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1#ifndef PKTLINE_H
2#define PKTLINE_H
3
4#include "strbuf.h"
5
6/*
7 * Write a packetized stream, where each line is preceded by
8 * its length (including the header) as a 4-byte hex number.
9 * A length of 'zero' means end of stream (and a length of 1-3
10 * would be an error).
11 *
12 * This is all pretty stupid, but we use this packetized line
13 * format to make a streaming format possible without ever
14 * over-running the read buffers. That way we'll never read
15 * into what might be the pack data (which should go to another
16 * process entirely).
17 *
18 * The writing side could use stdio, but since the reading
19 * side can't, we stay with pure read/write interfaces.
20 */
21void packet_flush(int fd);
22void packet_delim(int fd);
23void packet_response_end(int fd);
24void packet_write_fmt(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
25void packet_buf_flush(struct strbuf *buf);
26void packet_buf_delim(struct strbuf *buf);
27void set_packet_header(char *buf, int size);
28void packet_write(int fd_out, const char *buf, size_t size);
29void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
30int packet_flush_gently(int fd);
31int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
32int write_packetized_from_fd_no_flush(int fd_in, int fd_out);
33int write_packetized_from_buf_no_flush_count(const char *src_in, size_t len,
34 int fd_out, int *packet_counter);
35static inline int write_packetized_from_buf_no_flush(const char *src_in,
36 size_t len, int fd_out)
37{
38 return write_packetized_from_buf_no_flush_count(src_in, len, fd_out, NULL);
39}
40
41/*
42 * Stdio versions of packet_write functions. When mixing these with fd
43 * based functions, take care to call fflush(3) before doing fd writes or
44 * closing the fd.
45 */
46void packet_fwrite(FILE *f, const char *buf, size_t size);
47void packet_fwrite_fmt(FILE *f, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
48
49/* packet_fflush writes a flush packet and flushes the stdio buffer of f */
50void packet_fflush(FILE *f);
51
52/*
53 * Read a packetized line into the buffer, which must be at least size bytes
54 * long. The return value specifies the number of bytes read into the buffer.
55 *
56 * If options does not contain PACKET_READ_GENTLE_ON_EOF, we will die under any
57 * of the following conditions:
58 *
59 * 1. Read error from descriptor.
60 *
61 * 2. Protocol error from the remote (e.g., bogus length characters).
62 *
63 * 3. Receiving a packet larger than "size" bytes.
64 *
65 * 4. Truncated output from the remote (e.g., we expected a packet but got
66 * EOF, or we got a partial packet followed by EOF).
67 *
68 * If options does contain PACKET_READ_GENTLE_ON_EOF, we will not die on
69 * condition 4 (truncated input), but instead return -1. However, we will still
70 * die for the other 3 conditions.
71 *
72 * If options contains PACKET_READ_CHOMP_NEWLINE, a trailing newline (if
73 * present) is removed from the buffer before returning.
74 *
75 * If options contains PACKET_READ_DIE_ON_ERR_PACKET, it dies when it sees an
76 * ERR packet.
77 *
78 * If options contains PACKET_READ_GENTLE_ON_READ_ERROR, we will not die
79 * on read errors, but instead return -1. However, we may still die on an
80 * ERR packet (if requested).
81 */
82#define PACKET_READ_GENTLE_ON_EOF (1u<<0)
83#define PACKET_READ_CHOMP_NEWLINE (1u<<1)
84#define PACKET_READ_DIE_ON_ERR_PACKET (1u<<2)
85#define PACKET_READ_GENTLE_ON_READ_ERROR (1u<<3)
86#define PACKET_READ_REDACT_URI_PATH (1u<<4)
87#define PACKET_READ_USE_SIDEBAND (1u<<5)
88int packet_read(int fd, char *buffer, unsigned size, int options);
89
90/*
91 * Convert a four hex digit packet line length header into its numeric
92 * representation.
93 *
94 * If lenbuf_hex contains non-hex characters, return -1. Otherwise, return the
95 * numeric value of the length header.
96 */
97int packet_length(const char lenbuf_hex[4], size_t size);
98
99/*
100 * Read a packetized line into a buffer like the 'packet_read()' function but
101 * returns an 'enum packet_read_status' which indicates the status of the read.
102 * The number of bytes read will be assigned to *pktlen if the status of the
103 * read was 'PACKET_READ_NORMAL'.
104 *
105 * If src_buffer and *src_buffer are not NULL, it should point to a buffer
106 * containing the packet data to parse, of at least *src_len bytes. After the
107 * function returns, src_buf will be incremented and src_len decremented by the
108 * number of bytes consumed.
109 *
110 * If src_buffer (or *src_buffer) is NULL, then data is read from the
111 * descriptor "fd".
112 */
113enum packet_read_status {
114 PACKET_READ_EOF,
115 PACKET_READ_NORMAL,
116 PACKET_READ_FLUSH,
117 PACKET_READ_DELIM,
118 PACKET_READ_RESPONSE_END,
119};
120enum packet_read_status packet_read_with_status(int fd, char **src_buffer,
121 size_t *src_len, char *buffer,
122 unsigned size, int *pktlen,
123 int options);
124
125/*
126 * Convenience wrapper for packet_read that is not gentle, and sets the
127 * CHOMP_NEWLINE option. The return value is NULL for a flush packet,
128 * and otherwise points to a static buffer (that may be overwritten by
129 * subsequent calls). If the size parameter is not NULL, the length of the
130 * packet is written to it.
131 */
132char *packet_read_line(int fd, int *size);
133
134/*
135 * Convenience wrapper for packet_read that sets the PACKET_READ_GENTLE_ON_EOF
136 * and CHOMP_NEWLINE options. The return value specifies the number of bytes
137 * read into the buffer or -1 on truncated input. If the *dst_line parameter
138 * is not NULL it will return NULL for a flush packet or when the number of
139 * bytes copied is zero and otherwise points to a static buffer (that may be
140 * overwritten by subsequent calls). If the size parameter is not NULL, the
141 * length of the packet is written to it.
142 */
143int packet_read_line_gently(int fd, int *size, char **dst_line);
144
145/*
146 * Reads a stream of variable sized packets until a flush packet is detected.
147 */
148ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out, int options);
149
150/*
151 * Receive multiplexed output stream over git native protocol.
152 * in_stream is the input stream from the remote, which carries data
153 * in pkt_line format with band designator. Demultiplex it into out
154 * and err and return error appropriately. Band #1 carries the
155 * primary payload. Things coming over band #2 is not necessarily
156 * error; they are usually informative message on the standard error
157 * stream, aka "verbose"). A message over band #3 is a signal that
158 * the remote died unexpectedly. A flush() concludes the stream.
159 *
160 * Returns SIDEBAND_FLUSH upon a normal conclusion, and SIDEBAND_PROTOCOL_ERROR
161 * or SIDEBAND_REMOTE_ERROR if an error occurred.
162 */
163int recv_sideband(const char *me, int in_stream, int out);
164
165struct packet_reader {
166 /* source file descriptor */
167 int fd;
168
169 /* source buffer and its size */
170 char *src_buffer;
171 size_t src_len;
172
173 /* buffer that pkt-lines are read into and its size */
174 char *buffer;
175 unsigned buffer_size;
176
177 /* options to be used during reads */
178 int options;
179
180 /* status of the last read */
181 enum packet_read_status status;
182
183 /* length of data read during the last read */
184 int pktlen;
185
186 /* the last line read */
187 const char *line;
188
189 /* indicates if a line has been peeked */
190 int line_peeked;
191
192 unsigned use_sideband : 1;
193 const char *me;
194
195 /* hash algorithm in use */
196 const struct git_hash_algo *hash_algo;
197
198 /* hold temporary sideband message */
199 struct strbuf scratch;
200};
201
202/*
203 * Initialize a 'struct packet_reader' object which is an
204 * abstraction around the 'packet_read_with_status()' function.
205 */
206void packet_reader_init(struct packet_reader *reader, int fd,
207 char *src_buffer, size_t src_len,
208 int options);
209
210/*
211 * Perform a packet read and return the status of the read.
212 * The values of 'pktlen' and 'line' are updated based on the status of the
213 * read as follows:
214 *
215 * PACKET_READ_ERROR: 'pktlen' is set to '-1' and 'line' is set to NULL
216 * PACKET_READ_NORMAL: 'pktlen' is set to the number of bytes read
217 * 'line' is set to point at the read line
218 * PACKET_READ_FLUSH: 'pktlen' is set to '0' and 'line' is set to NULL
219 */
220enum packet_read_status packet_reader_read(struct packet_reader *reader);
221
222/*
223 * Peek the next packet line without consuming it and return the status.
224 * The next call to 'packet_reader_read()' will perform a read of the same line
225 * that was peeked, consuming the line.
226 *
227 * Peeking multiple times without calling 'packet_reader_read()' will return
228 * the same result.
229 */
230enum packet_read_status packet_reader_peek(struct packet_reader *reader);
231
232#define DEFAULT_PACKET_MAX 1000
233#define LARGE_PACKET_MAX 65520
234#define LARGE_PACKET_DATA_MAX (LARGE_PACKET_MAX - 4)
235extern char packet_buffer[LARGE_PACKET_MAX];
236
237struct packet_writer {
238 int dest_fd;
239 unsigned use_sideband : 1;
240};
241
242void packet_writer_init(struct packet_writer *writer, int dest_fd);
243
244/* These functions die upon failure. */
245__attribute__((format (printf, 2, 3)))
246void packet_writer_write(struct packet_writer *writer, const char *fmt, ...);
247__attribute__((format (printf, 2, 3)))
248void packet_writer_error(struct packet_writer *writer, const char *fmt, ...);
249void packet_writer_delim(struct packet_writer *writer);
250void packet_writer_flush(struct packet_writer *writer);
251
252void packet_trace_identity(const char *prog);
253
254#endif