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common/snprintf.c: preserve wide integer values #3598

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91e180c
common/snprintf.c: preserve wide integer values
Aug 31, 2026
17548a3
common/snprintf.c: explain unsigned negation
Sep 1, 2026
9d8e1f6
common/snprintf.c: keep magnitudes unsigned
Sep 1, 2026
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164 changes: 128 additions & 36 deletions common/snprintf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -53,10 +53,16 @@

#include "config.h"

#include <limits.h>
#include <string.h>
#include <ctype.h>
#include <sys/types.h>

#ifdef TEST_SNPRINTF
extern int printf (const char *format, ...);
extern int sprintf (char *str, const char *format, ...);
#endif

#if !defined(HAVE_SNPRINTF) || !defined(HAVE_VSNPRINTF)

/* Define this as a fall through, HAVE_STDARG_H is probably already set */
Expand Down Expand Up @@ -112,7 +118,8 @@ static void dopr (char *buffer, size_t maxlen, const char *format,
static void fmtstr (char *buffer, size_t *currlen, size_t maxlen,
char *value, int flags, int min, int max);
static void fmtint (char *buffer, size_t *currlen, size_t maxlen,
long value, int base, int min, int max, int flags);
unsigned LLONG uvalue, int negative,
int base, int min, int max, int flags);
static void fmtfp (char *buffer, size_t *currlen, size_t maxlen,
LDOUBLE fvalue, int min, int max, int flags);
static void dopr_outch (char *buffer, size_t *currlen, size_t maxlen, char c );
Expand Down Expand Up @@ -169,6 +176,7 @@ static void dopr (char *buffer, size_t maxlen, const char *format, va_list args)
{
char ch;
LLONG value;
unsigned LLONG uvalue;
LDOUBLE fvalue;
char *strvalue;
int min;
Expand Down Expand Up @@ -307,39 +315,40 @@ static void dopr (char *buffer, size_t maxlen, const char *format, va_list args)
value = va_arg (args, LLONG);
else
value = va_arg (args, int);
fmtint (buffer, &currlen, maxlen, value, 10, min, max, flags);
fmtint (buffer, &currlen, maxlen, (unsigned LLONG)value,
(value < 0), 10, min, max, flags);
break;
case 'o':
flags |= DP_F_UNSIGNED;
if (cflags == DP_C_SHORT)
#ifdef C89PLUS
value = (unsigned short int)va_arg (args, unsigned int);
uvalue = (unsigned short int)va_arg (args, unsigned int);
#else
value = va_arg (args, unsigned short int);
uvalue = va_arg (args, unsigned short int);
#endif
else if (cflags == DP_C_LONG)
value = (long)va_arg (args, unsigned long int);
uvalue = va_arg (args, unsigned long int);
else if (cflags == DP_C_LLONG)
value = (long)va_arg (args, unsigned LLONG);
uvalue = va_arg (args, unsigned LLONG);
else
value = (long)va_arg (args, unsigned int);
fmtint (buffer, &currlen, maxlen, value, 8, min, max, flags);
uvalue = va_arg (args, unsigned int);
fmtint (buffer, &currlen, maxlen, uvalue, 0, 8, min, max, flags);
break;
case 'u':
flags |= DP_F_UNSIGNED;
if (cflags == DP_C_SHORT)
#ifdef C89PLUS
value = (unsigned short int)va_arg (args, unsigned int);
uvalue = (unsigned short int)va_arg (args, unsigned int);
#else
value = va_arg (args, unsigned short int);
uvalue = va_arg (args, unsigned short int);
#endif
else if (cflags == DP_C_LONG)
value = (long)va_arg (args, unsigned long int);
uvalue = va_arg (args, unsigned long int);
else if (cflags == DP_C_LLONG)
value = (LLONG)va_arg (args, unsigned LLONG);
uvalue = va_arg (args, unsigned LLONG);
else
value = (long)va_arg (args, unsigned int);
fmtint (buffer, &currlen, maxlen, value, 10, min, max, flags);
uvalue = va_arg (args, unsigned int);
fmtint (buffer, &currlen, maxlen, uvalue, 0, 10, min, max, flags);
break;
case 'X':
flags |= DP_F_UP;
Expand All @@ -349,17 +358,17 @@ static void dopr (char *buffer, size_t maxlen, const char *format, va_list args)
flags |= DP_F_UNSIGNED;
if (cflags == DP_C_SHORT)
#ifdef C89PLUS
value = (unsigned short int)va_arg (args, unsigned int);
uvalue = (unsigned short int)va_arg (args, unsigned int);
#else
value = va_arg (args, unsigned short int);
uvalue = va_arg (args, unsigned short int);
#endif
else if (cflags == DP_C_LONG)
value = (long)va_arg (args, unsigned long int);
uvalue = va_arg (args, unsigned long int);
else if (cflags == DP_C_LLONG)
value = (LLONG)va_arg (args, unsigned LLONG);
uvalue = va_arg (args, unsigned LLONG);
else
value = (long)va_arg (args, unsigned int);
fmtint (buffer, &currlen, maxlen, value, 16, min, max, flags);
uvalue = va_arg (args, unsigned int);
fmtint (buffer, &currlen, maxlen, uvalue, 0, 16, min, max, flags);
break;
case 'f':
if (cflags == DP_C_LDOUBLE)
Expand Down Expand Up @@ -400,13 +409,9 @@ static void dopr (char *buffer, size_t maxlen, const char *format, va_list args)
break;
case 'p':
strvalue = va_arg (args, void *);
/* FIXME: in 64-bit (and Windows-targeted) builds this code yields:
* warning: cast from pointer to integer of different size
* so probably prints a truncated pointer value. Should check
* if sizeof(void*) == sizeof(long) and output e.g. two pieces
* (lower and upper long for bytes of the pointer).
*/
fmtint (buffer, &currlen, maxlen, (long) strvalue, 16, min, max, flags);
flags |= DP_F_UNSIGNED;
fmtint (buffer, &currlen, maxlen,
(unsigned LLONG)(size_t) strvalue, 0, 16, min, max, flags);
break;
case 'n':
if (cflags == DP_C_SHORT)
Expand Down Expand Up @@ -503,11 +508,11 @@ static void fmtstr (char *buffer, size_t *currlen, size_t maxlen,
/* Have to handle DP_F_NUM (ie 0x and 0 alternates) */

static void fmtint (char *buffer, size_t *currlen, size_t maxlen,
long value, int base, int min, int max, int flags)
unsigned LLONG uvalue, int negative,
int base, int min, int max, int flags)
{
int signvalue = 0;
unsigned long uvalue;
char convert[20];
char convert[sizeof(uvalue) * CHAR_BIT + 1];
int place = 0;
int spadlen = 0; /* amount to space pad */
int zpadlen = 0; /* amount to zero pad */
Expand All @@ -516,13 +521,14 @@ static void fmtint (char *buffer, size_t *currlen, size_t maxlen,
if (max < 0)
max = 0;

uvalue = value;

if(!(flags & DP_F_UNSIGNED))
{
if( value < 0 ) {
if( negative ) {
signvalue = '-';
uvalue = -value;
/* uvalue holds the signed argument converted to unsigned
* (defined modulo arithmetic); unsigned negation yields its
* magnitude without overflow, even for LLONG_MIN. */
uvalue = -uvalue;
Comment thread
jimklimov marked this conversation as resolved.
}
else
if (flags & DP_F_PLUS) /* Do a sign (+/i) */
Expand All @@ -539,8 +545,7 @@ static void fmtint (char *buffer, size_t *currlen, size_t maxlen,
(caps? "0123456789ABCDEF":"0123456789abcdef")
[uvalue % (unsigned)base ];
uvalue = (uvalue / (unsigned)base );
} while(uvalue && (place < 20));
if (place == 20) place--;
} while(uvalue && (place < (int)(sizeof(convert) - 1)));
convert[place] = 0;

zpadlen = max - place;
Expand Down Expand Up @@ -942,6 +947,18 @@ static void dopr_outch (char *buffer, size_t *currlen, size_t maxlen, char c)
NULL
};
long int_nums[] = { -1, 134, 91340, 341, 0203, 0};
static int pointer_num;
#ifdef HAVE_LONG_LONG_INT
LLONG llong_nums[] = { ((LLONG)1 << 32) + 1, LLONG_MIN };
char *ullong_fmt[] = { "%llu", "%llx", "%llo", NULL };
unsigned LLONG ullong_nums[] = {
ULLONG_MAX,
(unsigned LLONG)1 << (sizeof(unsigned LLONG) * CHAR_BIT - 1),
ULLONG_MAX
};
#endif
char *ptr1;
char *ptr2;
int x, y;
int fail = 0;
int num = 0;
Expand Down Expand Up @@ -975,6 +992,81 @@ static void dopr_outch (char *buffer, size_t *currlen, size_t maxlen, char c)
}
num++;
}

snprintf (buf1, sizeof (buf1), "%u", UINT_MAX);
sprintf (buf2, "%u", UINT_MAX);
if (strcmp (buf1, buf2))
{
printf("snprintf doesn't match Format: %%u\n\tsnprintf = %s\n\tsprintf = %s\n",
buf1, buf2);
fail++;
}
num++;

snprintf (buf1, sizeof (buf1), "%lu", ULONG_MAX);
sprintf (buf2, "%lu", ULONG_MAX);
if (strcmp (buf1, buf2))
{
printf("snprintf doesn't match Format: %%lu\n\tsnprintf = %s\n\tsprintf = %s\n",
buf1, buf2);
fail++;
}
num++;

snprintf (buf1, sizeof (buf1), "%p", (void *)&pointer_num);
sprintf (buf2, "%p", (void *)&pointer_num);
ptr1 = buf1;
ptr2 = buf2;
if (ptr1[0] == '0' && (ptr1[1] == 'x' || ptr1[1] == 'X'))
ptr1 += 2;
if (ptr2[0] == '0' && (ptr2[1] == 'x' || ptr2[1] == 'X'))
ptr2 += 2;
while (ptr1[0] == '0' && ptr1[1] != '\0')
ptr1++;
while (ptr2[0] == '0' && ptr2[1] != '\0')
ptr2++;
while (*ptr1 && *ptr2
&& tolower ((unsigned char)*ptr1) == tolower ((unsigned char)*ptr2))
{
ptr1++;
ptr2++;
}
if (*ptr1 || *ptr2)
{
printf("snprintf doesn't match Format: %%p\n\tsnprintf = %s\n\tsprintf = %s\n",
buf1, buf2);
fail++;
}
num++;

#ifdef HAVE_LONG_LONG_INT
for (x = 0; x < 2; x++)
{
snprintf (buf1, sizeof (buf1), "%lld", llong_nums[x]);
sprintf (buf2, "%lld", llong_nums[x]);
if (strcmp (buf1, buf2))
{
printf("snprintf doesn't match Format: %%lld\n\tsnprintf = %s\n\tsprintf = %s\n",
buf1, buf2);
fail++;
}
num++;
}

for (x = 0; ullong_fmt[x] != NULL; x++)
{
snprintf (buf1, sizeof (buf1), ullong_fmt[x], ullong_nums[x]);
sprintf (buf2, ullong_fmt[x], ullong_nums[x]);
if (strcmp (buf1, buf2))
{
printf("snprintf doesn't match Format: %s\n\tsnprintf = %s\n\tsprintf = %s\n",
ullong_fmt[x], buf1, buf2);
fail++;
}
num++;
}
#endif
printf ("%d tests failed out of %d.\n", fail, num);
return fail;
}
#endif /* SNPRINTF_TEST */
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