OK so this function htmlspecialchars has a variable new which is supposed to hold the size update after a character is escaped. Is it just me or does saying strlen(entity) increase it forgetting that the escaped character is already counted in old?
1 Answer
Since you asked: it's just you. It's not forgetting the escaped character, it's using that already-allocated space. A string needs to be allocated such that there is room for the null terminator. In the example where s = "&": new = strlen(s) = 1; strlen("&") = 5; so t is malloc'd for 6. Which is how much memory is required for a string of length 5.
answered Jun 9, 2016 at 16:40
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wait a sec... so I took a second look and now am wondering from your example, if Ur appending a new string, it means this time, a \0 exists already... could you please clarify? Jun 13, 2016 at 1:22
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man strcat says :
The strcat() function appends the src string to the dest string, overwriting the terminating null byte ('\0') at the end of dest, and then adds a terminating null byte.Jun 13, 2016 at 12:11 -
exactly my point... if it's being overwritten, what's the point of allocating that extra+1 space as in Ur example earlier Jun 14, 2016 at 4:04
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1I should have said
new + strlen(entity) + 1 - 1in the previous comment. new is the length of t. We are adding strlen(entity) chars, sonew = new + strlen(entity). But one of those chars is already included, sonew = new + strlen(entity) - 1. Finally, the realloc must allocate for the null byte sonew = new + strlen(entity) - 1 + 1. -1 + 1 is a wash, so it is correct to reallocate t for new + strlen(entity). Jun 14, 2016 at 17:41