root / include / qemu / iov.h @ 5a37532d
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1 | e4d5639d | Amit Shah | /*
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2 | 2278a69e | Michael Tokarev | * Helpers for using (partial) iovecs.
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3 | e4d5639d | Amit Shah | *
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4 | e4d5639d | Amit Shah | * Copyright (C) 2010 Red Hat, Inc.
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5 | e4d5639d | Amit Shah | *
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6 | e4d5639d | Amit Shah | * Author(s):
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7 | e4d5639d | Amit Shah | * Amit Shah <amit.shah@redhat.com>
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8 | 2278a69e | Michael Tokarev | * Michael Tokarev <mjt@tls.msk.ru>
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9 | e4d5639d | Amit Shah | *
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10 | e4d5639d | Amit Shah | * This work is licensed under the terms of the GNU GPL, version 2. See
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11 | e4d5639d | Amit Shah | * the COPYING file in the top-level directory.
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12 | e4d5639d | Amit Shah | */
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13 | e4d5639d | Amit Shah | |
14 | cb9c377f | Paolo Bonzini | #ifndef IOV_H
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15 | cb9c377f | Paolo Bonzini | #define IOV_H
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16 | cb9c377f | Paolo Bonzini | |
17 | e4d5639d | Amit Shah | #include "qemu-common.h" |
18 | e4d5639d | Amit Shah | |
19 | dcf6f5e1 | Michael Tokarev | /**
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20 | dcf6f5e1 | Michael Tokarev | * count and return data size, in bytes, of an iovec
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21 | dcf6f5e1 | Michael Tokarev | * starting at `iov' of `iov_cnt' number of elements.
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22 | dcf6f5e1 | Michael Tokarev | */
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23 | dcf6f5e1 | Michael Tokarev | size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt); |
24 | dcf6f5e1 | Michael Tokarev | |
25 | dcf6f5e1 | Michael Tokarev | /**
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26 | dcf6f5e1 | Michael Tokarev | * Copy from single continuous buffer to scatter-gather vector of buffers
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27 | dcf6f5e1 | Michael Tokarev | * (iovec) and back like memcpy() between two continuous memory regions.
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28 | dcf6f5e1 | Michael Tokarev | * Data in single continuous buffer starting at address `buf' and
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29 | dcf6f5e1 | Michael Tokarev | * `bytes' bytes long will be copied to/from an iovec `iov' with
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30 | dcf6f5e1 | Michael Tokarev | * `iov_cnt' number of elements, starting at byte position `offset'
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31 | dcf6f5e1 | Michael Tokarev | * within the iovec. If the iovec does not contain enough space,
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32 | dcf6f5e1 | Michael Tokarev | * only part of data will be copied, up to the end of the iovec.
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33 | dcf6f5e1 | Michael Tokarev | * Number of bytes actually copied will be returned, which is
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34 | dcf6f5e1 | Michael Tokarev | * min(bytes, iov_size(iov)-offset)
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35 | 2278a69e | Michael Tokarev | * `Offset' must point to the inside of iovec.
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36 | 2278a69e | Michael Tokarev | * It is okay to use very large value for `bytes' since we're
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37 | 2278a69e | Michael Tokarev | * limited by the size of the iovec anyway, provided that the
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38 | 2278a69e | Michael Tokarev | * buffer pointed to by buf has enough space. One possible
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39 | 2278a69e | Michael Tokarev | * such "large" value is -1 (sinice size_t is unsigned),
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40 | 2278a69e | Michael Tokarev | * so specifying `-1' as `bytes' means 'up to the end of iovec'.
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41 | dcf6f5e1 | Michael Tokarev | */
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42 | 844b5cea | Michael S. Tsirkin | size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt, |
43 | dcf6f5e1 | Michael Tokarev | size_t offset, const void *buf, size_t bytes); |
44 | 348e7b8d | Hannes Reinecke | size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt, |
45 | dcf6f5e1 | Michael Tokarev | size_t offset, void *buf, size_t bytes);
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46 | dcf6f5e1 | Michael Tokarev | |
47 | dcf6f5e1 | Michael Tokarev | /**
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48 | dcf6f5e1 | Michael Tokarev | * Set data bytes pointed out by iovec `iov' of size `iov_cnt' elements,
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49 | dcf6f5e1 | Michael Tokarev | * starting at byte offset `start', to value `fillc', repeating it
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50 | 2278a69e | Michael Tokarev | * `bytes' number of times. `Offset' must point to the inside of iovec.
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51 | dcf6f5e1 | Michael Tokarev | * If `bytes' is large enough, only last bytes portion of iovec,
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52 | dcf6f5e1 | Michael Tokarev | * up to the end of it, will be filled with the specified value.
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53 | dcf6f5e1 | Michael Tokarev | * Function return actual number of bytes processed, which is
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54 | dcf6f5e1 | Michael Tokarev | * min(size, iov_size(iov) - offset).
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55 | 2278a69e | Michael Tokarev | * Again, it is okay to use large value for `bytes' to mean "up to the end".
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56 | dcf6f5e1 | Michael Tokarev | */
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57 | dcf6f5e1 | Michael Tokarev | size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt, |
58 | dcf6f5e1 | Michael Tokarev | size_t offset, int fillc, size_t bytes);
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59 | dcf6f5e1 | Michael Tokarev | |
60 | 3e80bf93 | Michael Tokarev | /*
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61 | 3e80bf93 | Michael Tokarev | * Send/recv data from/to iovec buffers directly
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62 | 3e80bf93 | Michael Tokarev | *
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63 | 3e80bf93 | Michael Tokarev | * `offset' bytes in the beginning of iovec buffer are skipped and
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64 | 3e80bf93 | Michael Tokarev | * next `bytes' bytes are used, which must be within data of iovec.
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65 | 3e80bf93 | Michael Tokarev | *
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66 | 25e5e4c7 | Michael Tokarev | * r = iov_send_recv(sockfd, iov, iovcnt, offset, bytes, true);
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67 | 3e80bf93 | Michael Tokarev | *
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68 | 3e80bf93 | Michael Tokarev | * is logically equivalent to
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69 | 3e80bf93 | Michael Tokarev | *
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70 | 3e80bf93 | Michael Tokarev | * char *buf = malloc(bytes);
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71 | 3e80bf93 | Michael Tokarev | * iov_to_buf(iov, iovcnt, offset, buf, bytes);
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72 | 3e80bf93 | Michael Tokarev | * r = send(sockfd, buf, bytes, 0);
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73 | 3e80bf93 | Michael Tokarev | * free(buf);
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74 | 25e5e4c7 | Michael Tokarev | *
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75 | 25e5e4c7 | Michael Tokarev | * For iov_send_recv() _whole_ area being sent or received
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76 | 25e5e4c7 | Michael Tokarev | * should be within the iovec, not only beginning of it.
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77 | 3e80bf93 | Michael Tokarev | */
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78 | 25e5e4c7 | Michael Tokarev | ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, |
79 | e3e87df4 | Michael Tokarev | size_t offset, size_t bytes, bool do_send);
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80 | 25e5e4c7 | Michael Tokarev | #define iov_recv(sockfd, iov, iov_cnt, offset, bytes) \
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81 | 25e5e4c7 | Michael Tokarev | iov_send_recv(sockfd, iov, iov_cnt, offset, bytes, false)
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82 | 25e5e4c7 | Michael Tokarev | #define iov_send(sockfd, iov, iov_cnt, offset, bytes) \
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83 | 25e5e4c7 | Michael Tokarev | iov_send_recv(sockfd, iov, iov_cnt, offset, bytes, true)
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84 | 3e80bf93 | Michael Tokarev | |
85 | dcf6f5e1 | Michael Tokarev | /**
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86 | dcf6f5e1 | Michael Tokarev | * Produce a text hexdump of iovec `iov' with `iov_cnt' number of elements
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87 | dcf6f5e1 | Michael Tokarev | * in file `fp', prefixing each line with `prefix' and processing not more
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88 | dcf6f5e1 | Michael Tokarev | * than `limit' data bytes.
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89 | dcf6f5e1 | Michael Tokarev | */
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90 | 3a1dca94 | Gerd Hoffmann | void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt, |
91 | 3a1dca94 | Gerd Hoffmann | FILE *fp, const char *prefix, size_t limit); |
92 | d336336c | Michael S. Tsirkin | |
93 | d336336c | Michael S. Tsirkin | /*
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94 | d336336c | Michael S. Tsirkin | * Partial copy of vector from iov to dst_iov (data is not copied).
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95 | d336336c | Michael S. Tsirkin | * dst_iov overlaps iov at a specified offset.
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96 | d336336c | Michael S. Tsirkin | * size of dst_iov is at most bytes. dst vector count is returned.
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97 | d336336c | Michael S. Tsirkin | */
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98 | d336336c | Michael S. Tsirkin | unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt, |
99 | d336336c | Michael S. Tsirkin | const struct iovec *iov, unsigned int iov_cnt, |
100 | d336336c | Michael S. Tsirkin | size_t offset, size_t bytes); |
101 | cb9c377f | Paolo Bonzini | |
102 | d0277635 | Stefan Hajnoczi | /*
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103 | d0277635 | Stefan Hajnoczi | * Remove a given number of bytes from the front or back of a vector.
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104 | d0277635 | Stefan Hajnoczi | * This may update iov and/or iov_cnt to exclude iovec elements that are
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105 | d0277635 | Stefan Hajnoczi | * no longer required.
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106 | d0277635 | Stefan Hajnoczi | *
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107 | d0277635 | Stefan Hajnoczi | * The number of bytes actually discarded is returned. This number may be
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108 | d0277635 | Stefan Hajnoczi | * smaller than requested if the vector is too small.
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109 | d0277635 | Stefan Hajnoczi | */
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110 | d0277635 | Stefan Hajnoczi | size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, |
111 | d0277635 | Stefan Hajnoczi | size_t bytes); |
112 | d0277635 | Stefan Hajnoczi | size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt, |
113 | d0277635 | Stefan Hajnoczi | size_t bytes); |
114 | d0277635 | Stefan Hajnoczi | |
115 | cb9c377f | Paolo Bonzini | #endif |