Make send/receive-pack be closer to doing something interesting
[git/git.git] / pkt-line.c
CommitLineData
f3a3214e
LT
1#include "cache.h"
2#include "pkt-line.h"
3
4/*
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
8 * would be an error).
9 *
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
14 * process entirely).
15 *
16 * The writing side could use stdio, but since the reading
17 * side can't, we stay with pure read/write interfaces.
18 */
19static void safe_write(int fd, const void *buf, unsigned n)
20{
21 while (n) {
22 int ret = write(fd, buf, n);
23 if (ret > 0) {
24 buf += ret;
25 n -= ret;
26 continue;
27 }
28 if (!ret)
29 die("write error (disk full?)");
30 if (errno == EAGAIN || errno == EINTR)
31 continue;
32 die("write error (%s)", strerror(errno));
33 }
34}
35
36/*
37 * If we buffered things up above (we don't, but we should),
38 * we'd flush it here
39 */
40void packet_flush(int fd)
41{
42 safe_write(fd, "0000", 4);
43}
44
45#define hex(a) (hexchar[(a) & 15])
46void packet_write(int fd, const char *fmt, ...)
47{
48 static char buffer[1000];
49 static char hexchar[] = "0123456789abcdef";
50 va_list args;
51 unsigned n;
52
53 va_start(args, fmt);
54 n = vsnprintf(buffer + 4, sizeof(buffer) - 4, fmt, args);
55 va_end(args);
56 if (n >= sizeof(buffer)-4)
57 die("protocol error: impossibly long line");
58 n += 4;
59 buffer[0] = hex(n >> 12);
60 buffer[1] = hex(n >> 8);
61 buffer[2] = hex(n >> 4);
62 buffer[3] = hex(n);
63 safe_write(fd, buffer, n);
64}
65
66static void safe_read(int fd, void *buffer, unsigned size)
67{
68 int n = 0;
69
70 while (n < size) {
71 int ret = read(fd, buffer + n, size - n);
72 if (ret < 0) {
73 if (errno == EINTR || errno == EAGAIN)
74 continue;
75 die("read error (%s)", strerror(errno));
76 }
77 if (!ret)
78 die("unexpected EOF");
79 n += ret;
80 }
81}
82
83int packet_read_line(int fd, char *buffer, unsigned size)
84{
85 int n;
86 unsigned len;
87 char linelen[4];
88
89 safe_read(fd, linelen, 4);
90
91 len = 0;
92 for (n = 0; n < 4; n++) {
93 unsigned char c = linelen[n];
94 len <<= 4;
95 if (c >= '0' && c <= '9') {
96 len += c - '0';
97 continue;
98 }
99 if (c >= 'a' && c <= 'f') {
100 len += c - 'a' + 10;
101 continue;
102 }
103 if (c >= 'A' && c <= 'F') {
104 len += c - 'A' + 10;
105 continue;
106 }
107 die("protocol error: bad line length character");
108 }
109 if (!len)
110 return 0;
111 len -= 4;
112 if (len >= size)
113 die("protocol error: bad line length %d", len);
114 safe_read(fd, buffer, len);
115 buffer[len] = 0;
116 return len;
117}