提交 33413cdd 编写于 作者: R Rich Felker

simplify strftime and fix integer overflows

use a long long value so that even with offsets, values cannot
overflow. instead of using different format strings for different
numeric formats, simply use a per-format width and %0*lld for all of
them.

this width specifier is not for use with strftime field widths; that
will be a separate step in the caller.
上级 87e133b3
...@@ -6,8 +6,6 @@ ...@@ -6,8 +6,6 @@
#include <limits.h> #include <limits.h>
#include "libc.h" #include "libc.h"
// FIXME: integer overflows
const char *__nl_langinfo_l(nl_item, locale_t); const char *__nl_langinfo_l(nl_item, locale_t);
static int is_leap(int y) static int is_leap(int y)
...@@ -49,8 +47,9 @@ size_t __strftime_l(char *restrict, size_t, const char *restrict, const struct t ...@@ -49,8 +47,9 @@ size_t __strftime_l(char *restrict, size_t, const char *restrict, const struct t
const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *tm, locale_t loc) const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *tm, locale_t loc)
{ {
nl_item item; nl_item item;
int val; long long val;
const char *fmt; const char *fmt;
int width = 2;
switch (f) { switch (f) {
case 'a': case 'a':
...@@ -70,55 +69,45 @@ const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm * ...@@ -70,55 +69,45 @@ const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *
item = D_T_FMT; item = D_T_FMT;
goto nl_strftime; goto nl_strftime;
case 'C': case 'C':
val = (1900+tm->tm_year) / 100; val = (1900LL+tm->tm_year) / 100;
fmt = "%02d";
goto number; goto number;
case 'd': case 'd':
val = tm->tm_mday; val = tm->tm_mday;
fmt = "%02d";
goto number; goto number;
case 'D': case 'D':
fmt = "%m/%d/%y"; fmt = "%m/%d/%y";
goto recu_strftime; goto recu_strftime;
case 'e': case 'e':
val = tm->tm_mday; val = tm->tm_mday;
fmt = "%2d";
goto number; goto number;
case 'F': case 'F':
fmt = "%Y-%m-%d"; fmt = "%Y-%m-%d";
goto recu_strftime; goto recu_strftime;
case 'g': case 'g':
case 'G': case 'G':
fmt = "%04d"; val = tm->tm_year + 1900LL;
val = tm->tm_year + 1900;
if (tm->tm_yday < 3 && week_num(tm) != 1) val--; if (tm->tm_yday < 3 && week_num(tm) != 1) val--;
else if (tm->tm_yday > 360 && week_num(tm) == 1) val++; else if (tm->tm_yday > 360 && week_num(tm) == 1) val++;
if (f=='g') { if (f=='g') val %= 100;
fmt = "%02d"; else width = 4;
val %= 100;
}
goto number; goto number;
case 'H': case 'H':
val = tm->tm_hour; val = tm->tm_hour;
fmt = "%02d";
goto number; goto number;
case 'I': case 'I':
val = tm->tm_hour; val = tm->tm_hour;
if (!val) val = 12; if (!val) val = 12;
else if (val > 12) val -= 12; else if (val > 12) val -= 12;
fmt = "%02d";
goto number; goto number;
case 'j': case 'j':
val = tm->tm_yday+1; val = tm->tm_yday+1;
fmt = "%03d"; width = 3;
goto number; goto number;
case 'm': case 'm':
val = tm->tm_mon+1; val = tm->tm_mon+1;
fmt = "%02d";
goto number; goto number;
case 'M': case 'M':
val = tm->tm_min; val = tm->tm_min;
fmt = "%02d";
goto number; goto number;
case 'n': case 'n':
*l = 1; *l = 1;
...@@ -134,7 +123,6 @@ const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm * ...@@ -134,7 +123,6 @@ const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *
goto recu_strftime; goto recu_strftime;
case 'S': case 'S':
val = tm->tm_sec; val = tm->tm_sec;
fmt = "%02d";
goto number; goto number;
case 't': case 't':
*l = 1; *l = 1;
...@@ -144,23 +132,20 @@ const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm * ...@@ -144,23 +132,20 @@ const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *
goto recu_strftime; goto recu_strftime;
case 'u': case 'u':
val = tm->tm_wday ? tm->tm_wday : 7; val = tm->tm_wday ? tm->tm_wday : 7;
fmt = "%d"; width = 1;
goto number; goto number;
case 'U': case 'U':
val = (tm->tm_yday + 7 - tm->tm_wday) / 7; val = (tm->tm_yday + 7 - tm->tm_wday) / 7;
fmt = "%02d";
goto number; goto number;
case 'W': case 'W':
val = (tm->tm_yday + 7 - (tm->tm_wday+6)%7) / 7; val = (tm->tm_yday + 7 - (tm->tm_wday+6)%7) / 7;
fmt = "%02d";
goto number; goto number;
case 'V': case 'V':
val = week_num(tm); val = week_num(tm);
fmt = "%02d";
goto number; goto number;
case 'w': case 'w':
val = tm->tm_wday; val = tm->tm_wday;
fmt = "%d"; width = 1;
goto number; goto number;
case 'x': case 'x':
item = D_FMT; item = D_FMT;
...@@ -170,11 +155,10 @@ const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm * ...@@ -170,11 +155,10 @@ const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *
goto nl_strftime; goto nl_strftime;
case 'y': case 'y':
val = tm->tm_year % 100; val = tm->tm_year % 100;
fmt = "%02d";
goto number; goto number;
case 'Y': case 'Y':
val = tm->tm_year + 1900; val = tm->tm_year + 1900LL;
fmt = "%04d"; width = 4;
goto number; goto number;
case 'z': case 'z':
val = -tm->__tm_gmtoff; val = -tm->__tm_gmtoff;
...@@ -190,7 +174,7 @@ const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm * ...@@ -190,7 +174,7 @@ const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *
return 0; return 0;
} }
number: number:
*l = snprintf(*s, sizeof *s, fmt, val); *l = snprintf(*s, sizeof *s, "%0*lld", width, val);
return *s; return *s;
nl_strcat: nl_strcat:
fmt = __nl_langinfo_l(item, loc); fmt = __nl_langinfo_l(item, loc);
......
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