Buffer Overflow implementing Custom String Manipulation Function in C
I've looked through the documentation and I'm still confused about Quick question that's been bugging me - I'm working with a buffer overflow when using my custom string concatenation function in C, and I'm not sure where I went wrong. The function is supposed to concatenate two strings into a dynamically allocated buffer, but when I run my program, it sometimes crashes with a segmentation fault. Here's the code for the function: ```c char *str_concat(const char *str1, const char *str2) { size_t len1 = strlen(str1); size_t len2 = strlen(str2); char *result = malloc(len1 + len2 + 1); // +1 for the null terminator if (result == NULL) { return NULL; // Memory allocation failed } strcpy(result, str1); strcat(result, str2); return result; } ``` I use it as follows: ```c int main() { char *first = "Hello"; char *second = " World!"; char *combined = str_concat(first, second); if (combined) { printf("%s\n", combined); free(combined); } else { printf("Memory allocation failed.\n"); } return 0; } ``` While testing, I noticed that if either `str1` or `str2` is very long, it crashes with a segmentation fault at runtime. I have checked the string lengths, and I am definitely allocating enough memory. However, I suspect there might be something wrong with how I'm using `strcpy` and `strcat`. I've tried using `strncpy` instead, but that only added to the confusion. Can anyone spot the question? Additionally, is there a more efficient way to handle string concatenation in C, as I have a large number of concatenations throughout my program? I'm compiling this on GCC version 11.2 on Ubuntu 22.04. For context: I'm using C on Linux. How would you solve this? I'm working on a API that needs to handle this. Any ideas what could be causing this?