git/pkt-line.h
Brandon Williams 5d2124b34a pkt-line: add packet_write function
Add a function which can be used to write the contents of an arbitrary
buffer.  This makes it easy to build up data in a buffer before writing
the packet instead of formatting the entire contents of the packet using
'packet_write_fmt()'.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-17 10:51:29 +09:00

104 lines
4.1 KiB
C

#ifndef PKTLINE_H
#define PKTLINE_H
#include "git-compat-util.h"
#include "strbuf.h"
/*
* Write a packetized stream, where each line is preceded by
* its length (including the header) as a 4-byte hex number.
* A length of 'zero' means end of stream (and a length of 1-3
* would be an error).
*
* This is all pretty stupid, but we use this packetized line
* format to make a streaming format possible without ever
* over-running the read buffers. That way we'll never read
* into what might be the pack data (which should go to another
* process entirely).
*
* The writing side could use stdio, but since the reading
* side can't, we stay with pure read/write interfaces.
*/
void packet_flush(int fd);
void packet_write_fmt(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
void packet_buf_flush(struct strbuf *buf);
void packet_write(int fd_out, const char *buf, size_t size);
void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
int packet_flush_gently(int fd);
int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
int write_packetized_from_fd(int fd_in, int fd_out);
int write_packetized_from_buf(const char *src_in, size_t len, int fd_out);
/*
* Read a packetized line into the buffer, which must be at least size bytes
* long. The return value specifies the number of bytes read into the buffer.
*
* If src_buffer and *src_buffer are not NULL, it should point to a buffer
* containing the packet data to parse, of at least *src_len bytes. After the
* function returns, src_buf will be incremented and src_len decremented by the
* number of bytes consumed.
*
* If src_buffer (or *src_buffer) is NULL, then data is read from the
* descriptor "fd".
*
* If options does not contain PACKET_READ_GENTLE_ON_EOF, we will die under any
* of the following conditions:
*
* 1. Read error from descriptor.
*
* 2. Protocol error from the remote (e.g., bogus length characters).
*
* 3. Receiving a packet larger than "size" bytes.
*
* 4. Truncated output from the remote (e.g., we expected a packet but got
* EOF, or we got a partial packet followed by EOF).
*
* If options does contain PACKET_READ_GENTLE_ON_EOF, we will not die on
* condition 4 (truncated input), but instead return -1. However, we will still
* die for the other 3 conditions.
*
* If options contains PACKET_READ_CHOMP_NEWLINE, a trailing newline (if
* present) is removed from the buffer before returning.
*/
#define PACKET_READ_GENTLE_ON_EOF (1u<<0)
#define PACKET_READ_CHOMP_NEWLINE (1u<<1)
int packet_read(int fd, char **src_buffer, size_t *src_len, char
*buffer, unsigned size, int options);
/*
* Convenience wrapper for packet_read that is not gentle, and sets the
* CHOMP_NEWLINE option. The return value is NULL for a flush packet,
* and otherwise points to a static buffer (that may be overwritten by
* subsequent calls). If the size parameter is not NULL, the length of the
* packet is written to it.
*/
char *packet_read_line(int fd, int *size);
/*
* Convenience wrapper for packet_read that sets the PACKET_READ_GENTLE_ON_EOF
* and CHOMP_NEWLINE options. The return value specifies the number of bytes
* read into the buffer or -1 on truncated input. If the *dst_line parameter
* is not NULL it will return NULL for a flush packet or when the number of
* bytes copied is zero and otherwise points to a static buffer (that may be
* overwritten by subsequent calls). If the size parameter is not NULL, the
* length of the packet is written to it.
*/
int packet_read_line_gently(int fd, int *size, char **dst_line);
/*
* Same as packet_read_line, but read from a buf rather than a descriptor;
* see packet_read for details on how src_* is used.
*/
char *packet_read_line_buf(char **src_buf, size_t *src_len, int *size);
/*
* Reads a stream of variable sized packets until a flush packet is detected.
*/
ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out);
#define DEFAULT_PACKET_MAX 1000
#define LARGE_PACKET_MAX 65520
#define LARGE_PACKET_DATA_MAX (LARGE_PACKET_MAX - 4)
extern char packet_buffer[LARGE_PACKET_MAX];
#endif