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Fixes #87,#91: Now explicitly converting from size_t to `printf_siz…
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…e_t` as soon as possible, taking care not to exceed the maximum representable value of `printf_size_t`. From that point onwards (or rather inwards) - only `printf_size_t` is used for lengths and positions/indices. Also, no longer using `-1` magic numbers for the "maximum possible size/length".
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@eyalroz
eyalroz committed Feb 21, 2022
1 parent d97f069 commit 729d5da
Showing 1 changed file with 32 additions and 27 deletions.
59 changes: 32 additions & 27 deletions src/printf/printf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -222,6 +222,10 @@ typedef long printf_signed_value_t;
// precisions, offsets into buffers used for printing and the sizes
// of these buffers. instead, we use:
typedef unsigned int printf_size_t;
#define PRINTF_MAX_POSSIBLE_BUFFER_SIZE INT_MAX
// If we were to nitpick, this would actually be INT_MAX + 1,
// since INT_MAX is the maximum return value, which excludes the
// trailing '\0'.

#if (PRINTF_SUPPORT_DECIMAL_SPECIFIERS || PRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS)
#include <float.h>
Expand Down Expand Up @@ -289,7 +293,7 @@ static inline int get_exp2(double_with_bit_access x)
#define ABS_FOR_PRINTING(_x) ((printf_unsigned_value_t) ( (_x) > 0 ? (_x) : -((printf_signed_value_t)_x) ))

// output function type
typedef void (*out_fct_type)(char c, void* buffer, size_t idx, size_t maxlen);
typedef void (*out_fct_type)(char c, void* buffer, printf_size_t idx, printf_size_t maxlen);


// wrapper (used as buffer) for output function type
Expand All @@ -300,7 +304,7 @@ typedef struct {


// internal buffer output
static inline void out_buffer(char c, void* buffer, size_t idx, size_t maxlen)
static inline void out_buffer(char c, void* buffer, printf_size_t idx, printf_size_t maxlen)
{
if (idx < maxlen) {
((char*)buffer)[idx] = c;
Expand All @@ -309,14 +313,14 @@ static inline void out_buffer(char c, void* buffer, size_t idx, size_t maxlen)


// internal null output
static inline void out_discard(char c, void* buffer, size_t idx, size_t maxlen)
static inline void out_discard(char c, void* buffer, printf_size_t idx, printf_size_t maxlen)
{
(void)c; (void)buffer; (void)idx; (void)maxlen;
}


// internal putchar_ wrapper
static inline void out_putchar(char c, void* buffer, size_t idx, size_t maxlen)
static inline void out_putchar(char c, void* buffer, printf_size_t idx, printf_size_t maxlen)
{
(void)buffer; (void)idx; (void)maxlen;
if (c) {
Expand All @@ -326,7 +330,7 @@ static inline void out_putchar(char c, void* buffer, size_t idx, size_t maxlen)


// internal output function wrapper
static inline void out_wrapped_function(char c, void* wrapped_function, size_t idx, size_t maxlen)
static inline void out_wrapped_function(char c, void* wrapped_function, printf_size_t idx, printf_size_t maxlen)
{
(void)idx; (void)maxlen;
if (c) {
Expand Down Expand Up @@ -368,13 +372,13 @@ static printf_size_t atou_(const char** str)


// output the specified string in reverse, taking care of any zero-padding
static size_t out_rev_(out_fct_type out, char* buffer, size_t idx, size_t maxlen, const char* buf, size_t len, printf_size_t width, printf_flags_t flags)
static printf_size_t out_rev_(out_fct_type out, char* buffer, printf_size_t idx, printf_size_t maxlen, const char* buf, printf_size_t len, printf_size_t width, printf_flags_t flags)
{
const size_t start_idx = idx;
const printf_size_t start_idx = idx;

// pad spaces up to given width
if (!(flags & FLAGS_LEFT) && !(flags & FLAGS_ZEROPAD)) {
for (size_t i = len; i < width; i++) {
for (printf_size_t i = len; i < width; i++) {
out(' ', buffer, idx++, maxlen);
}
}
Expand All @@ -397,9 +401,9 @@ static size_t out_rev_(out_fct_type out, char* buffer, size_t idx, size_t maxlen

// Invoked by print_integer after the actual number has been printed, performing necessary
// work on the number's prefix (as the number is initially printed in reverse order)
static size_t print_integer_finalization(out_fct_type out, char* buffer, size_t idx, size_t maxlen, char* buf, size_t len, bool negative, numeric_base_t base, printf_size_t precision, printf_size_t width, printf_flags_t flags)
static printf_size_t print_integer_finalization(out_fct_type out, char* buffer, printf_size_t idx, printf_size_t maxlen, char* buf, printf_size_t len, bool negative, numeric_base_t base, printf_size_t precision, printf_size_t width, printf_flags_t flags)
{
size_t unpadded_len = len;
printf_size_t unpadded_len = len;

// pad with leading zeros
{
Expand Down Expand Up @@ -464,10 +468,10 @@ static size_t print_integer_finalization(out_fct_type out, char* buffer, size_t
}

// An internal itoa-like function
static size_t print_integer(out_fct_type out, char* buffer, size_t idx, size_t maxlen, printf_unsigned_value_t value, bool negative, numeric_base_t base, printf_size_t precision, printf_size_t width, printf_flags_t flags)
static printf_size_t print_integer(out_fct_type out, char* buffer, printf_size_t idx, printf_size_t maxlen, printf_unsigned_value_t value, bool negative, numeric_base_t base, printf_size_t precision, printf_size_t width, printf_flags_t flags)
{
char buf[PRINTF_INTEGER_BUFFER_SIZE];
size_t len = 0U;
printf_size_t len = 0U;

if (!value) {
if ( !(flags & FLAGS_PRECISION) ) {
Expand Down Expand Up @@ -629,9 +633,9 @@ static struct double_components get_normalized_components(bool negative, printf_
}
#endif // PRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS

static size_t print_broken_up_decimal(
struct double_components number_, out_fct_type out, char *buffer, size_t idx, size_t maxlen, printf_size_t precision,
printf_size_t width, printf_flags_t flags, char *buf, size_t len)
static printf_size_t print_broken_up_decimal(
struct double_components number_, out_fct_type out, char *buffer, printf_size_t idx, printf_size_t maxlen, printf_size_t precision,
printf_size_t width, printf_flags_t flags, char *buf, printf_size_t len)
{
if (precision != 0U) {
// do fractional part, as an unsigned number
Expand Down Expand Up @@ -712,15 +716,15 @@ static size_t print_broken_up_decimal(
}

// internal ftoa for fixed decimal floating point
static size_t print_decimal_number(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double number, printf_size_t precision, printf_size_t width, printf_flags_t flags, char* buf, size_t len)
static printf_size_t print_decimal_number(out_fct_type out, char* buffer, printf_size_t idx, printf_size_t maxlen, double number, printf_size_t precision, printf_size_t width, printf_flags_t flags, char* buf, printf_size_t len)
{
struct double_components value_ = get_components(number, precision);
return print_broken_up_decimal(value_, out, buffer, idx, maxlen, precision, width, flags, buf, len);
}

#if PRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS
// internal ftoa variant for exponential floating-point type, contributed by Martijn Jasperse <m.jasperse@gmail.com>
static size_t print_exponential_number(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double number, printf_size_t precision, printf_size_t width, printf_flags_t flags, char* buf, size_t len)
static printf_size_t print_exponential_number(out_fct_type out, char* buffer, printf_size_t idx, printf_size_t maxlen, double number, printf_size_t precision, printf_size_t width, printf_flags_t flags, char* buf, printf_size_t len)
{
const bool negative = get_sign(number);
// This number will decrease gradually (by factors of 10) as we "extract" the exponent out of it
Expand Down Expand Up @@ -828,7 +832,7 @@ static size_t print_exponential_number(out_fct_type out, char* buffer, size_t id
// characters as we need
0U);

const size_t start_idx = idx;
const printf_size_t start_idx = idx;
idx = print_broken_up_decimal(decimal_part_components, out, buffer, idx, maxlen, precision, decimal_part_width, flags, buf, len);

if (! fall_back_to_decimal_only_mode) {
Expand All @@ -846,10 +850,10 @@ static size_t print_exponential_number(out_fct_type out, char* buffer, size_t id
}
#endif // PRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS

static size_t print_floating_point(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double value, printf_size_t precision, printf_size_t width, printf_flags_t flags, bool prefer_exponential)
static printf_size_t print_floating_point(out_fct_type out, char* buffer, printf_size_t idx, printf_size_t maxlen, double value, printf_size_t precision, printf_size_t width, printf_flags_t flags, bool prefer_exponential)
{
char buf[PRINTF_FTOA_BUFFER_SIZE];
size_t len = 0U;
printf_size_t len = 0U;

// test for special values
if (value != value)
Expand Down Expand Up @@ -1155,7 +1159,7 @@ static int _vsnprintf(out_fct_type out, char* buffer, printf_size_t buffer_size,
idx = out_rev_(out, buffer, idx, buffer_size, ")llun(", 6, width, flags);
}
else {
printf_size_t l = strnlen_s_(p, precision ? precision : (printf_size_t) -1);
printf_size_t l = strnlen_s_(p, precision ? precision : PRINTF_MAX_POSSIBLE_BUFFER_SIZE);
// pre padding
if (flags & FLAGS_PRECISION) {
l = (l < precision ? l : precision);
Expand Down Expand Up @@ -1233,24 +1237,25 @@ static int _vsnprintf(out_fct_type out, char* buffer, printf_size_t buffer_size,

int vprintf_(const char* format, va_list arg)
{
char buffer[1];
return _vsnprintf(&out_putchar, buffer, (printf_size_t)-1, format, arg);
char buffer[1]; // will not be used
return _vsnprintf(&out_putchar, buffer, PRINTF_MAX_POSSIBLE_BUFFER_SIZE, format, arg);
}

int vsprintf_(char* s, const char* format, va_list arg)
{
return _vsnprintf(out_buffer, s, (printf_size_t)-1, format, arg);
return _vsnprintf(out_buffer, s, PRINTF_MAX_POSSIBLE_BUFFER_SIZE, format, arg);
}

int vsnprintf_(char* s, size_t n, const char* format, va_list arg)
{
return _vsnprintf(out_buffer, s, n, format, arg);
printf_size_t usable_buffer_size = (n > PRINTF_MAX_POSSIBLE_BUFFER_SIZE) ? PRINTF_MAX_POSSIBLE_BUFFER_SIZE : n;
return _vsnprintf(out_buffer, s, usable_buffer_size, format, arg);
}

int vfctprintf(void (*out)(char c, void* extra_arg), void* extra_arg, const char* format, va_list arg)
{
const out_function_wrapper_type out_fct_wrap = { out, extra_arg };
return _vsnprintf(out_wrapped_function, (char*)(uintptr_t)&out_fct_wrap, (printf_size_t)-1, format, arg);
const out_function_wrapper_type out_fct_wrap = {out, extra_arg };
return _vsnprintf(out_wrapped_function, (char*)(uintptr_t)&out_fct_wrap, PRINTF_MAX_POSSIBLE_BUFFER_SIZE, format, arg);
}

int printf_(const char* format, ...)
Expand Down

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