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efi/printf: Factor out width/precision parsing 

Factor out the width/precision parsing into a helper function.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200518190716.751506-12-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Arvind Sankar 2020-05-18 15:07:03 -04:00 committed by Ard Biesheuvel
parent 7c30fd7916
commit 3fbcf75bb4
1 changed files with 40 additions and 21 deletions
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61
drivers/firmware/efi/libstub/vsprintf.c
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@ -231,7 +231,20 @@ int get_flags(const char **fmt)
} while (1);
}
int vsprintf(char *buf, const char *fmt, va_list args)
static
int get_int(const char **fmt, va_list *ap)
{
if (isdigit(**fmt))
return skip_atoi(fmt);
if (**fmt == '*') {
++(*fmt);
/* it's the next argument */
return va_arg(*ap, int);
}
return 0;
}
int vsprintf(char *buf, const char *fmt, va_list ap)
{
int len;
unsigned long long num;
@ -246,6 +259,24 @@ int vsprintf(char *buf, const char *fmt, va_list args)
number of chars for from string */
int qualifier; /* 'h', 'hh', 'l' or 'll' for integer fields */
va_list args;
/*
* We want to pass our input va_list to helper functions by reference,
* but there's an annoying edge case. If va_list was originally passed
* to us by value, we could just pass &ap down to the helpers. This is
* the case on, for example, X86_32.
* However, on X86_64 (and possibly others), va_list is actually a
* size-1 array containing a structure. Our function parameter ap has
* decayed from T[1] to T*, and &ap has type T** rather than T(*)[1],
* which is what will be expected by a function taking a va_list *
* parameter.
* One standard way to solve this mess is by creating a copy in a local
* variable of type va_list and then passing a pointer to that local
* copy instead, which is what we do here.
*/
va_copy(args, ap);
for (str = buf; *fmt; ++fmt) {
if (*fmt != '%' || *++fmt == '%') {
*str++ = *fmt;
@ -256,32 +287,17 @@ int vsprintf(char *buf, const char *fmt, va_list args)
flags = get_flags(&fmt);
/* get field width */
field_width = -1;
if (isdigit(*fmt)) {
field_width = skip_atoi(&fmt);
} else if (*fmt == '*') {
++fmt;
/* it's the next argument */
field_width = va_arg(args, int);
if (field_width < 0) {
field_width = -field_width;
flags |= LEFT;
}
field_width = get_int(&fmt, &args);
if (field_width < 0) {
field_width = -field_width;
flags |= LEFT;
}
/* get the precision */
precision = -1;
if (*fmt == '.') {
++fmt;
if (isdigit(*fmt)) {
precision = skip_atoi(&fmt);
} else if (*fmt == '*') {
++fmt;
/* it's the next argument */
precision = va_arg(args, int);
} else {
precision = 0;
}
precision = get_int(&fmt, &args);
if (precision >= 0)
flags &= ~ZEROPAD;
}
@ -392,6 +408,9 @@ int vsprintf(char *buf, const char *fmt, va_list args)
str = number(str, num, base, field_width, precision, flags);
}
*str = '\0';
va_end(args);
return str - buf;
}