I am currently working on a project that includes some file I/O.
Due to it being cross platform I needed to account for different path separators and hence decided to create the following function to simplify the process of joining paths:
/** * @brief Joins two paths together. * * path = a + seperator + b +'\0' * * @param a First path. * @param b Second path. * * @return A pointer to the two paths combined. */char * join_paths(const char * a, const char * b){ const char separator[] = #ifdef _WIN32"\\"; #else"/"; #endif /* Get the sizes of all the strings to join. */ size_t a_len = strlen(a); size_t b_len = strlen(b); size_t s_len = strlen(separator); size_t total_len = a_len + b_len + s_len + 1; /* +1 for \0 */ /* path will contain a, b, the separator and \0 hence the total length is total_len. */ char * path = malloc(total_len); check( path != NULL,"Error allocating memory for path. " ); memcpy(path, a, a_len); /* path will begin with a */ strncat(path, separator, s_len); /* copy separator */ strncat(path, b, b_len); /* copy b */error: return path;}(Where check is a macro from here: http://pastebin.com/2mZxSX3S)
Which had been working fine until now, when I had to use GDB to debug something not related to file I/O and realized that all my file paths seemed to be corrupt (e.g. "¡║¯½½½½½½½½■¯■¯■¯■").
Also I got the error message:
"Free heap block modified after it was freed"
After further investigation I realized this all happens after the memcpy in join_paths.
However this all seems to only happen when running it from GDB. What is going wrong here?
