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_fmt(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 int packet_flush_gently(int fd);
  27 int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
  28 int write_packetized_from_fd(int fd_in, int fd_out);
  29 int write_packetized_from_buf(const char *src_in, size_t len, int fd_out);
  30
  31 /*
  32  * Read a packetized line into the buffer, which must be at least size bytes
  33  * long. The return value specifies the number of bytes read into the buffer.
  34  *
  35  * If src_buffer and *src_buffer are not NULL, it should point to a buffer
  36  * containing the packet data to parse, of at least *src_len bytes.  After the
  37  * function returns, src_buf will be incremented and src_len decremented by the
  38  * number of bytes consumed.
  39  *
  40  * If src_buffer (or *src_buffer) is NULL, then data is read from the
  41  * descriptor "fd".
  42  *
  43  * If options does not contain PACKET_READ_GENTLE_ON_EOF, we will die under any
  44  * of the following conditions:
  45  *
  46  *   1. Read error from descriptor.
  47  *
  48  *   2. Protocol error from the remote (e.g., bogus length characters).
  49  *
  50  *   3. Receiving a packet larger than "size" bytes.
  51  *
  52  *   4. Truncated output from the remote (e.g., we expected a packet but got
  53  *      EOF, or we got a partial packet followed by EOF).
  54  *
  55  * If options does contain PACKET_READ_GENTLE_ON_EOF, we will not die on
  56  * condition 4 (truncated input), but instead return -1. However, we will still
  57  * die for the other 3 conditions.
  58  *
  59  * If options contains PACKET_READ_CHOMP_NEWLINE, a trailing newline (if
  60  * present) is removed from the buffer before returning.
  61  */
  62 #define PACKET_READ_GENTLE_ON_EOF (1u<<0)
  63 #define PACKET_READ_CHOMP_NEWLINE (1u<<1)
  64 int packet_read(int fd, char **src_buffer, size_t *src_len, char
  65                 *buffer, unsigned size, int options);
  66
  67 /*
  68  * Convenience wrapper for packet_read that is not gentle, and sets the
  69  * CHOMP_NEWLINE option. The return value is NULL for a flush packet,
  70  * and otherwise points to a static buffer (that may be overwritten by
  71  * subsequent calls). If the size parameter is not NULL, the length of the
  72  * packet is written to it.
  73  */
  74 char *packet_read_line(int fd, int *size);
  75
  76 /*
  77  * Convenience wrapper for packet_read that sets the PACKET_READ_GENTLE_ON_EOF
  78  * and CHOMP_NEWLINE options. The return value specifies the number of bytes
  79  * read into the buffer or -1 on truncated input. If the *dst_line parameter
  80  * is not NULL it will return NULL for a flush packet or when the number of
  81  * bytes copied is zero and otherwise points to a static buffer (that may be
  82  * overwritten by subsequent calls). If the size parameter is not NULL, the
  83  * length of the packet is written to it.
  84  */
  85 int packet_read_line_gently(int fd, int *size, char **dst_line);
  86
  87 /*
  88  * Same as packet_read_line, but read from a buf rather than a descriptor;
  89  * see packet_read for details on how src_* is used.
  90  */
  91 char *packet_read_line_buf(char **src_buf, size_t *src_len, int *size);
  92
  93 /*
  94  * Reads a stream of variable sized packets until a flush packet is detected.
  95  */
  96 ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out);
  97
  98 #define DEFAULT_PACKET_MAX 1000
  99 #define LARGE_PACKET_MAX 65520
 100 #define LARGE_PACKET_DATA_MAX (LARGE_PACKET_MAX - 4)
 101 extern char packet_buffer[LARGE_PACKET_MAX];
 102
 103 #endif