Message ID | mvmeemi81yq.fsf@suse.de |
---|---|
State | New |
Headers | show |
Series | __vfscanf_internal: fix aliasing violation (bug 26690) | expand |
The 10/01/2020 16:17, Andreas Schwab wrote: > As noted in <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97264>, the cast > in the call to the read_int function is an aliasing violation. Change the > type of local variable f to a pointer to unsigned, which allows to > eliminate most casts while only adding three new ones. this looks good to me. > --- > stdio-common/vfscanf-internal.c | 22 +++++++++++----------- > 1 file changed, 11 insertions(+), 11 deletions(-) > > diff --git a/stdio-common/vfscanf-internal.c b/stdio-common/vfscanf-internal.c > index 95b46dcbeb..3a323547f9 100644 > --- a/stdio-common/vfscanf-internal.c > +++ b/stdio-common/vfscanf-internal.c > @@ -277,7 +277,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, > #endif > { > va_list arg; > - const CHAR_T *f = format; > + const UCHAR_T *f = (const UCHAR_T *) format; > UCHAR_T fc; /* Current character of the format. */ > WINT_T done = 0; /* Assignments done. */ > size_t read_in = 0; /* Chars read in. */ > @@ -415,10 +415,11 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, > #endif > > #ifndef COMPILE_WSCANF > - if (!isascii ((unsigned char) *f)) > + if (!isascii (*f)) > { > /* Non-ASCII, may be a multibyte. */ > - int len = __mbrlen (f, strlen (f), &state); > + int len = __mbrlen ((const char *) f, strlen ((const char *) f), > + &state); > if (len > 0) > { > do > @@ -426,7 +427,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, > c = inchar (); > if (__glibc_unlikely (c == EOF)) > input_error (); > - else if (c != (unsigned char) *f++) > + else if (c != *f++) > { > ungetc_not_eof (c, s); > conv_error (); > @@ -484,9 +485,9 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, > char_buffer_rewind (&charbuf); > > /* Check for a positional parameter specification. */ > - if (ISDIGIT ((UCHAR_T) *f)) > + if (ISDIGIT (*f)) > { > - argpos = read_int ((const UCHAR_T **) &f); > + argpos = read_int (&f); > if (*f == L_('$')) > ++f; > else > @@ -521,8 +522,8 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, > > /* Find the maximum field width. */ > width = 0; > - if (ISDIGIT ((UCHAR_T) *f)) > - width = read_int ((const UCHAR_T **) &f); > + if (ISDIGIT (*f)) > + width = read_int (&f); > got_width: > if (width == 0) > width = -1; > @@ -2522,12 +2523,11 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, > } > > while ((fc = *f++) != '\0' && fc != ']') > - if (fc == '-' && *f != '\0' && *f != ']' > - && (unsigned char) f[-2] <= (unsigned char) *f) > + if (fc == '-' && *f != '\0' && *f != ']' && f[-2] <= *f) > { > /* Add all characters from the one before the '-' > up to (but not including) the next format char. */ > - for (fc = (unsigned char) f[-2]; fc < (unsigned char) *f; ++fc) > + for (fc = f[-2]; fc < *f; ++fc) > ((char *)charbuf.scratch.data)[fc] = 1; > } > else > -- > 2.28.0 > > > -- > Andreas Schwab, SUSE Labs, schwab@suse.de > GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 > "And now for something completely different." --
diff --git a/stdio-common/vfscanf-internal.c b/stdio-common/vfscanf-internal.c index 95b46dcbeb..3a323547f9 100644 --- a/stdio-common/vfscanf-internal.c +++ b/stdio-common/vfscanf-internal.c @@ -277,7 +277,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, #endif { va_list arg; - const CHAR_T *f = format; + const UCHAR_T *f = (const UCHAR_T *) format; UCHAR_T fc; /* Current character of the format. */ WINT_T done = 0; /* Assignments done. */ size_t read_in = 0; /* Chars read in. */ @@ -415,10 +415,11 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, #endif #ifndef COMPILE_WSCANF - if (!isascii ((unsigned char) *f)) + if (!isascii (*f)) { /* Non-ASCII, may be a multibyte. */ - int len = __mbrlen (f, strlen (f), &state); + int len = __mbrlen ((const char *) f, strlen ((const char *) f), + &state); if (len > 0) { do @@ -426,7 +427,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, c = inchar (); if (__glibc_unlikely (c == EOF)) input_error (); - else if (c != (unsigned char) *f++) + else if (c != *f++) { ungetc_not_eof (c, s); conv_error (); @@ -484,9 +485,9 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, char_buffer_rewind (&charbuf); /* Check for a positional parameter specification. */ - if (ISDIGIT ((UCHAR_T) *f)) + if (ISDIGIT (*f)) { - argpos = read_int ((const UCHAR_T **) &f); + argpos = read_int (&f); if (*f == L_('$')) ++f; else @@ -521,8 +522,8 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, /* Find the maximum field width. */ width = 0; - if (ISDIGIT ((UCHAR_T) *f)) - width = read_int ((const UCHAR_T **) &f); + if (ISDIGIT (*f)) + width = read_int (&f); got_width: if (width == 0) width = -1; @@ -2522,12 +2523,11 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr, } while ((fc = *f++) != '\0' && fc != ']') - if (fc == '-' && *f != '\0' && *f != ']' - && (unsigned char) f[-2] <= (unsigned char) *f) + if (fc == '-' && *f != '\0' && *f != ']' && f[-2] <= *f) { /* Add all characters from the one before the '-' up to (but not including) the next format char. */ - for (fc = (unsigned char) f[-2]; fc < (unsigned char) *f; ++fc) + for (fc = f[-2]; fc < *f; ++fc) ((char *)charbuf.scratch.data)[fc] = 1; } else