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annotate ext/libpng-1.2.29/Y2KINFO @ 164:5b04a7d3ded6

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typo fix some missing event (de)registrations ability to capture one event multiple times (instead of only having one slot, we have groups and each group has an own slot, the default group is "default" so we are backward compatible
author spq@33b003aa-7bff-0310-803a-e67f0ece8222
date Wed, 15 Oct 2008 14:57:04 +0000
parents 4a0efb7baf70
children
rev   line source
0
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1 Y2K compliance in libpng:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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2 =========================
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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3
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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4 May 8, 2008
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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5
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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6 Since the PNG Development group is an ad-hoc body, we can't make
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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7 an official declaration.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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8
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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9 This is your unofficial assurance that libpng from version 0.71 and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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10 upward through 1.2.29 are Y2K compliant. It is my belief that earlier
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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11 versions were also Y2K compliant.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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12
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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13 Libpng only has three year fields. One is a 2-byte unsigned integer
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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14 that will hold years up to 65535. The other two hold the date in text
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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15 format, and will hold years up to 9999.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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16
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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17 The integer is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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18 "png_uint_16 year" in png_time_struct.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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19
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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20 The strings are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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21 "png_charp time_buffer" in png_struct and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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22 "near_time_buffer", which is a local character string in png.c.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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23
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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24 There are seven time-related functions:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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25
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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26 png_convert_to_rfc_1123() in png.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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27 (formerly png_convert_to_rfc_1152() in error)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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28 png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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29 png_convert_from_time_t() in pngwrite.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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30 png_get_tIME() in pngget.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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31 png_handle_tIME() in pngrutil.c, called in pngread.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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32 png_set_tIME() in pngset.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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33 png_write_tIME() in pngwutil.c, called in pngwrite.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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34
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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35 All appear to handle dates properly in a Y2K environment. The
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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36 png_convert_from_time_t() function calls gmtime() to convert from system
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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37 clock time, which returns (year - 1900), which we properly convert to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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38 the full 4-digit year. There is a possibility that applications using
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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39 libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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40 function, or that they are incorrectly passing only a 2-digit year
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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41 instead of "year - 1900" into the png_convert_from_struct_tm() function,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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42 but this is not under our control. The libpng documentation has always
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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43 stated that it works with 4-digit years, and the APIs have been
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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44 documented as such.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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45
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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46 The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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47 integer to hold the year, and can hold years as large as 65535.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
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48
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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49 zlib, upon which libpng depends, is also Y2K compliant. It contains
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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50 no date-related code.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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51
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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52
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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53 Glenn Randers-Pehrson
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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54 libpng maintainer
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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55 PNG Development Group