1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
|
#define VIRTUAL_PIPE_FLAG_WRITE 1
#define VIRTUAL_PIPE_FLAG_NONBLOCK 2
struct virtual_pipe {
unsigned char content[VIRTUAL_PIPE_SIZE];
unsigned used;
unsigned n_rd;
unsigned n_wr;
};
static struct virtual_pipe *pipe_desc[FD_SETSIZE] = { NULL };
static unsigned pipe_flags[FD_SETSIZE] = { 0 };
static struct virtual_pipe *get_virtual_pipe(int fd)
{
struct virtual_pipe *desc;
if (fd >= FD_SETSIZE || !pipe_desc[fd]) return NULL;
pipe_lock();
desc = pipe_desc[fd];
if (!desc) {
pipe_unlock();
return NULL;
}
return desc;
}
static int vpipe_read(int fd, void *buf, size_t size)
{
int should_wake;
struct virtual_pipe *desc;
test_again:
if (!(desc = get_virtual_pipe(fd)))
return -2;
if (pipe_flags[fd] & VIRTUAL_PIPE_FLAG_WRITE) internal_error("vpipe_read: reading from write pipe descriptor");
if (!desc->used) {
if (!desc->n_wr) {
#ifdef TRACE_PIPES
fprintf(stderr, "read(%d) -> zero.", fd);
#endif
pipe_unlock();
return 0;
}
if (pipe_flags[fd] & VIRTUAL_PIPE_FLAG_NONBLOCK) {
#ifdef TRACE_PIPES
fprintf(stderr, "read(%d) -> wouldblock.", fd);
#endif
pipe_unlock();
errno = EWOULDBLOCK;
return -1;
}
#ifdef TRACE_PIPES
fprintf(stderr, "read(%d) -> sleep.", fd);
#endif
pipe_unlock_wait();
pipe_unlock();
goto test_again;
}
should_wake = desc->used == VIRTUAL_PIPE_SIZE;
if (size > desc->used)
size = desc->used;
memcpy(buf, desc->content, size);
memmove(desc->content, desc->content + size, desc->used -= size);
#ifdef TRACE_PIPES
fprintf(stderr, "read(%d) -> %d. (%d)", fd, size, should_wake);
#endif
pipe_unlock();
if (should_wake) pipe_wake();
return size;
}
static int vpipe_write(int fd, const void *buf, size_t size)
{
int should_wake;
struct virtual_pipe *desc;
test_again:
if (!(desc = get_virtual_pipe(fd)))
return -2;
if (!(pipe_flags[fd] & VIRTUAL_PIPE_FLAG_WRITE)) internal_error("vpipe_write: writing to read pipe descriptor");
if (!desc->n_rd) {
#ifdef TRACE_PIPES
fprintf(stderr, "write(%d) -> epipe.", fd);
#endif
pipe_unlock();
errno = EPIPE;
return -1;
}
if (desc->used == VIRTUAL_PIPE_SIZE) {
if (pipe_flags[fd] & VIRTUAL_PIPE_FLAG_NONBLOCK) {
#ifdef TRACE_PIPES
fprintf(stderr, "write(%d) -> wouldblock.", fd);
#endif
pipe_unlock();
errno = EWOULDBLOCK;
return -1;
}
#ifdef TRACE_PIPES
fprintf(stderr, "write(%d) -> sleep.", fd);
#endif
pipe_unlock_wait();
pipe_unlock();
goto test_again;
}
should_wake = !desc->used;
if (size > (VIRTUAL_PIPE_SIZE - desc->used))
size = VIRTUAL_PIPE_SIZE - desc->used;
memcpy(desc->content + desc->used, buf, size);
desc->used += size;
#ifdef TRACE_PIPES
fprintf(stderr, "write(%d) -> %d.", fd, size);
#endif
pipe_unlock();
if (should_wake) pipe_wake();
return size;
}
static int vpipe_close(int fd)
{
struct virtual_pipe *desc;
if (!(desc = get_virtual_pipe(fd)))
return -2;
if (!(pipe_flags[fd] & VIRTUAL_PIPE_FLAG_WRITE)) {
if (!desc->n_rd) internal_error("vpipe_close: read counter underflow");
desc->n_rd--;
} else {
if (!desc->n_wr) internal_error("vpipe_close: write counter underflow");
desc->n_wr--;
}
pipe_desc[fd] = NULL;
pipe_flags[fd] = 0;
pipe_unlock();
if (!desc->n_rd && !desc->n_wr)
free(desc);
return close(fd);
}
static int vpipe_create(int fd[2])
{
int rs;
struct virtual_pipe *desc;
EINTRLOOP(fd[0], open("/dev/null", O_RDONLY));
if (fd[0] == -1)
goto err0;
EINTRLOOP(fd[1], open("/dev/null", O_WRONLY));
if (fd[1] == -1)
goto err1;
if (fd[0] >= FD_SETSIZE || fd[1] >= FD_SETSIZE) {
errno = EMFILE;
goto err2;
}
desc = malloc(sizeof(struct virtual_pipe));
if (!desc) goto err2;
desc->used = 0;
desc->n_rd = 1;
desc->n_wr = 1;
pipe_lock();
if (pipe_desc[fd[0]] || pipe_flags[fd[0]] || pipe_desc[fd[1]] || pipe_flags[fd[0]])
internal_error("c_pipe: pipe handles %d, %d already used: %p, %d, %p, %d", fd[0], fd[1], pipe_desc[fd[0]], pipe_flags[fd[0]], pipe_desc[fd[1]], pipe_flags[fd[0]]);
pipe_desc[fd[0]] = desc;
pipe_flags[fd[0]] = 0;
pipe_desc[fd[1]] = desc;
pipe_flags[fd[1]] = VIRTUAL_PIPE_FLAG_WRITE;
#ifdef DOS
pipe_flags[fd[0]] |= VIRTUAL_PIPE_FLAG_NONBLOCK;
pipe_flags[fd[1]] |= VIRTUAL_PIPE_FLAG_NONBLOCK;
#endif
pipe_unlock();
return 0;
err2:
EINTRLOOP(rs, close(fd[1]));
err1:
EINTRLOOP(rs, close(fd[0]));
err0:
return -1;
}
static int vpipe_may_read(int fd)
{
if (pipe_flags[fd] & VIRTUAL_PIPE_FLAG_WRITE) internal_error("vpipe_may_read: selecting write descriptor %d for read", fd);
return pipe_desc[fd]->used || !pipe_desc[fd]->n_wr;
}
static int vpipe_may_write(int fd)
{
if (!(pipe_flags[fd] & VIRTUAL_PIPE_FLAG_WRITE)) internal_error("vpipe_may_write: selecting read descriptor %d for write", fd);
return pipe_desc[fd]->used != VIRTUAL_PIPE_SIZE || !pipe_desc[fd]->n_rd;
}
static void clear_inactive(fd_set *fs, int i)
{
if (!fs) return;
while (--i >= 0) FD_CLR(i, fs);
}
|
