pkt-line.h

   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  */
  21 void packet_flush(int fd);
  22 void packet_delim(int fd);
  23 void packet_response_end(int fd);
  24 void packet_write_fmt(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  25 void packet_buf_flush(struct strbuf *buf);
  26 void packet_buf_delim(struct strbuf *buf);
  27 void set_packet_header(char *buf, int size);
  28 void packet_write(int fd_out, const char *buf, size_t size);
  29 void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  30 int packet_flush_gently(int fd);
  31 int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  32 int write_packetized_from_fd_no_flush(int fd_in, int fd_out);
  33 int write_packetized_from_buf_no_flush_count(const char *src_in, size_t len,
  34                                              int fd_out, int *packet_counter);
  35 static 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  */
  46 void packet_fwrite(FILE *f, const char *buf, size_t size);
  47 void 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 */
  50 void 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)
  88 int 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  */
  97 int 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  */
 113 enum 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 };
 120 enum 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  */
 132 char *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  */
 143 int 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  */
 148 ssize_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  */
 163 int recv_sideband(const char *me, int in_stream, int out);
 164
 165 struct 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  */
 206 void 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  */
 220 enum 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  */
 230 enum 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)
 235 extern char packet_buffer[LARGE_PACKET_MAX];
 236
 237 struct packet_writer {
 238         int dest_fd;
 239         unsigned use_sideband : 1;
 240 };
 241
 242 void packet_writer_init(struct packet_writer *writer, int dest_fd);
 243
 244 /* These functions die upon failure. */
 245 __attribute__((format (printf, 2, 3)))
 246 void packet_writer_write(struct packet_writer *writer, const char *fmt, ...);
 247 __attribute__((format (printf, 2, 3)))
 248 void packet_writer_error(struct packet_writer *writer, const char *fmt, ...);
 249 void packet_writer_delim(struct packet_writer *writer);
 250 void packet_writer_flush(struct packet_writer *writer);
 251
 252 void packet_trace_identity(const char *prog);
 253
 254 #endif