rebase --merge: fix for rebasing more than 7 commits.
[git/git.git] / pkt-line.c
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 */
19 static void safe_write(int fd, const void *buf, unsigned n)
20 {
21 while (n) {
22 int ret = xwrite(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 die("write error (%s)", strerror(errno));
31 }
32 }
33
34 /*
35 * If we buffered things up above (we don't, but we should),
36 * we'd flush it here
37 */
38 void packet_flush(int fd)
39 {
40 safe_write(fd, "0000", 4);
41 }
42
43 #define hex(a) (hexchar[(a) & 15])
44 void packet_write(int fd, const char *fmt, ...)
45 {
46 static char buffer[1000];
47 static char hexchar[] = "0123456789abcdef";
48 va_list args;
49 unsigned n;
50
51 va_start(args, fmt);
52 n = vsnprintf(buffer + 4, sizeof(buffer) - 4, fmt, args);
53 va_end(args);
54 if (n >= sizeof(buffer)-4)
55 die("protocol error: impossibly long line");
56 n += 4;
57 buffer[0] = hex(n >> 12);
58 buffer[1] = hex(n >> 8);
59 buffer[2] = hex(n >> 4);
60 buffer[3] = hex(n);
61 safe_write(fd, buffer, n);
62 }
63
64 static void safe_read(int fd, void *buffer, unsigned size)
65 {
66 int n = 0;
67
68 while (n < size) {
69 int ret = xread(fd, buffer + n, size - n);
70 if (ret < 0)
71 die("read error (%s)", strerror(errno));
72 if (!ret)
73 die("unexpected EOF");
74 n += ret;
75 }
76 }
77
78 int packet_read_line(int fd, char *buffer, unsigned size)
79 {
80 int n;
81 unsigned len;
82 char linelen[4];
83
84 safe_read(fd, linelen, 4);
85
86 len = 0;
87 for (n = 0; n < 4; n++) {
88 unsigned char c = linelen[n];
89 len <<= 4;
90 if (c >= '0' && c <= '9') {
91 len += c - '0';
92 continue;
93 }
94 if (c >= 'a' && c <= 'f') {
95 len += c - 'a' + 10;
96 continue;
97 }
98 if (c >= 'A' && c <= 'F') {
99 len += c - 'A' + 10;
100 continue;
101 }
102 die("protocol error: bad line length character");
103 }
104 if (!len)
105 return 0;
106 len -= 4;
107 if (len >= size)
108 die("protocol error: bad line length %d", len);
109 safe_read(fd, buffer, len);
110 buffer[len] = 0;
111 return len;
112 }