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Diffstat (limited to 'gnu/usr.bin/cvs/doc/RCSFILES')
| -rw-r--r-- | gnu/usr.bin/cvs/doc/RCSFILES | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/gnu/usr.bin/cvs/doc/RCSFILES b/gnu/usr.bin/cvs/doc/RCSFILES index 13c4f93c796..46503377901 100644 --- a/gnu/usr.bin/cvs/doc/RCSFILES +++ b/gnu/usr.bin/cvs/doc/RCSFILES @@ -136,6 +136,36 @@ Both RCS 5.7 and current versions of CVS handle the $Log keyword in a different way if the log message starts with "checked in with -k by ". I don't think this behavior is documented anywhere. +Here is a clarification regarding characters versus bytes in certain +character sets like JIS and Big5: + + The RCS file format, as described in the rcsfile(5) man page, is + actually byte-oriented, not character-oriented, despite hints to + the contrary in the man page. This distinction is important for + multibyte characters. For example, if a multibyte character + contains a `@' byte, the `@' must be doubled within strings in RCS + files, since RCS uses `@' bytes as escapes. + + This point is not an issue for encodings like ISO 8859, which do + not have multibyte characters. Nor is it an issue for encodings + like UTF-8 and EUC-JIS, which never uses ASCII bytes within a + multibyte character. It is an issue only for multibyte encodings + like JIS and BIG5, which _do_ usurp ASCII bytes. + + If `@' doubling occurs within a multibyte char, the resulting RCS + file is not a properly encoded text file. Instead, it is a byte + stream that does not use a consistent character encoding that can + be understood by the usual text tools, since doubling `@' messes + up the encoding. This point affects only programs that examine + the RCS files -- it doesn't affect the external RCS interface, as + the RCS commands always give you the properly encoded text files + and logs (assuming that you always check in properly encoded + text). + + CVS 1.10 (and earlier) probably has some bugs in this area on + systems where a C "char" is signed and where the data contains + bytes with the eighth bit set. + One common concern about the RCS file format is the fact that to get the head of a branch, one must apply deltas from the head of the trunk to the branchpoint, and then from the branchpoint to the head of the |