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Make the date parsing accept pretty much any random crap.
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This date parser turns line-noise into a date. Cool.
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Linus Torvalds committed Apr 30, 2005
1 parent 3a6a23e commit 8996702
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Showing 3 changed files with 238 additions and 106 deletions.
3 changes: 3 additions & 0 deletions Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,9 @@ CFLAGS += '-DSHA1_HEADER=$(SHA1_HEADER)'
$(LIB_FILE): $(LIB_OBJS)
$(AR) rcs $@ $(LIB_OBJS)

test-date: test-date.c date.o
$(CC) $(CFLAGS) -o $@ test-date.c date.o

git-%: %.c $(LIB_FILE)
$(CC) $(CFLAGS) -o $@ $(filter %.c,$^) $(LIBS)

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321 changes: 215 additions & 106 deletions date.c
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Original file line number Diff line number Diff line change
Expand Up @@ -30,144 +30,253 @@ static time_t my_mktime(struct tm *tm)
}

static const char *month_names[] = {
"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
"January", "February", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December"
};

static const char *weekday_names[] = {
"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
};

/*
* Check these. And note how it doesn't do the summer-time conversion.
*
* In my world, it's always summer, and things are probably a bit off
* in other ways too.
*/
static const struct {
const char *name;
int offset;
} timezone_names[] = {
{ "IDLW", -12 }, /* International Date Line West */
{ "NT", -11 }, /* Nome */
{ "CAT", -10 }, /* Central Alaska */
{ "HST", -10 }, /* Hawaii Standard */
{ "HDT", -9 }, /* Hawaii Daylight */
{ "YDT", -8 }, /* Yukon Daylight */
{ "YST", -9 }, /* Yukon Standard */
{ "PST", -8 }, /* Pacific Standard */
{ "PDT", -7 }, /* Pacific Daylight */
{ "MST", -7 }, /* Mountain Standard */
{ "MDT", -6 }, /* Mountain Daylight */
{ "CST", -6 }, /* Central Standard */
{ "CDT", -5 }, /* Central Daylight */
{ "EST", -5 }, /* Eastern Standard */
{ "EDT", -4 }, /* Eastern Daylight */
{ "AST", -3 }, /* Atlantic Standard */
{ "ADT", -2 }, /* Atlantic Daylight */
{ "WAT", -1 }, /* West Africa */

{ "GMT", 0 }, /* Greenwich Mean */
{ "UTC", 0 }, /* Universal (Coordinated) */

{ "WET", 0 }, /* Western European */
{ "BST", 0 }, /* British Summer */
{ "CET", +1 }, /* Central European */
{ "MET", +1 }, /* Middle European */
{ "MEWT", +1 }, /* Middle European Winter */
{ "MEST", +2 }, /* Middle European Summer */
{ "CEST", +2 }, /* Central European Summer */
{ "MESZ", +1 }, /* Middle European Summer */
{ "FWT", +1 }, /* French Winter */
{ "FST", +2 }, /* French Summer */
{ "EET", +2 }, /* Eastern Europe, USSR Zone 1 */
{ "WAST", +7 }, /* West Australian Standard */
{ "WADT", +8 }, /* West Australian Daylight */
{ "CCT", +8 }, /* China Coast, USSR Zone 7 */
{ "JST", +9 }, /* Japan Standard, USSR Zone 8 */
{ "EAST", +10 }, /* Eastern Australian Standard */
{ "EADT", +11 }, /* Eastern Australian Daylight */
{ "GST", +10 }, /* Guam Standard, USSR Zone 9 */
{ "NZT", +11 }, /* New Zealand */
{ "NZST", +11 }, /* New Zealand Standard */
{ "NZDT", +12 }, /* New Zealand Daylight */
{ "IDLE", +12 }, /* International Date Line East */
};

static char *skipfws(char *str)
#define NR_TZ (sizeof(timezone_names) / sizeof(timezone_names[0]))

static int match_string(const char *date, const char *str)
{
while (isspace(*str))
str++;
return str;
int i = 0;

for (i = 0; *date; date++, str++, i++) {
if (*date == *str)
continue;
if (toupper(*date) == toupper(*str))
continue;
if (!isalnum(*date))
break;
return 0;
}
return i;
}

/* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
(i.e. English) day/month names, and it doesn't work correctly with %z. */
void parse_date(char *date, char *result, int maxlen)
/*
* Parse month, weekday, or timezone name
*/
static int match_alpha(const char *date, struct tm *tm, int *offset)
{
struct tm tm;
char *p, *tz;
int i, offset;
time_t then;
int i;

memset(&tm, 0, sizeof(tm));

/* Skip day-name */
p = skipfws(date);
if (!isdigit(*p)) {
for (i=0; i<7; i++) {
if (!strncmp(p,weekday_names[i],3) && p[3] == ',') {
p = skipfws(p+4);
goto day;
}
for (i = 0; i < 12; i++) {
int match = match_string(date, month_names[i]);
if (match >= 3) {
tm->tm_mon = i;
return match;
}
return;
}

/* day */
day:
tm.tm_mday = strtoul(p, &p, 10);

if (tm.tm_mday < 1 || tm.tm_mday > 31)
return;

if (!isspace(*p))
return;

p = skipfws(p);
}

/* month */
for (i = 0; i < 7; i++) {
int match = match_string(date, weekday_names[i]);
if (match >= 3) {
tm->tm_wday = i;
return match;
}
}

for (i=0; i<12; i++) {
if (!strncmp(p, month_names[i], 3) && isspace(p[3])) {
tm.tm_mon = i;
p = skipfws(p+strlen(month_names[i]));
goto year;
for (i = 0; i < NR_TZ; i++) {
int match = match_string(date, timezone_names[i].name);
if (match >= 3) {
*offset = 60*timezone_names[i].offset;
return match;
}
}
return; /* Error -- bad month */

/* year */
year:
tm.tm_year = strtoul(p, &p, 10);
/* BAD CRAP */
return 0;
}

if (!tm.tm_year && !isspace(*p))
return;
static int match_digit(char *date, struct tm *tm, int *offset)
{
char *end, c;
unsigned long num, num2, num3;

num = strtoul(date, &end, 10);

/* Time? num:num[:num] */
if (num < 24 && end[0] == ':' && isdigit(end[1])) {
tm->tm_hour = num;
num = strtoul(end+1, &end, 10);
if (num < 60) {
tm->tm_min = num;
if (end[0] == ':' && isdigit(end[1])) {
num = strtoul(end+1, &end, 10);
if (num < 61)
tm->tm_sec = num;
}
}
return end - date;
}

if (tm.tm_year > 1900)
tm.tm_year -= 1900;
/* Year? Day of month? Numeric date-string?*/
c = *end;
switch (c) {
default:
if (num > 0 && num < 32) {
tm->tm_mday = num;
break;
}
if (num > 1900) {
tm->tm_year = num - 1900;
break;
}
if (num > 70) {
tm->tm_year = num;
break;
}
break;

case '-':
case '/':
if (num && num < 32 && isdigit(end[1])) {
num2 = strtoul(end+1, &end, 10);
if (!num2 || num2 > 31)
break;
if (num > 12) {
if (num2 > 12)
break;
num3 = num;
num = num2;
num2 = num3;
}
tm->tm_mon = num - 1;
tm->tm_mday = num2;
if (*end == c && isdigit(end[1])) {
num3 = strtoul(end, &end, 10);
if (num3 > 1900)
num3 -= 1900;
tm->tm_year = num3;
}
break;
}
}

p=skipfws(p);

/* hour */
if (!isdigit(*p))
return;
tm.tm_hour = strtoul(p, &p, 10);

if (tm.tm_hour > 23)
return;

if (*p != ':')
return; /* Error -- bad time */
p++;

/* minute */
if (!isdigit(*p))
return;
tm.tm_min = strtoul(p, &p, 10);

if (tm.tm_min > 59)
return;

if (*p != ':')
goto zone;
p++;

/* second */
if (!isdigit(*p))
return;
tm.tm_sec = strtoul(p, &p, 10);

if (tm.tm_sec > 60)
return;
return end - date;

}

zone:
if (!isspace(*p))
return;
static int match_tz(char *date, int *offp)
{
char *end;
int offset = strtoul(date+1, &end, 10);
int min, hour;

p = skipfws(p);
min = offset % 100;
hour = offset / 100;

if (*p == '-')
offset = -60;
else if (*p == '+')
offset = 60;
else
return;
offset = hour*60+min;
if (*date == '-')
offset = -offset;

if (!isdigit(p[1]) || !isdigit(p[2]) || !isdigit(p[3]) || !isdigit(p[4]))
return;
*offp = offset;
return end - date;
}

tz = p;
i = strtoul(p+1, NULL, 10);
offset *= ((i % 100) + ((i / 100) * 60));
/* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
(i.e. English) day/month names, and it doesn't work correctly with %z. */
void parse_date(char *date, char *result, int maxlen)
{
struct tm tm;
int offset;
time_t then;

p = skipfws(p + 5);
if (*p && *p != '(') /* trailing comment like (EDT) is ok */
return;
memset(&tm, 0, sizeof(tm));
tm.tm_year = -1;
tm.tm_mon = -1;
tm.tm_mday = -1;
offset = 0;

for (;;) {
int match = 0;
unsigned char c = *date;

/* Stop at end of string or newline */
if (!c || c == '\n')
break;

if (isalpha(c))
match = match_alpha(date, &tm, &offset);
else if (isdigit(c))
match = match_digit(date, &tm, &offset);
else if ((c == '-' || c == '+') && isdigit(date[1]))
match = match_tz(date, &offset);

if (!match) {
/* BAD CRAP */
match = 1;
}

date += match;
}

then = my_mktime(&tm); /* mktime uses local timezone */
if (then == -1)
return;

then -= offset;
then -= offset * 60;

snprintf(result, maxlen, "%lu %5.5s", then, tz);
snprintf(result, maxlen, "%lu %+03d%02d", then, offset/60, offset % 60);
}

void datestamp(char *buf, int bufsize)
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20 changes: 20 additions & 0 deletions test-date.c
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@@ -0,0 +1,20 @@
#include <stdio.h>
#include <time.h>

#include "cache.h"

int main(int argc, char **argv)
{
int i;

for (i = 1; i < argc; i++) {
char result[100];
time_t t;

memcpy(result, "bad", 4);
parse_date(argv[i], result, sizeof(result));
t = strtoul(result, NULL, 0);
printf("%s -> %s -> %s\n", argv[i], result, ctime(&t));
}
return 0;
}

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