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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 | ssize_t safe_write(int fd, const void *buf, ssize_t n) | |
20 | { | |
21 | ssize_t nn = n; | |
22 | while (n) { | |
23 | int ret = xwrite(fd, buf, n); | |
24 | if (ret > 0) { | |
25 | buf = (char *) buf + ret; | |
26 | n -= ret; | |
27 | continue; | |
28 | } | |
29 | if (!ret) | |
30 | die("write error (disk full?)"); | |
31 | die_errno("write error"); | |
32 | } | |
33 | return nn; | |
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 | void packet_buf_flush(struct strbuf *buf) | |
46 | { | |
47 | strbuf_add(buf, "0000", 4); | |
48 | } | |
49 | ||
50 | #define hex(a) (hexchar[(a) & 15]) | |
51 | static char buffer[1000]; | |
52 | static unsigned format_packet(const char *fmt, va_list args) | |
53 | { | |
54 | static char hexchar[] = "0123456789abcdef"; | |
55 | unsigned n; | |
56 | ||
57 | n = vsnprintf(buffer + 4, sizeof(buffer) - 4, fmt, args); | |
58 | if (n >= sizeof(buffer)-4) | |
59 | die("protocol error: impossibly long line"); | |
60 | n += 4; | |
61 | buffer[0] = hex(n >> 12); | |
62 | buffer[1] = hex(n >> 8); | |
63 | buffer[2] = hex(n >> 4); | |
64 | buffer[3] = hex(n); | |
65 | return n; | |
66 | } | |
67 | ||
68 | void packet_write(int fd, const char *fmt, ...) | |
69 | { | |
70 | va_list args; | |
71 | unsigned n; | |
72 | ||
73 | va_start(args, fmt); | |
74 | n = format_packet(fmt, args); | |
75 | va_end(args); | |
76 | safe_write(fd, buffer, n); | |
77 | } | |
78 | ||
79 | void packet_buf_write(struct strbuf *buf, const char *fmt, ...) | |
80 | { | |
81 | va_list args; | |
82 | unsigned n; | |
83 | ||
84 | va_start(args, fmt); | |
85 | n = format_packet(fmt, args); | |
86 | va_end(args); | |
87 | strbuf_add(buf, buffer, n); | |
88 | } | |
89 | ||
90 | static void safe_read(int fd, void *buffer, unsigned size) | |
91 | { | |
92 | ssize_t ret = read_in_full(fd, buffer, size); | |
93 | if (ret < 0) | |
94 | die_errno("read error"); | |
95 | else if (ret < size) | |
96 | die("The remote end hung up unexpectedly"); | |
97 | } | |
98 | ||
99 | static int packet_length(const char *linelen) | |
100 | { | |
101 | int n; | |
102 | int len = 0; | |
103 | ||
104 | for (n = 0; n < 4; n++) { | |
105 | unsigned char c = linelen[n]; | |
106 | len <<= 4; | |
107 | if (c >= '0' && c <= '9') { | |
108 | len += c - '0'; | |
109 | continue; | |
110 | } | |
111 | if (c >= 'a' && c <= 'f') { | |
112 | len += c - 'a' + 10; | |
113 | continue; | |
114 | } | |
115 | if (c >= 'A' && c <= 'F') { | |
116 | len += c - 'A' + 10; | |
117 | continue; | |
118 | } | |
119 | return -1; | |
120 | } | |
121 | return len; | |
122 | } | |
123 | ||
124 | int packet_read_line(int fd, char *buffer, unsigned size) | |
125 | { | |
126 | int len; | |
127 | char linelen[4]; | |
128 | ||
129 | safe_read(fd, linelen, 4); | |
130 | len = packet_length(linelen); | |
131 | if (len < 0) | |
132 | die("protocol error: bad line length character: %.4s", linelen); | |
133 | if (!len) | |
134 | return 0; | |
135 | len -= 4; | |
136 | if (len >= size) | |
137 | die("protocol error: bad line length %d", len); | |
138 | safe_read(fd, buffer, len); | |
139 | buffer[len] = 0; | |
140 | return len; | |
141 | } | |
142 | ||
143 | int packet_get_line(struct strbuf *out, | |
144 | char **src_buf, size_t *src_len) | |
145 | { | |
146 | int len; | |
147 | ||
148 | if (*src_len < 4) | |
149 | return -1; | |
150 | len = packet_length(*src_buf); | |
151 | if (len < 0) | |
152 | return -1; | |
153 | if (!len) { | |
154 | *src_buf += 4; | |
155 | *src_len -= 4; | |
156 | return 0; | |
157 | } | |
158 | if (*src_len < len) | |
159 | return -2; | |
160 | ||
161 | *src_buf += 4; | |
162 | *src_len -= 4; | |
163 | len -= 4; | |
164 | ||
165 | strbuf_add(out, *src_buf, len); | |
166 | *src_buf += len; | |
167 | *src_len -= len; | |
168 | return len; | |
169 | } |