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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 | */ | |
19 | static void safe_write(int fd, const void *buf, unsigned n) | |
20 | { | |
21 | while (n) { | |
1c15afb9 | 22 | int ret = xwrite(fd, buf, n); |
f3a3214e LT |
23 | if (ret > 0) { |
24 | buf += ret; | |
25 | n -= ret; | |
26 | continue; | |
27 | } | |
28 | if (!ret) | |
29 | die("write error (disk full?)"); | |
f3a3214e LT |
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) { | |
1c15afb9 JH |
69 | int ret = xread(fd, buffer + n, size - n); |
70 | if (ret < 0) | |
f3a3214e | 71 | die("read error (%s)", strerror(errno)); |
f3a3214e LT |
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 | } |