iconv: Add UTF-7-IMAP variant in utf-7.c

UTF-7-IMAP differs from UTF-7 in the followings ways (see RFC 3501[1]
for reference) :

- The shift character is '&' instead of '+'
- There is no "optional direct characters" and the "direct characters"
  set is different
- There is no implicit shift back to US-ASCII from BASE64, all BASE64
  sequences MUST be terminated with '-'

[1]: https://datatracker.ietf.org/doc/html/rfc3501#section-5.1.3

Signed-off-by: Max Gautier <mg@max.gautier.name>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 32 insertions, 0 deletions

diff --git a/iconvdata/testdata/UTF-7-IMAP..UTF8 b/iconvdata/testdata/UTF-7-IMAP..UTF8
new file mode 100644
index 0000000000..8b9add3670
--- /dev/null
+++ b/iconvdata/testdata/UTF-7-IMAP..UTF8
@@ -0,0 +1,32 @@
+አማርኛ       Amharic
+česky      Czech
+Dansk      Danish
+English    English
+Suomi      Finnish
+Français   French
+Deutsch    German
+Ελληνικά   Greek
+עברית      Hebrew
+Italiano   Italian
+Norsk      Norwegian
+Русский    Russian
+Español    Spanish
+Svenska    Swedish
+ภาษาไทย    Thai
+Türkçe     Turkish
+Tiếng Việt Vietnamese
+日本語     Japanese
+中文       Chinese
+한글       Korean
+
+// Checking for correct handling of shift characters ('&', '-') after base64 sequences
+한글&
+한글-
+
+// Checking for correct handling of litteral '&' and '-'
+---&&-
+
+// The last line of this file is missing the end-of-line terminator
+// on purpose, in order to test that the conversion empties the bit buffer
+// and shifts back to the initial state at the end of the conversion.
+A≢Α
\ No newline at end of file