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git/pkt-line.h

235 lines
8.3 KiB

#ifndef PKTLINE_H
#define PKTLINE_H
#include "git-compat-util.h"
#include "strbuf.h"
#include "sideband.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_delim(int fd);
void packet_response_end(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_buf_delim(struct strbuf *buf);
void set_packet_header(char *buf, int size);
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)));
void packet_buf_write_len(struct strbuf *buf, const char *data, size_t len);
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.
*
* If options contains PACKET_READ_DIE_ON_ERR_PACKET, it dies when it sees an
* ERR packet.
*/
#define PACKET_READ_GENTLE_ON_EOF (1u<<0)
#define PACKET_READ_CHOMP_NEWLINE (1u<<1)
#define PACKET_READ_DIE_ON_ERR_PACKET (1u<<2)
int packet_read(int fd, char **src_buffer, size_t *src_len, char
*buffer, unsigned size, int options);
/*
* Convert a four hex digit packet line length header into its numeric
* representation.
*
* If lenbuf_hex contains non-hex characters, return -1. Otherwise, return the
* numeric value of the length header.
*/
int packet_length(const char lenbuf_hex[4]);
/*
* Read a packetized line into a buffer like the 'packet_read()' function but
* returns an 'enum packet_read_status' which indicates the status of the read.
* The number of bytes read will be assigned to *pktlen if the status of the
* read was 'PACKET_READ_NORMAL'.
*/
enum packet_read_status {
PACKET_READ_EOF,
PACKET_READ_NORMAL,
PACKET_READ_FLUSH,
PACKET_READ_DELIM,
PACKET_READ_RESPONSE_END,
};
enum packet_read_status packet_read_with_status(int fd, char **src_buffer,
size_t *src_len, char *buffer,
unsigned size, int *pktlen,
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);
/*
* Receive multiplexed output stream over git native protocol.
* in_stream is the input stream from the remote, which carries data
* in pkt_line format with band designator. Demultiplex it into out
* and err and return error appropriately. Band #1 carries the
* primary payload. Things coming over band #2 is not necessarily
* error; they are usually informative message on the standard error
* stream, aka "verbose"). A message over band #3 is a signal that
* the remote died unexpectedly. A flush() concludes the stream.
*
* Returns SIDEBAND_FLUSH upon a normal conclusion, and SIDEBAND_PROTOCOL_ERROR
* or SIDEBAND_REMOTE_ERROR if an error occurred.
*/
int recv_sideband(const char *me, int in_stream, int out);
struct packet_reader {
/* source file descriptor */
int fd;
/* source buffer and its size */
char *src_buffer;
size_t src_len;
/* buffer that pkt-lines are read into and its size */
char *buffer;
unsigned buffer_size;
/* options to be used during reads */
int options;
/* status of the last read */
enum packet_read_status status;
/* length of data read during the last read */
int pktlen;
/* the last line read */
const char *line;
/* indicates if a line has been peeked */
int line_peeked;
unsigned use_sideband : 1;
const char *me;
/* hash algorithm in use */
const struct git_hash_algo *hash_algo;
};
/*
* Initialize a 'struct packet_reader' object which is an
* abstraction around the 'packet_read_with_status()' function.
*/
void packet_reader_init(struct packet_reader *reader, int fd,
char *src_buffer, size_t src_len,
int options);
/*
* Perform a packet read and return the status of the read.
* The values of 'pktlen' and 'line' are updated based on the status of the
* read as follows:
*
* PACKET_READ_ERROR: 'pktlen' is set to '-1' and 'line' is set to NULL
* PACKET_READ_NORMAL: 'pktlen' is set to the number of bytes read
* 'line' is set to point at the read line
* PACKET_READ_FLUSH: 'pktlen' is set to '0' and 'line' is set to NULL
*/
enum packet_read_status packet_reader_read(struct packet_reader *reader);
/*
* Peek the next packet line without consuming it and return the status.
* The next call to 'packet_reader_read()' will perform a read of the same line
* that was peeked, consuming the line.
*
* Peeking multiple times without calling 'packet_reader_read()' will return
* the same result.
*/
enum packet_read_status packet_reader_peek(struct packet_reader *reader);
#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];
struct packet_writer {
int dest_fd;
unsigned use_sideband : 1;
};
void packet_writer_init(struct packet_writer *writer, int dest_fd);
/* These functions die upon failure. */
__attribute__((format (printf, 2, 3)))
void packet_writer_write(struct packet_writer *writer, const char *fmt, ...);
__attribute__((format (printf, 2, 3)))
void packet_writer_error(struct packet_writer *writer, const char *fmt, ...);
void packet_writer_delim(struct packet_writer *writer);
void packet_writer_flush(struct packet_writer *writer);
#endif