pkt-line.h

   1 #ifndef PKTLINE_H
   2 #define PKTLINE_H
   3
   4 #include "git-compat-util.h"
   5 #include "strbuf.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_write(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  24 void packet_buf_flush(struct strbuf *buf);
  25 void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  26
  27 /*
  28  * Read a packetized line into the buffer, which must be at least size bytes
  29  * long. The return value specifies the number of bytes read into the buffer.
  30  *
  31  * If src_buffer is not NULL (and nor is *src_buffer), it should point to a
  32  * buffer containing the packet data to parse, of at least *src_len bytes.
  33  * After the function returns, src_buf will be incremented and src_len
  34  * decremented by the number of bytes consumed.
  35  *
  36  * If src_buffer (or *src_buffer) is NULL, then data is read from the
  37  * descriptor "fd".
  38  *
  39  * If options does not contain PACKET_READ_GENTLE_ON_EOF, we will die under any
  40  * of the following conditions:
  41  *
  42  *   1. Read error from descriptor.
  43  *
  44  *   2. Protocol error from the remote (e.g., bogus length characters).
  45  *
  46  *   3. Receiving a packet larger than "size" bytes.
  47  *
  48  *   4. Truncated output from the remote (e.g., we expected a packet but got
  49  *      EOF, or we got a partial packet followed by EOF).
  50  *
  51  * If options does contain PACKET_READ_GENTLE_ON_EOF, we will not die on
  52  * condition 4 (truncated input), but instead return -1. However, we will still
  53  * die for the other 3 conditions.
  54  *
  55  * If options contains PACKET_READ_CHOMP_NEWLINE, a trailing newline (if
  56  * present) is removed from the buffer before returning.
  57  */
  58 #define PACKET_READ_GENTLE_ON_EOF (1u<<0)
  59 #define PACKET_READ_CHOMP_NEWLINE (1u<<1)
  60 int packet_read(int fd, char **src_buffer, size_t *src_len, char
  61                 *buffer, unsigned size, int options);
  62
  63 /*
  64  * Convenience wrapper for packet_read that is not gentle, and sets the
  65  * CHOMP_NEWLINE option. The return value is NULL for a flush packet,
  66  * and otherwise points to a static buffer (that may be overwritten by
  67  * subsequent calls). If the size parameter is not NULL, the length of the
  68  * packet is written to it.
  69  */
  70 char *packet_read_line(int fd, int *size);
  71
  72 /*
  73  * Same as packet_read_line, but read from a buf rather than a descriptor;
  74  * see packet_read for details on how src_* is used.
  75  */
  76 char *packet_read_line_buf(char **src_buf, size_t *src_len, int *size);
  77
  78 #define DEFAULT_PACKET_MAX 1000
  79 #define LARGE_PACKET_MAX 65520
  80 extern char packet_buffer[LARGE_PACKET_MAX];
  81
  82 #endif