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