5 * Write a packetized stream, where each line is preceded by
6 * its length (including the header) as a 4-byte hex number.
7 * A length of 'zero' means end of stream (and a length of 1-3
10 * This is all pretty stupid, but we use this packetized line
11 * format to make a streaming format possible without ever
12 * over-running the read buffers. That way we'll never read
13 * into what might be the pack data (which should go to another
16 * The writing side could use stdio, but since the reading
17 * side can't, we stay with pure read/write interfaces.
19 static void safe_write(int fd, const void *buf, unsigned n)
22 int ret = write(fd, buf, n);
29 die("write error (disk full?)");
30 if (errno == EAGAIN || errno == EINTR)
32 die("write error (%s)", strerror(errno));
37 * If we buffered things up above (we don't, but we should),
40 void packet_flush(int fd)
42 safe_write(fd, "0000", 4);
45 #define hex(a) (hexchar[(a) & 15])
46 void packet_write(int fd, const char *fmt, ...)
48 static char buffer[1000];
49 static char hexchar[] = "0123456789abcdef";
54 n = vsnprintf(buffer + 4, sizeof(buffer) - 4, fmt, args);
56 if (n >= sizeof(buffer)-4)
57 die("protocol error: impossibly long line");
59 buffer[0] = hex(n >> 12);
60 buffer[1] = hex(n >> 8);
61 buffer[2] = hex(n >> 4);
63 safe_write(fd, buffer, n);
66 static void safe_read(int fd, void *buffer, unsigned size)
71 int ret = read(fd, buffer + n, size - n);
73 if (errno == EINTR || errno == EAGAIN)
75 die("read error (%s)", strerror(errno));
78 die("unexpected EOF");
83 int packet_read_line(int fd, char *buffer, unsigned size)
89 safe_read(fd, linelen, 4);
92 for (n = 0; n < 4; n++) {
93 unsigned char c = linelen[n];
95 if (c >= '0' && c <= '9') {
99 if (c >= 'a' && c <= 'f') {
103 if (c >= 'A' && c <= 'F') {
107 die("protocol error: bad line length character");
113 die("protocol error: bad line length %d", len);
114 safe_read(fd, buffer, len);