- `[[format(archetype, fmt-idx, ellipsis)]]` specifies that a function accepts a
format string and arguments according to `archetype`. This is how Clang
type-checks `printf` arguments based on the format string.
- Clang has a `-Wformat-nonliteral` warning that is triggered when a function
with the `format` attribute is called with a format string that is not
inspectable because it isn't constant. This warning is suppressed if the
caller has the `format` attribute itself and the format argument to the callee
is the caller's own format parameter.
- When using the `format` attribute on a block, Clang wouldn't recognize its
format parameter when calling another function with the format attribute. This
would cause unsuppressed -Wformat-nonliteral warnings for no supported reason.
Reviewed By: ahatanak
Differential Revision: https://reviews.llvm.org/D112569
Radar-Id: rdar://84603673
error: 'error' diagnostics expected but not seen:
File /vol/llvm/src/clang/local/test/Sema/wchar.c Line 22: initializing wide char array with non-wide string literal
error: 'error' diagnostics seen but not expected:
File /vol/llvm/src/clang/local/test/Sema/wchar.c Line 20: array initializer must be an initializer list
File /vol/llvm/src/clang/local/test/Sema/wchar.c Line 22: array initializer must be an initializer list
It turns out the definition is wrong, as can be seen in GCC's gcc/config/sol2.h:
/* wchar_t is called differently in <wchar.h> for 32 and 64-bit
compilations. This is called for by SCD 2.4.1, p. 6-83, Figure 6-65
(32-bit) and p. 6P-10, Figure 6.38 (64-bit). */
#undef WCHAR_TYPE
#define WCHAR_TYPE (TARGET_64BIT ? "int" : "long int")
The following patch implements this, and at the same time corrects the wint_t
definition which is the same:
/* Same for wint_t. See SCD 2.4.1, p. 6-83, Figure 6-66 (32-bit). There's
no corresponding 64-bit definition, but this is what Solaris 8
<iso/wchar_iso.h> uses. */
#undef WINT_TYPE
#define WINT_TYPE (TARGET_64BIT ? "int" : "long int")
Clang :: Preprocessor/wchar_t.c and Clang :: Sema/format-strings.c need to
be adjusted to account for that.
Tested on i386-pc-solaris2.11, x86_64-pc-solaris2.11, and x86_64-pc-linux-gnu.
Differential Revision: https://reviews.llvm.org/D62944
llvm-svn: 363612
Re-enable format string warnings on printf.
The warnings are still incomplete. Apparently it is undefined to use a
vector specifier without a length modifier, which is not currently
warned on. Additionally, type warnings appear to not be working with
the hh modifier, and aren't warning on all of the special restrictions
from c99 printf.
llvm-svn: 352540
This avoids spurious warnings, but could use
a lot of work. For example the number of vector
elements is not verified, and the passed
value type is not checked.
Fixes bug 39486
llvm-svn: 346806
I had locally changed the test to add an explicit triple to figure out the issue
with the SCEI buildbots, and that hid the error. This now works with and
without the explicit triple.
llvm-svn: 342581
In the case that `win_t` is an `unsigned short` (e.g. on Windows), we would
previously incorrectly diagnose the conversion because we would immediately
promote the argument type from `wint_t` (aka `unsigned short`) to `int` before
checking if the type matched. This should repair the Windows hosted bots.
llvm-svn: 342565
Summary:
The warning for a format string not being a string literal and therefore
being potentially insecure is overly strict for indices into string
literals. This fix checks if the index into the string literal is
precomputable. If that's the case it will check if the suffix of that
string literal is a valid format string string literal. It will still
issue the aforementioned warning for out of range indices into the
string literal.
Patch by Meike Baumgärtner (meikeb)
Reviewers: rsmith
Subscribers: srhines, cfe-commits
Differential Revision: https://reviews.llvm.org/D24584
llvm-svn: 281686
Summary: This reverts r281527 because I messed up the attribution.
Reviewers: srhines
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D24579
llvm-svn: 281530
Summary:
The warning for a format string not being a sting literal and therefore
being potentially insecure is overly strict for indecies into sting
literals. This fix checks if the index into the string literal is
precomputable. If thats the case it will check if the suffix of that
sting literal is a valid format string string literal. It will still
issue the aforementioned warning for out of range indecies into the
string literal.
Reviewers: rsmith
Subscribers: srhines, cfe-commits
Differential Revision: https://reviews.llvm.org/D23820
llvm-svn: 281527
r263299 added a fixit for the -Wformat-security warning, but that runs
into complications with our guideline that error recovery should be done
as-if the fixit had been applied. Putting the fixit on a note avoids that.
llvm-svn: 263584
Summary:
The printf/scanf format checker is a little over-zealous in handling the conditional operator. This patch reduces work by not checking code-paths that are never used and reduces false positives regarding uncovered arguments, for example in the code fragment:
printf(minimal ? "%i\n" : "%i: %s\n", code, msg);
Reviewers: rtrieu
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D15636
llvm-svn: 262025
glibc expects that stddef.h only defines a single thing if either of these
defines is set. For example, before this change, a C file containing
#include <stdlib.h>
int ptrdiff_t = 0;
would compile with gcc but not with clang. Now it compiles with clang too.
This also fixes PR12997, where older versions of the Linux headers would define
NULL incorrectly, and glibc would define __need_NULL and expect stddef.h to
redefine NULL with the correct definition.
llvm-svn: 207606
While '%n' can be used for evil in an attacker-controlled format string, there
isn't any acute danger in using it in a literal format string with an argument
of the appropriate type.
llvm-svn: 160984
about argument type mismatch.
This gives a nicer diagnostic in cases like
printf(fmt,
i);
where previously the snippet just pointed at 'fmt' (with a note at the
definition of fmt).
It's a wash for cases like
printf("%f",
i);
where previously we snippeted the offending portion of the format string,
but didn't indicate which argument was at fault.
llvm-svn: 156968
For "%hhx", printf expects an unsigned char. This makes Clang
accept a 'char' argument for that also when using -funsigned-char.
This fixes PR12761.
llvm-svn: 156388
Teach ASTContext about WIntType, and have it taken from TargetInfo like WCharType. Should fix test/Sema/format-strings.c for ARM, with the exception of one subtest which will fail if wint_t and wchar_t are the same size and wint_t is signed, wchar_t is unsigned.
There'll be a followup commit to fix that.
Reviewed by Chandler and Hans at http://llvm.org/reviews/r/8
llvm-svn: 156165
This adds the -Wformat-non-standard flag (off by default,
enabled by -pedantic), which warns about non-standard
things in format strings (such as the 'q' length modifier,
the 'S' conversion specifier, etc.)
llvm-svn: 151154
This is in preparation for being able to warn about 'q' and other
non-standard format string features.
It also allows us to print its name correctly.
llvm-svn: 150697
- Remove the printf0 special handling as we treat it as printf anyway.
- Perform basic checks (non-literal, empty) for all formats and not only printf/scanf.
llvm-svn: 149236
string is part of the function call, then there is no difference. If the
format string is not, the warning will point to the call site and a note
will point to where the format string is.
Fix-it hints for strings are moved to the note if a note is emitted. This will
prevent changes to format strings that may be used in multiple places.
llvm-svn: 143168
Félix Cloutier