pkt-line.h

   1 #ifndef PKTLINE_H
   2 #define PKTLINE_H
   3
   4 #include "strbuf.h"
   5 #include "sideband.h"
   6
   7 /*
   8  * Write a packetized stream, where each line is preceded by
   9  * its length (including the header) as a 4-byte hex number.
  10  * A length of 'zero' means end of stream (and a length of 1-3
  11  * would be an error).
  12  *
  13  * This is all pretty stupid, but we use this packetized line
  14  * format to make a streaming format possible without ever
  15  * over-running the read buffers. That way we'll never read
  16  * into what might be the pack data (which should go to another
  17  * process entirely).
  18  *
  19  * The writing side could use stdio, but since the reading
  20  * side can't, we stay with pure read/write interfaces.
  21  */
  22 void packet_flush(int fd);
  23 void packet_delim(int fd);
  24 void packet_response_end(int fd);
  25 void packet_write_fmt(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  26 void packet_buf_flush(struct strbuf *buf);
  27 void packet_buf_delim(struct strbuf *buf);
  28 void set_packet_header(char *buf, int size);
  29 void packet_write(int fd_out, const char *buf, size_t size);
  30 void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  31 int packet_flush_gently(int fd);
  32 int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  33 int write_packetized_from_fd_no_flush(int fd_in, int fd_out);
  34 int write_packetized_from_buf_no_flush_count(const char *src_in, size_t len,
  35                                              int fd_out, int *packet_counter);
  36 static inline int write_packetized_from_buf_no_flush(const char *src_in,
  37                                                      size_t len, int fd_out)
  38 {
  39         return write_packetized_from_buf_no_flush_count(src_in, len, fd_out, NULL);
  40 }
  41
  42 /*
  43  * Stdio versions of packet_write functions. When mixing these with fd
  44  * based functions, take care to call fflush(3) before doing fd writes or
  45  * closing the fd.
  46  */
  47 void packet_fwrite(FILE *f, const char *buf, size_t size);
  48 void packet_fwrite_fmt(FILE *f, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  49
  50 /* packet_fflush writes a flush packet and flushes the stdio buffer of f */
  51 void packet_fflush(FILE *f);
  52
  53 /*
  54  * Read a packetized line into the buffer, which must be at least size bytes
  55  * long. The return value specifies the number of bytes read into the buffer.
  56  *
  57  * If options does not contain PACKET_READ_GENTLE_ON_EOF, we will die under any
  58  * of the following conditions:
  59  *
  60  *   1. Read error from descriptor.
  61  *
  62  *   2. Protocol error from the remote (e.g., bogus length characters).
  63  *
  64  *   3. Receiving a packet larger than "size" bytes.
  65  *
  66  *   4. Truncated output from the remote (e.g., we expected a packet but got
  67  *      EOF, or we got a partial packet followed by EOF).
  68  *
  69  * If options does contain PACKET_READ_GENTLE_ON_EOF, we will not die on
  70  * condition 4 (truncated input), but instead return -1. However, we will still
  71  * die for the other 3 conditions.
  72  *
  73  * If options contains PACKET_READ_CHOMP_NEWLINE, a trailing newline (if
  74  * present) is removed from the buffer before returning.
  75  *
  76  * If options contains PACKET_READ_DIE_ON_ERR_PACKET, it dies when it sees an
  77  * ERR packet.
  78  *
  79  * If options contains PACKET_READ_GENTLE_ON_READ_ERROR, we will not die
  80  * on read errors, but instead return -1.  However, we may still die on an
  81  * ERR packet (if requested).
  82  */
  83 #define PACKET_READ_GENTLE_ON_EOF        (1u<<0)
  84 #define PACKET_READ_CHOMP_NEWLINE        (1u<<1)
  85 #define PACKET_READ_DIE_ON_ERR_PACKET    (1u<<2)
  86 #define PACKET_READ_GENTLE_ON_READ_ERROR (1u<<3)
  87 #define PACKET_READ_REDACT_URI_PATH      (1u<<4)
  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
 199 /*
 200  * Initialize a 'struct packet_reader' object which is an
 201  * abstraction around the 'packet_read_with_status()' function.
 202  */
 203 void packet_reader_init(struct packet_reader *reader, int fd,
 204                         char *src_buffer, size_t src_len,
 205                         int options);
 206
 207 /*
 208  * Perform a packet read and return the status of the read.
 209  * The values of 'pktlen' and 'line' are updated based on the status of the
 210  * read as follows:
 211  *
 212  * PACKET_READ_ERROR: 'pktlen' is set to '-1' and 'line' is set to NULL
 213  * PACKET_READ_NORMAL: 'pktlen' is set to the number of bytes read
 214  *                     'line' is set to point at the read line
 215  * PACKET_READ_FLUSH: 'pktlen' is set to '0' and 'line' is set to NULL
 216  */
 217 enum packet_read_status packet_reader_read(struct packet_reader *reader);
 218
 219 /*
 220  * Peek the next packet line without consuming it and return the status.
 221  * The next call to 'packet_reader_read()' will perform a read of the same line
 222  * that was peeked, consuming the line.
 223  *
 224  * Peeking multiple times without calling 'packet_reader_read()' will return
 225  * the same result.
 226  */
 227 enum packet_read_status packet_reader_peek(struct packet_reader *reader);
 228
 229 #define DEFAULT_PACKET_MAX 1000
 230 #define LARGE_PACKET_MAX 65520
 231 #define LARGE_PACKET_DATA_MAX (LARGE_PACKET_MAX - 4)
 232 extern char packet_buffer[LARGE_PACKET_MAX];
 233
 234 struct packet_writer {
 235         int dest_fd;
 236         unsigned use_sideband : 1;
 237 };
 238
 239 void packet_writer_init(struct packet_writer *writer, int dest_fd);
 240
 241 /* These functions die upon failure. */
 242 __attribute__((format (printf, 2, 3)))
 243 void packet_writer_write(struct packet_writer *writer, const char *fmt, ...);
 244 __attribute__((format (printf, 2, 3)))
 245 void packet_writer_error(struct packet_writer *writer, const char *fmt, ...);
 246 void packet_writer_delim(struct packet_writer *writer);
 247 void packet_writer_flush(struct packet_writer *writer);
 248
 249 void packet_trace_identity(const char *prog);
 250
 251 #endif