((struct buffer *, struct buffer *, int));
144extern int buf_copy_counted PROTO((struct buffer *, struct buffer *, int *));
145extern int buf_chain_length PROTO((struct buffer_data *));
146extern int buf_length PROTO((struct buffer *));
147extern int buf_shutdown PROTO((struct buffer *));
148
149#ifdef SERVER_FLOWCONTROL
150extern int buf_count_mem PROTO((struct buffer *));
151#endif /* SERVER_FLOWCONTROL */
152
153#endif /* defined (SERVER_SUPPORT) || defined (CLIENT_SUPPORT) */
154