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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 | */ | |
583b7ea3 | 19 | ssize_t safe_write(int fd, const void *buf, ssize_t n) |
f3a3214e | 20 | { |
583b7ea3 | 21 | ssize_t nn = n; |
f3a3214e | 22 | while (n) { |
1c15afb9 | 23 | int ret = xwrite(fd, buf, n); |
f3a3214e | 24 | if (ret > 0) { |
1d7f171c | 25 | buf = (char *) buf + ret; |
f3a3214e LT |
26 | n -= ret; |
27 | continue; | |
28 | } | |
29 | if (!ret) | |
30 | die("write error (disk full?)"); | |
f3a3214e LT |
31 | die("write error (%s)", strerror(errno)); |
32 | } | |
583b7ea3 | 33 | return nn; |
f3a3214e LT |
34 | } |
35 | ||
36 | /* | |
37 | * If we buffered things up above (we don't, but we should), | |
38 | * we'd flush it here | |
39 | */ | |
40 | void packet_flush(int fd) | |
41 | { | |
42 | safe_write(fd, "0000", 4); | |
43 | } | |
44 | ||
45 | #define hex(a) (hexchar[(a) & 15]) | |
46 | void 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 | ||
66 | static void safe_read(int fd, void *buffer, unsigned size) | |
67 | { | |
68 | int n = 0; | |
69 | ||
70 | while (n < size) { | |
1d7f171c | 71 | int ret = xread(fd, (char *) buffer + n, size - n); |
1c15afb9 | 72 | if (ret < 0) |
f3a3214e | 73 | die("read error (%s)", strerror(errno)); |
f3a3214e | 74 | if (!ret) |
b3d98993 | 75 | die("The remote end hung up unexpectedly"); |
f3a3214e LT |
76 | n += ret; |
77 | } | |
78 | } | |
79 | ||
80 | int packet_read_line(int fd, char *buffer, unsigned size) | |
81 | { | |
82 | int n; | |
83 | unsigned len; | |
84 | char linelen[4]; | |
85 | ||
86 | safe_read(fd, linelen, 4); | |
87 | ||
88 | len = 0; | |
89 | for (n = 0; n < 4; n++) { | |
90 | unsigned char c = linelen[n]; | |
91 | len <<= 4; | |
92 | if (c >= '0' && c <= '9') { | |
93 | len += c - '0'; | |
94 | continue; | |
95 | } | |
96 | if (c >= 'a' && c <= 'f') { | |
97 | len += c - 'a' + 10; | |
98 | continue; | |
99 | } | |
100 | if (c >= 'A' && c <= 'F') { | |
101 | len += c - 'A' + 10; | |
102 | continue; | |
103 | } | |
104 | die("protocol error: bad line length character"); | |
105 | } | |
106 | if (!len) | |
107 | return 0; | |
108 | len -= 4; | |
109 | if (len >= size) | |
110 | die("protocol error: bad line length %d", len); | |
111 | safe_read(fd, buffer, len); | |
112 | buffer[len] = 0; | |
113 | return len; | |
114 | } |