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 int packet_flush_gently(int fd);
  33 int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  34 int write_packetized_from_fd_no_flush(int fd_in, int fd_out);
  35 int write_packetized_from_buf_no_flush(const char *src_in, size_t len, int fd_out);
  36
  37 /*
  38  * Stdio versions of packet_write functions. When mixing these with fd
  39  * based functions, take care to call fflush(3) before doing fd writes or
  40  * closing the fd.
  41  */
  42 void packet_fwrite(FILE *f, const char *buf, size_t size);
  43 void packet_fwrite_fmt(FILE *f, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  44
  45 /* packet_fflush writes a flush packet and flushes the stdio buffer of f */
  46 void packet_fflush(FILE *f);
  47
  48 /*
  49  * Read a packetized line into the buffer, which must be at least size bytes
  50  * long. The return value specifies the number of bytes read into the buffer.
  51  *
  52  * If src_buffer and *src_buffer are not NULL, it should point to a buffer
  53  * containing the packet data to parse, of at least *src_len bytes.  After the
  54  * function returns, src_buf will be incremented and src_len decremented by the
  55  * number of bytes consumed.
  56  *
  57  * If src_buffer (or *src_buffer) is NULL, then data is read from the
  58  * descriptor "fd".
  59  *
  60  * If options does not contain PACKET_READ_GENTLE_ON_EOF, we will die under any
  61  * of the following conditions:
  62  *
  63  *   1. Read error from descriptor.
  64  *
  65  *   2. Protocol error from the remote (e.g., bogus length characters).
  66  *
  67  *   3. Receiving a packet larger than "size" bytes.
  68  *
  69  *   4. Truncated output from the remote (e.g., we expected a packet but got
  70  *      EOF, or we got a partial packet followed by EOF).
  71  *
  72  * If options does contain PACKET_READ_GENTLE_ON_EOF, we will not die on
  73  * condition 4 (truncated input), but instead return -1. However, we will still
  74  * die for the other 3 conditions.
  75  *
  76  * If options contains PACKET_READ_CHOMP_NEWLINE, a trailing newline (if
  77  * present) is removed from the buffer before returning.
  78  *
  79  * If options contains PACKET_READ_DIE_ON_ERR_PACKET, it dies when it sees an
  80  * ERR packet.
  81  *
  82  * If options contains PACKET_READ_GENTLE_ON_READ_ERROR, we will not die
  83  * on read errors, but instead return -1.  However, we may still die on an
  84  * ERR packet (if requested).
  85  */
  86 #define PACKET_READ_GENTLE_ON_EOF        (1u<<0)
  87 #define PACKET_READ_CHOMP_NEWLINE        (1u<<1)
  88 #define PACKET_READ_DIE_ON_ERR_PACKET    (1u<<2)
  89 #define PACKET_READ_GENTLE_ON_READ_ERROR (1u<<3)
  90 int packet_read(int fd, char *buffer, unsigned size, int options);
  91
  92 /*
  93  * Convert a four hex digit packet line length header into its numeric
  94  * representation.
  95  *
  96  * If lenbuf_hex contains non-hex characters, return -1. Otherwise, return the
  97  * numeric value of the length header.
  98  */
  99 int packet_length(const char lenbuf_hex[4]);
 100
 101 /*
 102  * Read a packetized line into a buffer like the 'packet_read()' function but
 103  * returns an 'enum packet_read_status' which indicates the status of the read.
 104  * The number of bytes read will be assigned to *pktlen if the status of the
 105  * read was 'PACKET_READ_NORMAL'.
 106  */
 107 enum packet_read_status {
 108         PACKET_READ_EOF,
 109         PACKET_READ_NORMAL,
 110         PACKET_READ_FLUSH,
 111         PACKET_READ_DELIM,
 112         PACKET_READ_RESPONSE_END,
 113 };
 114 enum packet_read_status packet_read_with_status(int fd, char **src_buffer,
 115                                                 size_t *src_len, char *buffer,
 116                                                 unsigned size, int *pktlen,
 117                                                 int options);
 118
 119 /*
 120  * Convenience wrapper for packet_read that is not gentle, and sets the
 121  * CHOMP_NEWLINE option. The return value is NULL for a flush packet,
 122  * and otherwise points to a static buffer (that may be overwritten by
 123  * subsequent calls). If the size parameter is not NULL, the length of the
 124  * packet is written to it.
 125  */
 126 char *packet_read_line(int fd, int *size);
 127
 128 /*
 129  * Convenience wrapper for packet_read that sets the PACKET_READ_GENTLE_ON_EOF
 130  * and CHOMP_NEWLINE options. The return value specifies the number of bytes
 131  * read into the buffer or -1 on truncated input. If the *dst_line parameter
 132  * is not NULL it will return NULL for a flush packet or when the number of
 133  * bytes copied is zero and otherwise points to a static buffer (that may be
 134  * overwritten by subsequent calls). If the size parameter is not NULL, the
 135  * length of the packet is written to it.
 136  */
 137 int packet_read_line_gently(int fd, int *size, char **dst_line);
 138
 139 /*
 140  * Reads a stream of variable sized packets until a flush packet is detected.
 141  */
 142 ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out, int options);
 143
 144 /*
 145  * Receive multiplexed output stream over git native protocol.
 146  * in_stream is the input stream from the remote, which carries data
 147  * in pkt_line format with band designator.  Demultiplex it into out
 148  * and err and return error appropriately.  Band #1 carries the
 149  * primary payload.  Things coming over band #2 is not necessarily
 150  * error; they are usually informative message on the standard error
 151  * stream, aka "verbose").  A message over band #3 is a signal that
 152  * the remote died unexpectedly.  A flush() concludes the stream.
 153  *
 154  * Returns SIDEBAND_FLUSH upon a normal conclusion, and SIDEBAND_PROTOCOL_ERROR
 155  * or SIDEBAND_REMOTE_ERROR if an error occurred.
 156  */
 157 int recv_sideband(const char *me, int in_stream, int out);
 158
 159 struct packet_reader {
 160         /* source file descriptor */
 161         int fd;
 162
 163         /* source buffer and its size */
 164         char *src_buffer;
 165         size_t src_len;
 166
 167         /* buffer that pkt-lines are read into and its size */
 168         char *buffer;
 169         unsigned buffer_size;
 170
 171         /* options to be used during reads */
 172         int options;
 173
 174         /* status of the last read */
 175         enum packet_read_status status;
 176
 177         /* length of data read during the last read */
 178         int pktlen;
 179
 180         /* the last line read */
 181         const char *line;
 182
 183         /* indicates if a line has been peeked */
 184         int line_peeked;
 185
 186         unsigned use_sideband : 1;
 187         const char *me;
 188
 189         /* hash algorithm in use */
 190         const struct git_hash_algo *hash_algo;
 191 };
 192
 193 /*
 194  * Initialize a 'struct packet_reader' object which is an
 195  * abstraction around the 'packet_read_with_status()' function.
 196  */
 197 void packet_reader_init(struct packet_reader *reader, int fd,
 198                         char *src_buffer, size_t src_len,
 199                         int options);
 200
 201 /*
 202  * Perform a packet read and return the status of the read.
 203  * The values of 'pktlen' and 'line' are updated based on the status of the
 204  * read as follows:
 205  *
 206  * PACKET_READ_ERROR: 'pktlen' is set to '-1' and 'line' is set to NULL
 207  * PACKET_READ_NORMAL: 'pktlen' is set to the number of bytes read
 208  *                     'line' is set to point at the read line
 209  * PACKET_READ_FLUSH: 'pktlen' is set to '0' and 'line' is set to NULL
 210  */
 211 enum packet_read_status packet_reader_read(struct packet_reader *reader);
 212
 213 /*
 214  * Peek the next packet line without consuming it and return the status.
 215  * The next call to 'packet_reader_read()' will perform a read of the same line
 216  * that was peeked, consuming the line.
 217  *
 218  * Peeking multiple times without calling 'packet_reader_read()' will return
 219  * the same result.
 220  */
 221 enum packet_read_status packet_reader_peek(struct packet_reader *reader);
 222
 223 #define DEFAULT_PACKET_MAX 1000
 224 #define LARGE_PACKET_MAX 65520
 225 #define LARGE_PACKET_DATA_MAX (LARGE_PACKET_MAX - 4)
 226 extern char packet_buffer[LARGE_PACKET_MAX];
 227
 228 struct packet_writer {
 229         int dest_fd;
 230         unsigned use_sideband : 1;
 231 };
 232
 233 void packet_writer_init(struct packet_writer *writer, int dest_fd);
 234
 235 /* These functions die upon failure. */
 236 __attribute__((format (printf, 2, 3)))
 237 void packet_writer_write(struct packet_writer *writer, const char *fmt, ...);
 238 __attribute__((format (printf, 2, 3)))
 239 void packet_writer_error(struct packet_writer *writer, const char *fmt, ...);
 240 void packet_writer_delim(struct packet_writer *writer);
 241 void packet_writer_flush(struct packet_writer *writer);
 242
 243 #endif