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libc: add basic maximum field width support to sscanf

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Change-Id: Iba6d8af32435beccf9a77d801b0eaac91549bc89
This commit is contained in:
Skye 2026-05-03 11:17:12 +09:00
parent 51abd937d5
commit 25551180ba
1 changed files with 28 additions and 11 deletions
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39
firmware/libc/sscanf.c
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@ -1,3 +1,4 @@
#include <limits.h>
#include <stdarg.h> #include <stdarg.h>
#include <string.h> #include <string.h>
#include <stdbool.h> #include <stdbool.h>
@ -21,7 +22,8 @@ static inline bool my_isxdigit(char c)
static int parse_dec(int (*peek)(void *userp), static int parse_dec(int (*peek)(void *userp),
void (*pop)(void *userp), void (*pop)(void *userp),
void *userp, void *userp,
long *vp) long *vp,
int max_len)
{ {
long v = 0; long v = 0;
int n = 0; int n = 0;
@ -45,7 +47,7 @@ static int parse_dec(int (*peek)(void *userp),
(*pop)(userp); (*pop)(userp);
n++; n++;
ch = (*peek)(userp); ch = (*peek)(userp);
} while (my_isdigit(ch)); } while (my_isdigit(ch) && n < max_len);
*vp = minus ? -v : v; *vp = minus ? -v : v;
return n; return n;
@ -55,13 +57,14 @@ static int parse_chars(int (*peek)(void *userp),
void (*pop)(void *userp), void (*pop)(void *userp),
void *userp, void *userp,
char *vp, char *vp,
bool fake) bool fake,
int max_len)
{ {
int n = 0; int n = 0;
char *pt=vp; char *pt=vp;
while (!my_isspace((*peek)(userp))) while (!my_isspace((*peek)(userp)) && n < max_len)
{ {
if(fake==false) if(fake==false)
*(pt++) = (*peek)(userp); *(pt++) = (*peek)(userp);
@ -79,7 +82,8 @@ static int parse_chars(int (*peek)(void *userp),
static int parse_hex(int (*peek)(void *userp), static int parse_hex(int (*peek)(void *userp),
void (*pop)(void *userp), void (*pop)(void *userp),
void *userp, void *userp,
unsigned long *vp) unsigned long *vp,
int max_len)
{ {
unsigned long v = 0; unsigned long v = 0;
int n = 0; int n = 0;
@ -101,7 +105,7 @@ static int parse_hex(int (*peek)(void *userp),
(*pop)(userp); (*pop)(userp);
n++; n++;
ch = (*peek)(userp); ch = (*peek)(userp);
} while (my_isxdigit(ch)); } while (my_isxdigit(ch) && n < max_len);
*vp = v; *vp = v;
return n; return n;
@ -151,11 +155,24 @@ static int scan(int (*peek)(void *userp),
skip=false; skip=false;
} }
int max_len = 0;
while('0' <= ch && ch <= '9')
{
max_len *= 10;
max_len += ch - '0';
ch=*fmt++;
}
if (max_len == 0) {
max_len = INT_MAX;
}
switch (ch) switch (ch)
{ {
case 'x': case 'x':
n_chars += skip_spaces(peek, pop, userp); n_chars += skip_spaces(peek, pop, userp);
if ((r = parse_hex(peek, pop, userp, &ulval)) >= 0) if ((r = parse_hex(peek, pop, userp, &ulval, max_len)) >= 0)
{ {
if(skip==false) if(skip==false)
{ {
@ -169,7 +186,7 @@ static int scan(int (*peek)(void *userp),
break; break;
case 'd': case 'd':
n_chars += skip_spaces(peek, pop, userp); n_chars += skip_spaces(peek, pop, userp);
if ((r = parse_dec(peek, pop, userp, &lval)) >= 0) if ((r = parse_dec(peek, pop, userp, &lval, max_len)) >= 0)
{ {
if(skip==false) if(skip==false)
{ {
@ -194,7 +211,7 @@ static int scan(int (*peek)(void *userp),
switch (ch) switch (ch)
{ {
case 'x': case 'x':
if ((r = parse_hex(peek, pop, userp, &ulval)) >= 0) if ((r = parse_hex(peek, pop, userp, &ulval, max_len)) >= 0)
{ {
if(skip==false) if(skip==false)
{ {
@ -207,7 +224,7 @@ static int scan(int (*peek)(void *userp),
return n; return n;
break; break;
case 'd': case 'd':
if ((r = parse_dec(peek, pop, userp, &lval)) >= 0) if ((r = parse_dec(peek, pop, userp, &lval, max_len)) >= 0)
{ {
if(skip==false) if(skip==false)
{ {
@ -228,7 +245,7 @@ static int scan(int (*peek)(void *userp),
break; break;
case 's': case 's':
n_chars += skip_spaces(peek, pop, userp); n_chars += skip_spaces(peek, pop, userp);
n_chars += parse_chars(peek,pop, userp,skip?0:va_arg(ap, char *), skip ); n_chars += parse_chars(peek,pop, userp,skip?0:va_arg(ap, char *), skip, max_len);
if(skip==false) if(skip==false)
{ {
n++; n++;