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Fix crash when using String::move on empty string (#10938) #10945

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merged 1 commit into from
Feb 13, 2025
+21 −33
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Fix crash when using String::move on empty string (#10938) #10945

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54 changes: 21 additions & 33 deletions cores/esp32/WString.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -226,11 +226,11 @@ bool String::changeBuffer(unsigned int maxStrLen) {
/*********************************************/

String &String::copy(const char *cstr, unsigned int length) {
if (!reserve(length)) {
if (cstr == nullptr || !reserve(length)) {
invalidate();
return *this;
}
memmove(wbuffer(), cstr, length + 1);
memmove(wbuffer(), cstr, length);
setLen(length);
return *this;
}
Expand All @@ -239,15 +239,18 @@ String &String::copy(const char *cstr, unsigned int length) {
void String::move(String &rhs) {
if (buffer()) {
if (capacity() >= rhs.len()) {
memmove(wbuffer(), rhs.buffer(), rhs.length() + 1);
// Use case: When 'reserve()' was called and the first
// assignment/append is the return value of a function.
if (rhs.len() && rhs.buffer()) {
memmove(wbuffer(), rhs.buffer(), rhs.length());
}
setLen(rhs.len());
rhs.invalidate();
return;
} else {
if (!isSSO()) {
free(wbuffer());
setBuffer(nullptr);
}
}
if (!isSSO()) {
free(wbuffer());
setBuffer(nullptr);
}
}
if (rhs.isSSO()) {
Expand All @@ -259,23 +262,15 @@ void String::move(String &rhs) {
}
setCapacity(rhs.capacity());
setLen(rhs.len());
rhs.setSSO(false);
rhs.setCapacity(0);
rhs.setBuffer(nullptr);
rhs.setLen(0);
rhs.init();
}
#endif

String &String::operator=(const String &rhs) {
if (this == &rhs) {
return *this;
}
if (rhs.buffer()) {
copy(rhs.buffer(), rhs.len());
} else {
invalidate();
}
return *this;
return copy(rhs.buffer(), rhs.len());
}

#ifdef __GXX_EXPERIMENTAL_CXX0X__
Expand All @@ -295,12 +290,7 @@ String &String::operator=(StringSumHelper &&rval) {
#endif

String &String::operator=(const char *cstr) {
if (cstr) {
copy(cstr, strlen(cstr));
} else {
invalidate();
}
return *this;
return copy(cstr, strlen(cstr));
}

/*********************************************/
Expand All @@ -311,23 +301,21 @@ bool 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 false;
}
if (s.len() == 0) {
return true;
}
if (!s.buffer()) {
return false;
}
unsigned int newlen = 2 * len();
if (!reserve(newlen)) {
return false;
}
memmove(wbuffer() + len(), buffer(), len());
setLen(newlen);
wbuffer()[len()] = 0;
return true;
} else {
return concat(s.buffer(), s.len());
}
return concat(s.buffer(), s.len());
}

bool String::concat(const char *cstr, unsigned int length) {
Expand All @@ -343,10 +331,10 @@ bool String::concat(const char *cstr, unsigned int length) {
}
if (cstr >= wbuffer() && cstr < wbuffer() + len()) {
// compatible with SSO in ram #6155 (case "x += x.c_str()")
memmove(wbuffer() + len(), cstr, length + 1);
memmove(wbuffer() + len(), cstr, length);
} else {
// compatible with source in flash #6367
memcpy_P(wbuffer() + len(), cstr, length + 1);
memcpy_P(wbuffer() + len(), cstr, length);
}
setLen(newlen);
return true;
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