Commit | Line | Data |
---|---|---|
7ee0f27f JA |
1 | /* |
2 | * Use vmsplice to fill some user memory into a pipe. vmsplice writes | |
3 | * to stdout, so that must be a pipe. | |
4 | */ | |
5 | #include <stdio.h> | |
6 | #include <stdlib.h> | |
7 | #include <unistd.h> | |
7ee0f27f | 8 | #include <limits.h> |
dbcd0883 JA |
9 | #include <string.h> |
10 | #include <getopt.h> | |
7ee0f27f | 11 | #include <sys/poll.h> |
7ee0f27f JA |
12 | #include <sys/types.h> |
13 | ||
14 | #include "splice.h" | |
15 | ||
88a9ff87 | 16 | #define ALIGN(buf) (void *) (((unsigned long) (buf) + align_mask) & ~align_mask) |
7ee0f27f | 17 | |
dbcd0883 | 18 | static int do_clear; |
88a9ff87 | 19 | static int align_mask = 65535; |
96897528 JA |
20 | static int force_unalign; |
21 | static int splice_flags; | |
dbcd0883 | 22 | |
88a9ff87 | 23 | int do_vmsplice(int fd, void *b1, void *b2, int len) |
7ee0f27f JA |
24 | { |
25 | struct pollfd pfd = { .fd = fd, .events = POLLOUT, }; | |
88a9ff87 JA |
26 | struct iovec iov[] = { |
27 | { | |
28 | .iov_base = b1, | |
29 | .iov_len = len / 2, | |
30 | }, | |
31 | { | |
32 | .iov_base = b2, | |
33 | .iov_len = len / 2, | |
34 | }, | |
35 | }; | |
36 | int written, idx = 0; | |
7ee0f27f JA |
37 | |
38 | while (len) { | |
39 | /* | |
40 | * in a real app you'd be more clever with poll of course, | |
41 | * here we are basically just blocking on output room and | |
42 | * not using the free time for anything interesting. | |
43 | */ | |
44 | if (poll(&pfd, 1, -1) < 0) | |
45 | return error("poll"); | |
46 | ||
96897528 | 47 | written = vmsplice(fd, &iov[idx], 2 - idx, splice_flags); |
7ee0f27f JA |
48 | |
49 | if (written <= 0) | |
50 | return error("vmsplice"); | |
51 | ||
52 | len -= written; | |
000b72a8 | 53 | if ((size_t) written >= iov[idx].iov_len) { |
88a9ff87 JA |
54 | int extra = written - iov[idx].iov_len; |
55 | ||
56 | idx++; | |
57 | iov[idx].iov_len -= extra; | |
58 | iov[idx].iov_base += extra; | |
59 | } else { | |
60 | iov[idx].iov_len -= written; | |
61 | iov[idx].iov_base += written; | |
62 | } | |
7ee0f27f JA |
63 | } |
64 | ||
65 | return 0; | |
66 | } | |
67 | ||
dbcd0883 JA |
68 | static int usage(char *name) |
69 | { | |
96897528 | 70 | fprintf(stderr, "%s: [-c(lear)] [-u(nalign)] [-g(ift)]| ...\n", name); |
dbcd0883 JA |
71 | return 1; |
72 | } | |
73 | ||
74 | static int parse_options(int argc, char *argv[]) | |
75 | { | |
76 | int c, index = 1; | |
77 | ||
96897528 | 78 | while ((c = getopt(argc, argv, "cug")) != -1) { |
dbcd0883 JA |
79 | switch (c) { |
80 | case 'c': | |
81 | do_clear = 1; | |
82 | index++; | |
83 | break; | |
88a9ff87 | 84 | case 'u': |
96897528 JA |
85 | force_unalign = 1; |
86 | index++; | |
87 | break; | |
88 | case 'g': | |
89 | splice_flags = SPLICE_F_GIFT; | |
88a9ff87 JA |
90 | index++; |
91 | break; | |
dbcd0883 JA |
92 | default: |
93 | return -1; | |
94 | } | |
95 | } | |
96 | ||
97 | return index; | |
98 | } | |
99 | ||
7ee0f27f JA |
100 | int main(int argc, char *argv[]) |
101 | { | |
88a9ff87 | 102 | unsigned char *b1, *b2; |
7ee0f27f | 103 | |
dbcd0883 JA |
104 | if (parse_options(argc, argv) < 0) |
105 | return usage(argv[0]); | |
106 | ||
76797253 | 107 | if (check_output_pipe()) |
f91353a3 | 108 | return usage(argv[0]); |
7ee0f27f | 109 | |
88a9ff87 JA |
110 | b1 = ALIGN(malloc(SPLICE_SIZE + align_mask)); |
111 | b2 = ALIGN(malloc(SPLICE_SIZE + align_mask)); | |
112 | ||
96897528 JA |
113 | if (force_unalign) { |
114 | b1 += 1024; | |
115 | b2 += 1024; | |
116 | } | |
117 | ||
88a9ff87 JA |
118 | memset(b1, 0xaa, SPLICE_SIZE); |
119 | memset(b2, 0xbb, SPLICE_SIZE); | |
7ee0f27f JA |
120 | |
121 | do { | |
88a9ff87 JA |
122 | int half = SPLICE_SIZE / 2; |
123 | ||
7ee0f27f JA |
124 | /* |
125 | * vmsplice the first half of the buffer into the pipe | |
126 | */ | |
88a9ff87 | 127 | if (do_vmsplice(STDOUT_FILENO, b1, b2, SPLICE_SIZE)) |
7ee0f27f JA |
128 | break; |
129 | ||
130 | /* | |
131 | * first half is now in pipe, but we don't quite know when | |
132 | * we can reuse it. | |
133 | */ | |
134 | ||
135 | /* | |
136 | * vmsplice second half | |
137 | */ | |
88a9ff87 | 138 | if (do_vmsplice(STDOUT_FILENO, b1 + half, b2 + half, SPLICE_SIZE)) |
7ee0f27f JA |
139 | break; |
140 | ||
141 | /* | |
142 | * We still don't know when we can reuse the second half of | |
143 | * the buffer, but we do now know that all parts of the first | |
144 | * half have been consumed from the pipe - so we can reuse that. | |
145 | */ | |
dbcd0883 JA |
146 | |
147 | /* | |
148 | * Test option - clear the first half of the buffer, should | |
149 | * be safe now | |
150 | */ | |
88a9ff87 JA |
151 | if (do_clear) { |
152 | memset(b1, 0x00, SPLICE_SIZE); | |
153 | memset(b2, 0x00, SPLICE_SIZE); | |
154 | } | |
7ee0f27f JA |
155 | } while (0); |
156 | ||
157 | return 0; | |
158 | } |