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Fix String creation and concat issues (#4955)

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When a string is concatted to itself, the pointer to its c_str can change
due to realloc().  This would invalidate the passed-in pointer being
concatted, and cause a use-after-free error.  Special case this to avoid
the issue.  Now "a += a;" works properly.

Also use sprintf(%{l}d) instead of non-POSIX ltoa/itoa calls to construct a
string from a signed number (in base 10 only).  The non-posix versions don't
handle INT_MIN properly on either host_tests or on the ESP8266.
This commit is contained in:
Earle F. Philhower, III 2018-07-24 13:20:57 -07:00 committed by Develo
parent bde83e8ea2
commit ff74813d54
1 changed files with 29 additions and 6 deletions
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29
cores/esp8266/WString.cpp
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@ -75,7 +75,11 @@ String::String(unsigned char value, unsigned char base) {
String::String(int value, unsigned char base) {
init();
char buf[2 + 8 * sizeof(int)];
if (base == 10) {
sprintf(buf, "%d", value);
} else {
itoa(value, buf, base);
}
*this = buf;
}
@ -89,7 +93,11 @@ String::String(unsigned int value, unsigned char base) {
String::String(long value, unsigned char base) {
init();
char buf[2 + 8 * sizeof(long)];
if (base==10) {
sprintf(buf, "%ld", value);
} else {
ltoa(value, buf, base);
}
*this = buf;
}
@ -252,7 +260,22 @@ String & String::operator = (const __FlashStringHelper *pstr)
// /*********************************************/
unsigned char String::concat(const String &s) {
// Special case if we're concatting ourself (s += s;) since we may end up
// realloc'ing the buffer and moving s.buffer in the method called
if (&s == this) {
unsigned int newlen = 2 * len;
if (!s.buffer)
return 0;
if (s.len == 0)
return 1;
if (!reserve(newlen))
return 0;
memcpy(s.buffer + len, s.buffer, len);
len = newlen;
return 1;
} else {
return concat(s.buffer, s.len);
}
}
unsigned char String::concat(const char *cstr, unsigned int length) {
@ -283,13 +306,13 @@ unsigned char String::concat(char c) {
unsigned char String::concat(unsigned char num) {
char buf[1 + 3 * sizeof(unsigned char)];
itoa(num, buf, 10);
sprintf(buf, "%d", num);
return concat(buf, strlen(buf));
}
unsigned char String::concat(int num) {
char buf[2 + 3 * sizeof(int)];
itoa(num, buf, 10);
sprintf(buf, "%d", num);
return concat(buf, strlen(buf));
}
@ -301,7 +324,7 @@ unsigned char String::concat(unsigned int num) {
unsigned char String::concat(long num) {
char buf[2 + 3 * sizeof(long)];
ltoa(num, buf, 10);
sprintf(buf, "%ld", num);
return concat(buf, strlen(buf));
}