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Refactor ::OnReadable() creating get_utf8_char_validated() (#136) 

Extract call to GLib's g_utf8_get_char_validated() and the associated
workaround to also read NUL characters into a separate function to make
PipeCapture::OnReadable() a little smaller and simpler, so easier to
understand.

Add max_len > 0 clause into get_utf8_char_validated() like this:
    if (uc == UTF8_PARTIAL && max_len > 0)
so that the NUL character reading workaround is only applied when
max_len specifies the maximum number of bytes to read, rather than
when -1 specifies reading a NUL termination string.  This makes
get_utf8_char_validated() a complete wrapper of
g_utf8_get_char_validated() [1], even though GParted always specifies
the maximum number of bytes to read.

No longer describe the inability to read NUL characters as a bug [2]
since the GLib author's said it wasn't [3].

[1] GLib Reference Manual, Unicode Manipulation Functions,
    g_utf8_get_char_validated ()
    https://developer.gnome.org/glib/stable/glib-Unicode-Manipulation.html#g-utf8-get-char-validated

[2] 8dbbb47ce2
    Workaround g_utf8_get_char_validate() bug with embedded NUL bytes
    (#777973)

[3] Bug 780095 - g_utf8_get_char_validated() stopping at nul byte even
    for length specified buffers
    https://bugzilla.gnome.org/show_bug.cgi?id=780095#18
        "If g_utf8_get_char_validated() encounters a nul byte in the
        middle of a string of given longer length, it returns -2,
        indicating a partial gunichar.  That is not the obvious
        behaviour, but since g_utf8_get_char_validated() has been API
        for a long time, the behaviour cannot be changed.
        "

Closes #136 - 1.2.0: test suite is failing in test_PipeCapture
This commit is contained in:
Mike Fleetwood 2021-02-20 23:30:41 +00:00 committed by Curtis Gedak
parent 0bcb224bdc
commit b1cad17a14
2 changed files with 30 additions and 15 deletions
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1
include/PipeCapture.h
View File

@ -45,6 +45,7 @@ private:
gpointer data );
static void append_unichar_vector_to_utf8( std::string & str,
const std::vector<gunichar> & ucvec );
static gunichar get_utf8_char_validated(const char *p, gssize max_len);
static int utf8_char_length( unsigned char firstbyte );
Glib::RefPtr<Glib::IOChannel> channel; // Wrapper around fd

44
src/PipeCapture.cc
View File

@ -30,6 +30,11 @@ namespace GParted {
const size_t READBUF_SIZE = 64*KIBIBYTE;
const gunichar UTF8_PARTIAL = (gunichar)-2;
const gunichar UTF8_INVALID = (gunichar)-1;
PipeCapture::PipeCapture( int fd, Glib::ustring &buffer ) : fill_offset( 0 ),
cursor( 0 ),
line_start( 0 ),
@ -125,21 +130,7 @@ bool PipeCapture::OnReadable( Glib::IOCondition condition )
fill_offset = 0;
while ( read_ptr < end_ptr )
{
const gunichar UTF8_PARTIAL = (gunichar)-2;
const gunichar UTF8_INVALID = (gunichar)-1;
gunichar uc = g_utf8_get_char_validated( read_ptr, end_ptr - read_ptr );
if ( uc == UTF8_PARTIAL )
{
// Workaround bug in g_utf8_get_char_validated() in which
// it reports an partial UTF-8 char when a NUL byte is
// encountered in the middle of a multi-byte character,
// yet there are more bytes available in the length
// specified buffer. Report as invalid character instead.
int len = utf8_char_length( *read_ptr );
if ( len == -1 || read_ptr + len <= end_ptr )
uc = UTF8_INVALID;
}
gunichar uc = get_utf8_char_validated(read_ptr, end_ptr - read_ptr);
if ( uc == UTF8_PARTIAL )
{
// Partial UTF-8 character at end of read buffer. Copy to
@ -258,6 +249,29 @@ void PipeCapture::append_unichar_vector_to_utf8( std::string & str, const std::v
}
}
// GLib's g_utf8_get_char_validated() always considers strings as being NUL terminated,
// even when max_len is specified, hence can't read NUL characters. This wrapper can read
// NUL characters when max_len is specified.
// Reference:
// https://developer.gnome.org/glib/stable/glib-Unicode-Manipulation.html#g-utf8-get-char-validated
gunichar PipeCapture::get_utf8_char_validated(const char *p, gssize max_len)
{
gunichar uc = g_utf8_get_char_validated(p, max_len);
if (uc == UTF8_PARTIAL && max_len > 0)
{
// If g_utf8_get_char_validated() found a NUL byte in the middle of a
// multi-byte character, even when there are more bytes available as
// specified by max_len, it reports a partial UTF-8 character. Report
// this case as an invalid character instead.
int len = utf8_char_length(*p);
if (len == -1 || (gssize)len <= max_len)
uc = UTF8_INVALID;
}
return uc;
}
int PipeCapture::utf8_char_length( unsigned char firstbyte )
{
// Recognise the size of FSS-UTF (1992) / UTF-8 (1993) characters given the first