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Replace va_list fmt() overload with vfmt()

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Using an overload that takes a va_list argument potentially causes
accidental misuse on platforms (e.g. 32-bit) where va_list is
implemented as a type that may collide with commonly-used argument
types.

For example:

    char* c = copy_string("hi");
    fmt("%s", (const char*)c);
    fmt("%s", c);

The first fmt() call correctly goes through fmt(const char*, ...) first,
but the second mistakenly goes through fmt(const char*, va_list) first
because variadic function overloads have lower priority during overload
resolution and va_list on a 32-bit system happens to be defined as a
pointer type that can match with "char*" but not "const char*".
This commit is contained in:
Jon Siwek 2020-02-14 21:26:55 -08:00
parent 8e353aafe5
commit 8fed26824b
5 changed files with 11 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

4
src/util.cc
View file

@ -817,7 +817,7 @@ const char* fmt_bytes(const char* data, int len)
return buf;
}
const char* fmt(const char* format, va_list al)
const char* vfmt(const char* format, va_list al)
{
static char* buf = 0;
static unsigned int buf_len = 1024;
@ -848,7 +848,7 @@ const char* fmt(const char* format, ...)
{
va_list al;
va_start(al, format);
auto rval = fmt(format, al);
auto rval = vfmt(format, al);
va_end(al);
return rval;
}