| #include "cache.h" |
| #include "pkt-line.h" |
| |
| /* |
| * Write a packetized stream, where each line is preceded by |
| * its length (including the header) as a 4-byte hex number. |
| * A length of 'zero' means end of stream (and a length of 1-3 |
| * would be an error). |
| * |
| * This is all pretty stupid, but we use this packetized line |
| * format to make a streaming format possible without ever |
| * over-running the read buffers. That way we'll never read |
| * into what might be the pack data (which should go to another |
| * process entirely). |
| * |
| * The writing side could use stdio, but since the reading |
| * side can't, we stay with pure read/write interfaces. |
| */ |
| static void safe_write(int fd, const void *buf, unsigned n) |
| { |
| while (n) { |
| int ret = write(fd, buf, n); |
| if (ret > 0) { |
| buf += ret; |
| n -= ret; |
| continue; |
| } |
| if (!ret) |
| die("write error (disk full?)"); |
| if (errno == EAGAIN || errno == EINTR) |
| continue; |
| die("write error (%s)", strerror(errno)); |
| } |
| } |
| |
| /* |
| * If we buffered things up above (we don't, but we should), |
| * we'd flush it here |
| */ |
| void packet_flush(int fd) |
| { |
| safe_write(fd, "0000", 4); |
| } |
| |
| #define hex(a) (hexchar[(a) & 15]) |
| void packet_write(int fd, const char *fmt, ...) |
| { |
| static char buffer[1000]; |
| static char hexchar[] = "0123456789abcdef"; |
| va_list args; |
| unsigned n; |
| |
| va_start(args, fmt); |
| n = vsnprintf(buffer + 4, sizeof(buffer) - 4, fmt, args); |
| va_end(args); |
| if (n >= sizeof(buffer)-4) |
| die("protocol error: impossibly long line"); |
| n += 4; |
| buffer[0] = hex(n >> 12); |
| buffer[1] = hex(n >> 8); |
| buffer[2] = hex(n >> 4); |
| buffer[3] = hex(n); |
| safe_write(fd, buffer, n); |
| } |
| |
| static void safe_read(int fd, void *buffer, unsigned size) |
| { |
| int n = 0; |
| |
| while (n < size) { |
| int ret = read(fd, buffer + n, size - n); |
| if (ret < 0) { |
| if (errno == EINTR || errno == EAGAIN) |
| continue; |
| die("read error (%s)", strerror(errno)); |
| } |
| if (!ret) |
| die("unexpected EOF"); |
| n += ret; |
| } |
| } |
| |
| int packet_read_line(int fd, char *buffer, unsigned size) |
| { |
| int n; |
| unsigned len; |
| char linelen[4]; |
| |
| safe_read(fd, linelen, 4); |
| |
| len = 0; |
| for (n = 0; n < 4; n++) { |
| unsigned char c = linelen[n]; |
| len <<= 4; |
| if (c >= '0' && c <= '9') { |
| len += c - '0'; |
| continue; |
| } |
| if (c >= 'a' && c <= 'f') { |
| len += c - 'a' + 10; |
| continue; |
| } |
| if (c >= 'A' && c <= 'F') { |
| len += c - 'A' + 10; |
| continue; |
| } |
| die("protocol error: bad line length character"); |
| } |
| if (!len) |
| return 0; |
| len -= 4; |
| if (len >= size) |
| die("protocol error: bad line length %d", len); |
| safe_read(fd, buffer, len); |
| buffer[len] = 0; |
| return len; |
| } |