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9gd_alter_frameoffset(3) GETDATA gd_alter_frameoffset(3)
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14 gd_alter_frameoffset — modify the starting frame of fields in a Dirfile
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18 #include <getdata.h>
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20 int gd_alter_frameoffset(DIRFILE *dirfile, off_t offset, int
21 fragment_index, int recode);
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25 The gd_alter_frameoffset() function sets the frame offset of the format
26 specification fragment given by fragment_index to offset in the
27 dirfile(5) database specified by dirfile. The frame offset of a frag‐
28 ment indicate the frame number of the first sample of data stored in
29 binary files associated with RAW fields defined in the specified frag‐
30 ment. The frame offset of a fragment containing no RAW fields is ig‐
31 nored. The frame offset may not be negative.
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33 The dirfile argument must point to a valid DIRFILE object previously
34 created by a call to gd_open(3).
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36 In addition to being simply a valid fragment index, fragment_index may
37 also be the special value GD_ALL_FRAGMENTS, which indicates that the
38 frame offset of all fragments in the database should be changed.
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40 If the recode argument is non-zero, this call will shift the binary da‐
41 ta of affected RAW fields to account for the change in frame offset.
42 If the new frame offset is larger than the old frame offset, this will
43 result in permanent deletion of data from the database. If the new
44 frame offset is smaller than the old frame offset, the binary file will
45 be padded at the front with zeroes. The I/O pointer of all affected
46 RAW fields is reset to the beginning-of-frame.
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48 If recode is zero, affected binary files are left untouched.
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52 Upon successful completion, gd_alter_frameoffset() returns zero. On
53 error, it returns a negative-valued error code. Possible error codes
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56 GD_E_ACCMODE
57 The specified dirfile was opened read-only.
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59 GD_E_ALLOC
60 The library was unable to allocate memory.
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62 GD_E_BAD_DIRFILE
63 The supplied dirfile was invalid.
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65 GD_E_BAD_INDEX
66 The supplied index was out of range.
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68 GD_E_IO An I/O error occurred while attempting to shift a binary file.
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70 GD_E_PROTECTED
71 The metadata of the given format specification fragment was
72 protected from change, or the binary data of the fragment was
73 protected from change and binary file shifting was requested.
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75 GD_E_RANGE
76 The supplied offset was less than zero.
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78 GD_E_UNCLEAN_DB
79 An error occurred while moving the shifted file into place. As
80 a result, the database may be in an unclean state. See the
81 NOTES section below for recovery instructions. In this case,
82 the dirfile will be flagged as invalid, to prevent further
83 database corruption. It should be immediately closed.
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85 GD_E_UNKNOWN_ENCODING
86 The encoding scheme of the fragment is unknown.
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88 GD_E_UNSUPPORTED
89 The encoding scheme of the fragment does not support binary
90 file shifting.
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92 The error code is also stored in the DIRFILE object and may be re‐
93 trieved after this function returns by calling gd_error(3). A descrip‐
94 tive error string for the error may be obtained by calling
95 gd_error_string(3).
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99 A binary file shift occurs out-of-place. As a result, sufficient space
100 must be present on the filesystem for the binary files of all RAW
101 fields in the fragment both before and after translation. If all frag‐
102 ments are updated by specifying GD_ALL_FRAGMENTS, the shifting occurs
103 one fragment at a time.
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105 An error code of GD_E_UNCLEAN_DB indicates a system error occurred
106 while moving the shifted binary data into place or when deleting the
107 old data. If this happens, the database may be left in an unclean
108 state. The caller should check the filesystem directly to ascertain
109 the state of the dirfile data before continuing. For recovery instruc‐
110 tions, see the file /usr/share/doc/getdata/unclean_database_recov‐
111 ery.txt.
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115 The function dirfile_alter_frameoffset() appeared in GetData-0.5.0.
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117 In GetData-0.7.0, this function was renamed to gd_alter_frameoffset().
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119 in GetData-0.10.0, the error return from this function changed from -1
120 to a negative-valued error code.
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124 gd_open(3), gd_error(3), gd_error_string(3), gd_frameoffset(3),
125 dirfile(5), dirfile-format(5)
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129Version 0.10.0 25 December 2016 gd_alter_frameoffset(3)