pkt-line: share buffer/descriptor reading implementation
[git/git.git] / pkt-line.h
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1#ifndef PKTLINE_H
2#define PKTLINE_H
3
07d68930 4#include "git-compat-util.h"
f5615d24 5#include "strbuf.h"
07d68930 6
f3a3214e 7/*
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8 * Write a packetized stream, where each line is preceded by
9 * its length (including the header) as a 4-byte hex number.
10 * A length of 'zero' means end of stream (and a length of 1-3
11 * would be an error).
12 *
13 * This is all pretty stupid, but we use this packetized line
14 * format to make a streaming format possible without ever
15 * over-running the read buffers. That way we'll never read
16 * into what might be the pack data (which should go to another
17 * process entirely).
18 *
19 * The writing side could use stdio, but since the reading
20 * side can't, we stay with pure read/write interfaces.
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21 */
22void packet_flush(int fd);
4ec99bf0 23void packet_write(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
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24void packet_buf_flush(struct strbuf *buf);
25void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
f3a3214e 26
03809429 27/*
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28 * Read a packetized line into the buffer, which must be at least size bytes
29 * long. The return value specifies the number of bytes read into the buffer.
30 *
31 * If src_buffer is not NULL (and nor is *src_buffer), it should point to a
32 * buffer containing the packet data to parse, of at least *src_len bytes.
33 * After the function returns, src_buf will be incremented and src_len
34 * decremented by the number of bytes consumed.
35 *
36 * If src_buffer (or *src_buffer) is NULL, then data is read from the
37 * descriptor "fd".
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38 *
39 * If options does not contain PACKET_READ_GENTLE_ON_EOF, we will die under any
40 * of the following conditions:
41 *
42 * 1. Read error from descriptor.
43 *
44 * 2. Protocol error from the remote (e.g., bogus length characters).
45 *
46 * 3. Receiving a packet larger than "size" bytes.
47 *
48 * 4. Truncated output from the remote (e.g., we expected a packet but got
49 * EOF, or we got a partial packet followed by EOF).
50 *
51 * If options does contain PACKET_READ_GENTLE_ON_EOF, we will not die on
52 * condition 4 (truncated input), but instead return -1. However, we will still
53 * die for the other 3 conditions.
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54 *
55 * If options contains PACKET_READ_CHOMP_NEWLINE, a trailing newline (if
56 * present) is removed from the buffer before returning.
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57 */
58#define PACKET_READ_GENTLE_ON_EOF (1u<<0)
819b929d 59#define PACKET_READ_CHOMP_NEWLINE (1u<<1)
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60int packet_read(int fd, char **src_buffer, size_t *src_len, char
61 *buffer, unsigned size, int options);
03809429 62
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63/*
64 * Convenience wrapper for packet_read that is not gentle, and sets the
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65 * CHOMP_NEWLINE option. The return value is NULL for a flush packet,
66 * and otherwise points to a static buffer (that may be overwritten by
67 * subsequent calls). If the size parameter is not NULL, the length of the
68 * packet is written to it.
819b929d 69 */
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70char *packet_read_line(int fd, int *size);
71
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72/*
73 * Same as packet_read_line, but read from a buf rather than a descriptor;
74 * see packet_read for details on how src_* is used.
75 */
76char *packet_read_line_buf(char **src_buf, size_t *src_len, int *size);
03809429 77
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78#define DEFAULT_PACKET_MAX 1000
79#define LARGE_PACKET_MAX 65520
74543a04 80extern char packet_buffer[LARGE_PACKET_MAX];
047ec602 81
f3a3214e 82#endif