#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <sys/mman.h>struct tar {
char name[100]; char _unused[24];
char size[12]; char _padding[376];
} *tar;int is_file_in_tar(struct tar *tar, char *name, char **start, int *length )
{
for( ; tar->name[0]; tar+=1+(*length+511)/512 )
{
sscanf(tar->size, "%o", length);
if( !strcmp(tar->name,name) ){ *start = (char*)(tar+1); return 1; }
}return 0;
}int main()
{
int fd=open("/mnt/hgfs/F/gif.tar", O_RDONLY );
tar=mmap(NULL, 9348608, PROT_READ, MAP_PRIVATE, fd, 0);char *start; int length;
char name[32];
for(int i=0;i<25;i++)
{
snprintf(name, sizeof(name), "gif/xoApQkbkFnCkrao-%d.bmp", i);
if( is_file_in_tar(tar,name,&start,&length) )
{
printf("%s.%d.%x\n", name, length, start);
}
}
}
编译指令:
gcc -o test test.c --std c99
运行结果:
bugfix@ubuntu:/$ ./test
gif/xoApQkbkFnCkrao-0.bmp.332986.4cd36400
gif/xoApQkbkFnCkrao-1.bmp.332986.4cd87c00
gif/xoApQkbkFnCkrao-2.bmp.332986.4d108400
gif/xoApQkbkFnCkrao-3.bmp.332986.4d3e5c00
gif/xoApQkbkFnCkrao-4.bmp.332986.4d437400
gif/xoApQkbkFnCkrao-5.bmp.332986.4d488c00
gif/xoApQkbkFnCkrao-6.bmp.332986.4d4da400
gif/xoApQkbkFnCkrao-7.bmp.332986.4d52bc00
gif/xoApQkbkFnCkrao-8.bmp.332986.4d57d400
gif/xoApQkbkFnCkrao-9.bmp.332986.4d5cec00
gif/xoApQkbkFnCkrao-10.bmp.332986.4cdd9400
gif/xoApQkbkFnCkrao-11.bmp.332986.4ce2ac00
gif/xoApQkbkFnCkrao-12.bmp.332986.4ce7c400
gif/xoApQkbkFnCkrao-13.bmp.332986.4cecdc00
gif/xoApQkbkFnCkrao-14.bmp.332986.4cf1f400
gif/xoApQkbkFnCkrao-15.bmp.332986.4cf70c00
gif/xoApQkbkFnCkrao-16.bmp.332986.4cfc2400
gif/xoApQkbkFnCkrao-17.bmp.332986.4d013c00
gif/xoApQkbkFnCkrao-18.bmp.332986.4d065400
gif/xoApQkbkFnCkrao-19.bmp.332986.4d0b6c00
gif/xoApQkbkFnCkrao-20.bmp.332986.4d159c00
gif/xoApQkbkFnCkrao-21.bmp.332986.4d1ab400
gif/xoApQkbkFnCkrao-22.bmp.332986.4d1fcc00
gif/xoApQkbkFnCkrao-23.bmp.332986.4d24e400
gif/xoApQkbkFnCkrao-24.bmp.332986.4d29fc00
离线
正准备把上面这段代码移到 u-boot 上去， 发现sscanf链接错误， 看来u-boot不能用标准C库了，得自己去实现一个，谷歌去找找。
离线
终于找到一个 http://blog.csdn.net/jiangdou88/article/details/46865797，
加到 lib/vsprintf.c 可以用上,
然后继续搜了一下， 应该是从Linux里面拷过来的: lib/vsprintf.c
离线
#define USHRT_MAX ((u16)(~0U))
#define SHRT_MAX ((s16)(USHRT_MAX>>1))
/**
* simple_strtoll - convert a string to a signed long long
* @cp: The start of the string
* @endp: A pointer to the end of the parsed string will be placed here
* @base: The number base to use
*/
long long simple_strtoll(const char *cp, char **endp, unsigned int base)
{
if (*cp == '-')
return -simple_strtoull(cp + 1, endp, base);
return simple_strtoull(cp, endp, base);
}
/* Convert a character to lower case */
__inline__ static char
_tolower (char c)
{
if ((c >= 'A') && (c <= 'Z'))
{
c = (c - 'A') + 'a';
}
return c;
}
/**
* vsscanf - Unformat a buffer into a list of arguments
* @buf: input buffer
* @fmt: format of buffer
* @args: arguments
*/
int vsscanf(const char *buf, const char *fmt, va_list args)
{
const char *str = buf;
char *next;
char digit;
int num = 0;
u8 qualifier;
u8 base;
s16 field_width;
char is_sign;
while (*fmt && *str) {
/* skip any white space in format */
/* white space in format matchs any amount of
* white space, including none, in the input.
*/
if (isspace(*fmt)) {
fmt = skip_spaces(++fmt);
str = skip_spaces(str);
}
/* anything that is not a conversion must match exactly */
if (*fmt != '%' && *fmt) {
if (*fmt++ != *str++)
break;
continue;
}
if (!*fmt)
break;
++fmt;
/* skip this conversion.
* advance both strings to next white space
*/
if (*fmt == '*') {
while (!isspace(*fmt) && *fmt != '%' && *fmt)
fmt++;
while (!isspace(*str) && *str)
str++;
continue;
}
/* get field width */
field_width = -1;
if (isdigit(*fmt))
field_width = skip_atoi(&fmt);
/* get conversion qualifier */
qualifier = -1;
if (*fmt == 'h' || _tolower(*fmt) == 'l' ||
_tolower(*fmt) == 'z') {
qualifier = *fmt++;
if (unlikely(qualifier == *fmt)) {
if (qualifier == 'h') {
qualifier = 'H';
fmt++;
} else if (qualifier == 'l') {
qualifier = 'L';
fmt++;
}
}
}
if (!*fmt || !*str)
break;
base = 10;
is_sign = 0;
switch (*fmt++) {
case 'c':
{
char *s = (char *)va_arg(args, char*);
if (field_width == -1)
field_width = 1;
do {
*s++ = *str++;
} while (--field_width > 0 && *str);
num++;
}
continue;
case 's':
{
char *s = (char *)va_arg(args, char *);
if (field_width == -1)
field_width = SHRT_MAX;
/* first, skip leading white space in buffer */
str = skip_spaces(str);
/* now copy until next white space */
while (*str && !isspace(*str) && field_width--)
*s++ = *str++;
*s = '\0';
num++;
}
continue;
case 'n':
/* return number of characters read so far */
{
int *i = (int *)va_arg(args, int*);
*i = str - buf;
}
continue;
case 'o':
base = 8;
break;
case 'x':
case 'X':
base = 16;
break;
case 'i':
base = 0;
case 'd':
is_sign = 1;
case 'u':
break;
case '%':
/* looking for '%' in str */
if (*str++ != '%')
return num;
continue;
default:
/* invalid format; stop here */
return num;
}
/* have some sort of integer conversion.
* first, skip white space in buffer.
*/
str = skip_spaces(str);
digit = *str;
if (is_sign && digit == '-')
digit = *(str + 1);
if (!digit
|| (base == 16 && !isxdigit(digit))
|| (base == 10 && !isdigit(digit))
|| (base == 8 && (!isdigit(digit) || digit > '7'))
|| (base == 0 && !isdigit(digit)))
break;
switch (qualifier) {
case 'H': /* that's 'hh' in format */
if (is_sign) {
signed char *s = (signed char *)va_arg(args, signed char *);
*s = (signed char)simple_strtol(str, &next, base);
} else {
unsigned char *s = (unsigned char *)va_arg(args, unsigned char *);
*s = (unsigned char)simple_strtoul(str, &next, base);
}
break;
case 'h':
if (is_sign) {
short *s = (short *)va_arg(args, short *);
*s = (short)simple_strtol(str, &next, base);
} else {
unsigned short *s = (unsigned short *)va_arg(args, unsigned short *);
*s = (unsigned short)simple_strtoul(str, &next, base);
}
break;
case 'l':
if (is_sign) {
long *l = (long *)va_arg(args, long *);
*l = simple_strtol(str, &next, base);
} else {
unsigned long *l = (unsigned long *)va_arg(args, unsigned long *);
*l = simple_strtoul(str, &next, base);
}
break;
case 'L':
if (is_sign) {
long long *l = (long long *)va_arg(args, long long *);
*l = simple_strtoll(str, &next, base);
} else {
unsigned long long *l = (unsigned long long *)va_arg(args, unsigned long long *);
*l = simple_strtoull(str, &next, base);
}
break;
case 'Z':
case 'z':
{
size_t *s = (size_t *)va_arg(args, size_t *);
*s = (size_t)simple_strtoul(str, &next, base);
}
break;
default:
if (is_sign) {
int *i = (int *)va_arg(args, int *);
*i = (int)simple_strtol(str, &next, base);
} else {
unsigned int *i = (unsigned int *)va_arg(args, unsigned int*);
*i = (unsigned int)simple_strtoul(str, &next, base);
}
break;
}
num++;
if (!next)
break;
str = next;
}
/*
* Now we've come all the way through so either the input string or the
* format ended. In the former case, there can be a %n at the current
* position in the format that needs to be filled.
*/
if (*fmt == '%' && *(fmt + 1) == 'n') {
int *p = (int *)va_arg(args, int *);
*p = str - buf;
}
return num;
}
/**
* sscanf - Unformat a buffer into a list of arguments
* @buf: input buffer
* @fmt: formatting of buffer
* @...: resulting arguments
*/
int sscanf(const char *buf, const char *fmt, ...)
{
va_list args;
int i;
va_start(args, fmt);
i = vsscanf(buf, fmt, args);
va_end(args);
return i;
}离线