pkt-line.h

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