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annotate ext/libpng-1.2.29/Y2KINFO @ 15:5582579d1bca

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* Fixing debugging target * Thanks to Adus for the hint
author mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
date Sun, 06 Jul 2008 23:14:24 +0000
parents 4a0efb7baf70
children
rev   line source
0
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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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
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7 an official declaration.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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8
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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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
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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
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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
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16
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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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
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23
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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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
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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
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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
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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
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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
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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
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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
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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